Adding upstream version 1.12.0.upstream/1.12.0upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

75 files changed, 11901 insertions, 0 deletions

diff --git a/libnetdata/Makefile.am b/libnetdata/Makefile.am
new file mode 100644
index 0000000..d2710f0
--- /dev/null
+++ b/libnetdata/Makefile.am
@@ -0,0 +1,28 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
+
+SUBDIRS = \
+    adaptive_resortable_list \
+    avl \
+    buffer \
+    clocks \
+    config \
+    dictionary \
+    eval \
+    locks \
+    log \
+    popen \
+    procfile \
+    simple_pattern \
+    socket \
+    statistical \
+    storage_number \
+    threads \
+    url \
+    $(NULL)
+
+dist_noinst_DATA = \
+	README.md \
+	$(NULL)
diff --git a/libnetdata/README.md b/libnetdata/README.md
new file mode 100644
index 0000000..9892d67
--- /dev/null
+++ b/libnetdata/README.md
@@ -0,0 +1,8 @@
+# libnetdata
+
+`libnetdata` is a collection of library code that is used by all netdata `C` programs.
+
+
+
+
+[![analytics](https://www.google-analytics.com/collect?v=1&aip=1&t=pageview&_s=1&ds=github&dr=https%3A%2F%2Fgithub.com%2Fnetdata%2Fnetdata&dl=https%3A%2F%2Fmy-netdata.io%2Fgithub%2Flibnetdata%2FREADME&_u=MAC~&cid=5792dfd7-8dc4-476b-af31-da2fdb9f93d2&tid=UA-64295674-3)]()
diff --git a/libnetdata/adaptive_resortable_list/Makefile.am b/libnetdata/adaptive_resortable_list/Makefile.am
new file mode 100644
index 0000000..1cb69ed
--- /dev/null
+++ b/libnetdata/adaptive_resortable_list/Makefile.am
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
+
+
+dist_noinst_DATA = \
+	README.md \
+	$(NULL)
diff --git a/libnetdata/adaptive_resortable_list/README.md b/libnetdata/adaptive_resortable_list/README.md
new file mode 100644
index 0000000..ab0d7c5
--- /dev/null
+++ b/libnetdata/adaptive_resortable_list/README.md
@@ -0,0 +1,95 @@
+
+# Adaptive Re-sortable List (ARL)
+
+This library allows netdata to read a series of `name - value` pairs
+in the **fastest possible way**.
+
+ARLs are used all over netdata, as they are the most
+CPU utilization efficient way to process `/proc` files. They are used to
+process both vertical (csv like) and horizontal (one pair per line) `name - value` pairs.
+
+## How ARL works
+
+It maintains a linked list of all `NAME` (keywords), sorted in the
+order found in the data source. The linked list is kept
+sorted at all times - the data source may change at any time, the
+linked list will adapt at the next iteration.
+
+### Initialization
+
+During initialization (just once), the caller:
+
+- calls `arl_create()` to create the ARL
+
+- calls `arl_expect()` multiple times to register the expected keywords
+
+The library will call the `processor()` function (given to
+`arl_create()`), for each expected keyword found.
+The default `processor()` expects `dst` to be an `unsigned long long *`.
+
+Each `name` keyword may have a different `processor()` (by calling
+`arl_expect_custom()` instead of `arl_expect()`).
+
+### Data collection iterations
+
+For each iteration through the data source, the caller:
+
+- calls `arl_begin()` to initiate a data collection iteration.
+   This is to be called just ONCE every time the source is re-evaluated.
+
+- calls `arl_check()` for each entry read from the file.
+
+### Cleanup
+
+When the caller exits:
+
+- calls `arl_free()` to destroy this and free all memory.
+
+### Performance
+
+ARL maintains a list of `name` keywords found in the data source (even the ones
+that are not useful for data collection).
+
+If the data source maintains the same order on the `name-value` pairs, for each
+each call to `arl_check()` only an `strcmp()` is executed to verify the
+expected order has not changed, a counter is incremented and a pointer is changed.
+So, if the data source has 100 `name-value` pairs, and their order remains constant
+over time, 100 successful `strcmp()` are executed.
+
+In the unlikely event that an iteration sees the data source with a different order,
+for each out-of-order keyword, a full search of the remaining keywords is made. But
+this search uses 32bit hashes, not string comparisons, so it should also be fast. 
+
+When all expectations are satisfied (even in the middle of an iteration),
+the call to `arl_check()` will return 1, to signal the caller to stop the loop,
+saving valuable CPU resources for the rest of the data source. 
+
+In the following test we used alternative methods to process, **1M times**,
+a data source like `/proc/meminfo`, already tokenized, in memory,
+to extract the same number of expected metrics:
+
+test|code|string comparison|number parsing|duration
+:---:|:---:|:---:|:---:|:---:|
+1|if-else-if-else-if|`strcmp()`|`strtoull()`|4630.337 ms
+2|nested loops|inline `simple_hash()` and `strcmp()`|`strtoull()`|1597.481 ms
+3|nested loops|inline `simple_hash()` and `strcmp()`|`str2ull()`|923.523 ms
+4|if-else-if-else-if|inline `simple_hash()` and `strcmp()`|`strtoull()`| 854.574 ms
+5|if-else-if-else-if|statement expression `simple_hash()` and `strcmp()`|`strtoull()`|912.013 ms
+6|if-continue|inline `simple_hash()` and `strcmp()`|`strtoull()`|842.279 ms
+7|if-else-if-else-if|inline `simple_hash()` and `strcmp()`|`str2ull()`|602.837 ms
+8|ARL|ARL|`strtoull()`|350.360 ms
+9|ARL|ARL|`str2ull()`|157.237 ms
+
+Compared to unoptimized code (test No 1: 4.6sec):
+ 
+ - before ARL netdata was using test No **7** with hashing and a custom `str2ull()` to achieve 602ms.
+ - the current ARL implementation is test No **9** that needs only 157ms (29 times faster vs unoptimized code, about 4 times faster vs optimized code).
+
+[Check the source code of this test](../../tests/profile/benchmark-value-pairs.c).
+
+## Limitations
+
+Do not use ARL if the a name/keyword may appear more than once in the
+source data. 
+
+[![analytics](https://www.google-analytics.com/collect?v=1&aip=1&t=pageview&_s=1&ds=github&dr=https%3A%2F%2Fgithub.com%2Fnetdata%2Fnetdata&dl=https%3A%2F%2Fmy-netdata.io%2Fgithub%2Flibnetdata%2Fadaptive_resortable_list%2FREADME&_u=MAC~&cid=5792dfd7-8dc4-476b-af31-da2fdb9f93d2&tid=UA-64295674-3)]()
diff --git a/libnetdata/adaptive_resortable_list/adaptive_resortable_list.c b/libnetdata/adaptive_resortable_list/adaptive_resortable_list.c
new file mode 100644
index 0000000..7f4c6c5
--- /dev/null
+++ b/libnetdata/adaptive_resortable_list/adaptive_resortable_list.c
@@ -0,0 +1,280 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../libnetdata.h"
+
+// the default processor() of the ARL
+// can be overwritten at arl_create()
+inline void arl_callback_str2ull(const char *name, uint32_t hash, const char *value, void *dst) {
+    (void)name;
+    (void)hash;
+
+    register unsigned long long *d = dst;
+    *d = str2ull(value);
+    // fprintf(stderr, "name '%s' with hash %u and value '%s' is %llu\n", name, hash, value, *d);
+}
+
+inline void arl_callback_str2kernel_uint_t(const char *name, uint32_t hash, const char *value, void *dst) {
+    (void)name;
+    (void)hash;
+
+    register kernel_uint_t *d = dst;
+    *d = str2kernel_uint_t(value);
+    // fprintf(stderr, "name '%s' with hash %u and value '%s' is %llu\n", name, hash, value, (unsigned long long)*d);
+}
+
+inline void arl_callback_ssize_t(const char *name, uint32_t hash, const char *value, void *dst) {
+    (void)name;
+    (void)hash;
+
+    register ssize_t *d = dst;
+    *d = (ssize_t)str2ll(value, NULL);
+    // fprintf(stderr, "name '%s' with hash %u and value '%s' is %zd\n", name, hash, value, *d);
+}
+
+// create a new ARL
+ARL_BASE *arl_create(const char *name, void (*processor)(const char *, uint32_t, const char *, void *), size_t rechecks) {
+    ARL_BASE *base = callocz(1, sizeof(ARL_BASE));
+
+    base->name = strdupz(name);
+
+    if(!processor)
+        base->processor = arl_callback_str2ull;
+    else
+        base->processor = processor;
+
+    base->rechecks = rechecks;
+
+    return base;
+}
+
+void arl_free(ARL_BASE *arl_base) {
+    if(unlikely(!arl_base))
+        return;
+
+    while(arl_base->head) {
+        ARL_ENTRY *e = arl_base->head;
+        arl_base->head = e->next;
+
+        freez(e->name);
+#ifdef NETDATA_INTERNAL_CHECKS
+        memset(e, 0, sizeof(ARL_ENTRY));
+#endif
+        freez(e);
+    }
+
+    freez(arl_base->name);
+
+#ifdef NETDATA_INTERNAL_CHECKS
+    memset(arl_base, 0, sizeof(ARL_BASE));
+#endif
+
+    freez(arl_base);
+}
+
+void arl_begin(ARL_BASE *base) {
+
+#ifdef NETDATA_INTERNAL_CHECKS
+    if(likely(base->iteration > 10)) {
+        // do these checks after the ARL has been sorted
+
+        if(unlikely(base->relinkings > (base->expected + base->allocated)))
+            info("ARL '%s' has %zu relinkings with %zu expected and %zu allocated entries. Is the source changing so fast?"
+                 , base->name, base->relinkings, base->expected, base->allocated);
+
+        if(unlikely(base->slow > base->fast))
+            info("ARL '%s' has %zu fast searches and %zu slow searches. Is the source really changing so fast?"
+                 , base->name, base->fast, base->slow);
+
+        /*
+        if(unlikely(base->iteration % 60 == 0)) {
+            info("ARL '%s' statistics: iteration %zu, expected %zu, wanted %zu, allocated %zu, fred %zu, relinkings %zu, found %zu, added %zu, fast %zu, slow %zu"
+                 , base->name
+                 , base->iteration
+                 , base->expected
+                 , base->wanted
+                 , base->allocated
+                 , base->fred
+                 , base->relinkings
+                 , base->found
+                 , base->added
+                 , base->fast
+                 , base->slow
+            );
+            // for(e = base->head; e; e = e->next) fprintf(stderr, "%s ", e->name);
+            // fprintf(stderr, "\n");
+        }
+        */
+    }
+#endif
+
+    if(unlikely(base->iteration > 0 && (base->added || (base->iteration % base->rechecks) == 0))) {
+        int wanted_equals_expected = ((base->iteration % base->rechecks) == 0);
+
+        // fprintf(stderr, "\n\narl_begin() rechecking, added %zu, iteration %zu, rechecks %zu, wanted_equals_expected %d\n\n\n", base->added, base->iteration, base->rechecks, wanted_equals_expected);
+
+        base->added = 0;
+        base->wanted = (wanted_equals_expected)?base->expected:0;
+
+        ARL_ENTRY *e = base->head;
+        while(e) {
+            if(e->flags & ARL_ENTRY_FLAG_FOUND) {
+
+                // remove the found flag
+                e->flags &= ~ARL_ENTRY_FLAG_FOUND;
+
+                // count it in wanted
+                if(!wanted_equals_expected && e->flags & ARL_ENTRY_FLAG_EXPECTED)
+                    base->wanted++;
+
+            }
+            else if(e->flags & ARL_ENTRY_FLAG_DYNAMIC && !(base->head == e && !e->next)) { // not last entry
+                // we can remove this entry
+                // it is not found, and it was created because
+                // it was found in the source file
+
+                // remember the next one
+                ARL_ENTRY *t = e->next;
+
+                // remove it from the list
+                if(e->next) e->next->prev = e->prev;
+                if(e->prev) e->prev->next = e->next;
+                if(base->head == e) base->head = e->next;
+
+                // free it
+                freez(e->name);
+                freez(e);
+
+                // count it
+                base->fred++;
+
+                // continue
+                e = t;
+                continue;
+            }
+
+            e = e->next;
+        }
+    }
+
+    if(unlikely(!base->head)) {
+        // hm... no nodes at all in the list #1700
+        // add a fake one to prevent a crash
+        // this is better than checking for the existence of nodes all the time
+        arl_expect(base, "a-really-not-existing-source-keyword", NULL);
+    }
+
+    base->iteration++;
+    base->next_keyword = base->head;
+    base->found = 0;
+
+}
+
+// register an expected keyword to the ARL
+// together with its destination ( i.e. the output of the processor() )
+ARL_ENTRY *arl_expect_custom(ARL_BASE *base, const char *keyword, void (*processor)(const char *name, uint32_t hash, const char *value, void *dst), void *dst) {
+    ARL_ENTRY *e = callocz(1, sizeof(ARL_ENTRY));
+    e->name = strdupz(keyword);
+    e->hash = simple_hash(e->name);
+    e->processor = (processor)?processor:base->processor;
+    e->dst = dst;
+    e->flags = ARL_ENTRY_FLAG_EXPECTED;
+    e->prev = NULL;
+    e->next = base->head;
+
+    if(base->head) base->head->prev = e;
+    else base->next_keyword = e;
+
+    base->head = e;
+    base->expected++;
+    base->allocated++;
+
+    base->wanted = base->expected;
+
+    return e;
+}
+
+int arl_find_or_create_and_relink(ARL_BASE *base, const char *s, const char *value) {
+    ARL_ENTRY *e;
+
+    uint32_t hash = simple_hash(s);
+
+    // find if it already exists in the data
+    for(e = base->head; e ; e = e->next)
+        if(e->hash == hash && !strcmp(e->name, s))
+            break;
+
+#ifdef NETDATA_INTERNAL_CHECKS
+    if(unlikely(base->next_keyword && e == base->next_keyword))
+        fatal("Internal Error: e == base->last");
+#endif
+
+    if(e) {
+        // found it in the keywords
+
+        base->relinkings++;
+
+        // run the processor for it
+        if(unlikely(e->dst)) {
+            e->processor(e->name, hash, value, e->dst);
+            base->found++;
+        }
+
+        // unlink it - we will relink it below
+        if(e->next) e->next->prev = e->prev;
+        if(e->prev) e->prev->next = e->next;
+
+        // make sure the head is properly linked
+        if(base->head == e)
+            base->head = e->next;
+    }
+    else {
+        // not found
+
+        // create it
+        e = callocz(1, sizeof(ARL_ENTRY));
+        e->name = strdupz(s);
+        e->hash = hash;
+        e->flags = ARL_ENTRY_FLAG_DYNAMIC;
+
+        base->allocated++;
+        base->added++;
+    }
+
+#ifdef NETDATA_INTERNAL_CHECKS
+    if(unlikely(base->iteration % 60 == 0 && e->flags & ARL_ENTRY_FLAG_FOUND))
+        info("ARL '%s': entry '%s' is already found. Did you forget to call arl_begin()?", base->name, s);
+#endif
+
+    e->flags |= ARL_ENTRY_FLAG_FOUND;
+
+    // link it here
+    e->next = base->next_keyword;
+    if(base->next_keyword) {
+        e->prev = base->next_keyword->prev;
+        base->next_keyword->prev = e;
+
+        if(e->prev)
+            e->prev->next = e;
+
+        if(base->head == base->next_keyword)
+            base->head = e;
+    }
+    else {
+        e->prev = NULL;
+
+        if(!base->head)
+            base->head = e;
+    }
+
+    // prepare the next iteration
+    base->next_keyword = e->next;
+    if(unlikely(!base->next_keyword))
+        base->next_keyword = base->head;
+
+    if(unlikely(base->found == base->wanted)) {
+        // fprintf(stderr, "FOUND ALL WANTED 1: found = %zu, wanted = %zu, expected %zu\n", base->found, base->wanted, base->expected);
+        return 1;
+    }
+
+    return 0;
+}
diff --git a/libnetdata/adaptive_resortable_list/adaptive_resortable_list.h b/libnetdata/adaptive_resortable_list/adaptive_resortable_list.h
new file mode 100644
index 0000000..011ee73
--- /dev/null
+++ b/libnetdata/adaptive_resortable_list/adaptive_resortable_list.h
@@ -0,0 +1,138 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../libnetdata.h"
+
+#ifndef NETDATA_ADAPTIVE_RESORTABLE_LIST_H
+#define NETDATA_ADAPTIVE_RESORTABLE_LIST_H 1
+
+#define ARL_ENTRY_FLAG_FOUND    0x01    // the entry has been found in the source data
+#define ARL_ENTRY_FLAG_EXPECTED 0x02    // the entry is expected by the program
+#define ARL_ENTRY_FLAG_DYNAMIC  0x04    // the entry was dynamically allocated, from source data
+
+typedef struct arl_entry {
+    char *name;             // the keywords
+    uint32_t hash;          // the hash of the keyword
+
+    void *dst;              // the dst to pass to the processor
+
+    uint8_t flags;          // ARL_ENTRY_FLAG_*
+
+    // the processor to do the job
+    void (*processor)(const char *name, uint32_t hash, const char *value, void *dst);
+
+    // double linked list for fast re-linkings
+    struct arl_entry *prev, *next;
+} ARL_ENTRY;
+
+typedef struct arl_base {
+    char *name;
+
+    size_t iteration;   // incremented on each iteration (arl_begin())
+    size_t found;       // the number of expected keywords found in this iteration
+    size_t expected;    // the number of expected keywords
+    size_t wanted;      // the number of wanted keywords
+                        // i.e. the number of keywords found and expected
+
+    size_t relinkings;  // the number of relinkings we have made so far
+
+    size_t allocated;   // the number of keywords allocated
+    size_t fred;        // the number of keywords cleaned up
+
+    size_t rechecks;    // the number of iterations between re-checks of the
+                        // wanted number of keywords
+                        // this is only needed in cases where the source
+                        // is having less lines over time.
+
+    size_t added;       // it is non-zero if new keywords have been added
+                        // this is only needed to detect new lines have
+                        // been added to the file, over time.
+
+#ifdef NETDATA_INTERNAL_CHECKS
+    size_t fast;        // the number of times we have taken the fast path
+    size_t slow;        // the number of times we have taken the slow path
+#endif
+
+    // the processor to do the job
+    void (*processor)(const char *name, uint32_t hash, const char *value, void *dst);
+
+    // the linked list of the keywords
+    ARL_ENTRY *head;
+
+    // since we keep the list of keywords sorted (as found in the source data)
+    // this is next keyword that we expect to find in the source data.
+    ARL_ENTRY *next_keyword;
+} ARL_BASE;
+
+// create a new ARL
+extern ARL_BASE *arl_create(const char *name, void (*processor)(const char *, uint32_t, const char *, void *), size_t rechecks);
+
+// free an ARL
+extern void arl_free(ARL_BASE *arl_base);
+
+// register an expected keyword to the ARL
+// together with its destination ( i.e. the output of the processor() )
+extern ARL_ENTRY *arl_expect_custom(ARL_BASE *base, const char *keyword, void (*processor)(const char *name, uint32_t hash, const char *value, void *dst), void *dst);
+#define arl_expect(base, keyword, dst) arl_expect_custom(base, keyword, NULL, dst)
+
+// an internal call to complete the check() call
+extern int arl_find_or_create_and_relink(ARL_BASE *base, const char *s, const char *value);
+
+// begin an ARL iteration
+extern void arl_begin(ARL_BASE *base);
+
+extern void arl_callback_str2ull(const char *name, uint32_t hash, const char *value, void *dst);
+extern void arl_callback_str2kernel_uint_t(const char *name, uint32_t hash, const char *value, void *dst);
+extern void arl_callback_ssize_t(const char *name, uint32_t hash, const char *value, void *dst);
+
+// check a keyword against the ARL
+// this is to be called for each keyword read from source data
+// s = the keyword, as collected
+// src = the src data to be passed to the processor
+// it is defined in the header file in order to be inlined
+static inline int arl_check(ARL_BASE *base, const char *keyword, const char *value) {
+    ARL_ENTRY *e = base->next_keyword;
+
+#ifdef NETDATA_INTERNAL_CHECKS
+    if(unlikely((base->fast + base->slow) % (base->expected + base->allocated) == 0 && (base->fast + base->slow) > (base->expected + base->allocated) * base->iteration))
+        info("ARL '%s': Did you forget to call arl_begin()?", base->name);
+#endif
+
+    // it should be the first entry (pointed by base->next_keyword)
+    if(likely(!strcmp(keyword, e->name))) {
+        // it is
+
+#ifdef NETDATA_INTERNAL_CHECKS
+        base->fast++;
+#endif
+
+        e->flags |= ARL_ENTRY_FLAG_FOUND;
+
+        // execute the processor
+        if(unlikely(e->dst)) {
+            e->processor(e->name, e->hash, value, e->dst);
+            base->found++;
+        }
+
+        // be prepared for the next iteration
+        base->next_keyword = e->next;
+        if(unlikely(!base->next_keyword))
+            base->next_keyword = base->head;
+
+        // stop if we collected all the values for this iteration
+        if(unlikely(base->found == base->wanted)) {
+            // fprintf(stderr, "FOUND ALL WANTED 2: found = %zu, wanted = %zu, expected %zu\n", base->found, base->wanted, base->expected);
+            return 1;
+        }
+
+        return 0;
+    }
+
+#ifdef NETDATA_INTERNAL_CHECKS
+    base->slow++;
+#endif
+
+    // we read from source, a not-expected keyword
+    return arl_find_or_create_and_relink(base, keyword, value);
+}
+
+#endif //NETDATA_ADAPTIVE_RESORTABLE_LIST_H
diff --git a/libnetdata/avl/Makefile.am b/libnetdata/avl/Makefile.am
new file mode 100644
index 0000000..1cb69ed
--- /dev/null
+++ b/libnetdata/avl/Makefile.am
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
+
+
+dist_noinst_DATA = \
+	README.md \
+	$(NULL)
diff --git a/libnetdata/avl/README.md b/libnetdata/avl/README.md
new file mode 100644
index 0000000..c4c72ff
--- /dev/null
+++ b/libnetdata/avl/README.md
@@ -0,0 +1,12 @@
+# AVL
+
+AVL is a library indexing objects in B-Trees.
+
+`avl_insert()`, `avl_remove()` and `avl_search()` are adaptations
+of the AVL algorithm found in `libavl` v2.0.3, so that they do not
+use any memory allocations and their memory footprint is optimized
+(by eliminating non-necessary data members).
+
+In addition to the above, this version of AVL, provides versions using locks
+and traversal functions.
+[![analytics](https://www.google-analytics.com/collect?v=1&aip=1&t=pageview&_s=1&ds=github&dr=https%3A%2F%2Fgithub.com%2Fnetdata%2Fnetdata&dl=https%3A%2F%2Fmy-netdata.io%2Fgithub%2Flibnetdata%2Favl%2FREADME&_u=MAC~&cid=5792dfd7-8dc4-476b-af31-da2fdb9f93d2&tid=UA-64295674-3)]()
diff --git a/libnetdata/avl/avl.c b/libnetdata/avl/avl.c
new file mode 100644
index 0000000..c44bef3
--- /dev/null
+++ b/libnetdata/avl/avl.c
@@ -0,0 +1,404 @@
+// SPDX-License-Identifier: LGPL-3.0-or-later
+
+#include "../libnetdata.h"
+
+/* ------------------------------------------------------------------------- */
+/*
+ * avl_insert(), avl_remove() and avl_search()
+ * are adaptations (by Costa Tsaousis) of the AVL algorithm found in libavl
+ * v2.0.3, so that they do not use any memory allocations and their memory
+ * footprint is optimized (by eliminating non-necessary data members).
+ *
+ * libavl - library for manipulation of binary trees.
+ * Copyright (C) 1998, 1999, 2000, 2001, 2002, 2004 Free Software
+ * Foundation, Inc.
+*/
+
+
+/* Search |tree| for an item matching |item|, and return it if found.
+     Otherwise return |NULL|. */
+avl *avl_search(avl_tree *tree, avl *item) {
+    avl *p;
+
+    // assert (tree != NULL && item != NULL);
+
+    for (p = tree->root; p != NULL; ) {
+        int cmp = tree->compar(item, p);
+
+        if (cmp < 0)
+            p = p->avl_link[0];
+        else if (cmp > 0)
+            p = p->avl_link[1];
+        else /* |cmp == 0| */
+            return p;
+    }
+
+    return NULL;
+}
+
+/* Inserts |item| into |tree| and returns a pointer to |item|'s address.
+     If a duplicate item is found in the tree,
+     returns a pointer to the duplicate without inserting |item|.
+ */
+avl *avl_insert(avl_tree *tree, avl *item) {
+    avl *y, *z; /* Top node to update balance factor, and parent. */
+    avl *p, *q; /* Iterator, and parent. */
+    avl *n;     /* Newly inserted node. */
+    avl *w;     /* New root of rebalanced subtree. */
+    unsigned char dir; /* Direction to descend. */
+
+    unsigned char da[AVL_MAX_HEIGHT]; /* Cached comparison results. */
+    int k = 0;              /* Number of cached results. */
+
+    // assert(tree != NULL && item != NULL);
+
+    z = (avl *) &tree->root;
+    y = tree->root;
+    dir = 0;
+    for (q = z, p = y; p != NULL; q = p, p = p->avl_link[dir]) {
+        int cmp = tree->compar(item, p);
+        if (cmp == 0)
+            return p;
+
+        if (p->avl_balance != 0)
+            z = q, y = p, k = 0;
+        da[k++] = dir = (unsigned char)(cmp > 0);
+    }
+
+    n = q->avl_link[dir] = item;
+
+    // tree->avl_count++;
+    n->avl_link[0] = n->avl_link[1] = NULL;
+    n->avl_balance = 0;
+    if (y == NULL) return n;
+
+    for (p = y, k = 0; p != n; p = p->avl_link[da[k]], k++)
+        if (da[k] == 0)
+            p->avl_balance--;
+        else
+            p->avl_balance++;
+
+    if (y->avl_balance == -2) {
+        avl *x = y->avl_link[0];
+        if (x->avl_balance == -1) {
+            w = x;
+            y->avl_link[0] = x->avl_link[1];
+            x->avl_link[1] = y;
+            x->avl_balance = y->avl_balance = 0;
+        }
+        else {
+            // assert (x->avl_balance == +1);
+            w = x->avl_link[1];
+            x->avl_link[1] = w->avl_link[0];
+            w->avl_link[0] = x;
+            y->avl_link[0] = w->avl_link[1];
+            w->avl_link[1] = y;
+            if (w->avl_balance == -1)
+                x->avl_balance = 0, y->avl_balance = +1;
+            else if (w->avl_balance == 0)
+                x->avl_balance = y->avl_balance = 0;
+            else /* |w->avl_balance == +1| */
+                x->avl_balance = -1, y->avl_balance = 0;
+            w->avl_balance = 0;
+        }
+    }
+    else if (y->avl_balance == +2) {
+        avl *x = y->avl_link[1];
+        if (x->avl_balance == +1) {
+            w = x;
+            y->avl_link[1] = x->avl_link[0];
+            x->avl_link[0] = y;
+            x->avl_balance = y->avl_balance = 0;
+        }
+        else {
+            // assert (x->avl_balance == -1);
+            w = x->avl_link[0];
+            x->avl_link[0] = w->avl_link[1];
+            w->avl_link[1] = x;
+            y->avl_link[1] = w->avl_link[0];
+            w->avl_link[0] = y;
+            if (w->avl_balance == +1)
+                x->avl_balance = 0, y->avl_balance = -1;
+            else if (w->avl_balance == 0)
+                x->avl_balance = y->avl_balance = 0;
+            else /* |w->avl_balance == -1| */
+                x->avl_balance = +1, y->avl_balance = 0;
+            w->avl_balance = 0;
+        }
+    }
+    else return n;
+
+    z->avl_link[y != z->avl_link[0]] = w;
+
+    // tree->avl_generation++;
+    return n;
+}
+
+/* Deletes from |tree| and returns an item matching |item|.
+     Returns a null pointer if no matching item found. */
+avl *avl_remove(avl_tree *tree, avl *item) {
+    /* Stack of nodes. */
+    avl *pa[AVL_MAX_HEIGHT]; /* Nodes. */
+    unsigned char da[AVL_MAX_HEIGHT];    /* |avl_link[]| indexes. */
+    int k;                               /* Stack pointer. */
+
+    avl *p;   /* Traverses tree to find node to delete. */
+    int cmp;              /* Result of comparison between |item| and |p|. */
+
+    // assert (tree != NULL && item != NULL);
+
+    k = 0;
+    p = (avl *) &tree->root;
+    for(cmp = -1; cmp != 0; cmp = tree->compar(item, p)) {
+        unsigned char dir = (unsigned char)(cmp > 0);
+
+        pa[k] = p;
+        da[k++] = dir;
+
+        p = p->avl_link[dir];
+        if(p == NULL) return NULL;
+    }
+
+    item = p;
+
+    if (p->avl_link[1] == NULL)
+        pa[k - 1]->avl_link[da[k - 1]] = p->avl_link[0];
+    else {
+        avl *r = p->avl_link[1];
+        if (r->avl_link[0] == NULL) {
+            r->avl_link[0] = p->avl_link[0];
+            r->avl_balance = p->avl_balance;
+            pa[k - 1]->avl_link[da[k - 1]] = r;
+            da[k] = 1;
+            pa[k++] = r;
+        }
+        else {
+            avl *s;
+            int j = k++;
+
+            for (;;) {
+                da[k] = 0;
+                pa[k++] = r;
+                s = r->avl_link[0];
+                if (s->avl_link[0] == NULL) break;
+
+                r = s;
+            }
+
+            s->avl_link[0] = p->avl_link[0];
+            r->avl_link[0] = s->avl_link[1];
+            s->avl_link[1] = p->avl_link[1];
+            s->avl_balance = p->avl_balance;
+
+            pa[j - 1]->avl_link[da[j - 1]] = s;
+            da[j] = 1;
+            pa[j] = s;
+        }
+    }
+
+    // assert (k > 0);
+    while (--k > 0) {
+        avl *y = pa[k];
+
+        if (da[k] == 0) {
+            y->avl_balance++;
+            if (y->avl_balance == +1) break;
+            else if (y->avl_balance == +2) {
+                avl *x = y->avl_link[1];
+                if (x->avl_balance == -1) {
+                    avl *w;
+                    // assert (x->avl_balance == -1);
+                    w = x->avl_link[0];
+                    x->avl_link[0] = w->avl_link[1];
+                    w->avl_link[1] = x;
+                    y->avl_link[1] = w->avl_link[0];
+                    w->avl_link[0] = y;
+                    if (w->avl_balance == +1)
+                        x->avl_balance = 0, y->avl_balance = -1;
+                    else if (w->avl_balance == 0)
+                        x->avl_balance = y->avl_balance = 0;
+                    else /* |w->avl_balance == -1| */
+                        x->avl_balance = +1, y->avl_balance = 0;
+                    w->avl_balance = 0;
+                    pa[k - 1]->avl_link[da[k - 1]] = w;
+                }
+                else {
+                    y->avl_link[1] = x->avl_link[0];
+                    x->avl_link[0] = y;
+                    pa[k - 1]->avl_link[da[k - 1]] = x;
+                    if (x->avl_balance == 0) {
+                        x->avl_balance = -1;
+                        y->avl_balance = +1;
+                        break;
+                    }
+                    else x->avl_balance = y->avl_balance = 0;
+                }
+            }
+        }
+        else
+        {
+            y->avl_balance--;
+            if (y->avl_balance == -1) break;
+            else if (y->avl_balance == -2) {
+                avl *x = y->avl_link[0];
+                if (x->avl_balance == +1) {
+                    avl *w;
+                    // assert (x->avl_balance == +1);
+                    w = x->avl_link[1];
+                    x->avl_link[1] = w->avl_link[0];
+                    w->avl_link[0] = x;
+                    y->avl_link[0] = w->avl_link[1];
+                    w->avl_link[1] = y;
+                    if (w->avl_balance == -1)
+                        x->avl_balance = 0, y->avl_balance = +1;
+                    else if (w->avl_balance == 0)
+                        x->avl_balance = y->avl_balance = 0;
+                    else /* |w->avl_balance == +1| */
+                        x->avl_balance = -1, y->avl_balance = 0;
+                    w->avl_balance = 0;
+                    pa[k - 1]->avl_link[da[k - 1]] = w;
+                }
+                else {
+                    y->avl_link[0] = x->avl_link[1];
+                    x->avl_link[1] = y;
+                    pa[k - 1]->avl_link[da[k - 1]] = x;
+                    if (x->avl_balance == 0) {
+                        x->avl_balance = +1;
+                        y->avl_balance = -1;
+                        break;
+                    }
+                    else x->avl_balance = y->avl_balance = 0;
+                }
+            }
+        }
+    }
+
+    // tree->avl_count--;
+    // tree->avl_generation++;
+    return item;
+}
+
+/* ------------------------------------------------------------------------- */
+// below are functions by (C) Costa Tsaousis
+
+// ---------------------------
+// traversing
+
+int avl_walker(avl *node, int (*callback)(void * /*entry*/, void * /*data*/), void *data) {
+    int total = 0, ret = 0;
+
+    if(node->avl_link[0]) {
+        ret = avl_walker(node->avl_link[0], callback, data);
+        if(ret < 0) return ret;
+        total += ret;
+    }
+
+    ret = callback(node, data);
+    if(ret < 0) return ret;
+    total += ret;
+
+    if(node->avl_link[1]) {
+        ret = avl_walker(node->avl_link[1], callback, data);
+        if (ret < 0) return ret;
+        total += ret;
+    }
+
+    return total;
+}
+
+int avl_traverse(avl_tree *tree, int (*callback)(void * /*entry*/, void * /*data*/), void *data) {
+    if(tree->root)
+        return avl_walker(tree->root, callback, data);
+    else
+        return 0;
+}
+
+// ---------------------------
+// locks
+
+void avl_read_lock(avl_tree_lock *t) {
+#ifndef AVL_WITHOUT_PTHREADS
+#ifdef AVL_LOCK_WITH_MUTEX
+    netdata_mutex_lock(&t->mutex);
+#else
+    netdata_rwlock_rdlock(&t->rwlock);
+#endif
+#endif /* AVL_WITHOUT_PTHREADS */
+}
+
+void avl_write_lock(avl_tree_lock *t) {
+#ifndef AVL_WITHOUT_PTHREADS
+#ifdef AVL_LOCK_WITH_MUTEX
+    netdata_mutex_lock(&t->mutex);
+#else
+    netdata_rwlock_wrlock(&t->rwlock);
+#endif
+#endif /* AVL_WITHOUT_PTHREADS */
+}
+
+void avl_unlock(avl_tree_lock *t) {
+#ifndef AVL_WITHOUT_PTHREADS
+#ifdef AVL_LOCK_WITH_MUTEX
+    netdata_mutex_unlock(&t->mutex);
+#else
+    netdata_rwlock_unlock(&t->rwlock);
+#endif
+#endif /* AVL_WITHOUT_PTHREADS */
+}
+
+// ---------------------------
+// operations with locking
+
+void avl_init_lock(avl_tree_lock *tree, int (*compar)(void * /*a*/, void * /*b*/)) {
+    avl_init(&tree->avl_tree, compar);
+
+#ifndef AVL_WITHOUT_PTHREADS
+    int lock;
+
+#ifdef AVL_LOCK_WITH_MUTEX
+    lock = netdata_mutex_init(&tree->mutex, NULL);
+#else
+    lock = netdata_rwlock_init(&tree->rwlock);
+#endif
+
+    if(lock != 0)
+        fatal("Failed to initialize AVL mutex/rwlock, error: %d", lock);
+
+#endif /* AVL_WITHOUT_PTHREADS */
+}
+
+avl *avl_search_lock(avl_tree_lock *tree, avl *item) {
+    avl_read_lock(tree);
+    avl *ret = avl_search(&tree->avl_tree, item);
+    avl_unlock(tree);
+    return ret;
+}
+
+avl * avl_remove_lock(avl_tree_lock *tree, avl *item) {
+    avl_write_lock(tree);
+    avl *ret = avl_remove(&tree->avl_tree, item);
+    avl_unlock(tree);
+    return ret;
+}
+
+avl *avl_insert_lock(avl_tree_lock *tree, avl *item) {
+    avl_write_lock(tree);
+    avl * ret = avl_insert(&tree->avl_tree, item);
+    avl_unlock(tree);
+    return ret;
+}
+
+int avl_traverse_lock(avl_tree_lock *tree, int (*callback)(void * /*entry*/, void * /*data*/), void *data) {
+    int ret;
+    avl_read_lock(tree);
+    ret = avl_traverse(&tree->avl_tree, callback, data);
+    avl_unlock(tree);
+    return ret;
+}
+
+void avl_init(avl_tree *tree, int (*compar)(void * /*a*/, void * /*b*/)) {
+    tree->root = NULL;
+    tree->compar = compar;
+}
+
+// ------------------
diff --git a/libnetdata/avl/avl.h b/libnetdata/avl/avl.h
new file mode 100644
index 0000000..070bb3d
--- /dev/null
+++ b/libnetdata/avl/avl.h
@@ -0,0 +1,89 @@
+// SPDX-License-Identifier: LGPL-3.0-or-later
+
+#ifndef _AVL_H
+#define _AVL_H 1
+
+#include "../libnetdata.h"
+
+/* Maximum AVL tree height. */
+#ifndef AVL_MAX_HEIGHT
+#define AVL_MAX_HEIGHT 92
+#endif
+
+#ifndef AVL_WITHOUT_PTHREADS
+#include <pthread.h>
+
+// #define AVL_LOCK_WITH_MUTEX 1
+
+#ifdef AVL_LOCK_WITH_MUTEX
+#define AVL_LOCK_INITIALIZER NETDATA_MUTEX_INITIALIZER
+#else /* AVL_LOCK_WITH_MUTEX */
+#define AVL_LOCK_INITIALIZER NETDATA_RWLOCK_INITIALIZER
+#endif /* AVL_LOCK_WITH_MUTEX */
+
+#else /* AVL_WITHOUT_PTHREADS */
+#define AVL_LOCK_INITIALIZER
+#endif /* AVL_WITHOUT_PTHREADS */
+
+/* Data structures */
+
+/* One element of the AVL tree */
+typedef struct avl {
+    struct avl *avl_link[2];  /* Subtrees. */
+    signed char avl_balance;       /* Balance factor. */
+} avl;
+
+/* An AVL tree */
+typedef struct avl_tree {
+    avl *root;
+    int (*compar)(void *a, void *b);
+} avl_tree;
+
+typedef struct avl_tree_lock {
+    avl_tree avl_tree;
+
+#ifndef AVL_WITHOUT_PTHREADS
+#ifdef AVL_LOCK_WITH_MUTEX
+    netdata_mutex_t mutex;
+#else /* AVL_LOCK_WITH_MUTEX */
+    netdata_rwlock_t rwlock;
+#endif /* AVL_LOCK_WITH_MUTEX */
+#endif /* AVL_WITHOUT_PTHREADS */
+} avl_tree_lock;
+
+/* Public methods */
+
+/* Insert element a into the AVL tree t
+ * returns the added element a, or a pointer the
+ * element that is equal to a (as returned by t->compar())
+ * a is linked directly to the tree, so it has to
+ * be properly allocated by the caller.
+ */
+avl *avl_insert_lock(avl_tree_lock *tree, avl *item) NEVERNULL WARNUNUSED;
+avl *avl_insert(avl_tree *tree, avl *item) NEVERNULL WARNUNUSED;
+
+/* Remove an element a from the AVL tree t
+ * returns a pointer to the removed element
+ * or NULL if an element equal to a is not found
+ * (equal as returned by t->compar())
+ */
+avl *avl_remove_lock(avl_tree_lock *tree, avl *item) WARNUNUSED;
+avl *avl_remove(avl_tree *tree, avl *item) WARNUNUSED;
+
+/* Find the element into the tree that equal to a
+ * (equal as returned by t->compar())
+ * returns NULL is no element is equal to a
+ */
+avl *avl_search_lock(avl_tree_lock *tree, avl *item);
+avl *avl_search(avl_tree *tree, avl *item);
+
+/* Initialize the avl_tree_lock
+ */
+void avl_init_lock(avl_tree_lock *tree, int (*compar)(void *a, void *b));
+void avl_init(avl_tree *tree, int (*compar)(void *a, void *b));
+
+
+int avl_traverse_lock(avl_tree_lock *tree, int (*callback)(void *entry, void *data), void *data);
+int avl_traverse(avl_tree *tree, int (*callback)(void *entry, void *data), void *data);
+
+#endif /* avl.h */
diff --git a/libnetdata/buffer/Makefile.am b/libnetdata/buffer/Makefile.am
new file mode 100644
index 0000000..1cb69ed
--- /dev/null
+++ b/libnetdata/buffer/Makefile.am
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
+
+
+dist_noinst_DATA = \
+	README.md \
+	$(NULL)
diff --git a/libnetdata/buffer/README.md b/libnetdata/buffer/README.md
new file mode 100644
index 0000000..48072e9
--- /dev/null
+++ b/libnetdata/buffer/README.md
@@ -0,0 +1,12 @@
+# BUFFER
+
+`BUFFER` is a convenience library for working with strings in `C`.
+Mainly, `BUFFER`s eliminate the need for tracking the string length, thus providing
+a safe alternative for string operations.
+
+Also, they are super fast in printing and appending data to the string and its `buffer_strlen()`
+is just a lookup (it does not traverse the string).
+
+Netdata uses `BUFFER`s for preparing web responses and buffering data to be sent upstream or
+to backend databases.
+[![analytics](https://www.google-analytics.com/collect?v=1&aip=1&t=pageview&_s=1&ds=github&dr=https%3A%2F%2Fgithub.com%2Fnetdata%2Fnetdata&dl=https%3A%2F%2Fmy-netdata.io%2Fgithub%2Flibnetdata%2Fbuffer%2FREADME&_u=MAC~&cid=5792dfd7-8dc4-476b-af31-da2fdb9f93d2&tid=UA-64295674-3)]()
diff --git a/libnetdata/buffer/buffer.c b/libnetdata/buffer/buffer.c
new file mode 100644
index 0000000..5067232
--- /dev/null
+++ b/libnetdata/buffer/buffer.c
@@ -0,0 +1,401 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../libnetdata.h"
+
+#define BUFFER_OVERFLOW_EOF "EOF"
+
+static inline void buffer_overflow_init(BUFFER *b)
+{
+    b->buffer[b->size] = '\0';
+    strcpy(&b->buffer[b->size + 1], BUFFER_OVERFLOW_EOF);
+}
+
+#ifdef NETDATA_INTERNAL_CHECKS
+#define buffer_overflow_check(b) _buffer_overflow_check(b, __FILE__, __FUNCTION__, __LINE__)
+#else
+#define buffer_overflow_check(b)
+#endif
+
+static inline void _buffer_overflow_check(BUFFER *b, const char *file, const char *function, const unsigned long line)
+{
+    if(b->len > b->size) {
+        error("BUFFER: length %zu is above size %zu, at line %lu, at function %s() of file '%s'.", b->len, b->size, line, function, file);
+        b->len = b->size;
+    }
+
+    if(b->buffer[b->size] != '\0' || strcmp(&b->buffer[b->size + 1], BUFFER_OVERFLOW_EOF) != 0) {
+        error("BUFFER: detected overflow at line %lu, at function %s() of file '%s'.", line, function, file);
+        buffer_overflow_init(b);
+    }
+}
+
+
+void buffer_reset(BUFFER *wb)
+{
+    buffer_flush(wb);
+
+    wb->contenttype = CT_TEXT_PLAIN;
+    wb->options = 0;
+    wb->date = 0;
+    wb->expires = 0;
+
+    buffer_overflow_check(wb);
+}
+
+const char *buffer_tostring(BUFFER *wb)
+{
+    buffer_need_bytes(wb, 1);
+    wb->buffer[wb->len] = '\0';
+
+    buffer_overflow_check(wb);
+
+    return(wb->buffer);
+}
+
+void buffer_char_replace(BUFFER *wb, char from, char to)
+{
+    char *s = wb->buffer, *end = &wb->buffer[wb->len];
+
+    while(s != end) {
+        if(*s == from) *s = to;
+        s++;
+    }
+
+    buffer_overflow_check(wb);
+}
+
+// This trick seems to give an 80% speed increase in 32bit systems
+// print_calculated_number_llu_r() will just print the digits up to the
+// point the remaining value fits in 32 bits, and then calls
+// print_calculated_number_lu_r() to print the rest with 32 bit arithmetic.
+
+inline char *print_number_lu_r(char *str, unsigned long uvalue) {
+    char *wstr = str;
+
+    // print each digit
+    do *wstr++ = (char)('0' + (uvalue % 10)); while(uvalue /= 10);
+    return wstr;
+}
+
+inline char *print_number_llu_r(char *str, unsigned long long uvalue) {
+    char *wstr = str;
+
+    // print each digit
+    do *wstr++ = (char)('0' + (uvalue % 10)); while((uvalue /= 10) && uvalue > (unsigned long long)0xffffffff);
+    if(uvalue) return print_number_lu_r(wstr, uvalue);
+    return wstr;
+}
+
+inline char *print_number_llu_r_smart(char *str, unsigned long long uvalue) {
+#ifdef ENVIRONMENT32
+    if(uvalue > (unsigned long long)0xffffffff)
+        str = print_number_llu_r(str, uvalue);
+    else
+        str = print_number_lu_r(str, uvalue);
+#else
+    do *str++ = (char)('0' + (uvalue % 10)); while(uvalue /= 10);
+#endif
+
+    return str;
+}
+
+void buffer_print_llu(BUFFER *wb, unsigned long long uvalue)
+{
+    buffer_need_bytes(wb, 50);
+
+    char *str = &wb->buffer[wb->len];
+    char *wstr = str;
+
+#ifdef ENVIRONMENT32
+    if(uvalue > (unsigned long long)0xffffffff)
+        wstr = print_number_llu_r(wstr, uvalue);
+    else
+        wstr = print_number_lu_r(wstr, uvalue);
+#else
+    do *wstr++ = (char)('0' + (uvalue % 10)); while(uvalue /= 10);
+#endif
+
+    // terminate it
+    *wstr = '\0';
+
+    // reverse it
+    char *begin = str, *end = wstr - 1, aux;
+    while (end > begin) aux = *end, *end-- = *begin, *begin++ = aux;
+
+    // return the buffer length
+    wb->len += wstr - str;
+}
+
+void buffer_strcat(BUFFER *wb, const char *txt)
+{
+    // buffer_sprintf(wb, "%s", txt);
+
+    if(unlikely(!txt || !*txt)) return;
+
+    buffer_need_bytes(wb, 1);
+
+    char *s = &wb->buffer[wb->len], *start, *end = &wb->buffer[wb->size];
+    size_t len = wb->len;
+
+    start = s;
+    while(*txt && s != end)
+        *s++ = *txt++;
+
+    len += s - start;
+
+    wb->len = len;
+    buffer_overflow_check(wb);
+
+    if(*txt) {
+        debug(D_WEB_BUFFER, "strcat(): increasing web_buffer at position %zu, size = %zu\n", wb->len, wb->size);
+        len = strlen(txt);
+        buffer_increase(wb, len);
+        buffer_strcat(wb, txt);
+    }
+    else {
+        // terminate the string
+        // without increasing the length
+        buffer_need_bytes(wb, (size_t)1);
+        wb->buffer[wb->len] = '\0';
+    }
+}
+
+void buffer_strcat_htmlescape(BUFFER *wb, const char *txt)
+{
+    while(*txt) {
+        switch(*txt) {
+            case '&': buffer_strcat(wb, "&amp;"); break;
+            case '<': buffer_strcat(wb, "&lt;"); break;
+            case '>': buffer_strcat(wb, "&gt;"); break;
+            case '"': buffer_strcat(wb, "&quot;"); break;
+            case '/': buffer_strcat(wb, "&#x2F;"); break;
+            case '\'': buffer_strcat(wb, "&#x27;"); break;
+            default: {
+                buffer_need_bytes(wb, 1);
+                wb->buffer[wb->len++] = *txt;
+            }
+        }
+        txt++;
+    }
+
+    buffer_overflow_check(wb);
+}
+
+void buffer_snprintf(BUFFER *wb, size_t len, const char *fmt, ...)
+{
+    if(unlikely(!fmt || !*fmt)) return;
+
+    buffer_need_bytes(wb, len + 1);
+
+    va_list args;
+    va_start(args, fmt);
+    wb->len += vsnprintfz(&wb->buffer[wb->len], len, fmt, args);
+    va_end(args);
+
+    buffer_overflow_check(wb);
+
+    // the buffer is \0 terminated by vsnprintfz
+}
+
+void buffer_vsprintf(BUFFER *wb, const char *fmt, va_list args)
+{
+    if(unlikely(!fmt || !*fmt)) return;
+
+    buffer_need_bytes(wb, 2);
+
+    size_t len = wb->size - wb->len - 1;
+
+    wb->len += vsnprintfz(&wb->buffer[wb->len], len, fmt, args);
+
+    buffer_overflow_check(wb);
+
+    // the buffer is \0 terminated by vsnprintfz
+}
+
+void buffer_sprintf(BUFFER *wb, const char *fmt, ...)
+{
+    if(unlikely(!fmt || !*fmt)) return;
+
+    va_list args;
+    size_t wrote = 0, need = 2, multiplier = 0, len;
+
+    do {
+        need += wrote + multiplier * WEB_DATA_LENGTH_INCREASE_STEP;
+        multiplier++;
+
+        debug(D_WEB_BUFFER, "web_buffer_sprintf(): increasing web_buffer at position %zu, size = %zu, by %zu bytes (wrote = %zu)\n", wb->len, wb->size, need, wrote);
+        buffer_need_bytes(wb, need);
+
+        len = wb->size - wb->len - 1;
+
+        va_start(args, fmt);
+        wrote = (size_t) vsnprintfz(&wb->buffer[wb->len], len, fmt, args);
+        va_end(args);
+
+    } while(wrote >= len);
+
+    wb->len += wrote;
+
+    // the buffer is \0 terminated by vsnprintf
+}
+
+
+void buffer_rrd_value(BUFFER *wb, calculated_number value)
+{
+    buffer_need_bytes(wb, 50);
+
+    if(isnan(value) || isinf(value)) {
+        buffer_strcat(wb, "null");
+        return;
+    }
+    else
+        wb->len += print_calculated_number(&wb->buffer[wb->len], value);
+
+    // terminate it
+    buffer_need_bytes(wb, 1);
+    wb->buffer[wb->len] = '\0';
+
+    buffer_overflow_check(wb);
+}
+
+// generate a javascript date, the fastest possible way...
+void buffer_jsdate(BUFFER *wb, int year, int month, int day, int hours, int minutes, int seconds)
+{
+  //         10        20        30      = 35
+    // 01234567890123456789012345678901234
+    // Date(2014,04,01,03,28,20)
+
+    buffer_need_bytes(wb, 30);
+
+    char *b = &wb->buffer[wb->len], *p;
+  unsigned int *q = (unsigned int *)b;  
+
+  #if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+    *q++ = 0x65746144;  // "Date" backwards.
+  #else
+    *q++ = 0x44617465;  // "Date"
+  #endif
+  p = (char *)q;
+
+  *p++ = '(';
+  *p++ = '0' + year / 1000; year %= 1000;
+  *p++ = '0' + year / 100;  year %= 100;
+  *p++ = '0' + year / 10;
+  *p++ = '0' + year % 10;
+  *p++ = ',';
+  *p   = '0' + month / 10; if (*p != '0') p++;
+  *p++ = '0' + month % 10;
+  *p++ = ',';
+  *p   = '0' + day / 10; if (*p != '0') p++;
+  *p++ = '0' + day % 10;
+  *p++ = ',';
+  *p   = '0' + hours / 10; if (*p != '0') p++;
+  *p++ = '0' + hours % 10;
+  *p++ = ',';
+  *p   = '0' + minutes / 10; if (*p != '0') p++;
+  *p++ = '0' + minutes % 10;
+  *p++ = ',';
+  *p   = '0' + seconds / 10; if (*p != '0') p++;
+  *p++ = '0' + seconds % 10;
+
+  unsigned short *r = (unsigned short *)p;
+
+#if __BYTE_ORDER__ == __ORDER_LITTLE_ENDIAN__
+    *r++ = 0x0029;  // ")\0" backwards.  
+  #else
+    *r++ = 0x2900;  // ")\0"
+  #endif
+
+    wb->len += (size_t)((char *)r - b - 1);
+
+    // terminate it
+    wb->buffer[wb->len] = '\0';
+    buffer_overflow_check(wb);
+}
+
+// generate a date, the fastest possible way...
+void buffer_date(BUFFER *wb, int year, int month, int day, int hours, int minutes, int seconds)
+{
+    //         10        20        30      = 35
+    // 01234567890123456789012345678901234
+    // 2014-04-01 03:28:20
+
+    buffer_need_bytes(wb, 36);
+
+    char *b = &wb->buffer[wb->len];
+  char *p = b;
+
+  *p++ = '0' + year / 1000; year %= 1000;
+  *p++ = '0' + year / 100;  year %= 100;
+  *p++ = '0' + year / 10;
+  *p++ = '0' + year % 10;
+  *p++ = '-';
+  *p++ = '0' + month / 10;
+  *p++ = '0' + month % 10;
+  *p++ = '-';
+  *p++ = '0' + day / 10;
+  *p++ = '0' + day % 10;
+  *p++ = ' ';
+  *p++ = '0' + hours / 10;
+  *p++ = '0' + hours % 10;
+  *p++ = ':';
+  *p++ = '0' + minutes / 10;
+  *p++ = '0' + minutes % 10;
+  *p++ = ':';
+  *p++ = '0' + seconds / 10;
+  *p++ = '0' + seconds % 10;
+  *p = '\0';
+
+    wb->len += (size_t)(p - b);
+
+    // terminate it
+    wb->buffer[wb->len] = '\0';
+    buffer_overflow_check(wb);
+}
+
+BUFFER *buffer_create(size_t size)
+{
+    BUFFER *b;
+
+    debug(D_WEB_BUFFER, "Creating new web buffer of size %zu.", size);
+
+    b = callocz(1, sizeof(BUFFER));
+    b->buffer = mallocz(size + sizeof(BUFFER_OVERFLOW_EOF) + 2);
+    b->buffer[0] = '\0';
+    b->size = size;
+    b->contenttype = CT_TEXT_PLAIN;
+    buffer_overflow_init(b);
+    buffer_overflow_check(b);
+
+    return(b);
+}
+
+void buffer_free(BUFFER *b) {
+    if(unlikely(!b)) return;
+
+    buffer_overflow_check(b);
+
+    debug(D_WEB_BUFFER, "Freeing web buffer of size %zu.", b->size);
+
+    freez(b->buffer);
+    freez(b);
+}
+
+void buffer_increase(BUFFER *b, size_t free_size_required) {
+    buffer_overflow_check(b);
+
+    size_t left = b->size - b->len;
+
+    if(left >= free_size_required) return;
+
+    size_t increase = free_size_required - left;
+    if(increase < WEB_DATA_LENGTH_INCREASE_STEP) increase = WEB_DATA_LENGTH_INCREASE_STEP;
+
+    debug(D_WEB_BUFFER, "Increasing data buffer from size %zu to %zu.", b->size, b->size + increase);
+
+    b->buffer = reallocz(b->buffer, b->size + increase + sizeof(BUFFER_OVERFLOW_EOF) + 2);
+    b->size += increase;
+
+    buffer_overflow_init(b);
+    buffer_overflow_check(b);
+}
diff --git a/libnetdata/buffer/buffer.h b/libnetdata/buffer/buffer.h
new file mode 100644
index 0000000..8e431bf
--- /dev/null
+++ b/libnetdata/buffer/buffer.h
@@ -0,0 +1,85 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_WEB_BUFFER_H
+#define NETDATA_WEB_BUFFER_H 1
+
+#include "../libnetdata.h"
+
+#define WEB_DATA_LENGTH_INCREASE_STEP 1024
+
+typedef struct web_buffer {
+    size_t size;        	// allocation size of buffer, in bytes
+    size_t len;     		// current data length in buffer, in bytes
+    char *buffer;   		// the buffer itself
+    uint8_t contenttype;	// the content type of the data in the buffer
+    uint8_t options;		// options related to the content
+    time_t date;    		// the timestamp this content has been generated
+    time_t expires;			// the timestamp this content expires
+} BUFFER;
+
+// options
+#define WB_CONTENT_CACHEABLE            1
+#define WB_CONTENT_NO_CACHEABLE         2
+
+// content-types
+#define CT_APPLICATION_JSON             1
+#define CT_TEXT_PLAIN                   2
+#define CT_TEXT_HTML                    3
+#define CT_APPLICATION_X_JAVASCRIPT     4
+#define CT_TEXT_CSS                     5
+#define CT_TEXT_XML                     6
+#define CT_APPLICATION_XML              7
+#define CT_TEXT_XSL                     8
+#define CT_APPLICATION_OCTET_STREAM     9
+#define CT_APPLICATION_X_FONT_TRUETYPE  10
+#define CT_APPLICATION_X_FONT_OPENTYPE  11
+#define CT_APPLICATION_FONT_WOFF        12
+#define CT_APPLICATION_FONT_WOFF2       13
+#define CT_APPLICATION_VND_MS_FONTOBJ   14
+#define CT_IMAGE_SVG_XML                15
+#define CT_IMAGE_PNG                    16
+#define CT_IMAGE_JPG                    17
+#define CT_IMAGE_GIF                    18
+#define CT_IMAGE_XICON                  19
+#define CT_IMAGE_ICNS                   20
+#define CT_IMAGE_BMP                    21
+#define CT_PROMETHEUS                   22
+
+#define buffer_cacheable(wb)    do { (wb)->options |= WB_CONTENT_CACHEABLE;    if((wb)->options & WB_CONTENT_NO_CACHEABLE) (wb)->options &= ~WB_CONTENT_NO_CACHEABLE; } while(0)
+#define buffer_no_cacheable(wb) do { (wb)->options |= WB_CONTENT_NO_CACHEABLE; if((wb)->options & WB_CONTENT_CACHEABLE)    (wb)->options &= ~WB_CONTENT_CACHEABLE;  (wb)->expires = 0; } while(0)
+
+#define buffer_strlen(wb) ((wb)->len)
+extern const char *buffer_tostring(BUFFER *wb);
+
+#define buffer_flush(wb) wb->buffer[(wb)->len = 0] = '\0'
+extern void buffer_reset(BUFFER *wb);
+
+extern void buffer_strcat(BUFFER *wb, const char *txt);
+extern void buffer_rrd_value(BUFFER *wb, calculated_number value);
+
+extern void buffer_date(BUFFER *wb, int year, int month, int day, int hours, int minutes, int seconds);
+extern void buffer_jsdate(BUFFER *wb, int year, int month, int day, int hours, int minutes, int seconds);
+
+extern BUFFER *buffer_create(size_t size);
+extern void buffer_free(BUFFER *b);
+extern void buffer_increase(BUFFER *b, size_t free_size_required);
+
+extern void buffer_snprintf(BUFFER *wb, size_t len, const char *fmt, ...) PRINTFLIKE(3, 4);
+extern void buffer_vsprintf(BUFFER *wb, const char *fmt, va_list args);
+extern void buffer_sprintf(BUFFER *wb, const char *fmt, ...) PRINTFLIKE(2,3);
+extern void buffer_strcat_htmlescape(BUFFER *wb, const char *txt);
+
+extern void buffer_char_replace(BUFFER *wb, char from, char to);
+
+extern char *print_number_lu_r(char *str, unsigned long uvalue);
+extern char *print_number_llu_r(char *str, unsigned long long uvalue);
+extern char *print_number_llu_r_smart(char *str, unsigned long long uvalue);
+
+extern void buffer_print_llu(BUFFER *wb, unsigned long long uvalue);
+
+static inline void buffer_need_bytes(BUFFER *buffer, size_t needed_free_size) {
+    if(unlikely(buffer->size - buffer->len < needed_free_size))
+        buffer_increase(buffer, needed_free_size);
+}
+
+#endif /* NETDATA_WEB_BUFFER_H */
diff --git a/libnetdata/clocks/Makefile.am b/libnetdata/clocks/Makefile.am
new file mode 100644
index 0000000..1cb69ed
--- /dev/null
+++ b/libnetdata/clocks/Makefile.am
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
+
+
+dist_noinst_DATA = \
+	README.md \
+	$(NULL)
diff --git a/libnetdata/clocks/README.md b/libnetdata/clocks/README.md
new file mode 100644
index 0000000..c4215a7
--- /dev/null
+++ b/libnetdata/clocks/README.md
@@ -0,0 +1,2 @@
+
+[![analytics](https://www.google-analytics.com/collect?v=1&aip=1&t=pageview&_s=1&ds=github&dr=https%3A%2F%2Fgithub.com%2Fnetdata%2Fnetdata&dl=https%3A%2F%2Fmy-netdata.io%2Fgithub%2Flibnetdata%2Fclocks%2FREADME&_u=MAC~&cid=5792dfd7-8dc4-476b-af31-da2fdb9f93d2&tid=UA-64295674-3)]()
diff --git a/libnetdata/clocks/clocks.c b/libnetdata/clocks/clocks.c
new file mode 100644
index 0000000..f303ccd
--- /dev/null
+++ b/libnetdata/clocks/clocks.c
@@ -0,0 +1,204 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../libnetdata.h"
+
+#ifndef HAVE_CLOCK_GETTIME
+inline int clock_gettime(clockid_t clk_id, struct timespec *ts) {
+    struct timeval tv;
+    if(unlikely(gettimeofday(&tv, NULL) == -1)) {
+        error("gettimeofday() failed.");
+        return -1;
+    }
+    ts->tv_sec = tv.tv_sec;
+    ts->tv_nsec = (tv.tv_usec % USEC_PER_SEC) * NSEC_PER_USEC;
+    return 0;
+}
+#endif
+
+static inline time_t now_sec(clockid_t clk_id) {
+    struct timespec ts;
+    if(unlikely(clock_gettime(clk_id, &ts) == -1)) {
+        error("clock_gettime(%d, &timespec) failed.", clk_id);
+        return 0;
+    }
+    return ts.tv_sec;
+}
+
+static inline usec_t now_usec(clockid_t clk_id) {
+    struct timespec ts;
+    if(unlikely(clock_gettime(clk_id, &ts) == -1)) {
+        error("clock_gettime(%d, &timespec) failed.", clk_id);
+        return 0;
+    }
+    return (usec_t)ts.tv_sec * USEC_PER_SEC + (ts.tv_nsec % NSEC_PER_SEC) / NSEC_PER_USEC;
+}
+
+static inline int now_timeval(clockid_t clk_id, struct timeval *tv) {
+    struct timespec ts;
+
+    if(unlikely(clock_gettime(clk_id, &ts) == -1)) {
+        error("clock_gettime(%d, &timespec) failed.", clk_id);
+        tv->tv_sec = 0;
+        tv->tv_usec = 0;
+        return -1;
+    }
+
+    tv->tv_sec = ts.tv_sec;
+    tv->tv_usec = (suseconds_t)((ts.tv_nsec % NSEC_PER_SEC) / NSEC_PER_USEC);
+    return 0;
+}
+
+inline time_t now_realtime_sec(void) {
+    return now_sec(CLOCK_REALTIME);
+}
+
+inline usec_t now_realtime_usec(void) {
+    return now_usec(CLOCK_REALTIME);
+}
+
+inline int now_realtime_timeval(struct timeval *tv) {
+    return now_timeval(CLOCK_REALTIME, tv);
+}
+
+inline time_t now_monotonic_sec(void) {
+    return now_sec(CLOCK_MONOTONIC);
+}
+
+inline usec_t now_monotonic_usec(void) {
+    return now_usec(CLOCK_MONOTONIC);
+}
+
+inline int now_monotonic_timeval(struct timeval *tv) {
+    return now_timeval(CLOCK_MONOTONIC, tv);
+}
+
+inline time_t now_boottime_sec(void) {
+    return now_sec(CLOCK_BOOTTIME);
+}
+
+inline usec_t now_boottime_usec(void) {
+    return now_usec(CLOCK_BOOTTIME);
+}
+
+inline int now_boottime_timeval(struct timeval *tv) {
+    return now_timeval(CLOCK_BOOTTIME, tv);
+}
+
+inline usec_t timeval_usec(struct timeval *tv) {
+    return (usec_t)tv->tv_sec * USEC_PER_SEC + (tv->tv_usec % USEC_PER_SEC);
+}
+
+inline msec_t timeval_msec(struct timeval *tv) {
+    return (msec_t)tv->tv_sec * MSEC_PER_SEC + ((tv->tv_usec % USEC_PER_SEC) / MSEC_PER_SEC);
+}
+
+inline susec_t dt_usec_signed(struct timeval *now, struct timeval *old) {
+    usec_t ts1 = timeval_usec(now);
+    usec_t ts2 = timeval_usec(old);
+
+    if(likely(ts1 >= ts2)) return (susec_t)(ts1 - ts2);
+    return -((susec_t)(ts2 - ts1));
+}
+
+inline usec_t dt_usec(struct timeval *now, struct timeval *old) {
+    usec_t ts1 = timeval_usec(now);
+    usec_t ts2 = timeval_usec(old);
+    return (ts1 > ts2) ? (ts1 - ts2) : (ts2 - ts1);
+}
+
+inline void heartbeat_init(heartbeat_t *hb)
+{
+    hb->monotonic = hb->realtime = 0ULL;
+}
+
+// waits for the next heartbeat
+// it waits using the monotonic clock
+// it returns the dt using the realtime clock
+
+usec_t heartbeat_next(heartbeat_t *hb, usec_t tick) {
+    heartbeat_t now;
+    now.monotonic = now_monotonic_usec();
+    now.realtime  = now_realtime_usec();
+
+    usec_t next_monotonic = now.monotonic - (now.monotonic % tick) + tick;
+
+    while(now.monotonic < next_monotonic) {
+        sleep_usec(next_monotonic - now.monotonic);
+        now.monotonic = now_monotonic_usec();
+        now.realtime  = now_realtime_usec();
+    }
+
+    if(likely(hb->realtime != 0ULL)) {
+        usec_t dt_monotonic = now.monotonic - hb->monotonic;
+        usec_t dt_realtime  = now.realtime - hb->realtime;
+
+        hb->monotonic = now.monotonic;
+        hb->realtime  = now.realtime;
+
+        if(unlikely(dt_monotonic >= tick + tick / 2)) {
+            errno = 0;
+            error("heartbeat missed %llu monotonic microseconds", dt_monotonic - tick);
+        }
+
+        return dt_realtime;
+    }
+    else {
+        hb->monotonic = now.monotonic;
+        hb->realtime  = now.realtime;
+        return 0ULL;
+    }
+}
+
+// returned the elapsed time, since the last heartbeat
+// using the monotonic clock
+
+inline usec_t heartbeat_monotonic_dt_to_now_usec(heartbeat_t *hb) {
+    if(!hb || !hb->monotonic) return 0ULL;
+    return now_monotonic_usec() - hb->monotonic;
+}
+
+int sleep_usec(usec_t usec) {
+
+#ifndef NETDATA_WITH_USLEEP
+    // we expect microseconds (1.000.000 per second)
+    // but timespec is nanoseconds (1.000.000.000 per second)
+    struct timespec rem, req = {
+            .tv_sec = (time_t) (usec / 1000000),
+            .tv_nsec = (suseconds_t) ((usec % 1000000) * 1000)
+    };
+
+    while (nanosleep(&req, &rem) == -1) {
+        if (likely(errno == EINTR)) {
+            debug(D_SYSTEM, "nanosleep() interrupted (while sleeping for %llu microseconds).", usec);
+            req.tv_sec = rem.tv_sec;
+            req.tv_nsec = rem.tv_nsec;
+        } else {
+            error("Cannot nanosleep() for %llu microseconds.", usec);
+            break;
+        }
+    }
+
+    return 0;
+#else
+    int ret = usleep(usec);
+    if(unlikely(ret == -1 && errno == EINVAL)) {
+        // on certain systems, usec has to be up to 999999
+        if(usec > 999999) {
+            int counter = usec / 999999;
+            while(counter--)
+                usleep(999999);
+
+            usleep(usec % 999999);
+        }
+        else {
+            error("Cannot usleep() for %llu microseconds.", usec);
+            return ret;
+        }
+    }
+
+    if(ret != 0)
+        error("usleep() failed for %llu microseconds.", usec);
+
+    return ret;
+#endif
+}
diff --git a/libnetdata/clocks/clocks.h b/libnetdata/clocks/clocks.h
new file mode 100644
index 0000000..d576d86
--- /dev/null
+++ b/libnetdata/clocks/clocks.h
@@ -0,0 +1,133 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_CLOCKS_H
+#define NETDATA_CLOCKS_H 1
+
+#include "../libnetdata.h"
+
+#ifndef HAVE_STRUCT_TIMESPEC
+struct timespec {
+    time_t tv_sec;  /* seconds */
+    long   tv_nsec; /* nanoseconds */
+};
+#endif
+
+#ifndef HAVE_CLOCKID_T
+typedef int clockid_t;
+#endif
+
+typedef unsigned long long nsec_t;
+typedef unsigned long long msec_t;
+typedef unsigned long long usec_t;
+typedef long long susec_t;
+
+typedef struct heartbeat {
+    usec_t monotonic;
+    usec_t realtime;
+} heartbeat_t;
+
+/* Linux value is as good as any other */
+#ifndef CLOCK_REALTIME
+#define CLOCK_REALTIME  0
+#endif
+
+#ifndef CLOCK_MONOTONIC
+/* fallback to CLOCK_REALTIME if not available */
+#define CLOCK_MONOTONIC CLOCK_REALTIME
+#endif
+
+#ifndef CLOCK_BOOTTIME
+
+#ifdef CLOCK_UPTIME
+/* CLOCK_BOOTTIME falls back to CLOCK_UPTIME on FreeBSD */
+#define CLOCK_BOOTTIME CLOCK_UPTIME
+#else // CLOCK_UPTIME
+/* CLOCK_BOOTTIME falls back to CLOCK_MONOTONIC */
+#define CLOCK_BOOTTIME  CLOCK_MONOTONIC
+#endif // CLOCK_UPTIME
+
+#else // CLOCK_BOOTTIME
+
+#ifdef HAVE_CLOCK_GETTIME
+#define CLOCK_BOOTTIME_IS_AVAILABLE 1 // required for /proc/uptime
+#endif // HAVE_CLOCK_GETTIME
+
+#endif // CLOCK_BOOTTIME
+
+#define NSEC_PER_MSEC   1000000ULL
+
+#define NSEC_PER_SEC    1000000000ULL
+#define NSEC_PER_USEC   1000ULL
+
+#define USEC_PER_SEC    1000000ULL
+#define MSEC_PER_SEC    1000ULL
+
+#define USEC_PER_MS     1000ULL
+
+#ifndef HAVE_CLOCK_GETTIME
+/* Fallback function for POSIX.1-2001 clock_gettime() function.
+ *
+ * We use a realtime clock from gettimeofday(), this will
+ * make systems without clock_gettime() support sensitive
+ * to time jumps or hibernation/suspend side effects.
+ */
+extern int clock_gettime(clockid_t clk_id, struct timespec *ts);
+#endif
+
+/*
+ * Three clocks are available (cf. man 3 clock_gettime):
+ *
+ * REALTIME clock (i.e. wall-clock):
+ *  This clock is affected by discontinuous jumps in the system time
+ *  (e.g., if the system administrator manually changes the clock), and by the incremental adjustments performed by adjtime(3) and NTP.
+ *
+ * MONOTONIC clock
+ *  Clock that cannot be set and represents monotonic time since some unspecified starting point.
+ *  This clock is not affected by discontinuous jumps in the system time
+ *  (e.g., if the system administrator manually changes the clock), but is affected by the incremental adjustments performed by adjtime(3) and NTP.
+ *  If not available on the system, this clock falls back to REALTIME clock.
+ *
+ * BOOTTIME clock
+ *  Identical to  CLOCK_MONOTONIC, except it also includes any time that the system is suspended.
+ *  This allows applications to get a suspend-aware monotonic clock without having to deal with the complications of CLOCK_REALTIME,
+ *  which may have discontinuities if the time is changed using settimeofday(2).
+ *  If not available on the system, this clock falls back to MONOTONIC clock.
+ *
+ * All now_*_timeval() functions fill the `struct timeval` with the time from the appropriate clock.
+ * Those functions return 0 on success, -1 else with errno set appropriately.
+ *
+ * All now_*_sec() functions return the time in seconds from the approriate clock, or 0 on error.
+ * All now_*_usec() functions return the time in microseconds from the approriate clock, or 0 on error.
+ */
+extern int now_realtime_timeval(struct timeval *tv);
+extern time_t now_realtime_sec(void);
+extern usec_t now_realtime_usec(void);
+
+extern int now_monotonic_timeval(struct timeval *tv);
+extern time_t now_monotonic_sec(void);
+extern usec_t now_monotonic_usec(void);
+
+extern int now_boottime_timeval(struct timeval *tv);
+extern time_t now_boottime_sec(void);
+extern usec_t now_boottime_usec(void);
+
+
+extern usec_t timeval_usec(struct timeval *tv);
+extern msec_t timeval_msec(struct timeval *tv);
+
+extern usec_t dt_usec(struct timeval *now, struct timeval *old);
+extern susec_t dt_usec_signed(struct timeval *now, struct timeval *old);
+
+extern void heartbeat_init(heartbeat_t *hb);
+
+/* Sleeps until next multiple of tick using monotonic clock.
+ * Returns elapsed time in microseconds since previous heartbeat
+ */
+extern usec_t heartbeat_next(heartbeat_t *hb, usec_t tick);
+
+/* Returns elapsed time in microseconds since last heartbeat */
+extern usec_t heartbeat_monotonic_dt_to_now_usec(heartbeat_t *hb);
+
+extern int sleep_usec(usec_t usec);
+
+#endif /* NETDATA_CLOCKS_H */
diff --git a/libnetdata/config/Makefile.am b/libnetdata/config/Makefile.am
new file mode 100644
index 0000000..1cb69ed
--- /dev/null
+++ b/libnetdata/config/Makefile.am
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
+
+
+dist_noinst_DATA = \
+	README.md \
+	$(NULL)
diff --git a/libnetdata/config/README.md b/libnetdata/config/README.md
new file mode 100644
index 0000000..f0a27d9
--- /dev/null
+++ b/libnetdata/config/README.md
@@ -0,0 +1,48 @@
+# netdata ini config files
+
+Configuration files `netdata.conf` and `stream.conf` are netdata ini files.
+
+## Motivation
+
+The whole idea came up when we were evaluating the documentation involved
+in maintaining a complex configuration system. Our intention was to give
+configuration options for everything imaginable. But then, documenting all
+these options would require a tremendous amount of time, users would have
+to search through endless pages for the option they need, etc.
+
+We concluded then that **configuring software like that is a waste of time
+and effort**. Of course there must be plenty of configuration options, but
+the implementation itself should require a lot less effort for both the
+developers and the users.
+
+So, we did this:
+
+1. No configuration is required to run netdata
+2. There are plenty of options to tweak
+3. There is minimal documentation (or no at all)
+
+## Why this works?
+
+The configuration file is a `name = value` dictionary with `[sections]`.
+Write whatever you like there as long as it follows this simple format.
+
+Netdata loads this dictionary and then when the code needs a value from
+it, it just looks up the `name` in the dictionary at the proper `section`.
+In all places, in the code, there are both the `names` and their
+`default values`, so if something is not found in the configuration
+file, the default is used. The lookup is made using B-Trees and hashes
+(no string comparisons), so they are super fast. Also the `names` of the
+settings can be `my super duper setting that once set to yes, will turn the world upside down = no`
+- so goodbye to most of the documentation involved.
+
+Next, netdata can generate a valid configuration for the user to edit.
+No need to remember anything or copy and paste settings. Just get the
+configuration from the server (`/netdata.conf` on your netdata server),
+edit it and save it.
+
+Last, what about options you believe you have set, but you misspelled?
+When you get the configuration file from the server, there will be a
+comment above all `name = value` pairs the server does not use.
+So you know that whatever you wrote there, is not used.
+
+[![analytics](https://www.google-analytics.com/collect?v=1&aip=1&t=pageview&_s=1&ds=github&dr=https%3A%2F%2Fgithub.com%2Fnetdata%2Fnetdata&dl=https%3A%2F%2Fmy-netdata.io%2Fgithub%2Flibnetdata%2Fconfig%2FREADME&_u=MAC~&cid=5792dfd7-8dc4-476b-af31-da2fdb9f93d2&tid=UA-64295674-3)]()
diff --git a/libnetdata/config/appconfig.c b/libnetdata/config/appconfig.c
new file mode 100644
index 0000000..9e6a0c0
--- /dev/null
+++ b/libnetdata/config/appconfig.c
@@ -0,0 +1,588 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../libnetdata.h"
+
+#define CONFIG_FILE_LINE_MAX ((CONFIG_MAX_NAME + CONFIG_MAX_VALUE + 1024) * 2)
+
+// ----------------------------------------------------------------------------
+// definitions
+
+#define CONFIG_VALUE_LOADED  0x01 // has been loaded from the config
+#define CONFIG_VALUE_USED    0x02 // has been accessed from the program
+#define CONFIG_VALUE_CHANGED 0x04 // has been changed from the loaded value or the internal default value
+#define CONFIG_VALUE_CHECKED 0x08 // has been checked if the value is different from the default
+
+struct config_option {
+    avl avl;                // the index entry of this entry - this has to be first!
+
+    uint8_t flags;
+    uint32_t hash;          // a simple hash to speed up searching
+                            // we first compare hashes, and only if the hashes are equal we do string comparisons
+
+    char *name;
+    char *value;
+
+    struct config_option *next; // config->mutex protects just this
+};
+
+struct section {
+    avl avl;                // the index entry of this section - this has to be first!
+
+    uint32_t hash;          // a simple hash to speed up searching
+                            // we first compare hashes, and only if the hashes are equal we do string comparisons
+
+    char *name;
+
+    struct section *next;    // gloabl config_mutex protects just this
+
+    struct config_option *values;
+    avl_tree_lock values_index;
+
+    netdata_mutex_t mutex;  // this locks only the writers, to ensure atomic updates
+                            // readers are protected using the rwlock in avl_tree_lock
+};
+
+
+// ----------------------------------------------------------------------------
+// locking
+
+static inline void appconfig_wrlock(struct config *root) {
+    netdata_mutex_lock(&root->mutex);
+}
+
+static inline void appconfig_unlock(struct config *root) {
+    netdata_mutex_unlock(&root->mutex);
+}
+
+static inline void config_section_wrlock(struct section *co) {
+    netdata_mutex_lock(&co->mutex);
+}
+
+static inline void config_section_unlock(struct section *co) {
+    netdata_mutex_unlock(&co->mutex);
+}
+
+
+// ----------------------------------------------------------------------------
+// config name-value index
+
+static int appconfig_option_compare(void *a, void *b) {
+    if(((struct config_option *)a)->hash < ((struct config_option *)b)->hash) return -1;
+    else if(((struct config_option *)a)->hash > ((struct config_option *)b)->hash) return 1;
+    else return strcmp(((struct config_option *)a)->name, ((struct config_option *)b)->name);
+}
+
+#define appconfig_option_index_add(co, cv) (struct config_option *)avl_insert_lock(&((co)->values_index), (avl *)(cv))
+#define appconfig_option_index_del(co, cv) (struct config_option *)avl_remove_lock(&((co)->values_index), (avl *)(cv))
+
+static struct config_option *appconfig_option_index_find(struct section *co, const char *name, uint32_t hash) {
+    struct config_option tmp;
+    tmp.hash = (hash)?hash:simple_hash(name);
+    tmp.name = (char *)name;
+
+    return (struct config_option *)avl_search_lock(&(co->values_index), (avl *) &tmp);
+}
+
+
+// ----------------------------------------------------------------------------
+// config sections index
+
+int appconfig_section_compare(void *a, void *b) {
+    if(((struct section *)a)->hash < ((struct section *)b)->hash) return -1;
+    else if(((struct section *)a)->hash > ((struct section *)b)->hash) return 1;
+    else return strcmp(((struct section *)a)->name, ((struct section *)b)->name);
+}
+
+#define appconfig_index_add(root, cfg) (struct section *)avl_insert_lock(&(root)->index, (avl *)(cfg))
+#define appconfig_index_del(root, cfg) (struct section *)avl_remove_lock(&(root)->index, (avl *)(cfg))
+
+static struct section *appconfig_index_find(struct config *root, const char *name, uint32_t hash) {
+    struct section tmp;
+    tmp.hash = (hash)?hash:simple_hash(name);
+    tmp.name = (char *)name;
+
+    return (struct section *)avl_search_lock(&root->index, (avl *) &tmp);
+}
+
+
+// ----------------------------------------------------------------------------
+// config section methods
+
+static inline struct section *appconfig_section_find(struct config *root, const char *section) {
+    return appconfig_index_find(root, section, 0);
+}
+
+static inline struct section *appconfig_section_create(struct config *root, const char *section) {
+    debug(D_CONFIG, "Creating section '%s'.", section);
+
+    struct section *co = callocz(1, sizeof(struct section));
+    co->name = strdupz(section);
+    co->hash = simple_hash(co->name);
+    netdata_mutex_init(&co->mutex);
+
+    avl_init_lock(&co->values_index, appconfig_option_compare);
+
+    if(unlikely(appconfig_index_add(root, co) != co))
+        error("INTERNAL ERROR: indexing of section '%s', already exists.", co->name);
+
+    appconfig_wrlock(root);
+    struct section *co2 = root->sections;
+    if(co2) {
+        while (co2->next) co2 = co2->next;
+        co2->next = co;
+    }
+    else root->sections = co;
+    appconfig_unlock(root);
+
+    return co;
+}
+
+
+// ----------------------------------------------------------------------------
+// config name-value methods
+
+static inline struct config_option *appconfig_value_create(struct section *co, const char *name, const char *value) {
+    debug(D_CONFIG, "Creating config entry for name '%s', value '%s', in section '%s'.", name, value, co->name);
+
+    struct config_option *cv = callocz(1, sizeof(struct config_option));
+    cv->name = strdupz(name);
+    cv->hash = simple_hash(cv->name);
+    cv->value = strdupz(value);
+
+    struct config_option *found = appconfig_option_index_add(co, cv);
+    if(found != cv) {
+        error("indexing of config '%s' in section '%s': already exists - using the existing one.", cv->name, co->name);
+        freez(cv->value);
+        freez(cv->name);
+        freez(cv);
+        return found;
+    }
+
+    config_section_wrlock(co);
+    struct config_option *cv2 = co->values;
+    if(cv2) {
+        while (cv2->next) cv2 = cv2->next;
+        cv2->next = cv;
+    }
+    else co->values = cv;
+    config_section_unlock(co);
+
+    return cv;
+}
+
+int appconfig_exists(struct config *root, const char *section, const char *name) {
+    struct config_option *cv;
+
+    debug(D_CONFIG, "request to get config in section '%s', name '%s'", section, name);
+
+    struct section *co = appconfig_section_find(root, section);
+    if(!co) return 0;
+
+    cv = appconfig_option_index_find(co, name, 0);
+    if(!cv) return 0;
+
+    return 1;
+}
+
+int appconfig_move(struct config *root, const char *section_old, const char *name_old, const char *section_new, const char *name_new) {
+    struct config_option *cv_old, *cv_new;
+    int ret = -1;
+
+    debug(D_CONFIG, "request to rename config in section '%s', old name '%s', to section '%s', new name '%s'", section_old, name_old, section_new, name_new);
+
+    struct section *co_old = appconfig_section_find(root, section_old);
+    if(!co_old) return ret;
+
+    struct section *co_new = appconfig_section_find(root, section_new);
+    if(!co_new) co_new = appconfig_section_create(root, section_new);
+
+    config_section_wrlock(co_old);
+    if(co_old != co_new)
+        config_section_wrlock(co_new);
+
+    cv_old = appconfig_option_index_find(co_old, name_old, 0);
+    if(!cv_old) goto cleanup;
+
+    cv_new = appconfig_option_index_find(co_new, name_new, 0);
+    if(cv_new) goto cleanup;
+
+    if(unlikely(appconfig_option_index_del(co_old, cv_old) != cv_old))
+        error("INTERNAL ERROR: deletion of config '%s' from section '%s', deleted tge wrong config entry.", cv_old->name, co_old->name);
+
+    if(co_old->values == cv_old) {
+        co_old->values = cv_old->next;
+    }
+    else {
+        struct config_option *t;
+        for(t = co_old->values; t && t->next != cv_old ;t = t->next) ;
+        if(!t || t->next != cv_old)
+            error("INTERNAL ERROR: cannot find variable '%s' in section '%s' of the config - but it should be there.", cv_old->name, co_old->name);
+        else
+            t->next = cv_old->next;
+    }
+
+    freez(cv_old->name);
+    cv_old->name = strdupz(name_new);
+    cv_old->hash = simple_hash(cv_old->name);
+
+    cv_new = cv_old;
+    cv_new->next = co_new->values;
+    co_new->values = cv_new;
+
+    if(unlikely(appconfig_option_index_add(co_new, cv_old) != cv_old))
+        error("INTERNAL ERROR: re-indexing of config '%s' in section '%s', already exists.", cv_old->name, co_new->name);
+
+    ret = 0;
+
+cleanup:
+    if(co_old != co_new)
+        config_section_unlock(co_new);
+    config_section_unlock(co_old);
+    return ret;
+}
+
+char *appconfig_get(struct config *root, const char *section, const char *name, const char *default_value)
+{
+    struct config_option *cv;
+
+    debug(D_CONFIG, "request to get config in section '%s', name '%s', default_value '%s'", section, name, default_value);
+
+    struct section *co = appconfig_section_find(root, section);
+    if(!co) co = appconfig_section_create(root, section);
+
+    cv = appconfig_option_index_find(co, name, 0);
+    if(!cv) {
+        cv = appconfig_value_create(co, name, default_value);
+        if(!cv) return NULL;
+    }
+    cv->flags |= CONFIG_VALUE_USED;
+
+    if((cv->flags & CONFIG_VALUE_LOADED) || (cv->flags & CONFIG_VALUE_CHANGED)) {
+        // this is a loaded value from the config file
+        // if it is different that the default, mark it
+        if(!(cv->flags & CONFIG_VALUE_CHECKED)) {
+            if(strcmp(cv->value, default_value) != 0) cv->flags |= CONFIG_VALUE_CHANGED;
+            cv->flags |= CONFIG_VALUE_CHECKED;
+        }
+    }
+
+    return(cv->value);
+}
+
+long long appconfig_get_number(struct config *root, const char *section, const char *name, long long value)
+{
+    char buffer[100], *s;
+    sprintf(buffer, "%lld", value);
+
+    s = appconfig_get(root, section, name, buffer);
+    if(!s) return value;
+
+    return strtoll(s, NULL, 0);
+}
+
+LONG_DOUBLE appconfig_get_float(struct config *root, const char *section, const char *name, LONG_DOUBLE value)
+{
+    char buffer[100], *s;
+    sprintf(buffer, "%0.5" LONG_DOUBLE_MODIFIER, value);
+
+    s = appconfig_get(root, section, name, buffer);
+    if(!s) return value;
+
+    return str2ld(s, NULL);
+}
+
+int appconfig_get_boolean(struct config *root, const char *section, const char *name, int value)
+{
+    char *s;
+    if(value) s = "yes";
+    else s = "no";
+
+    s = appconfig_get(root, section, name, s);
+    if(!s) return value;
+
+    if(!strcasecmp(s, "yes") || !strcasecmp(s, "true") || !strcasecmp(s, "on") || !strcasecmp(s, "auto") || !strcasecmp(s, "on demand")) return 1;
+    return 0;
+}
+
+int appconfig_get_boolean_ondemand(struct config *root, const char *section, const char *name, int value)
+{
+    char *s;
+
+    if(value == CONFIG_BOOLEAN_AUTO)
+        s = "auto";
+
+    else if(value == CONFIG_BOOLEAN_NO)
+        s = "no";
+
+    else
+        s = "yes";
+
+    s = appconfig_get(root, section, name, s);
+    if(!s) return value;
+
+    if(!strcmp(s, "yes"))
+        return CONFIG_BOOLEAN_YES;
+    else if(!strcmp(s, "no"))
+        return CONFIG_BOOLEAN_NO;
+    else if(!strcmp(s, "auto") || !strcmp(s, "on demand"))
+        return CONFIG_BOOLEAN_AUTO;
+
+    return value;
+}
+
+const char *appconfig_set_default(struct config *root, const char *section, const char *name, const char *value)
+{
+    struct config_option *cv;
+
+    debug(D_CONFIG, "request to set default config in section '%s', name '%s', value '%s'", section, name, value);
+
+    struct section *co = appconfig_section_find(root, section);
+    if(!co) return appconfig_set(root, section, name, value);
+
+    cv = appconfig_option_index_find(co, name, 0);
+    if(!cv) return appconfig_set(root, section, name, value);
+
+    cv->flags |= CONFIG_VALUE_USED;
+
+    if(cv->flags & CONFIG_VALUE_LOADED)
+        return cv->value;
+
+    if(strcmp(cv->value, value) != 0) {
+        cv->flags |= CONFIG_VALUE_CHANGED;
+
+        freez(cv->value);
+        cv->value = strdupz(value);
+    }
+
+    return cv->value;
+}
+
+const char *appconfig_set(struct config *root, const char *section, const char *name, const char *value)
+{
+    struct config_option *cv;
+
+    debug(D_CONFIG, "request to set config in section '%s', name '%s', value '%s'", section, name, value);
+
+    struct section *co = appconfig_section_find(root, section);
+    if(!co) co = appconfig_section_create(root, section);
+
+    cv = appconfig_option_index_find(co, name, 0);
+    if(!cv) cv = appconfig_value_create(co, name, value);
+    cv->flags |= CONFIG_VALUE_USED;
+
+    if(strcmp(cv->value, value) != 0) {
+        cv->flags |= CONFIG_VALUE_CHANGED;
+
+        freez(cv->value);
+        cv->value = strdupz(value);
+    }
+
+    return value;
+}
+
+long long appconfig_set_number(struct config *root, const char *section, const char *name, long long value)
+{
+    char buffer[100];
+    sprintf(buffer, "%lld", value);
+
+    appconfig_set(root, section, name, buffer);
+
+    return value;
+}
+
+LONG_DOUBLE appconfig_set_float(struct config *root, const char *section, const char *name, LONG_DOUBLE value)
+{
+    char buffer[100];
+    sprintf(buffer, "%0.5" LONG_DOUBLE_MODIFIER, value);
+
+    appconfig_set(root, section, name, buffer);
+
+    return value;
+}
+
+int appconfig_set_boolean(struct config *root, const char *section, const char *name, int value)
+{
+    char *s;
+    if(value) s = "yes";
+    else s = "no";
+
+    appconfig_set(root, section, name, s);
+
+    return value;
+}
+
+
+// ----------------------------------------------------------------------------
+// config load/save
+
+int appconfig_load(struct config *root, char *filename, int overwrite_used)
+{
+    int line = 0;
+    struct section *co = NULL;
+
+    char buffer[CONFIG_FILE_LINE_MAX + 1], *s;
+
+    if(!filename) filename = CONFIG_DIR "/" CONFIG_FILENAME;
+
+    debug(D_CONFIG, "CONFIG: opening config file '%s'", filename);
+
+    FILE *fp = fopen(filename, "r");
+    if(!fp) {
+        // info("CONFIG: cannot open file '%s'. Using internal defaults.", filename);
+        return 0;
+    }
+
+    while(fgets(buffer, CONFIG_FILE_LINE_MAX, fp) != NULL) {
+        buffer[CONFIG_FILE_LINE_MAX] = '\0';
+        line++;
+
+        s = trim(buffer);
+        if(!s || *s == '#') {
+            debug(D_CONFIG, "CONFIG: ignoring line %d of file '%s', it is empty.", line, filename);
+            continue;
+        }
+
+        int len = (int) strlen(s);
+        if(*s == '[' && s[len - 1] == ']') {
+            // new section
+            s[len - 1] = '\0';
+            s++;
+
+            co = appconfig_section_find(root, s);
+            if(!co) co = appconfig_section_create(root, s);
+
+            continue;
+        }
+
+        if(!co) {
+            // line outside a section
+            error("CONFIG: ignoring line %d ('%s') of file '%s', it is outside all sections.", line, s, filename);
+            continue;
+        }
+
+        char *name = s;
+        char *value = strchr(s, '=');
+        if(!value) {
+            error("CONFIG: ignoring line %d ('%s') of file '%s', there is no = in it.", line, s, filename);
+            continue;
+        }
+        *value = '\0';
+        value++;
+
+        name = trim(name);
+        value = trim(value);
+
+        if(!name || *name == '#') {
+            error("CONFIG: ignoring line %d of file '%s', name is empty.", line, filename);
+            continue;
+        }
+
+        if(!value) value = "";
+
+        struct config_option *cv = appconfig_option_index_find(co, name, 0);
+
+        if(!cv) cv = appconfig_value_create(co, name, value);
+        else {
+            if(((cv->flags & CONFIG_VALUE_USED) && overwrite_used) || !(cv->flags & CONFIG_VALUE_USED)) {
+                debug(D_CONFIG, "CONFIG: line %d of file '%s', overwriting '%s/%s'.", line, filename, co->name, cv->name);
+                freez(cv->value);
+                cv->value = strdupz(value);
+            }
+            else
+                debug(D_CONFIG, "CONFIG: ignoring line %d of file '%s', '%s/%s' is already present and used.", line, filename, co->name, cv->name);
+        }
+        cv->flags |= CONFIG_VALUE_LOADED;
+    }
+
+    fclose(fp);
+
+    return 1;
+}
+
+void appconfig_generate(struct config *root, BUFFER *wb, int only_changed)
+{
+    int i, pri;
+    struct section *co;
+    struct config_option *cv;
+
+    for(i = 0; i < 3 ;i++) {
+        switch(i) {
+            case 0:
+                buffer_strcat(wb,
+                    "# netdata configuration\n"
+                    "#\n"
+                    "# You can download the latest version of this file, using:\n"
+                    "#\n"
+                    "#  wget -O /etc/netdata/netdata.conf http://localhost:19999/netdata.conf\n"
+                    "# or\n"
+                    "#  curl -o /etc/netdata/netdata.conf http://localhost:19999/netdata.conf\n"
+                    "#\n"
+                    "# You can uncomment and change any of the options below.\n"
+                    "# The value shown in the commented settings, is the default value.\n"
+                    "#\n"
+                    "\n# global netdata configuration\n");
+                break;
+
+            case 1:
+                buffer_strcat(wb, "\n\n# per plugin configuration\n");
+                break;
+
+            case 2:
+                buffer_strcat(wb, "\n\n# per chart configuration\n");
+                break;
+        }
+
+        appconfig_wrlock(root);
+        for(co = root->sections; co ; co = co->next) {
+            if(!strcmp(co->name, CONFIG_SECTION_GLOBAL)
+               || !strcmp(co->name, CONFIG_SECTION_WEB)
+               || !strcmp(co->name, CONFIG_SECTION_STATSD)
+               || !strcmp(co->name, CONFIG_SECTION_PLUGINS)
+               || !strcmp(co->name, CONFIG_SECTION_CLOUD)
+               || !strcmp(co->name, CONFIG_SECTION_REGISTRY)
+               || !strcmp(co->name, CONFIG_SECTION_HEALTH)
+               || !strcmp(co->name, CONFIG_SECTION_BACKEND)
+               || !strcmp(co->name, CONFIG_SECTION_STREAM)
+                    )
+                pri = 0;
+            else if(!strncmp(co->name, "plugin:", 7)) pri = 1;
+            else pri = 2;
+
+            if(i == pri) {
+                int loaded = 0;
+                int used = 0;
+                int changed = 0;
+                int count = 0;
+
+                config_section_wrlock(co);
+                for(cv = co->values; cv ; cv = cv->next) {
+                    used += (cv->flags & CONFIG_VALUE_USED)?1:0;
+                    loaded += (cv->flags & CONFIG_VALUE_LOADED)?1:0;
+                    changed += (cv->flags & CONFIG_VALUE_CHANGED)?1:0;
+                    count++;
+                }
+                config_section_unlock(co);
+
+                if(!count) continue;
+                if(only_changed && !changed && !loaded) continue;
+
+                if(!used) {
+                    buffer_sprintf(wb, "\n# section '%s' is not used.", co->name);
+                }
+
+                buffer_sprintf(wb, "\n[%s]\n", co->name);
+
+                config_section_wrlock(co);
+                for(cv = co->values; cv ; cv = cv->next) {
+
+                    if(used && !(cv->flags & CONFIG_VALUE_USED)) {
+                        buffer_sprintf(wb, "\n\t# option '%s' is not used.\n", cv->name);
+                    }
+                    buffer_sprintf(wb, "\t%s%s = %s\n", ((!(cv->flags & CONFIG_VALUE_LOADED)) && (!(cv->flags & CONFIG_VALUE_CHANGED)) && (cv->flags & CONFIG_VALUE_USED))?"# ":"", cv->name, cv->value);
+                }
+                config_section_unlock(co);
+            }
+        }
+        appconfig_unlock(root);
+    }
+}
diff --git a/libnetdata/config/appconfig.h b/libnetdata/config/appconfig.h
new file mode 100644
index 0000000..78099aa
--- /dev/null
+++ b/libnetdata/config/appconfig.h
@@ -0,0 +1,136 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+/*
+ * This section manages ini config files, like netdata.conf and stream.conf
+ *
+ * It is organized like this:
+ *
+ * struct config (i.e. netdata.conf or stream.conf)
+ *   .sections    = a linked list of struct section
+ *   .mutex       = a mutex to protect the above linked list due to multi-threading
+ *   .index       = an AVL tree of struct section
+ *
+ * struct section (i.e. [global] or [health] of netdata.conf)
+ *   .value       = a linked list of struct config_option
+ *   .mutex       = a mutex to protect the above linked list due to multi-threading
+ *   .value_index = an AVL tree of struct config_option
+ *
+ * struct config_option (ie. a name-value pair for each ini file option)
+ *
+ * The following operations on name-value options are supported:
+ *    SET           to set the value of an option
+ *    SET DEFAULT   to set the value and the default value of an option
+ *    GET           to get the value of an option
+ *    EXISTS        to check if an option exists
+ *    MOVE          to move an option from a section to another section, and/or rename it
+ *
+ *    GET and SET operations are provided for the following data types:
+ *                  STRING
+ *                  NUMBER (long long)
+ *                  FLOAT (long double)
+ *                  BOOLEAN (false, true)
+ *                  BOOLEAN ONDEMAND (false, true, auto)
+ *
+ *   GET and SET operations create struct config_option, if it is not already present.
+ *   This allows netdata to run even without netdata.conf and stream.conf. The internal
+ *   defaults are used to create the structure that should exist in the ini file and the config
+ *   file can be downloaded from the server.
+ *
+ *   Also 2 operations are supported for the whole config file:
+ *
+ *     LOAD         To load the ini file from disk
+ *     GENERATE     To generate the ini file (this is used to download the ini file from the server)
+ *
+ * For each option (name-value pair), the system maintains 4 flags:
+ *   LOADED   to indicate that the value has been loaded from the file
+ *   USED     to indicate that netdata used the value
+ *   CHANGED  to indicate that the value has been changed from the loaded value or the internal default value
+ *   CHECKED  is used internally for optimization (to avoid an strcmp() every time GET is called).
+ *
+ * TODO:
+ * 1. The linked lists and the mutexes can be removed and the AVL trees can become DICTIONARY.
+ *    This part of the code was written before we add traversal to AVL.
+ *
+ * 2. High level data types could be supported, to simplify the rest of the code:
+ *       MULTIPLE CHOICE  to let the user select one of the supported keywords
+ *                        this would allow users see in comments the available options
+ *
+ *       SIMPLE PATTERN   to let the user define netdata SIMPLE PATTERNS
+ *
+ * 3. Sorting of options should be supported.
+ *    Today, when the ini file is downloaded from the server, the options are shown in the order
+ *    they appear in the linked list (the order they were added, listing changed options first).
+ *    If we remove the linked list, the order they appear in the AVL tree will be used (which is
+ *    random due to simple_hash()).
+ *    Ideally, we support sorting of options when generating the ini file.
+ *
+ * 4. There is no free() operation. So, memory is freed on netdata exit.
+ *
+ * 5. Avoid memory fragmentation
+ *    Since entries are created from multiple threads and a lot of allocations are required
+ *    for each config_option, fragmentation can be a problem for IoT.
+ *
+ * 6. Although this way of managing options is quite flexible and dynamic, it wastes memory
+ *    for the names of the options. Since most of the option names are static, we could provide
+ *    a method to allocate only the dynamic option names.
+ */
+
+#ifndef NETDATA_CONFIG_H
+#define NETDATA_CONFIG_H 1
+
+#include "../libnetdata.h"
+
+#define CONFIG_FILENAME "netdata.conf"
+
+#define CONFIG_SECTION_GLOBAL   "global"
+#define CONFIG_SECTION_WEB      "web"
+#define CONFIG_SECTION_STATSD   "statsd"
+#define CONFIG_SECTION_PLUGINS  "plugins"
+#define CONFIG_SECTION_CLOUD    "cloud"
+#define CONFIG_SECTION_REGISTRY "registry"
+#define CONFIG_SECTION_HEALTH   "health"
+#define CONFIG_SECTION_BACKEND  "backend"
+#define CONFIG_SECTION_STREAM   "stream"
+
+// these are used to limit the configuration names and values lengths
+// they are not enforced by config.c functions (they will strdup() all strings, no matter of their length)
+#define CONFIG_MAX_NAME 1024
+#define CONFIG_MAX_VALUE 2048
+
+struct config {
+    struct section *sections;
+    netdata_mutex_t mutex;
+    avl_tree_lock index;
+};
+
+#define CONFIG_BOOLEAN_INVALID 100  // an invalid value to check for validity (used as default initialization when needed)
+
+#define CONFIG_BOOLEAN_NO   0       // disabled
+#define CONFIG_BOOLEAN_YES  1       // enabled
+
+#ifndef CONFIG_BOOLEAN_AUTO
+#define CONFIG_BOOLEAN_AUTO 2       // enabled if it has useful info when enabled
+#endif
+
+extern int appconfig_load(struct config *root, char *filename, int overwrite_used);
+
+extern char *appconfig_get(struct config *root, const char *section, const char *name, const char *default_value);
+extern long long appconfig_get_number(struct config *root, const char *section, const char *name, long long value);
+extern LONG_DOUBLE appconfig_get_float(struct config *root, const char *section, const char *name, LONG_DOUBLE value);
+extern int appconfig_get_boolean(struct config *root, const char *section, const char *name, int value);
+extern int appconfig_get_boolean_ondemand(struct config *root, const char *section, const char *name, int value);
+
+extern const char *appconfig_set(struct config *root, const char *section, const char *name, const char *value);
+extern const char *appconfig_set_default(struct config *root, const char *section, const char *name, const char *value);
+extern long long appconfig_set_number(struct config *root, const char *section, const char *name, long long value);
+extern LONG_DOUBLE appconfig_set_float(struct config *root, const char *section, const char *name, LONG_DOUBLE value);
+extern int appconfig_set_boolean(struct config *root, const char *section, const char *name, int value);
+
+extern int appconfig_exists(struct config *root, const char *section, const char *name);
+extern int appconfig_move(struct config *root, const char *section_old, const char *name_old, const char *section_new, const char *name_new);
+
+extern void appconfig_generate(struct config *root, BUFFER *wb, int only_changed);
+
+extern int appconfig_section_compare(void *a, void *b);
+
+#endif /* NETDATA_CONFIG_H */
diff --git a/libnetdata/dictionary/Makefile.am b/libnetdata/dictionary/Makefile.am
new file mode 100644
index 0000000..1cb69ed
--- /dev/null
+++ b/libnetdata/dictionary/Makefile.am
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
+
+
+dist_noinst_DATA = \
+	README.md \
+	$(NULL)
diff --git a/libnetdata/dictionary/README.md b/libnetdata/dictionary/README.md
new file mode 100644
index 0000000..9c70522
--- /dev/null
+++ b/libnetdata/dictionary/README.md
@@ -0,0 +1,2 @@
+
+[![analytics](https://www.google-analytics.com/collect?v=1&aip=1&t=pageview&_s=1&ds=github&dr=https%3A%2F%2Fgithub.com%2Fnetdata%2Fnetdata&dl=https%3A%2F%2Fmy-netdata.io%2Fgithub%2Flibnetdata%2Fdictionary%2FREADME&_u=MAC~&cid=5792dfd7-8dc4-476b-af31-da2fdb9f93d2&tid=UA-64295674-3)]()
diff --git a/libnetdata/dictionary/dictionary.c b/libnetdata/dictionary/dictionary.c
new file mode 100644
index 0000000..cfcf1fb
--- /dev/null
+++ b/libnetdata/dictionary/dictionary.c
@@ -0,0 +1,329 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../libnetdata.h"
+
+// ----------------------------------------------------------------------------
+// dictionary statistics
+
+static inline void NETDATA_DICTIONARY_STATS_INSERTS_PLUS1(DICTIONARY *dict) {
+    if(likely(dict->stats))
+        dict->stats->inserts++;
+}
+static inline void NETDATA_DICTIONARY_STATS_DELETES_PLUS1(DICTIONARY *dict) {
+    if(likely(dict->stats))
+        dict->stats->deletes++;
+}
+static inline void NETDATA_DICTIONARY_STATS_SEARCHES_PLUS1(DICTIONARY *dict) {
+    if(likely(dict->stats))
+        dict->stats->searches++;
+}
+static inline void NETDATA_DICTIONARY_STATS_ENTRIES_PLUS1(DICTIONARY *dict) {
+    if(likely(dict->stats))
+        dict->stats->entries++;
+}
+static inline void NETDATA_DICTIONARY_STATS_ENTRIES_MINUS1(DICTIONARY *dict) {
+    if(likely(dict->stats))
+        dict->stats->entries--;
+}
+
+
+// ----------------------------------------------------------------------------
+// dictionary locks
+
+static inline void dictionary_read_lock(DICTIONARY *dict) {
+    if(likely(dict->rwlock)) {
+        // debug(D_DICTIONARY, "Dictionary READ lock");
+        netdata_rwlock_rdlock(dict->rwlock);
+    }
+}
+
+static inline void dictionary_write_lock(DICTIONARY *dict) {
+    if(likely(dict->rwlock)) {
+        // debug(D_DICTIONARY, "Dictionary WRITE lock");
+        netdata_rwlock_wrlock(dict->rwlock);
+    }
+}
+
+static inline void dictionary_unlock(DICTIONARY *dict) {
+    if(likely(dict->rwlock)) {
+        // debug(D_DICTIONARY, "Dictionary UNLOCK lock");
+        netdata_rwlock_unlock(dict->rwlock);
+    }
+}
+
+
+// ----------------------------------------------------------------------------
+// avl index
+
+static int name_value_compare(void* a, void* b) {
+    if(((NAME_VALUE *)a)->hash < ((NAME_VALUE *)b)->hash) return -1;
+    else if(((NAME_VALUE *)a)->hash > ((NAME_VALUE *)b)->hash) return 1;
+    else return strcmp(((NAME_VALUE *)a)->name, ((NAME_VALUE *)b)->name);
+}
+
+static inline NAME_VALUE *dictionary_name_value_index_find_nolock(DICTIONARY *dict, const char *name, uint32_t hash) {
+    NAME_VALUE tmp;
+    tmp.hash = (hash)?hash:simple_hash(name);
+    tmp.name = (char *)name;
+
+    NETDATA_DICTIONARY_STATS_SEARCHES_PLUS1(dict);
+    return (NAME_VALUE *)avl_search(&(dict->values_index), (avl *) &tmp);
+}
+
+// ----------------------------------------------------------------------------
+// internal methods
+
+static NAME_VALUE *dictionary_name_value_create_nolock(DICTIONARY *dict, const char *name, void *value, size_t value_len, uint32_t hash) {
+    debug(D_DICTIONARY, "Creating name value entry for name '%s'.", name);
+
+    NAME_VALUE *nv = callocz(1, sizeof(NAME_VALUE));
+
+    if(dict->flags & DICTIONARY_FLAG_NAME_LINK_DONT_CLONE)
+        nv->name = (char *)name;
+    else {
+        nv->name = strdupz(name);
+    }
+
+    nv->hash = (hash)?hash:simple_hash(nv->name);
+
+    if(dict->flags & DICTIONARY_FLAG_VALUE_LINK_DONT_CLONE)
+        nv->value = value;
+    else {
+        nv->value = mallocz(value_len);
+        memcpy(nv->value, value, value_len);
+    }
+
+    // index it
+    NETDATA_DICTIONARY_STATS_INSERTS_PLUS1(dict);
+    if(unlikely(avl_insert(&((dict)->values_index), (avl *)(nv)) != (avl *)nv))
+        error("dictionary: INTERNAL ERROR: duplicate insertion to dictionary.");
+
+    NETDATA_DICTIONARY_STATS_ENTRIES_PLUS1(dict);
+
+    return nv;
+}
+
+static void dictionary_name_value_destroy_nolock(DICTIONARY *dict, NAME_VALUE *nv) {
+    debug(D_DICTIONARY, "Destroying name value entry for name '%s'.", nv->name);
+
+    NETDATA_DICTIONARY_STATS_DELETES_PLUS1(dict);
+    if(unlikely(avl_remove(&(dict->values_index), (avl *)(nv)) != (avl *)nv))
+        error("dictionary: INTERNAL ERROR: dictionary invalid removal of node.");
+
+    NETDATA_DICTIONARY_STATS_ENTRIES_MINUS1(dict);
+
+    if(!(dict->flags & DICTIONARY_FLAG_VALUE_LINK_DONT_CLONE)) {
+        debug(D_REGISTRY, "Dictionary freeing value of '%s'", nv->name);
+        freez(nv->value);
+    }
+
+    if(!(dict->flags & DICTIONARY_FLAG_NAME_LINK_DONT_CLONE)) {
+        debug(D_REGISTRY, "Dictionary freeing name '%s'", nv->name);
+        freez(nv->name);
+    }
+
+    freez(nv);
+}
+
+// ----------------------------------------------------------------------------
+// API - basic methods
+
+DICTIONARY *dictionary_create(uint8_t flags) {
+    debug(D_DICTIONARY, "Creating dictionary.");
+
+    DICTIONARY *dict = callocz(1, sizeof(DICTIONARY));
+
+    if(flags & DICTIONARY_FLAG_WITH_STATISTICS)
+        dict->stats = callocz(1, sizeof(struct dictionary_stats));
+
+    if(!(flags & DICTIONARY_FLAG_SINGLE_THREADED)) {
+        dict->rwlock = callocz(1, sizeof(netdata_rwlock_t));
+        netdata_rwlock_init(dict->rwlock);
+    }
+
+    avl_init(&dict->values_index, name_value_compare);
+    dict->flags = flags;
+
+    return dict;
+}
+
+void dictionary_destroy(DICTIONARY *dict) {
+    debug(D_DICTIONARY, "Destroying dictionary.");
+
+    dictionary_write_lock(dict);
+
+    while(dict->values_index.root)
+        dictionary_name_value_destroy_nolock(dict, (NAME_VALUE *)dict->values_index.root);
+
+    dictionary_unlock(dict);
+
+    if(dict->stats)
+        freez(dict->stats);
+
+    if(dict->rwlock) {
+        netdata_rwlock_destroy(dict->rwlock);
+        freez(dict->rwlock);
+    }
+
+    freez(dict);
+}
+
+// ----------------------------------------------------------------------------
+
+void *dictionary_set(DICTIONARY *dict, const char *name, void *value, size_t value_len) {
+    debug(D_DICTIONARY, "SET dictionary entry with name '%s'.", name);
+
+    uint32_t hash = simple_hash(name);
+
+    dictionary_write_lock(dict);
+
+    NAME_VALUE *nv = dictionary_name_value_index_find_nolock(dict, name, hash);
+    if(unlikely(!nv)) {
+        debug(D_DICTIONARY, "Dictionary entry with name '%s' not found. Creating a new one.", name);
+
+        nv = dictionary_name_value_create_nolock(dict, name, value, value_len, hash);
+        if(unlikely(!nv))
+            fatal("Cannot create name_value.");
+    }
+    else {
+        debug(D_DICTIONARY, "Dictionary entry with name '%s' found. Changing its value.", name);
+
+        if(dict->flags & DICTIONARY_FLAG_VALUE_LINK_DONT_CLONE) {
+            debug(D_REGISTRY, "Dictionary: linking value to '%s'", name);
+            nv->value = value;
+        }
+        else {
+            debug(D_REGISTRY, "Dictionary: cloning value to '%s'", name);
+
+            // copy the new value without breaking
+            // any other thread accessing the same entry
+            void *new = mallocz(value_len),
+                    *old = nv->value;
+
+            memcpy(new, value, value_len);
+            nv->value = new;
+
+            debug(D_REGISTRY, "Dictionary: freeing old value of '%s'", name);
+            freez(old);
+        }
+    }
+
+    dictionary_unlock(dict);
+
+    return nv->value;
+}
+
+void *dictionary_get(DICTIONARY *dict, const char *name) {
+    debug(D_DICTIONARY, "GET dictionary entry with name '%s'.", name);
+
+    dictionary_read_lock(dict);
+    NAME_VALUE *nv = dictionary_name_value_index_find_nolock(dict, name, 0);
+    dictionary_unlock(dict);
+
+    if(unlikely(!nv)) {
+        debug(D_DICTIONARY, "Not found dictionary entry with name '%s'.", name);
+        return NULL;
+    }
+
+    debug(D_DICTIONARY, "Found dictionary entry with name '%s'.", name);
+    return nv->value;
+}
+
+int dictionary_del(DICTIONARY *dict, const char *name) {
+    int ret;
+
+    debug(D_DICTIONARY, "DEL dictionary entry with name '%s'.", name);
+
+    dictionary_write_lock(dict);
+
+    NAME_VALUE *nv = dictionary_name_value_index_find_nolock(dict, name, 0);
+    if(unlikely(!nv)) {
+        debug(D_DICTIONARY, "Not found dictionary entry with name '%s'.", name);
+        ret = -1;
+    }
+    else {
+        debug(D_DICTIONARY, "Found dictionary entry with name '%s'.", name);
+        dictionary_name_value_destroy_nolock(dict, nv);
+        ret = 0;
+    }
+
+    dictionary_unlock(dict);
+
+    return ret;
+}
+
+
+// ----------------------------------------------------------------------------
+// API - walk through the dictionary
+// the dictionary is locked for reading while this happens
+// do not user other dictionary calls while walking the dictionary - deadlock!
+
+static int dictionary_walker(avl *a, int (*callback)(void *entry, void *data), void *data) {
+    int total = 0, ret = 0;
+
+    if(a->avl_link[0]) {
+        ret = dictionary_walker(a->avl_link[0], callback, data);
+        if(ret < 0) return ret;
+        total += ret;
+    }
+
+    ret = callback(((NAME_VALUE *)a)->value, data);
+    if(ret < 0) return ret;
+    total += ret;
+
+    if(a->avl_link[1]) {
+        ret = dictionary_walker(a->avl_link[1], callback, data);
+        if (ret < 0) return ret;
+        total += ret;
+    }
+
+    return total;
+}
+
+int dictionary_get_all(DICTIONARY *dict, int (*callback)(void *entry, void *data), void *data) {
+    int ret = 0;
+
+    dictionary_read_lock(dict);
+
+    if(likely(dict->values_index.root))
+        ret = dictionary_walker(dict->values_index.root, callback, data);
+
+    dictionary_unlock(dict);
+
+    return ret;
+}
+
+static int dictionary_walker_name_value(avl *a, int (*callback)(char *name, void *entry, void *data), void *data) {
+    int total = 0, ret = 0;
+
+    if(a->avl_link[0]) {
+        ret = dictionary_walker_name_value(a->avl_link[0], callback, data);
+        if(ret < 0) return ret;
+        total += ret;
+    }
+
+    ret = callback(((NAME_VALUE *)a)->name, ((NAME_VALUE *)a)->value, data);
+    if(ret < 0) return ret;
+    total += ret;
+
+    if(a->avl_link[1]) {
+        ret = dictionary_walker_name_value(a->avl_link[1], callback, data);
+        if (ret < 0) return ret;
+        total += ret;
+    }
+
+    return total;
+}
+
+int dictionary_get_all_name_value(DICTIONARY *dict, int (*callback)(char *name, void *entry, void *data), void *data) {
+    int ret = 0;
+
+    dictionary_read_lock(dict);
+
+    if(likely(dict->values_index.root))
+        ret = dictionary_walker_name_value(dict->values_index.root, callback, data);
+
+    dictionary_unlock(dict);
+
+    return ret;
+}
diff --git a/libnetdata/dictionary/dictionary.h b/libnetdata/dictionary/dictionary.h
new file mode 100644
index 0000000..9be261e
--- /dev/null
+++ b/libnetdata/dictionary/dictionary.h
@@ -0,0 +1,49 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_DICTIONARY_H
+#define NETDATA_DICTIONARY_H 1
+
+#include "../libnetdata.h"
+
+struct dictionary_stats {
+    unsigned long long inserts;
+    unsigned long long deletes;
+    unsigned long long searches;
+    unsigned long long entries;
+};
+
+typedef struct name_value {
+    avl avl;                // the index - this has to be first!
+
+    uint32_t hash;          // a simple hash to speed up searching
+                            // we first compare hashes, and only if the hashes are equal we do string comparisons
+
+    char *name;
+    void *value;
+} NAME_VALUE;
+
+typedef struct dictionary {
+    avl_tree values_index;
+
+    uint8_t flags;
+
+    struct dictionary_stats *stats;
+    netdata_rwlock_t *rwlock;
+} DICTIONARY;
+
+#define DICTIONARY_FLAG_DEFAULT                 0x00000000
+#define DICTIONARY_FLAG_SINGLE_THREADED         0x00000001
+#define DICTIONARY_FLAG_VALUE_LINK_DONT_CLONE   0x00000002
+#define DICTIONARY_FLAG_NAME_LINK_DONT_CLONE    0x00000004
+#define DICTIONARY_FLAG_WITH_STATISTICS         0x00000008
+
+extern DICTIONARY *dictionary_create(uint8_t flags);
+extern void dictionary_destroy(DICTIONARY *dict);
+extern void *dictionary_set(DICTIONARY *dict, const char *name, void *value, size_t value_len) NEVERNULL;
+extern void *dictionary_get(DICTIONARY *dict, const char *name);
+extern int dictionary_del(DICTIONARY *dict, const char *name);
+
+extern int dictionary_get_all(DICTIONARY *dict, int (*callback)(void *entry, void *d), void *data);
+extern int dictionary_get_all_name_value(DICTIONARY *dict, int (*callback)(char *name, void *entry, void *d), void *data);
+
+#endif /* NETDATA_DICTIONARY_H */
diff --git a/libnetdata/eval/Makefile.am b/libnetdata/eval/Makefile.am
new file mode 100644
index 0000000..1cb69ed
--- /dev/null
+++ b/libnetdata/eval/Makefile.am
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
+
+
+dist_noinst_DATA = \
+	README.md \
+	$(NULL)
diff --git a/libnetdata/eval/README.md b/libnetdata/eval/README.md
new file mode 100644
index 0000000..e7b4579
--- /dev/null
+++ b/libnetdata/eval/README.md
@@ -0,0 +1,2 @@
+
+[![analytics](https://www.google-analytics.com/collect?v=1&aip=1&t=pageview&_s=1&ds=github&dr=https%3A%2F%2Fgithub.com%2Fnetdata%2Fnetdata&dl=https%3A%2F%2Fmy-netdata.io%2Fgithub%2Flibnetdata%2Feval%2FREADME&_u=MAC~&cid=5792dfd7-8dc4-476b-af31-da2fdb9f93d2&tid=UA-64295674-3)]()
diff --git a/libnetdata/eval/eval.c b/libnetdata/eval/eval.c
new file mode 100644
index 0000000..0316eda
--- /dev/null
+++ b/libnetdata/eval/eval.c
@@ -0,0 +1,1190 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../libnetdata.h"
+
+// ----------------------------------------------------------------------------
+// data structures for storing the parsed expression in memory
+
+typedef struct eval_value {
+    int type;
+
+    union {
+        calculated_number number;
+        EVAL_VARIABLE *variable;
+        struct eval_node *expression;
+    };
+} EVAL_VALUE;
+
+typedef struct eval_node {
+    int id;
+    unsigned char operator;
+    int precedence;
+
+    int count;
+    EVAL_VALUE ops[];
+} EVAL_NODE;
+
+// these are used for EVAL_NODE.operator
+// they are used as internal IDs to identify an operator
+// THEY ARE NOT USED FOR PARSING OPERATORS LIKE THAT
+#define EVAL_OPERATOR_NOP                   '\0'
+#define EVAL_OPERATOR_EXPRESSION_OPEN       '('
+#define EVAL_OPERATOR_EXPRESSION_CLOSE      ')'
+#define EVAL_OPERATOR_NOT                   '!'
+#define EVAL_OPERATOR_PLUS                  '+'
+#define EVAL_OPERATOR_MINUS                 '-'
+#define EVAL_OPERATOR_AND                   '&'
+#define EVAL_OPERATOR_OR                    '|'
+#define EVAL_OPERATOR_GREATER_THAN_OR_EQUAL 'G'
+#define EVAL_OPERATOR_LESS_THAN_OR_EQUAL    'L'
+#define EVAL_OPERATOR_NOT_EQUAL             '~'
+#define EVAL_OPERATOR_EQUAL                 '='
+#define EVAL_OPERATOR_LESS                  '<'
+#define EVAL_OPERATOR_GREATER               '>'
+#define EVAL_OPERATOR_MULTIPLY              '*'
+#define EVAL_OPERATOR_DIVIDE                '/'
+#define EVAL_OPERATOR_SIGN_PLUS             'P'
+#define EVAL_OPERATOR_SIGN_MINUS            'M'
+#define EVAL_OPERATOR_ABS                   'A'
+#define EVAL_OPERATOR_IF_THEN_ELSE          '?'
+
+// ----------------------------------------------------------------------------
+// forward function definitions
+
+static inline void eval_node_free(EVAL_NODE *op);
+static inline EVAL_NODE *parse_full_expression(const char **string, int *error);
+static inline EVAL_NODE *parse_one_full_operand(const char **string, int *error);
+static inline calculated_number eval_node(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error);
+static inline void print_parsed_as_node(BUFFER *out, EVAL_NODE *op, int *error);
+static inline void print_parsed_as_constant(BUFFER *out, calculated_number n);
+
+// ----------------------------------------------------------------------------
+// evaluation of expressions
+
+static inline calculated_number eval_variable(EVAL_EXPRESSION *exp, EVAL_VARIABLE *v, int *error) {
+    static uint32_t this_hash = 0, now_hash = 0, after_hash = 0, before_hash = 0, status_hash = 0, removed_hash = 0, uninitialized_hash = 0, undefined_hash = 0, clear_hash = 0, warning_hash = 0, critical_hash = 0;
+    calculated_number n;
+
+    if(unlikely(this_hash == 0)) {
+        this_hash = simple_hash("this");
+        now_hash = simple_hash("now");
+        after_hash = simple_hash("after");
+        before_hash = simple_hash("before");
+        status_hash = simple_hash("status");
+        removed_hash = simple_hash("REMOVED");
+        uninitialized_hash = simple_hash("UNINITIALIZED");
+        undefined_hash = simple_hash("UNDEFINED");
+        clear_hash = simple_hash("CLEAR");
+        warning_hash = simple_hash("WARNING");
+        critical_hash = simple_hash("CRITICAL");
+    }
+
+    if(unlikely(v->hash == this_hash && !strcmp(v->name, "this"))) {
+        n = (exp->this)?*exp->this:NAN;
+        buffer_strcat(exp->error_msg, "[ $this = ");
+        print_parsed_as_constant(exp->error_msg, n);
+        buffer_strcat(exp->error_msg, " ] ");
+        return n;
+    }
+
+    if(unlikely(v->hash == after_hash && !strcmp(v->name, "after"))) {
+        n = (exp->after && *exp->after)?*exp->after:NAN;
+        buffer_strcat(exp->error_msg, "[ $after = ");
+        print_parsed_as_constant(exp->error_msg, n);
+        buffer_strcat(exp->error_msg, " ] ");
+        return n;
+    }
+
+    if(unlikely(v->hash == before_hash && !strcmp(v->name, "before"))) {
+        n = (exp->before && *exp->before)?*exp->before:NAN;
+        buffer_strcat(exp->error_msg, "[ $before = ");
+        print_parsed_as_constant(exp->error_msg, n);
+        buffer_strcat(exp->error_msg, " ] ");
+        return n;
+    }
+
+    if(unlikely(v->hash == now_hash && !strcmp(v->name, "now"))) {
+        n = now_realtime_sec();
+        buffer_strcat(exp->error_msg, "[ $now = ");
+        print_parsed_as_constant(exp->error_msg, n);
+        buffer_strcat(exp->error_msg, " ] ");
+        return n;
+    }
+
+    if(unlikely(v->hash == status_hash && !strcmp(v->name, "status"))) {
+        n = (exp->status)?*exp->status:RRDCALC_STATUS_UNINITIALIZED;
+        buffer_strcat(exp->error_msg, "[ $status = ");
+        print_parsed_as_constant(exp->error_msg, n);
+        buffer_strcat(exp->error_msg, " ] ");
+        return n;
+    }
+
+    if(unlikely(v->hash == removed_hash && !strcmp(v->name, "REMOVED"))) {
+        n = RRDCALC_STATUS_REMOVED;
+        buffer_strcat(exp->error_msg, "[ $REMOVED = ");
+        print_parsed_as_constant(exp->error_msg, n);
+        buffer_strcat(exp->error_msg, " ] ");
+        return n;
+    }
+
+    if(unlikely(v->hash == uninitialized_hash && !strcmp(v->name, "UNINITIALIZED"))) {
+        n = RRDCALC_STATUS_UNINITIALIZED;
+        buffer_strcat(exp->error_msg, "[ $UNINITIALIZED = ");
+        print_parsed_as_constant(exp->error_msg, n);
+        buffer_strcat(exp->error_msg, " ] ");
+        return n;
+    }
+
+    if(unlikely(v->hash == undefined_hash && !strcmp(v->name, "UNDEFINED"))) {
+        n = RRDCALC_STATUS_UNDEFINED;
+        buffer_strcat(exp->error_msg, "[ $UNDEFINED = ");
+        print_parsed_as_constant(exp->error_msg, n);
+        buffer_strcat(exp->error_msg, " ] ");
+        return n;
+    }
+
+    if(unlikely(v->hash == clear_hash && !strcmp(v->name, "CLEAR"))) {
+        n = RRDCALC_STATUS_CLEAR;
+        buffer_strcat(exp->error_msg, "[ $CLEAR = ");
+        print_parsed_as_constant(exp->error_msg, n);
+        buffer_strcat(exp->error_msg, " ] ");
+        return n;
+    }
+
+    if(unlikely(v->hash == warning_hash && !strcmp(v->name, "WARNING"))) {
+        n = RRDCALC_STATUS_WARNING;
+        buffer_strcat(exp->error_msg, "[ $WARNING = ");
+        print_parsed_as_constant(exp->error_msg, n);
+        buffer_strcat(exp->error_msg, " ] ");
+        return n;
+    }
+
+    if(unlikely(v->hash == critical_hash && !strcmp(v->name, "CRITICAL"))) {
+        n = RRDCALC_STATUS_CRITICAL;
+        buffer_strcat(exp->error_msg, "[ $CRITICAL = ");
+        print_parsed_as_constant(exp->error_msg, n);
+        buffer_strcat(exp->error_msg, " ] ");
+        return n;
+    }
+
+    if(exp->rrdcalc && health_variable_lookup(v->name, v->hash, exp->rrdcalc, &n)) {
+        buffer_sprintf(exp->error_msg, "[ ${%s} = ", v->name);
+        print_parsed_as_constant(exp->error_msg, n);
+        buffer_strcat(exp->error_msg, " ] ");
+        return n;
+    }
+
+    *error = EVAL_ERROR_UNKNOWN_VARIABLE;
+    buffer_sprintf(exp->error_msg, "[ undefined variable '%s' ] ", v->name);
+    return 0;
+}
+
+static inline calculated_number eval_value(EVAL_EXPRESSION *exp, EVAL_VALUE *v, int *error) {
+    calculated_number n;
+
+    switch(v->type) {
+        case EVAL_VALUE_EXPRESSION:
+            n = eval_node(exp, v->expression, error);
+            break;
+
+        case EVAL_VALUE_NUMBER:
+            n = v->number;
+            break;
+
+        case EVAL_VALUE_VARIABLE:
+            n = eval_variable(exp, v->variable, error);
+            break;
+
+        default:
+            *error = EVAL_ERROR_INVALID_VALUE;
+            n = 0;
+            break;
+    }
+
+    return n;
+}
+
+static inline int is_true(calculated_number n) {
+    if(isnan(n)) return 0;
+    if(isinf(n)) return 1;
+    if(n == 0) return 0;
+    return 1;
+}
+
+calculated_number eval_and(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+    return is_true(eval_value(exp, &op->ops[0], error)) && is_true(eval_value(exp, &op->ops[1], error));
+}
+calculated_number eval_or(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+    return is_true(eval_value(exp, &op->ops[0], error)) || is_true(eval_value(exp, &op->ops[1], error));
+}
+calculated_number eval_greater_than_or_equal(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+    calculated_number n1 = eval_value(exp, &op->ops[0], error);
+    calculated_number n2 = eval_value(exp, &op->ops[1], error);
+    return isgreaterequal(n1, n2);
+}
+calculated_number eval_less_than_or_equal(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+    calculated_number n1 = eval_value(exp, &op->ops[0], error);
+    calculated_number n2 = eval_value(exp, &op->ops[1], error);
+    return islessequal(n1, n2);
+}
+calculated_number eval_equal(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+    calculated_number n1 = eval_value(exp, &op->ops[0], error);
+    calculated_number n2 = eval_value(exp, &op->ops[1], error);
+    if(isnan(n1) && isnan(n2)) return 1;
+    if(isinf(n1) && isinf(n2)) return 1;
+    if(isnan(n1) || isnan(n2)) return 0;
+    if(isinf(n1) || isinf(n2)) return 0;
+    return calculated_number_equal(n1, n2);
+}
+calculated_number eval_not_equal(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+    return !eval_equal(exp, op, error);
+}
+calculated_number eval_less(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+    calculated_number n1 = eval_value(exp, &op->ops[0], error);
+    calculated_number n2 = eval_value(exp, &op->ops[1], error);
+    return isless(n1, n2);
+}
+calculated_number eval_greater(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+    calculated_number n1 = eval_value(exp, &op->ops[0], error);
+    calculated_number n2 = eval_value(exp, &op->ops[1], error);
+    return isgreater(n1, n2);
+}
+calculated_number eval_plus(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+    calculated_number n1 = eval_value(exp, &op->ops[0], error);
+    calculated_number n2 = eval_value(exp, &op->ops[1], error);
+    if(isnan(n1) || isnan(n2)) return NAN;
+    if(isinf(n1) || isinf(n2)) return INFINITY;
+    return n1 + n2;
+}
+calculated_number eval_minus(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+    calculated_number n1 = eval_value(exp, &op->ops[0], error);
+    calculated_number n2 = eval_value(exp, &op->ops[1], error);
+    if(isnan(n1) || isnan(n2)) return NAN;
+    if(isinf(n1) || isinf(n2)) return INFINITY;
+    return n1 - n2;
+}
+calculated_number eval_multiply(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+    calculated_number n1 = eval_value(exp, &op->ops[0], error);
+    calculated_number n2 = eval_value(exp, &op->ops[1], error);
+    if(isnan(n1) || isnan(n2)) return NAN;
+    if(isinf(n1) || isinf(n2)) return INFINITY;
+    return n1 * n2;
+}
+calculated_number eval_divide(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+    calculated_number n1 = eval_value(exp, &op->ops[0], error);
+    calculated_number n2 = eval_value(exp, &op->ops[1], error);
+    if(isnan(n1) || isnan(n2)) return NAN;
+    if(isinf(n1) || isinf(n2)) return INFINITY;
+    return n1 / n2;
+}
+calculated_number eval_nop(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+    return eval_value(exp, &op->ops[0], error);
+}
+calculated_number eval_not(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+    return !is_true(eval_value(exp, &op->ops[0], error));
+}
+calculated_number eval_sign_plus(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+    return eval_value(exp, &op->ops[0], error);
+}
+calculated_number eval_sign_minus(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+    calculated_number n1 = eval_value(exp, &op->ops[0], error);
+    if(isnan(n1)) return NAN;
+    if(isinf(n1)) return INFINITY;
+    return -n1;
+}
+calculated_number eval_abs(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+    calculated_number n1 = eval_value(exp, &op->ops[0], error);
+    if(isnan(n1)) return NAN;
+    if(isinf(n1)) return INFINITY;
+    return abs(n1);
+}
+calculated_number eval_if_then_else(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+    if(is_true(eval_value(exp, &op->ops[0], error)))
+        return eval_value(exp, &op->ops[1], error);
+    else
+        return eval_value(exp, &op->ops[2], error);
+}
+
+static struct operator {
+    const char *print_as;
+    char precedence;
+    char parameters;
+    char isfunction;
+    calculated_number (*eval)(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error);
+} operators[256] = {
+        // this is a random access array
+        // we always access it with a known EVAL_OPERATOR_X
+
+        [EVAL_OPERATOR_AND]                   = { "&&", 2, 2, 0, eval_and },
+        [EVAL_OPERATOR_OR]                    = { "||", 2, 2, 0, eval_or },
+        [EVAL_OPERATOR_GREATER_THAN_OR_EQUAL] = { ">=", 3, 2, 0, eval_greater_than_or_equal },
+        [EVAL_OPERATOR_LESS_THAN_OR_EQUAL]    = { "<=", 3, 2, 0, eval_less_than_or_equal },
+        [EVAL_OPERATOR_NOT_EQUAL]             = { "!=", 3, 2, 0, eval_not_equal },
+        [EVAL_OPERATOR_EQUAL]                 = { "==", 3, 2, 0, eval_equal },
+        [EVAL_OPERATOR_LESS]                  = { "<",  3, 2, 0, eval_less },
+        [EVAL_OPERATOR_GREATER]               = { ">",  3, 2, 0, eval_greater },
+        [EVAL_OPERATOR_PLUS]                  = { "+",  4, 2, 0, eval_plus },
+        [EVAL_OPERATOR_MINUS]                 = { "-",  4, 2, 0, eval_minus },
+        [EVAL_OPERATOR_MULTIPLY]              = { "*",  5, 2, 0, eval_multiply },
+        [EVAL_OPERATOR_DIVIDE]                = { "/",  5, 2, 0, eval_divide },
+        [EVAL_OPERATOR_NOT]                   = { "!",  6, 1, 0, eval_not },
+        [EVAL_OPERATOR_SIGN_PLUS]             = { "+",  6, 1, 0, eval_sign_plus },
+        [EVAL_OPERATOR_SIGN_MINUS]            = { "-",  6, 1, 0, eval_sign_minus },
+        [EVAL_OPERATOR_ABS]                   = { "abs(",6,1, 1, eval_abs },
+        [EVAL_OPERATOR_IF_THEN_ELSE]          = { "?",  7, 3, 0, eval_if_then_else },
+        [EVAL_OPERATOR_NOP]                   = { NULL, 8, 1, 0, eval_nop },
+        [EVAL_OPERATOR_EXPRESSION_OPEN]       = { NULL, 8, 1, 0, eval_nop },
+
+        // this should exist in our evaluation list
+        [EVAL_OPERATOR_EXPRESSION_CLOSE]      = { NULL, 99, 1, 0, eval_nop }
+};
+
+#define eval_precedence(operator) (operators[(unsigned char)(operator)].precedence)
+
+static inline calculated_number eval_node(EVAL_EXPRESSION *exp, EVAL_NODE *op, int *error) {
+    if(unlikely(op->count != operators[op->operator].parameters)) {
+        *error = EVAL_ERROR_INVALID_NUMBER_OF_OPERANDS;
+        return 0;
+    }
+
+    calculated_number n = operators[op->operator].eval(exp, op, error);
+
+    return n;
+}
+
+// ----------------------------------------------------------------------------
+// parsed-as generation
+
+static inline void print_parsed_as_variable(BUFFER *out, EVAL_VARIABLE *v, int *error) {
+    (void)error;
+    buffer_sprintf(out, "${%s}", v->name);
+}
+
+static inline void print_parsed_as_constant(BUFFER *out, calculated_number n) {
+    if(unlikely(isnan(n))) {
+        buffer_strcat(out, "nan");
+        return;
+    }
+
+    if(unlikely(isinf(n))) {
+        buffer_strcat(out, "inf");
+        return;
+    }
+
+    char b[100+1], *s;
+    snprintfz(b, 100, CALCULATED_NUMBER_FORMAT, n);
+
+    s = &b[strlen(b) - 1];
+    while(s > b && *s == '0') {
+        *s ='\0';
+        s--;
+    }
+
+    if(s > b && *s == '.')
+        *s = '\0';
+
+    buffer_strcat(out, b);
+}
+
+static inline void print_parsed_as_value(BUFFER *out, EVAL_VALUE *v, int *error) {
+    switch(v->type) {
+        case EVAL_VALUE_EXPRESSION:
+            print_parsed_as_node(out, v->expression, error);
+            break;
+
+        case EVAL_VALUE_NUMBER:
+            print_parsed_as_constant(out, v->number);
+            break;
+
+        case EVAL_VALUE_VARIABLE:
+            print_parsed_as_variable(out, v->variable, error);
+            break;
+
+        default:
+            *error = EVAL_ERROR_INVALID_VALUE;
+            break;
+    }
+}
+
+static inline void print_parsed_as_node(BUFFER *out, EVAL_NODE *op, int *error) {
+    if(unlikely(op->count != operators[op->operator].parameters)) {
+        *error = EVAL_ERROR_INVALID_NUMBER_OF_OPERANDS;
+        return;
+    }
+
+    if(operators[op->operator].parameters == 1) {
+
+        if(operators[op->operator].print_as)
+            buffer_sprintf(out, "%s", operators[op->operator].print_as);
+
+        //if(op->operator == EVAL_OPERATOR_EXPRESSION_OPEN)
+        //    buffer_strcat(out, "(");
+
+        print_parsed_as_value(out, &op->ops[0], error);
+
+        //if(op->operator == EVAL_OPERATOR_EXPRESSION_OPEN)
+        //    buffer_strcat(out, ")");
+    }
+
+    else if(operators[op->operator].parameters == 2) {
+        buffer_strcat(out, "(");
+        print_parsed_as_value(out, &op->ops[0], error);
+
+        if(operators[op->operator].print_as)
+            buffer_sprintf(out, " %s ", operators[op->operator].print_as);
+
+        print_parsed_as_value(out, &op->ops[1], error);
+        buffer_strcat(out, ")");
+    }
+    else if(op->operator == EVAL_OPERATOR_IF_THEN_ELSE && operators[op->operator].parameters == 3) {
+        buffer_strcat(out, "(");
+        print_parsed_as_value(out, &op->ops[0], error);
+
+        if(operators[op->operator].print_as)
+            buffer_sprintf(out, " %s ", operators[op->operator].print_as);
+
+        print_parsed_as_value(out, &op->ops[1], error);
+        buffer_strcat(out, " : ");
+        print_parsed_as_value(out, &op->ops[2], error);
+        buffer_strcat(out, ")");
+    }
+
+    if(operators[op->operator].isfunction)
+        buffer_strcat(out, ")");
+}
+
+// ----------------------------------------------------------------------------
+// parsing expressions
+
+// skip spaces
+static inline void skip_spaces(const char **string) {
+    const char *s = *string;
+    while(isspace(*s)) s++;
+    *string = s;
+}
+
+// what character can appear just after an operator keyword
+// like NOT AND OR ?
+static inline int isoperatorterm_word(const char s) {
+    if(isspace(s) || s == '(' || s == '$' || s == '!' || s == '-' || s == '+' || isdigit(s) || !s)
+        return 1;
+
+    return 0;
+}
+
+// what character can appear just after an operator symbol?
+static inline int isoperatorterm_symbol(const char s) {
+    if(isoperatorterm_word(s) || isalpha(s))
+        return 1;
+
+    return 0;
+}
+
+// return 1 if the character should never appear in a variable
+static inline int isvariableterm(const char s) {
+    if(isalnum(s) || s == '.' || s == '_')
+        return 0;
+
+    return 1;
+}
+
+// ----------------------------------------------------------------------------
+// parse operators
+
+static inline int parse_and(const char **string) {
+    const char *s = *string;
+
+    // AND
+    if((s[0] == 'A' || s[0] == 'a') && (s[1] == 'N' || s[1] == 'n') && (s[2] == 'D' || s[2] == 'd') && isoperatorterm_word(s[3])) {
+        *string = &s[4];
+        return 1;
+    }
+
+    // &&
+    if(s[0] == '&' && s[1] == '&' && isoperatorterm_symbol(s[2])) {
+        *string = &s[2];
+        return 1;
+    }
+
+    return 0;
+}
+
+static inline int parse_or(const char **string) {
+    const char *s = *string;
+
+    // OR
+    if((s[0] == 'O' || s[0] == 'o') && (s[1] == 'R' || s[1] == 'r') && isoperatorterm_word(s[2])) {
+        *string = &s[3];
+        return 1;
+    }
+
+    // ||
+    if(s[0] == '|' && s[1] == '|' && isoperatorterm_symbol(s[2])) {
+        *string = &s[2];
+        return 1;
+    }
+
+    return 0;
+}
+
+static inline int parse_greater_than_or_equal(const char **string) {
+    const char *s = *string;
+
+    // >=
+    if(s[0] == '>' && s[1] == '=' && isoperatorterm_symbol(s[2])) {
+        *string = &s[2];
+        return 1;
+    }
+
+    return 0;
+}
+
+static inline int parse_less_than_or_equal(const char **string) {
+    const char *s = *string;
+
+    // <=
+    if (s[0] == '<' && s[1] == '=' && isoperatorterm_symbol(s[2])) {
+        *string = &s[2];
+        return 1;
+    }
+
+    return 0;
+}
+
+static inline int parse_greater(const char **string) {
+    const char *s = *string;
+
+    // >
+    if(s[0] == '>' && isoperatorterm_symbol(s[1])) {
+        *string = &s[1];
+        return 1;
+    }
+
+    return 0;
+}
+
+static inline int parse_less(const char **string) {
+    const char *s = *string;
+
+    // <
+    if(s[0] == '<' && isoperatorterm_symbol(s[1])) {
+        *string = &s[1];
+        return 1;
+    }
+
+    return 0;
+}
+
+static inline int parse_equal(const char **string) {
+    const char *s = *string;
+
+    // ==
+    if(s[0] == '=' && s[1] == '=' && isoperatorterm_symbol(s[2])) {
+        *string = &s[2];
+        return 1;
+    }
+
+    // =
+    if(s[0] == '=' && isoperatorterm_symbol(s[1])) {
+        *string = &s[1];
+        return 1;
+    }
+
+    return 0;
+}
+
+static inline int parse_not_equal(const char **string) {
+    const char *s = *string;
+
+    // !=
+    if(s[0] == '!' && s[1] == '=' && isoperatorterm_symbol(s[2])) {
+        *string = &s[2];
+        return 1;
+    }
+
+    // <>
+    if(s[0] == '<' && s[1] == '>' && isoperatorterm_symbol(s[2])) {
+        *string = &s[2];
+    }
+
+    return 0;
+}
+
+static inline int parse_not(const char **string) {
+    const char *s = *string;
+
+    // NOT
+    if((s[0] == 'N' || s[0] == 'n') && (s[1] == 'O' || s[1] == 'o') && (s[2] == 'T' || s[2] == 't') && isoperatorterm_word(s[3])) {
+        *string = &s[3];
+        return 1;
+    }
+
+    if(s[0] == '!') {
+        *string = &s[1];
+        return 1;
+    }
+
+    return 0;
+}
+
+static inline int parse_multiply(const char **string) {
+    const char *s = *string;
+
+    // *
+    if(s[0] == '*' && isoperatorterm_symbol(s[1])) {
+        *string = &s[1];
+        return 1;
+    }
+
+    return 0;
+}
+
+static inline int parse_divide(const char **string) {
+    const char *s = *string;
+
+    // /
+    if(s[0] == '/' && isoperatorterm_symbol(s[1])) {
+        *string = &s[1];
+        return 1;
+    }
+
+    return 0;
+}
+
+static inline int parse_minus(const char **string) {
+    const char *s = *string;
+
+    // -
+    if(s[0] == '-' && isoperatorterm_symbol(s[1])) {
+        *string = &s[1];
+        return 1;
+    }
+
+    return 0;
+}
+
+static inline int parse_plus(const char **string) {
+    const char *s = *string;
+
+    // +
+    if(s[0] == '+' && isoperatorterm_symbol(s[1])) {
+        *string = &s[1];
+        return 1;
+    }
+
+    return 0;
+}
+
+static inline int parse_open_subexpression(const char **string) {
+    const char *s = *string;
+
+    // (
+    if(s[0] == '(') {
+        *string = &s[1];
+        return 1;
+    }
+
+    return 0;
+}
+
+#define parse_close_function(x) parse_close_subexpression(x)
+
+static inline int parse_close_subexpression(const char **string) {
+    const char *s = *string;
+
+    // )
+    if(s[0] == ')') {
+        *string = &s[1];
+        return 1;
+    }
+
+    return 0;
+}
+
+static inline int parse_variable(const char **string, char *buffer, size_t len) {
+    const char *s = *string;
+
+    // $
+    if(*s == '$') {
+        size_t i = 0;
+        s++;
+
+        if(*s == '{') {
+            // ${variable_name}
+
+            s++;
+            while (*s && *s != '}' && i < len)
+                buffer[i++] = *s++;
+
+            if(*s == '}')
+                s++;
+        }
+        else {
+            // $variable_name
+
+            while (*s && !isvariableterm(*s) && i < len)
+                buffer[i++] = *s++;
+        }
+
+        buffer[i] = '\0';
+
+        if (buffer[0]) {
+            *string = s;
+            return 1;
+        }
+    }
+
+    return 0;
+}
+
+static inline int parse_constant(const char **string, calculated_number *number) {
+    char *end = NULL;
+    calculated_number n = str2ld(*string, &end);
+    if(unlikely(!end || *string == end)) {
+        *number = 0;
+        return 0;
+    }
+    *number = n;
+    *string = end;
+    return 1;
+}
+
+static inline int parse_abs(const char **string) {
+    const char *s = *string;
+
+    // ABS
+    if((s[0] == 'A' || s[0] == 'a') && (s[1] == 'B' || s[1] == 'b') && (s[2] == 'S' || s[2] == 's') && s[3] == '(') {
+        *string = &s[3];
+        return 1;
+    }
+
+    return 0;
+}
+
+static inline int parse_if_then_else(const char **string) {
+    const char *s = *string;
+
+    // ?
+    if(s[0] == '?') {
+        *string = &s[1];
+        return 1;
+    }
+
+    return 0;
+}
+
+static struct operator_parser {
+    unsigned char id;
+    int (*parse)(const char **);
+} operator_parsers[] = {
+        // the order in this list is important!
+        // the first matching will be used
+        // so place the longer of overlapping ones
+        // at the top
+
+        { EVAL_OPERATOR_AND,                   parse_and },
+        { EVAL_OPERATOR_OR,                    parse_or },
+        { EVAL_OPERATOR_GREATER_THAN_OR_EQUAL, parse_greater_than_or_equal },
+        { EVAL_OPERATOR_LESS_THAN_OR_EQUAL,    parse_less_than_or_equal },
+        { EVAL_OPERATOR_NOT_EQUAL,             parse_not_equal },
+        { EVAL_OPERATOR_EQUAL,                 parse_equal },
+        { EVAL_OPERATOR_LESS,                  parse_less },
+        { EVAL_OPERATOR_GREATER,               parse_greater },
+        { EVAL_OPERATOR_PLUS,                  parse_plus },
+        { EVAL_OPERATOR_MINUS,                 parse_minus },
+        { EVAL_OPERATOR_MULTIPLY,              parse_multiply },
+        { EVAL_OPERATOR_DIVIDE,                parse_divide },
+        { EVAL_OPERATOR_IF_THEN_ELSE,          parse_if_then_else },
+
+        /* we should not put in this list the following:
+         *
+         *  - NOT
+         *  - (
+         *  - )
+         *
+         * these are handled in code
+         */
+
+        // termination
+        { EVAL_OPERATOR_NOP, NULL }
+};
+
+static inline unsigned char parse_operator(const char **string, int *precedence) {
+    skip_spaces(string);
+
+    int i;
+    for(i = 0 ; operator_parsers[i].parse != NULL ; i++)
+        if(operator_parsers[i].parse(string)) {
+            if(precedence) *precedence = eval_precedence(operator_parsers[i].id);
+            return operator_parsers[i].id;
+        }
+
+    return EVAL_OPERATOR_NOP;
+}
+
+// ----------------------------------------------------------------------------
+// memory management
+
+static inline EVAL_NODE *eval_node_alloc(int count) {
+    static int id = 1;
+
+    EVAL_NODE *op = callocz(1, sizeof(EVAL_NODE) + (sizeof(EVAL_VALUE) * count));
+
+    op->id = id++;
+    op->operator = EVAL_OPERATOR_NOP;
+    op->precedence = eval_precedence(EVAL_OPERATOR_NOP);
+    op->count = count;
+    return op;
+}
+
+static inline void eval_node_set_value_to_node(EVAL_NODE *op, int pos, EVAL_NODE *value) {
+    if(pos >= op->count)
+        fatal("Invalid request to set position %d of OPERAND that has only %d values", pos + 1, op->count + 1);
+
+    op->ops[pos].type = EVAL_VALUE_EXPRESSION;
+    op->ops[pos].expression = value;
+}
+
+static inline void eval_node_set_value_to_constant(EVAL_NODE *op, int pos, calculated_number value) {
+    if(pos >= op->count)
+        fatal("Invalid request to set position %d of OPERAND that has only %d values", pos + 1, op->count + 1);
+
+    op->ops[pos].type = EVAL_VALUE_NUMBER;
+    op->ops[pos].number = value;
+}
+
+static inline void eval_node_set_value_to_variable(EVAL_NODE *op, int pos, const char *variable) {
+    if(pos >= op->count)
+        fatal("Invalid request to set position %d of OPERAND that has only %d values", pos + 1, op->count + 1);
+
+    op->ops[pos].type = EVAL_VALUE_VARIABLE;
+    op->ops[pos].variable = callocz(1, sizeof(EVAL_VARIABLE));
+    op->ops[pos].variable->name = strdupz(variable);
+    op->ops[pos].variable->hash = simple_hash(op->ops[pos].variable->name);
+}
+
+static inline void eval_variable_free(EVAL_VARIABLE *v) {
+    freez(v->name);
+    freez(v);
+}
+
+static inline void eval_value_free(EVAL_VALUE *v) {
+    switch(v->type) {
+        case EVAL_VALUE_EXPRESSION:
+            eval_node_free(v->expression);
+            break;
+
+        case EVAL_VALUE_VARIABLE:
+            eval_variable_free(v->variable);
+            break;
+
+        default:
+            break;
+    }
+}
+
+static inline void eval_node_free(EVAL_NODE *op) {
+    if(op->count) {
+        int i;
+        for(i = op->count - 1; i >= 0 ;i--)
+            eval_value_free(&op->ops[i]);
+    }
+
+    freez(op);
+}
+
+// ----------------------------------------------------------------------------
+// the parsing logic
+
+// helper function to avoid allocations all over the place
+static inline EVAL_NODE *parse_next_operand_given_its_operator(const char **string, unsigned char operator_type, int *error) {
+    EVAL_NODE *sub = parse_one_full_operand(string, error);
+    if(!sub) return NULL;
+
+    EVAL_NODE *op = eval_node_alloc(1);
+    op->operator = operator_type;
+    eval_node_set_value_to_node(op, 0, sub);
+    return op;
+}
+
+// parse a full operand, including its sign or other associative operator (e.g. NOT)
+static inline EVAL_NODE *parse_one_full_operand(const char **string, int *error) {
+    char variable_buffer[EVAL_MAX_VARIABLE_NAME_LENGTH + 1];
+    EVAL_NODE *op1 = NULL;
+    calculated_number number;
+
+    *error = EVAL_ERROR_OK;
+
+    skip_spaces(string);
+    if(!(**string)) {
+        *error = EVAL_ERROR_MISSING_OPERAND;
+        return NULL;
+    }
+
+    if(parse_not(string)) {
+        op1 = parse_next_operand_given_its_operator(string, EVAL_OPERATOR_NOT, error);
+        op1->precedence = eval_precedence(EVAL_OPERATOR_NOT);
+    }
+    else if(parse_plus(string)) {
+        op1 = parse_next_operand_given_its_operator(string, EVAL_OPERATOR_SIGN_PLUS, error);
+        op1->precedence = eval_precedence(EVAL_OPERATOR_SIGN_PLUS);
+    }
+    else if(parse_minus(string)) {
+        op1 = parse_next_operand_given_its_operator(string, EVAL_OPERATOR_SIGN_MINUS, error);
+        op1->precedence = eval_precedence(EVAL_OPERATOR_SIGN_MINUS);
+    }
+    else if(parse_abs(string)) {
+        op1 = parse_next_operand_given_its_operator(string, EVAL_OPERATOR_ABS, error);
+        op1->precedence = eval_precedence(EVAL_OPERATOR_ABS);
+    }
+    else if(parse_open_subexpression(string)) {
+        EVAL_NODE *sub = parse_full_expression(string, error);
+        if(sub) {
+            op1 = eval_node_alloc(1);
+            op1->operator = EVAL_OPERATOR_EXPRESSION_OPEN;
+            op1->precedence = eval_precedence(EVAL_OPERATOR_EXPRESSION_OPEN);
+            eval_node_set_value_to_node(op1, 0, sub);
+            if(!parse_close_subexpression(string)) {
+                *error = EVAL_ERROR_MISSING_CLOSE_SUBEXPRESSION;
+                eval_node_free(op1);
+                return NULL;
+            }
+        }
+    }
+    else if(parse_variable(string, variable_buffer, EVAL_MAX_VARIABLE_NAME_LENGTH)) {
+        op1 = eval_node_alloc(1);
+        op1->operator = EVAL_OPERATOR_NOP;
+        eval_node_set_value_to_variable(op1, 0, variable_buffer);
+    }
+    else if(parse_constant(string, &number)) {
+        op1 = eval_node_alloc(1);
+        op1->operator = EVAL_OPERATOR_NOP;
+        eval_node_set_value_to_constant(op1, 0, number);
+    }
+    else if(**string)
+        *error = EVAL_ERROR_UNKNOWN_OPERAND;
+    else
+        *error = EVAL_ERROR_MISSING_OPERAND;
+
+    return op1;
+}
+
+// parse an operator and the rest of the expression
+// precedence processing is handled here
+static inline EVAL_NODE *parse_rest_of_expression(const char **string, int *error, EVAL_NODE *op1) {
+    EVAL_NODE *op2 = NULL;
+    unsigned char operator;
+    int precedence;
+
+    operator = parse_operator(string, &precedence);
+    skip_spaces(string);
+
+    if(operator != EVAL_OPERATOR_NOP) {
+        op2 = parse_one_full_operand(string, error);
+        if(!op2) {
+            // error is already reported
+            eval_node_free(op1);
+            return NULL;
+        }
+
+        EVAL_NODE *op = eval_node_alloc(operators[operator].parameters);
+        op->operator = operator;
+        op->precedence = precedence;
+
+        if(operator == EVAL_OPERATOR_IF_THEN_ELSE && op->count == 3) {
+            skip_spaces(string);
+
+            if(**string != ':') {
+                eval_node_free(op);
+                eval_node_free(op1);
+                eval_node_free(op2);
+                *error = EVAL_ERROR_IF_THEN_ELSE_MISSING_ELSE;
+                return NULL;
+            }
+            (*string)++;
+
+            skip_spaces(string);
+
+            EVAL_NODE *op3 = parse_one_full_operand(string, error);
+            if(!op3) {
+                eval_node_free(op);
+                eval_node_free(op1);
+                eval_node_free(op2);
+                // error is already reported
+                return NULL;
+            }
+
+            eval_node_set_value_to_node(op, 2, op3);
+        }
+
+        eval_node_set_value_to_node(op, 1, op2);
+
+        // precedence processing
+        // if this operator has a higher precedence compared to its next
+        // put the next operator on top of us (top = evaluated later)
+        // function recursion does the rest...
+        if(op->precedence > op1->precedence && op1->count == 2 && op1->operator != '(' && op1->ops[1].type == EVAL_VALUE_EXPRESSION) {
+            eval_node_set_value_to_node(op, 0, op1->ops[1].expression);
+            op1->ops[1].expression = op;
+            op = op1;
+        }
+        else
+            eval_node_set_value_to_node(op, 0, op1);
+
+        return parse_rest_of_expression(string, error, op);
+    }
+    else if(**string == ')') {
+        ;
+    }
+    else if(**string) {
+        eval_node_free(op1);
+        op1 = NULL;
+        *error = EVAL_ERROR_MISSING_OPERATOR;
+    }
+
+    return op1;
+}
+
+// high level function to parse an expression or a sub-expression
+static inline EVAL_NODE *parse_full_expression(const char **string, int *error) {
+    EVAL_NODE *op1 = parse_one_full_operand(string, error);
+    if(!op1) {
+        *error = EVAL_ERROR_MISSING_OPERAND;
+        return NULL;
+    }
+
+    return parse_rest_of_expression(string, error, op1);
+}
+
+// ----------------------------------------------------------------------------
+// public API
+
+int expression_evaluate(EVAL_EXPRESSION *expression) {
+    expression->error = EVAL_ERROR_OK;
+
+    buffer_reset(expression->error_msg);
+    expression->result = eval_node(expression, (EVAL_NODE *)expression->nodes, &expression->error);
+
+    if(unlikely(isnan(expression->result))) {
+        if(expression->error == EVAL_ERROR_OK)
+            expression->error = EVAL_ERROR_VALUE_IS_NAN;
+    }
+    else if(unlikely(isinf(expression->result))) {
+        if(expression->error == EVAL_ERROR_OK)
+            expression->error = EVAL_ERROR_VALUE_IS_INFINITE;
+    }
+    else if(unlikely(expression->error == EVAL_ERROR_UNKNOWN_VARIABLE)) {
+        // although there is an unknown variable
+        // the expression was evaluated successfully
+        expression->error = EVAL_ERROR_OK;
+    }
+
+    if(expression->error != EVAL_ERROR_OK) {
+        expression->result = NAN;
+
+        if(buffer_strlen(expression->error_msg))
+            buffer_strcat(expression->error_msg, "; ");
+
+        buffer_sprintf(expression->error_msg, "failed to evaluate expression with error %d (%s)", expression->error, expression_strerror(expression->error));
+        return 0;
+    }
+
+    return 1;
+}
+
+EVAL_EXPRESSION *expression_parse(const char *string, const char **failed_at, int *error) {
+    const char *s = string;
+    int err = EVAL_ERROR_OK;
+
+    EVAL_NODE *op = parse_full_expression(&s, &err);
+
+    if(*s) {
+        if(op) {
+            eval_node_free(op);
+            op = NULL;
+        }
+        err = EVAL_ERROR_REMAINING_GARBAGE;
+    }
+
+    if (failed_at) *failed_at = s;
+    if (error) *error = err;
+
+    if(!op) {
+        unsigned long pos = s - string + 1;
+        error("failed to parse expression '%s': %s at character %lu (i.e.: '%s').", string, expression_strerror(err), pos, s);
+        return NULL;
+    }
+
+    BUFFER *out = buffer_create(1024);
+    print_parsed_as_node(out, op, &err);
+    if(err != EVAL_ERROR_OK) {
+        error("failed to re-generate expression '%s' with reason: %s", string, expression_strerror(err));
+        eval_node_free(op);
+        buffer_free(out);
+        return NULL;
+    }
+
+    EVAL_EXPRESSION *exp = callocz(1, sizeof(EVAL_EXPRESSION));
+
+    exp->source = strdupz(string);
+    exp->parsed_as = strdupz(buffer_tostring(out));
+    buffer_free(out);
+
+    exp->error_msg = buffer_create(100);
+    exp->nodes = (void *)op;
+
+    return exp;
+}
+
+void expression_free(EVAL_EXPRESSION *expression) {
+    if(!expression) return;
+
+    if(expression->nodes) eval_node_free((EVAL_NODE *)expression->nodes);
+    freez((void *)expression->source);
+    freez((void *)expression->parsed_as);
+    buffer_free(expression->error_msg);
+    freez(expression);
+}
+
+const char *expression_strerror(int error) {
+    switch(error) {
+        case EVAL_ERROR_OK:
+            return "success";
+
+        case EVAL_ERROR_MISSING_CLOSE_SUBEXPRESSION:
+            return "missing closing parenthesis";
+
+        case EVAL_ERROR_UNKNOWN_OPERAND:
+            return "unknown operand";
+
+        case EVAL_ERROR_MISSING_OPERAND:
+            return "expected operand";
+
+        case EVAL_ERROR_MISSING_OPERATOR:
+            return "expected operator";
+
+        case EVAL_ERROR_REMAINING_GARBAGE:
+            return "remaining characters after expression";
+
+        case EVAL_ERROR_INVALID_VALUE:
+            return "invalid value structure - internal error";
+
+        case EVAL_ERROR_INVALID_NUMBER_OF_OPERANDS:
+            return "wrong number of operands for operation - internal error";
+
+        case EVAL_ERROR_VALUE_IS_NAN:
+            return "value is unset";
+
+        case EVAL_ERROR_VALUE_IS_INFINITE:
+            return "computed value is infinite";
+
+        case EVAL_ERROR_UNKNOWN_VARIABLE:
+            return "undefined variable";
+
+        case EVAL_ERROR_IF_THEN_ELSE_MISSING_ELSE:
+            return "missing second sub-expression of inline conditional";
+
+        default:
+            return "unknown error";
+    }
+}
diff --git a/libnetdata/eval/eval.h b/libnetdata/eval/eval.h
new file mode 100644
index 0000000..57dae9d
--- /dev/null
+++ b/libnetdata/eval/eval.h
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_EVAL_H
+#define NETDATA_EVAL_H 1
+
+#include "../libnetdata.h"
+
+#define EVAL_MAX_VARIABLE_NAME_LENGTH 300
+
+typedef enum rrdcalc_status {
+    RRDCALC_STATUS_REMOVED       = -2,
+    RRDCALC_STATUS_UNDEFINED     = -1,
+    RRDCALC_STATUS_UNINITIALIZED =  0,
+    RRDCALC_STATUS_CLEAR         =  1,
+    RRDCALC_STATUS_RAISED        =  2,
+    RRDCALC_STATUS_WARNING       =  3,
+    RRDCALC_STATUS_CRITICAL      =  4
+} RRDCALC_STATUS;
+
+typedef struct eval_variable {
+    char *name;
+    uint32_t hash;
+    struct eval_variable *next;
+} EVAL_VARIABLE;
+
+typedef struct eval_expression {
+    const char *source;
+    const char *parsed_as;
+
+    RRDCALC_STATUS *status;
+    calculated_number *this;
+    time_t *after;
+    time_t *before;
+
+    calculated_number result;
+
+    int error;
+    BUFFER *error_msg;
+
+    // hidden EVAL_NODE *
+    void *nodes;
+
+    // custom data to be used for looking up variables
+    struct rrdcalc *rrdcalc;
+} EVAL_EXPRESSION;
+
+#define EVAL_VALUE_INVALID    0
+#define EVAL_VALUE_NUMBER     1
+#define EVAL_VALUE_VARIABLE   2
+#define EVAL_VALUE_EXPRESSION 3
+
+// parsing and evaluation
+#define EVAL_ERROR_OK                             0
+
+// parsing errors
+#define EVAL_ERROR_MISSING_CLOSE_SUBEXPRESSION    1
+#define EVAL_ERROR_UNKNOWN_OPERAND                2
+#define EVAL_ERROR_MISSING_OPERAND                3
+#define EVAL_ERROR_MISSING_OPERATOR               4
+#define EVAL_ERROR_REMAINING_GARBAGE              5
+#define EVAL_ERROR_IF_THEN_ELSE_MISSING_ELSE      6
+
+// evaluation errors
+#define EVAL_ERROR_INVALID_VALUE                101
+#define EVAL_ERROR_INVALID_NUMBER_OF_OPERANDS   102
+#define EVAL_ERROR_VALUE_IS_NAN                 103
+#define EVAL_ERROR_VALUE_IS_INFINITE            104
+#define EVAL_ERROR_UNKNOWN_VARIABLE             105
+
+// parse the given string as an expression and return:
+//   a pointer to an expression if it parsed OK
+//   NULL in which case the pointer to error has the error code
+extern EVAL_EXPRESSION *expression_parse(const char *string, const char **failed_at, int *error);
+
+// free all resources allocated for an expression
+extern void expression_free(EVAL_EXPRESSION *expression);
+
+// convert an error code to a message
+extern const char *expression_strerror(int error);
+
+// evaluate an expression and return
+// 1 = OK, the result is in: expression->result
+// 2 = FAILED, the error message is in: buffer_tostring(expression->error_msg)
+extern int expression_evaluate(EVAL_EXPRESSION *expression);
+
+extern int health_variable_lookup(const char *variable, uint32_t hash, struct rrdcalc *rc, calculated_number *result);
+
+#endif //NETDATA_EVAL_H
diff --git a/libnetdata/inlined.h b/libnetdata/inlined.h
new file mode 100644
index 0000000..6a5994c
--- /dev/null
+++ b/libnetdata/inlined.h
@@ -0,0 +1,298 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_INLINED_H
+#define NETDATA_INLINED_H 1
+
+#include "libnetdata.h"
+
+#ifdef KERNEL_32BIT
+typedef uint32_t kernel_uint_t;
+#define str2kernel_uint_t(string) str2uint32_t(string)
+#define KERNEL_UINT_FORMAT "%u"
+#else
+typedef uint64_t kernel_uint_t;
+#define str2kernel_uint_t(string) str2uint64_t(string)
+#define KERNEL_UINT_FORMAT "%" PRIu64
+#endif
+
+#define str2pid_t(string) str2uint32_t(string)
+
+
+// for faster execution, allow the compiler to inline
+// these functions that are called thousands of times per second
+
+static inline uint32_t simple_hash(const char *name) {
+    unsigned char *s = (unsigned char *) name;
+    uint32_t hval = 0x811c9dc5;
+    while (*s) {
+        hval *= 16777619;
+        hval ^= (uint32_t) *s++;
+    }
+    return hval;
+}
+
+static inline uint32_t simple_uhash(const char *name) {
+    unsigned char *s = (unsigned char *) name;
+    uint32_t hval = 0x811c9dc5, c;
+    while ((c = *s++)) {
+        if (unlikely(c >= 'A' && c <= 'Z')) c += 'a' - 'A';
+        hval *= 16777619;
+        hval ^= c;
+    }
+    return hval;
+}
+
+static inline int simple_hash_strcmp(const char *name, const char *b, uint32_t *hash) {
+    unsigned char *s = (unsigned char *) name;
+    uint32_t hval = 0x811c9dc5;
+    int ret = 0;
+    while (*s) {
+        if(!ret) ret = *s - *b++;
+        hval *= 16777619;
+        hval ^= (uint32_t) *s++;
+    }
+    *hash = hval;
+    return ret;
+}
+
+static inline int str2i(const char *s) {
+    int n = 0;
+    char c, negative = (*s == '-');
+
+    for(c = (negative)?*(++s):*s; c >= '0' && c <= '9' ; c = *(++s)) {
+        n *= 10;
+        n += c - '0';
+    }
+
+    if(unlikely(negative))
+        return -n;
+
+    return n;
+}
+
+static inline long str2l(const char *s) {
+    long n = 0;
+    char c, negative = (*s == '-');
+
+    for(c = (negative)?*(++s):*s; c >= '0' && c <= '9' ; c = *(++s)) {
+        n *= 10;
+        n += c - '0';
+    }
+
+    if(unlikely(negative))
+        return -n;
+
+    return n;
+}
+
+static inline uint32_t str2uint32_t(const char *s) {
+    uint32_t n = 0;
+    char c;
+    for(c = *s; c >= '0' && c <= '9' ; c = *(++s)) {
+        n *= 10;
+        n += c - '0';
+    }
+    return n;
+}
+
+static inline uint64_t str2uint64_t(const char *s) {
+    uint64_t n = 0;
+    char c;
+    for(c = *s; c >= '0' && c <= '9' ; c = *(++s)) {
+        n *= 10;
+        n += c - '0';
+    }
+    return n;
+}
+
+static inline unsigned long str2ul(const char *s) {
+    unsigned long n = 0;
+    char c;
+    for(c = *s; c >= '0' && c <= '9' ; c = *(++s)) {
+        n *= 10;
+        n += c - '0';
+    }
+    return n;
+}
+
+static inline unsigned long long str2ull(const char *s) {
+    unsigned long long n = 0;
+    char c;
+    for(c = *s; c >= '0' && c <= '9' ; c = *(++s)) {
+        n *= 10;
+        n += c - '0';
+    }
+    return n;
+}
+
+static inline long long str2ll(const char *s, char **endptr) {
+    int negative = 0;
+
+    if(unlikely(*s == '-')) {
+        s++;
+        negative = 1;
+    }
+    else if(unlikely(*s == '+'))
+        s++;
+
+    long long n = 0;
+    char c;
+    for(c = *s; c >= '0' && c <= '9' ; c = *(++s)) {
+        n *= 10;
+        n += c - '0';
+    }
+
+    if(unlikely(endptr))
+        *endptr = (char *)s;
+
+    if(unlikely(negative))
+        return -n;
+    else
+        return n;
+}
+
+static inline long double str2ld(const char *s, char **endptr) {
+    int negative = 0;
+    const char *start = s;
+    unsigned long long integer_part = 0;
+    unsigned long decimal_part = 0;
+    size_t decimal_digits = 0;
+
+    switch(*s) {
+        case '-':
+            s++;
+            negative = 1;
+            break;
+
+        case '+':
+            s++;
+            break;
+
+        case 'n':
+            if(s[1] == 'a' && s[2] == 'n') {
+                if(endptr) *endptr = (char *)&s[3];
+                return NAN;
+            }
+            break;
+
+        case 'i':
+            if(s[1] == 'n' && s[2] == 'f') {
+                if(endptr) *endptr = (char *)&s[3];
+                return INFINITY;
+            }
+            break;
+
+        default:
+            break;
+    }
+
+    while (*s >= '0' && *s <= '9') {
+        integer_part = (integer_part * 10) + (*s - '0');
+        s++;
+    }
+
+    if(unlikely(*s == '.')) {
+        decimal_part = 0;
+        s++;
+
+        while (*s >= '0' && *s <= '9') {
+            decimal_part = (decimal_part * 10) + (*s - '0');
+            s++;
+            decimal_digits++;
+        }
+    }
+
+    if(unlikely(*s == 'e' || *s == 'E'))
+        return strtold(start, endptr);
+
+    if(unlikely(endptr))
+        *endptr = (char *)s;
+
+    if(unlikely(negative)) {
+        if(unlikely(decimal_digits))
+            return -((long double)integer_part + (long double)decimal_part / powl(10.0, decimal_digits));
+        else
+            return -((long double)integer_part);
+    }
+    else {
+        if(unlikely(decimal_digits))
+            return (long double)integer_part + (long double)decimal_part / powl(10.0, decimal_digits);
+        else
+            return (long double)integer_part;
+    }
+}
+
+#ifdef NETDATA_STRCMP_OVERRIDE
+#ifdef strcmp
+#undef strcmp
+#endif
+#define strcmp(a, b) strsame(a, b)
+#endif // NETDATA_STRCMP_OVERRIDE
+
+static inline int strsame(const char *a, const char *b) {
+    if(unlikely(a == b)) return 0;
+    while(*a && *a == *b) { a++; b++; }
+    return *a - *b;
+}
+
+static inline char *strncpyz(char *dst, const char *src, size_t n) {
+    char *p = dst;
+
+    while (*src && n--)
+        *dst++ = *src++;
+
+    *dst = '\0';
+
+    return p;
+}
+
+static inline int read_file(const char *filename, char *buffer, size_t size) {
+    if(unlikely(!size)) return 3;
+
+    int fd = open(filename, O_RDONLY, 0666);
+    if(unlikely(fd == -1)) {
+        buffer[0] = '\0';
+        return 1;
+    }
+
+    ssize_t r = read(fd, buffer, size);
+    if(unlikely(r == -1)) {
+        buffer[0] = '\0';
+        close(fd);
+        return 2;
+    }
+    buffer[r] = '\0';
+
+    close(fd);
+    return 0;
+}
+
+static inline int read_single_number_file(const char *filename, unsigned long long *result) {
+    char buffer[30 + 1];
+
+    int ret = read_file(filename, buffer, 30);
+    if(unlikely(ret)) {
+        *result = 0;
+        return ret;
+    }
+
+    buffer[30] = '\0';
+    *result = str2ull(buffer);
+    return 0;
+}
+
+static inline int read_single_signed_number_file(const char *filename, long long *result) {
+    char buffer[30 + 1];
+
+    int ret = read_file(filename, buffer, 30);
+    if(unlikely(ret)) {
+        *result = 0;
+        return ret;
+    }
+
+    buffer[30] = '\0';
+    *result = atoll(buffer);
+    return 0;
+}
+
+#endif //NETDATA_INLINED_H
diff --git a/libnetdata/libnetdata.c b/libnetdata/libnetdata.c
new file mode 100644
index 0000000..095c38c
--- /dev/null
+++ b/libnetdata/libnetdata.c
@@ -0,0 +1,1454 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "libnetdata.h"
+
+#ifdef __APPLE__
+#define INHERIT_NONE 0
+#endif /* __APPLE__ */
+#if defined(__FreeBSD__) || defined(__APPLE__)
+#    define O_NOATIME     0
+#    define MADV_DONTFORK INHERIT_NONE
+#endif /* __FreeBSD__ || __APPLE__*/
+
+struct rlimit rlimit_nofile = { .rlim_cur = 1024, .rlim_max = 1024 };
+int enable_ksm = 1;
+
+volatile sig_atomic_t netdata_exit = 0;
+const char *os_type = NETDATA_OS_TYPE;
+const char *program_version = VERSION;
+
+// ----------------------------------------------------------------------------
+// memory allocation functions that handle failures
+
+// although netdata does not use memory allocations too often (netdata tries to
+// maintain its memory footprint stable during runtime, i.e. all buffers are
+// allocated during initialization and are adapted to current use throughout
+// its lifetime), these can be used to override the default system allocation
+// routines.
+
+#ifdef NETDATA_LOG_ALLOCATIONS
+static __thread struct memory_statistics {
+    volatile ssize_t malloc_calls_made;
+    volatile ssize_t calloc_calls_made;
+    volatile ssize_t realloc_calls_made;
+    volatile ssize_t strdup_calls_made;
+    volatile ssize_t free_calls_made;
+    volatile ssize_t memory_calls_made;
+    volatile ssize_t allocated_memory;
+    volatile ssize_t mmapped_memory;
+} memory_statistics = { 0, 0, 0, 0, 0, 0, 0, 0 };
+
+__thread size_t log_thread_memory_allocations = 0;
+
+static inline void print_allocations(const char *file, const char *function, const unsigned long line, const char *type, size_t size) {
+    static __thread struct memory_statistics old = { 0, 0, 0, 0, 0, 0, 0, 0 };
+
+    fprintf(stderr, "%s iteration %zu MEMORY TRACE: %lu@%s : %s : %s : %zu\n",
+            netdata_thread_tag(),
+            log_thread_memory_allocations,
+            line, file, function,
+            type, size
+    );
+
+    fprintf(stderr, "%s iteration %zu MEMORY ALLOCATIONS: (%04lu@%-40.40s:%-40.40s): Allocated %zd KiB (%+zd B), mmapped %zd KiB (%+zd B): %s : malloc %zd (%+zd), calloc %zd (%+zd), realloc %zd (%+zd), strdup %zd (%+zd), free %zd (%+zd)\n",
+            netdata_thread_tag(),
+            log_thread_memory_allocations,
+            line, file, function,
+            (memory_statistics.allocated_memory + 512) / 1024, memory_statistics.allocated_memory - old.allocated_memory,
+            (memory_statistics.mmapped_memory + 512) / 1024, memory_statistics.mmapped_memory - old.mmapped_memory,
+            type,
+            memory_statistics.malloc_calls_made, memory_statistics.malloc_calls_made - old.malloc_calls_made,
+            memory_statistics.calloc_calls_made, memory_statistics.calloc_calls_made - old.calloc_calls_made,
+            memory_statistics.realloc_calls_made, memory_statistics.realloc_calls_made - old.realloc_calls_made,
+            memory_statistics.strdup_calls_made, memory_statistics.strdup_calls_made - old.strdup_calls_made,
+            memory_statistics.free_calls_made, memory_statistics.free_calls_made - old.free_calls_made
+    );
+
+    memcpy(&old, &memory_statistics, sizeof(struct memory_statistics));
+}
+
+static inline void mmap_accounting(size_t size) {
+    if(log_thread_memory_allocations) {
+        memory_statistics.memory_calls_made++;
+        memory_statistics.mmapped_memory += size;
+    }
+}
+
+void *mallocz_int(const char *file, const char *function, const unsigned long line, size_t size) {
+    if(log_thread_memory_allocations) {
+        memory_statistics.memory_calls_made++;
+        memory_statistics.malloc_calls_made++;
+        memory_statistics.allocated_memory += size;
+        print_allocations(file, function, line, "malloc()", size);
+    }
+
+    size_t *n = (size_t *)malloc(sizeof(size_t) + size);
+    if (unlikely(!n)) fatal("mallocz() cannot allocate %zu bytes of memory.", size);
+    *n = size;
+    return (void *)&n[1];
+}
+
+void *callocz_int(const char *file, const char *function, const unsigned long line, size_t nmemb, size_t size) {
+    size = nmemb * size;
+
+    if(log_thread_memory_allocations) {
+        memory_statistics.memory_calls_made++;
+        memory_statistics.calloc_calls_made++;
+        memory_statistics.allocated_memory += size;
+        print_allocations(file, function, line, "calloc()", size);
+    }
+
+    size_t *n = (size_t *)calloc(1, sizeof(size_t) + size);
+    if (unlikely(!n)) fatal("callocz() cannot allocate %zu bytes of memory.", size);
+    *n = size;
+    return (void *)&n[1];
+}
+
+void *reallocz_int(const char *file, const char *function, const unsigned long line, void *ptr, size_t size) {
+    if(!ptr) return mallocz_int(file, function, line, size);
+
+    size_t *n = (size_t *)ptr;
+    n--;
+    size_t old_size = *n;
+
+    n = realloc(n, sizeof(size_t) + size);
+    if (unlikely(!n)) fatal("reallocz() cannot allocate %zu bytes of memory (from %zu bytes).", size, old_size);
+
+    if(log_thread_memory_allocations) {
+        memory_statistics.memory_calls_made++;
+        memory_statistics.realloc_calls_made++;
+        memory_statistics.allocated_memory += (size - old_size);
+        print_allocations(file, function, line, "realloc()", size - old_size);
+    }
+
+    *n = size;
+    return (void *)&n[1];
+}
+
+char *strdupz_int(const char *file, const char *function, const unsigned long line, const char *s) {
+    size_t size = strlen(s) + 1;
+
+    if(log_thread_memory_allocations) {
+        memory_statistics.memory_calls_made++;
+        memory_statistics.strdup_calls_made++;
+        memory_statistics.allocated_memory += size;
+        print_allocations(file, function, line, "strdup()", size);
+    }
+
+    size_t *n = (size_t *)malloc(sizeof(size_t) + size);
+    if (unlikely(!n)) fatal("strdupz() cannot allocate %zu bytes of memory.", size);
+
+    *n = size;
+    char *t = (char *)&n[1];
+    strcpy(t, s);
+    return t;
+}
+
+void freez_int(const char *file, const char *function, const unsigned long line, void *ptr) {
+    if(unlikely(!ptr)) return;
+
+    size_t *n = (size_t *)ptr;
+    n--;
+    size_t size = *n;
+
+    if(log_thread_memory_allocations) {
+        memory_statistics.memory_calls_made++;
+        memory_statistics.free_calls_made++;
+        memory_statistics.allocated_memory -= size;
+        print_allocations(file, function, line, "free()", size);
+    }
+
+    free(n);
+}
+#else
+
+char *strdupz(const char *s) {
+    char *t = strdup(s);
+    if (unlikely(!t)) fatal("Cannot strdup() string '%s'", s);
+    return t;
+}
+
+void freez(void *ptr) {
+    free(ptr);
+}
+
+void *mallocz(size_t size) {
+    void *p = malloc(size);
+    if (unlikely(!p)) fatal("Cannot allocate %zu bytes of memory.", size);
+    return p;
+}
+
+void *callocz(size_t nmemb, size_t size) {
+    void *p = calloc(nmemb, size);
+    if (unlikely(!p)) fatal("Cannot allocate %zu bytes of memory.", nmemb * size);
+    return p;
+}
+
+void *reallocz(void *ptr, size_t size) {
+    void *p = realloc(ptr, size);
+    if (unlikely(!p)) fatal("Cannot re-allocate memory to %zu bytes.", size);
+    return p;
+}
+
+#endif
+
+// --------------------------------------------------------------------------------------------------------------------
+
+void json_escape_string(char *dst, const char *src, size_t size) {
+    const char *t;
+    char *d = dst, *e = &dst[size - 1];
+
+    for(t = src; *t && d < e ;t++) {
+        if(unlikely(*t == '\\' || *t == '"')) {
+            if(unlikely(d + 1 >= e)) break;
+            *d++ = '\\';
+        }
+        *d++ = *t;
+    }
+
+    *d = '\0';
+}
+
+void json_fix_string(char *s) {
+    unsigned char c;
+    while((c = (unsigned char)*s)) {
+        if(unlikely(c == '\\'))
+            *s++ = '/';
+        else if(unlikely(c == '"'))
+            *s++ = '\'';
+        else if(unlikely(isspace(c) || iscntrl(c)))
+            *s++ = ' ';
+        else if(unlikely(!isprint(c) || c > 127))
+            *s++ = '_';
+        else
+            s++;
+    }
+}
+
+unsigned char netdata_map_chart_names[256] = {
+        [0] = '\0', //
+        [1] = '_', //
+        [2] = '_', //
+        [3] = '_', //
+        [4] = '_', //
+        [5] = '_', //
+        [6] = '_', //
+        [7] = '_', //
+        [8] = '_', //
+        [9] = '_', //
+        [10] = '_', //
+        [11] = '_', //
+        [12] = '_', //
+        [13] = '_', //
+        [14] = '_', //
+        [15] = '_', //
+        [16] = '_', //
+        [17] = '_', //
+        [18] = '_', //
+        [19] = '_', //
+        [20] = '_', //
+        [21] = '_', //
+        [22] = '_', //
+        [23] = '_', //
+        [24] = '_', //
+        [25] = '_', //
+        [26] = '_', //
+        [27] = '_', //
+        [28] = '_', //
+        [29] = '_', //
+        [30] = '_', //
+        [31] = '_', //
+        [32] = '_', //
+        [33] = '_', // !
+        [34] = '_', // "
+        [35] = '_', // #
+        [36] = '_', // $
+        [37] = '_', // %
+        [38] = '_', // &
+        [39] = '_', // '
+        [40] = '_', // (
+        [41] = '_', // )
+        [42] = '_', // *
+        [43] = '_', // +
+        [44] = '.', // ,
+        [45] = '-', // -
+        [46] = '.', // .
+        [47] = '/', // /
+        [48] = '0', // 0
+        [49] = '1', // 1
+        [50] = '2', // 2
+        [51] = '3', // 3
+        [52] = '4', // 4
+        [53] = '5', // 5
+        [54] = '6', // 6
+        [55] = '7', // 7
+        [56] = '8', // 8
+        [57] = '9', // 9
+        [58] = '_', // :
+        [59] = '_', // ;
+        [60] = '_', // <
+        [61] = '_', // =
+        [62] = '_', // >
+        [63] = '_', // ?
+        [64] = '_', // @
+        [65] = 'a', // A
+        [66] = 'b', // B
+        [67] = 'c', // C
+        [68] = 'd', // D
+        [69] = 'e', // E
+        [70] = 'f', // F
+        [71] = 'g', // G
+        [72] = 'h', // H
+        [73] = 'i', // I
+        [74] = 'j', // J
+        [75] = 'k', // K
+        [76] = 'l', // L
+        [77] = 'm', // M
+        [78] = 'n', // N
+        [79] = 'o', // O
+        [80] = 'p', // P
+        [81] = 'q', // Q
+        [82] = 'r', // R
+        [83] = 's', // S
+        [84] = 't', // T
+        [85] = 'u', // U
+        [86] = 'v', // V
+        [87] = 'w', // W
+        [88] = 'x', // X
+        [89] = 'y', // Y
+        [90] = 'z', // Z
+        [91] = '_', // [
+        [92] = '/', // backslash
+        [93] = '_', // ]
+        [94] = '_', // ^
+        [95] = '_', // _
+        [96] = '_', // `
+        [97] = 'a', // a
+        [98] = 'b', // b
+        [99] = 'c', // c
+        [100] = 'd', // d
+        [101] = 'e', // e
+        [102] = 'f', // f
+        [103] = 'g', // g
+        [104] = 'h', // h
+        [105] = 'i', // i
+        [106] = 'j', // j
+        [107] = 'k', // k
+        [108] = 'l', // l
+        [109] = 'm', // m
+        [110] = 'n', // n
+        [111] = 'o', // o
+        [112] = 'p', // p
+        [113] = 'q', // q
+        [114] = 'r', // r
+        [115] = 's', // s
+        [116] = 't', // t
+        [117] = 'u', // u
+        [118] = 'v', // v
+        [119] = 'w', // w
+        [120] = 'x', // x
+        [121] = 'y', // y
+        [122] = 'z', // z
+        [123] = '_', // {
+        [124] = '_', // |
+        [125] = '_', // }
+        [126] = '_', // ~
+        [127] = '_', //
+        [128] = '_', //
+        [129] = '_', //
+        [130] = '_', //
+        [131] = '_', //
+        [132] = '_', //
+        [133] = '_', //
+        [134] = '_', //
+        [135] = '_', //
+        [136] = '_', //
+        [137] = '_', //
+        [138] = '_', //
+        [139] = '_', //
+        [140] = '_', //
+        [141] = '_', //
+        [142] = '_', //
+        [143] = '_', //
+        [144] = '_', //
+        [145] = '_', //
+        [146] = '_', //
+        [147] = '_', //
+        [148] = '_', //
+        [149] = '_', //
+        [150] = '_', //
+        [151] = '_', //
+        [152] = '_', //
+        [153] = '_', //
+        [154] = '_', //
+        [155] = '_', //
+        [156] = '_', //
+        [157] = '_', //
+        [158] = '_', //
+        [159] = '_', //
+        [160] = '_', //
+        [161] = '_', //
+        [162] = '_', //
+        [163] = '_', //
+        [164] = '_', //
+        [165] = '_', //
+        [166] = '_', //
+        [167] = '_', //
+        [168] = '_', //
+        [169] = '_', //
+        [170] = '_', //
+        [171] = '_', //
+        [172] = '_', //
+        [173] = '_', //
+        [174] = '_', //
+        [175] = '_', //
+        [176] = '_', //
+        [177] = '_', //
+        [178] = '_', //
+        [179] = '_', //
+        [180] = '_', //
+        [181] = '_', //
+        [182] = '_', //
+        [183] = '_', //
+        [184] = '_', //
+        [185] = '_', //
+        [186] = '_', //
+        [187] = '_', //
+        [188] = '_', //
+        [189] = '_', //
+        [190] = '_', //
+        [191] = '_', //
+        [192] = '_', //
+        [193] = '_', //
+        [194] = '_', //
+        [195] = '_', //
+        [196] = '_', //
+        [197] = '_', //
+        [198] = '_', //
+        [199] = '_', //
+        [200] = '_', //
+        [201] = '_', //
+        [202] = '_', //
+        [203] = '_', //
+        [204] = '_', //
+        [205] = '_', //
+        [206] = '_', //
+        [207] = '_', //
+        [208] = '_', //
+        [209] = '_', //
+        [210] = '_', //
+        [211] = '_', //
+        [212] = '_', //
+        [213] = '_', //
+        [214] = '_', //
+        [215] = '_', //
+        [216] = '_', //
+        [217] = '_', //
+        [218] = '_', //
+        [219] = '_', //
+        [220] = '_', //
+        [221] = '_', //
+        [222] = '_', //
+        [223] = '_', //
+        [224] = '_', //
+        [225] = '_', //
+        [226] = '_', //
+        [227] = '_', //
+        [228] = '_', //
+        [229] = '_', //
+        [230] = '_', //
+        [231] = '_', //
+        [232] = '_', //
+        [233] = '_', //
+        [234] = '_', //
+        [235] = '_', //
+        [236] = '_', //
+        [237] = '_', //
+        [238] = '_', //
+        [239] = '_', //
+        [240] = '_', //
+        [241] = '_', //
+        [242] = '_', //
+        [243] = '_', //
+        [244] = '_', //
+        [245] = '_', //
+        [246] = '_', //
+        [247] = '_', //
+        [248] = '_', //
+        [249] = '_', //
+        [250] = '_', //
+        [251] = '_', //
+        [252] = '_', //
+        [253] = '_', //
+        [254] = '_', //
+        [255] = '_'  //
+};
+
+// make sure the supplied string
+// is good for a netdata chart/dimension ID/NAME
+void netdata_fix_chart_name(char *s) {
+    while ((*s = netdata_map_chart_names[(unsigned char) *s])) s++;
+}
+
+unsigned char netdata_map_chart_ids[256] = {
+        [0] = '\0', //
+        [1] = '_', //
+        [2] = '_', //
+        [3] = '_', //
+        [4] = '_', //
+        [5] = '_', //
+        [6] = '_', //
+        [7] = '_', //
+        [8] = '_', //
+        [9] = '_', //
+        [10] = '_', //
+        [11] = '_', //
+        [12] = '_', //
+        [13] = '_', //
+        [14] = '_', //
+        [15] = '_', //
+        [16] = '_', //
+        [17] = '_', //
+        [18] = '_', //
+        [19] = '_', //
+        [20] = '_', //
+        [21] = '_', //
+        [22] = '_', //
+        [23] = '_', //
+        [24] = '_', //
+        [25] = '_', //
+        [26] = '_', //
+        [27] = '_', //
+        [28] = '_', //
+        [29] = '_', //
+        [30] = '_', //
+        [31] = '_', //
+        [32] = '_', //
+        [33] = '_', // !
+        [34] = '_', // "
+        [35] = '_', // #
+        [36] = '_', // $
+        [37] = '_', // %
+        [38] = '_', // &
+        [39] = '_', // '
+        [40] = '_', // (
+        [41] = '_', // )
+        [42] = '_', // *
+        [43] = '_', // +
+        [44] = '.', // ,
+        [45] = '-', // -
+        [46] = '.', // .
+        [47] = '_', // /
+        [48] = '0', // 0
+        [49] = '1', // 1
+        [50] = '2', // 2
+        [51] = '3', // 3
+        [52] = '4', // 4
+        [53] = '5', // 5
+        [54] = '6', // 6
+        [55] = '7', // 7
+        [56] = '8', // 8
+        [57] = '9', // 9
+        [58] = '_', // :
+        [59] = '_', // ;
+        [60] = '_', // <
+        [61] = '_', // =
+        [62] = '_', // >
+        [63] = '_', // ?
+        [64] = '_', // @
+        [65] = 'a', // A
+        [66] = 'b', // B
+        [67] = 'c', // C
+        [68] = 'd', // D
+        [69] = 'e', // E
+        [70] = 'f', // F
+        [71] = 'g', // G
+        [72] = 'h', // H
+        [73] = 'i', // I
+        [74] = 'j', // J
+        [75] = 'k', // K
+        [76] = 'l', // L
+        [77] = 'm', // M
+        [78] = 'n', // N
+        [79] = 'o', // O
+        [80] = 'p', // P
+        [81] = 'q', // Q
+        [82] = 'r', // R
+        [83] = 's', // S
+        [84] = 't', // T
+        [85] = 'u', // U
+        [86] = 'v', // V
+        [87] = 'w', // W
+        [88] = 'x', // X
+        [89] = 'y', // Y
+        [90] = 'z', // Z
+        [91] = '_', // [
+        [92] = '/', // backslash
+        [93] = '_', // ]
+        [94] = '_', // ^
+        [95] = '_', // _
+        [96] = '_', // `
+        [97] = 'a', // a
+        [98] = 'b', // b
+        [99] = 'c', // c
+        [100] = 'd', // d
+        [101] = 'e', // e
+        [102] = 'f', // f
+        [103] = 'g', // g
+        [104] = 'h', // h
+        [105] = 'i', // i
+        [106] = 'j', // j
+        [107] = 'k', // k
+        [108] = 'l', // l
+        [109] = 'm', // m
+        [110] = 'n', // n
+        [111] = 'o', // o
+        [112] = 'p', // p
+        [113] = 'q', // q
+        [114] = 'r', // r
+        [115] = 's', // s
+        [116] = 't', // t
+        [117] = 'u', // u
+        [118] = 'v', // v
+        [119] = 'w', // w
+        [120] = 'x', // x
+        [121] = 'y', // y
+        [122] = 'z', // z
+        [123] = '_', // {
+        [124] = '_', // |
+        [125] = '_', // }
+        [126] = '_', // ~
+        [127] = '_', //
+        [128] = '_', //
+        [129] = '_', //
+        [130] = '_', //
+        [131] = '_', //
+        [132] = '_', //
+        [133] = '_', //
+        [134] = '_', //
+        [135] = '_', //
+        [136] = '_', //
+        [137] = '_', //
+        [138] = '_', //
+        [139] = '_', //
+        [140] = '_', //
+        [141] = '_', //
+        [142] = '_', //
+        [143] = '_', //
+        [144] = '_', //
+        [145] = '_', //
+        [146] = '_', //
+        [147] = '_', //
+        [148] = '_', //
+        [149] = '_', //
+        [150] = '_', //
+        [151] = '_', //
+        [152] = '_', //
+        [153] = '_', //
+        [154] = '_', //
+        [155] = '_', //
+        [156] = '_', //
+        [157] = '_', //
+        [158] = '_', //
+        [159] = '_', //
+        [160] = '_', //
+        [161] = '_', //
+        [162] = '_', //
+        [163] = '_', //
+        [164] = '_', //
+        [165] = '_', //
+        [166] = '_', //
+        [167] = '_', //
+        [168] = '_', //
+        [169] = '_', //
+        [170] = '_', //
+        [171] = '_', //
+        [172] = '_', //
+        [173] = '_', //
+        [174] = '_', //
+        [175] = '_', //
+        [176] = '_', //
+        [177] = '_', //
+        [178] = '_', //
+        [179] = '_', //
+        [180] = '_', //
+        [181] = '_', //
+        [182] = '_', //
+        [183] = '_', //
+        [184] = '_', //
+        [185] = '_', //
+        [186] = '_', //
+        [187] = '_', //
+        [188] = '_', //
+        [189] = '_', //
+        [190] = '_', //
+        [191] = '_', //
+        [192] = '_', //
+        [193] = '_', //
+        [194] = '_', //
+        [195] = '_', //
+        [196] = '_', //
+        [197] = '_', //
+        [198] = '_', //
+        [199] = '_', //
+        [200] = '_', //
+        [201] = '_', //
+        [202] = '_', //
+        [203] = '_', //
+        [204] = '_', //
+        [205] = '_', //
+        [206] = '_', //
+        [207] = '_', //
+        [208] = '_', //
+        [209] = '_', //
+        [210] = '_', //
+        [211] = '_', //
+        [212] = '_', //
+        [213] = '_', //
+        [214] = '_', //
+        [215] = '_', //
+        [216] = '_', //
+        [217] = '_', //
+        [218] = '_', //
+        [219] = '_', //
+        [220] = '_', //
+        [221] = '_', //
+        [222] = '_', //
+        [223] = '_', //
+        [224] = '_', //
+        [225] = '_', //
+        [226] = '_', //
+        [227] = '_', //
+        [228] = '_', //
+        [229] = '_', //
+        [230] = '_', //
+        [231] = '_', //
+        [232] = '_', //
+        [233] = '_', //
+        [234] = '_', //
+        [235] = '_', //
+        [236] = '_', //
+        [237] = '_', //
+        [238] = '_', //
+        [239] = '_', //
+        [240] = '_', //
+        [241] = '_', //
+        [242] = '_', //
+        [243] = '_', //
+        [244] = '_', //
+        [245] = '_', //
+        [246] = '_', //
+        [247] = '_', //
+        [248] = '_', //
+        [249] = '_', //
+        [250] = '_', //
+        [251] = '_', //
+        [252] = '_', //
+        [253] = '_', //
+        [254] = '_', //
+        [255] = '_'  //
+};
+
+// make sure the supplied string
+// is good for a netdata chart/dimension ID/NAME
+void netdata_fix_chart_id(char *s) {
+    while ((*s = netdata_map_chart_ids[(unsigned char) *s])) s++;
+}
+
+/*
+// http://stackoverflow.com/questions/7666509/hash-function-for-string
+uint32_t simple_hash(const char *name)
+{
+    const char *s = name;
+    uint32_t hash = 5381;
+    int i;
+
+    while((i = *s++)) hash = ((hash << 5) + hash) + i;
+
+    // fprintf(stderr, "HASH: %lu %s\n", hash, name);
+
+    return hash;
+}
+*/
+
+/*
+// http://isthe.com/chongo/tech/comp/fnv/#FNV-1a
+uint32_t simple_hash(const char *name) {
+    unsigned char *s = (unsigned char *) name;
+    uint32_t hval = 0x811c9dc5;
+
+    // FNV-1a algorithm
+    while (*s) {
+        // multiply by the 32 bit FNV magic prime mod 2^32
+        // NOTE: No need to optimize with left shifts.
+        //       GCC will use imul instruction anyway.
+        //       Tested with 'gcc -O3 -S'
+        //hval += (hval<<1) + (hval<<4) + (hval<<7) + (hval<<8) + (hval<<24);
+        hval *= 16777619;
+
+        // xor the bottom with the current octet
+        hval ^= (uint32_t) *s++;
+    }
+
+    // fprintf(stderr, "HASH: %u = %s\n", hval, name);
+    return hval;
+}
+
+uint32_t simple_uhash(const char *name) {
+    unsigned char *s = (unsigned char *) name;
+    uint32_t hval = 0x811c9dc5, c;
+
+    // FNV-1a algorithm
+    while ((c = *s++)) {
+        if (unlikely(c >= 'A' && c <= 'Z')) c += 'a' - 'A';
+        hval *= 16777619;
+        hval ^= c;
+    }
+    return hval;
+}
+*/
+
+/*
+// http://eternallyconfuzzled.com/tuts/algorithms/jsw_tut_hashing.aspx
+// one at a time hash
+uint32_t simple_hash(const char *name) {
+    unsigned char *s = (unsigned char *)name;
+    uint32_t h = 0;
+
+    while(*s) {
+        h += *s++;
+        h += (h << 10);
+        h ^= (h >> 6);
+    }
+
+    h += (h << 3);
+    h ^= (h >> 11);
+    h += (h << 15);
+
+    // fprintf(stderr, "HASH: %u = %s\n", h, name);
+
+    return h;
+}
+*/
+
+void strreverse(char *begin, char *end) {
+    while (end > begin) {
+        // clearer code.
+        char aux = *end;
+        *end-- = *begin;
+        *begin++ = aux;
+    }
+}
+
+char *strsep_on_1char(char **ptr, char c) {
+    if(unlikely(!ptr || !*ptr))
+        return NULL;
+
+    // remember the position we started
+    char *s = *ptr;
+
+    // skip separators in front
+    while(*s == c) s++;
+    char *ret = s;
+
+    // find the next separator
+    while(*s++) {
+        if(unlikely(*s == c)) {
+            *s++ = '\0';
+            *ptr = s;
+            return ret;
+        }
+    }
+
+    *ptr = NULL;
+    return ret;
+}
+
+char *mystrsep(char **ptr, char *s) {
+    char *p = "";
+    while (p && !p[0] && *ptr) p = strsep(ptr, s);
+    return (p);
+}
+
+char *trim(char *s) {
+    // skip leading spaces
+    while (*s && isspace(*s)) s++;
+    if (!*s) return NULL;
+
+    // skip tailing spaces
+    // this way is way faster. Writes only one NUL char.
+    ssize_t l = strlen(s);
+    if (--l >= 0) {
+        char *p = s + l;
+        while (p > s && isspace(*p)) p--;
+        *++p = '\0';
+    }
+
+    if (!*s) return NULL;
+
+    return s;
+}
+
+inline char *trim_all(char *buffer) {
+    char *d = buffer, *s = buffer;
+
+    // skip spaces
+    while(isspace(*s)) s++;
+
+    while(*s) {
+        // copy the non-space part
+        while(*s && !isspace(*s)) *d++ = *s++;
+
+        // add a space if we have to
+        if(*s && isspace(*s)) {
+            *d++ = ' ';
+            s++;
+        }
+
+        // skip spaces
+        while(isspace(*s)) s++;
+    }
+
+    *d = '\0';
+
+    if(d > buffer) {
+        d--;
+        if(isspace(*d)) *d = '\0';
+    }
+
+    if(!buffer[0]) return NULL;
+    return buffer;
+}
+
+static int memory_file_open(const char *filename, size_t size) {
+    // info("memory_file_open('%s', %zu", filename, size);
+
+    int fd = open(filename, O_RDWR | O_CREAT | O_NOATIME, 0664);
+    if (fd != -1) {
+        if (lseek(fd, size, SEEK_SET) == (off_t) size) {
+            if (write(fd, "", 1) == 1) {
+                if (ftruncate(fd, size))
+                    error("Cannot truncate file '%s' to size %zu. Will use the larger file.", filename, size);
+            }
+            else error("Cannot write to file '%s' at position %zu.", filename, size);
+        }
+        else error("Cannot seek file '%s' to size %zu.", filename, size);
+    }
+    else error("Cannot create/open file '%s'.", filename);
+
+    return fd;
+}
+
+// mmap_shared is used for memory mode = map
+static void *memory_file_mmap(const char *filename, size_t size, int flags) {
+    // info("memory_file_mmap('%s', %zu", filename, size);
+    static int log_madvise = 1;
+
+    int fd = -1;
+    if(filename) {
+        fd = memory_file_open(filename, size);
+        if(fd == -1) return MAP_FAILED;
+    }
+
+    void *mem = mmap(NULL, size, PROT_READ | PROT_WRITE, flags, fd, 0);
+    if (mem != MAP_FAILED) {
+#ifdef NETDATA_LOG_ALLOCATIONS
+        mmap_accounting(size);
+#endif
+        int advise = MADV_SEQUENTIAL | MADV_DONTFORK;
+        if (flags & MAP_SHARED) advise |= MADV_WILLNEED;
+
+        if (madvise(mem, size, advise) != 0 && log_madvise) {
+            error("Cannot advise the kernel about shared memory usage.");
+            log_madvise--;
+        }
+    }
+
+    if(fd != -1)
+        close(fd);
+
+    return mem;
+}
+
+#ifdef MADV_MERGEABLE
+static void *memory_file_mmap_ksm(const char *filename, size_t size, int flags) {
+    // info("memory_file_mmap_ksm('%s', %zu", filename, size);
+    static int log_madvise_2 = 1, log_madvise_3 = 1;
+
+    int fd = -1;
+    if(filename) {
+        fd = memory_file_open(filename, size);
+        if(fd == -1) return MAP_FAILED;
+    }
+
+    void *mem = mmap(NULL, size, PROT_READ | PROT_WRITE, flags | MAP_ANONYMOUS, -1, 0);
+    if (mem != MAP_FAILED) {
+#ifdef NETDATA_LOG_ALLOCATIONS
+        mmap_accounting(size);
+#endif
+        if(fd != -1) {
+            if (lseek(fd, 0, SEEK_SET) == 0) {
+                if (read(fd, mem, size) != (ssize_t) size)
+                    error("Cannot read from file '%s'", filename);
+            }
+            else error("Cannot seek to beginning of file '%s'.", filename);
+        }
+
+        // don't use MADV_SEQUENTIAL|MADV_DONTFORK, they disable MADV_MERGEABLE
+        if (madvise(mem, size, MADV_SEQUENTIAL | MADV_DONTFORK) != 0 && log_madvise_2) {
+            error("Cannot advise the kernel about the memory usage (MADV_SEQUENTIAL|MADV_DONTFORK) of file '%s'.", filename);
+            log_madvise_2--;
+        }
+
+        if (madvise(mem, size, MADV_MERGEABLE) != 0 && log_madvise_3) {
+            error("Cannot advise the kernel about the memory usage (MADV_MERGEABLE) of file '%s'.", filename);
+            log_madvise_3--;
+        }
+    }
+
+    if(fd != -1)
+        close(fd);
+
+    return mem;
+}
+#else
+static void *memory_file_mmap_ksm(const char *filename, size_t size, int flags) {
+    // info("memory_file_mmap_ksm FALLBACK ('%s', %zu", filename, size);
+
+    if(filename)
+        return memory_file_mmap(filename, size, flags);
+
+    // when KSM is not available and no filename is given (memory mode = ram),
+    // we just report failure
+    return MAP_FAILED;
+}
+#endif
+
+void *mymmap(const char *filename, size_t size, int flags, int ksm) {
+    void *mem = NULL;
+
+    if (filename && (flags & MAP_SHARED || !enable_ksm || !ksm))
+        // memory mode = map | save
+        // when KSM is not enabled
+        // MAP_SHARED is used for memory mode = map (no KSM possible)
+        mem = memory_file_mmap(filename, size, flags);
+
+    else
+        // memory mode = save | ram
+        // when KSM is enabled
+        // for memory mode = ram, the filename is NULL
+        mem = memory_file_mmap_ksm(filename, size, flags);
+
+    if(mem == MAP_FAILED) return NULL;
+
+    errno = 0;
+    return mem;
+}
+
+int memory_file_save(const char *filename, void *mem, size_t size) {
+    char tmpfilename[FILENAME_MAX + 1];
+
+    snprintfz(tmpfilename, FILENAME_MAX, "%s.%ld.tmp", filename, (long) getpid());
+
+    int fd = open(tmpfilename, O_RDWR | O_CREAT | O_NOATIME, 0664);
+    if (fd < 0) {
+        error("Cannot create/open file '%s'.", filename);
+        return -1;
+    }
+
+    if (write(fd, mem, size) != (ssize_t) size) {
+        error("Cannot write to file '%s' %ld bytes.", filename, (long) size);
+        close(fd);
+        return -1;
+    }
+
+    close(fd);
+
+    if (rename(tmpfilename, filename)) {
+        error("Cannot rename '%s' to '%s'", tmpfilename, filename);
+        return -1;
+    }
+
+    return 0;
+}
+
+int fd_is_valid(int fd) {
+    return fcntl(fd, F_GETFD) != -1 || errno != EBADF;
+}
+
+char *fgets_trim_len(char *buf, size_t buf_size, FILE *fp, size_t *len) {
+    char *s = fgets(buf, (int)buf_size, fp);
+    if (!s) return NULL;
+
+    char *t = s;
+    if (*t != '\0') {
+        // find the string end
+        while (*++t != '\0');
+
+        // trim trailing spaces/newlines/tabs
+        while (--t > s && *t == '\n')
+            *t = '\0';
+    }
+
+    if (len)
+        *len = t - s + 1;
+
+    return s;
+}
+
+int vsnprintfz(char *dst, size_t n, const char *fmt, va_list args) {
+    int size = vsnprintf(dst, n, fmt, args);
+
+    if (unlikely((size_t) size > n)) {
+        // truncated
+        size = (int)n;
+    }
+
+    dst[size] = '\0';
+    return size;
+}
+
+int snprintfz(char *dst, size_t n, const char *fmt, ...) {
+    va_list args;
+
+    va_start(args, fmt);
+    int ret = vsnprintfz(dst, n, fmt, args);
+    va_end(args);
+
+    return ret;
+}
+
+/*
+// poor man cycle counting
+static unsigned long tsc;
+void begin_tsc(void) {
+    unsigned long a, d;
+    asm volatile ("cpuid\nrdtsc" : "=a" (a), "=d" (d) : "0" (0) : "ebx", "ecx");
+    tsc = ((unsigned long)d << 32) | (unsigned long)a;
+}
+unsigned long end_tsc(void) {
+    unsigned long a, d;
+    asm volatile ("rdtscp" : "=a" (a), "=d" (d) : : "ecx");
+    return (((unsigned long)d << 32) | (unsigned long)a) - tsc;
+}
+*/
+
+int recursively_delete_dir(const char *path, const char *reason) {
+    DIR *dir = opendir(path);
+    if(!dir) {
+        error("Cannot read %s directory to be deleted '%s'", reason?reason:"", path);
+        return -1;
+    }
+
+    int ret = 0;
+    struct dirent *de = NULL;
+    while((de = readdir(dir))) {
+        if(de->d_type == DT_DIR
+           && (
+                   (de->d_name[0] == '.' && de->d_name[1] == '\0')
+                   || (de->d_name[0] == '.' && de->d_name[1] == '.' && de->d_name[2] == '\0')
+           ))
+            continue;
+
+        char fullpath[FILENAME_MAX + 1];
+        snprintfz(fullpath, FILENAME_MAX, "%s/%s", path, de->d_name);
+
+        if(de->d_type == DT_DIR) {
+            int r = recursively_delete_dir(fullpath, reason);
+            if(r > 0) ret += r;
+            continue;
+        }
+
+        info("Deleting %s file '%s'", reason?reason:"", fullpath);
+        if(unlikely(unlink(fullpath) == -1))
+            error("Cannot delete %s file '%s'", reason?reason:"", fullpath);
+        else
+            ret++;
+    }
+
+    info("Deleting empty directory '%s'", path);
+    if(unlikely(rmdir(path) == -1))
+        error("Cannot delete empty directory '%s'", path);
+    else
+        ret++;
+
+    closedir(dir);
+
+    return ret;
+}
+
+static int is_virtual_filesystem(const char *path, char **reason) {
+
+#if defined(__APPLE__) || defined(__FreeBSD__)
+    (void)path;
+    (void)reason;
+#else
+    struct statfs stat;
+    // stat.f_fsid.__val[0] is a file system id
+    // stat.f_fsid.__val[1] is the inode
+    // so their combination uniquely identifies the file/dir
+
+    if (statfs(path, &stat) == -1) {
+        if(reason) *reason = "failed to statfs()";
+        return -1;
+    }
+
+    if(stat.f_fsid.__val[0] != 0 || stat.f_fsid.__val[1] != 0) {
+        errno = EINVAL;
+        if(reason) *reason = "is not a virtual file system";
+        return -1;
+    }
+#endif
+
+    return 0;
+}
+
+int verify_netdata_host_prefix() {
+    if(!netdata_configured_host_prefix)
+        netdata_configured_host_prefix = "";
+
+    if(!*netdata_configured_host_prefix)
+        return 0;
+
+    char buffer[FILENAME_MAX + 1];
+    char *path = netdata_configured_host_prefix;
+    char *reason = "unknown reason";
+    errno = 0;
+
+    struct stat sb;
+    if (stat(path, &sb) == -1) {
+        reason = "failed to stat()";
+        goto failed;
+    }
+
+    if((sb.st_mode & S_IFMT) != S_IFDIR) {
+        errno = EINVAL;
+        reason = "is not a directory";
+        goto failed;
+    }
+
+    path = buffer;
+    snprintfz(path, FILENAME_MAX, "%s/proc", netdata_configured_host_prefix);
+    if(is_virtual_filesystem(path, &reason) == -1)
+        goto failed;
+
+    snprintfz(path, FILENAME_MAX, "%s/sys", netdata_configured_host_prefix);
+    if(is_virtual_filesystem(path, &reason) == -1)
+        goto failed;
+
+    if(netdata_configured_host_prefix && *netdata_configured_host_prefix)
+        info("Using host prefix directory '%s'", netdata_configured_host_prefix);
+
+    return 0;
+
+failed:
+    error("Ignoring host prefix '%s': path '%s' %s", netdata_configured_host_prefix, path, reason);
+    netdata_configured_host_prefix = "";
+    return -1;
+}
+
+char *strdupz_path_subpath(const char *path, const char *subpath) {
+    if(unlikely(!path || !*path)) path = ".";
+    if(unlikely(!subpath)) subpath = "";
+
+    // skip trailing slashes in path
+    size_t len = strlen(path);
+    while(len > 0 && path[len - 1] == '/') len--;
+
+    // skip leading slashes in subpath
+    while(subpath[0] == '/') subpath++;
+
+    // if the last character in path is / and (there is a subpath or path is now empty)
+    // keep the trailing slash in path and remove the additional slash
+    char *slash = "/";
+    if(path[len] == '/' && (*subpath || len == 0)) {
+        slash = "";
+        len++;
+    }
+    else if(!*subpath) {
+        // there is no subpath
+        // no need for trailing slash
+        slash = "";
+    }
+
+    char buffer[FILENAME_MAX + 1];
+    snprintfz(buffer, FILENAME_MAX, "%.*s%s%s", (int)len, path, slash, subpath);
+    return strdupz(buffer);
+}
+
+int path_is_dir(const char *path, const char *subpath) {
+    char *s = strdupz_path_subpath(path, subpath);
+
+    size_t max_links = 100;
+
+    int is_dir = 0;
+    struct stat statbuf;
+    while(max_links-- && stat(s, &statbuf) == 0) {
+        if((statbuf.st_mode & S_IFMT) == S_IFDIR) {
+            is_dir = 1;
+            break;
+        }
+        else if((statbuf.st_mode & S_IFMT) == S_IFLNK) {
+            char buffer[FILENAME_MAX + 1];
+            ssize_t l = readlink(s, buffer, FILENAME_MAX);
+            if(l > 0) {
+                buffer[l] = '\0';
+                freez(s);
+                s = strdupz(buffer);
+                continue;
+            }
+            else {
+                is_dir = 0;
+                break;
+            }
+        }
+        else {
+            is_dir = 0;
+            break;
+        }
+    }
+
+    freez(s);
+    return is_dir;
+}
+
+int path_is_file(const char *path, const char *subpath) {
+    char *s = strdupz_path_subpath(path, subpath);
+
+    size_t max_links = 100;
+
+    int is_file = 0;
+    struct stat statbuf;
+    while(max_links-- && stat(s, &statbuf) == 0) {
+        if((statbuf.st_mode & S_IFMT) == S_IFREG) {
+            is_file = 1;
+            break;
+        }
+        else if((statbuf.st_mode & S_IFMT) == S_IFLNK) {
+            char buffer[FILENAME_MAX + 1];
+            ssize_t l = readlink(s, buffer, FILENAME_MAX);
+            if(l > 0) {
+                buffer[l] = '\0';
+                freez(s);
+                s = strdupz(buffer);
+                continue;
+            }
+            else {
+                is_file = 0;
+                break;
+            }
+        }
+        else {
+            is_file = 0;
+            break;
+        }
+    }
+
+    freez(s);
+    return is_file;
+}
+
+void recursive_config_double_dir_load(const char *user_path, const char *stock_path, const char *subpath, int (*callback)(const char *filename, void *data), void *data, size_t depth) {
+    if(depth > 3) {
+        error("CONFIG: Max directory depth reached while reading user path '%s', stock path '%s', subpath '%s'", user_path, stock_path, subpath);
+        return;
+    }
+
+    char *udir = strdupz_path_subpath(user_path, subpath);
+    char *sdir = strdupz_path_subpath(stock_path, subpath);
+
+    debug(D_HEALTH, "CONFIG traversing user-config directory '%s', stock config directory '%s'", udir, sdir);
+
+    DIR *dir = opendir(udir);
+    if (!dir) {
+        error("CONFIG cannot open user-config directory '%s'.", udir);
+    }
+    else {
+        struct dirent *de = NULL;
+        while((de = readdir(dir))) {
+            if(de->d_type == DT_DIR || de->d_type == DT_LNK) {
+                if( !de->d_name[0] ||
+                    (de->d_name[0] == '.' && de->d_name[1] == '\0') ||
+                    (de->d_name[0] == '.' && de->d_name[1] == '.' && de->d_name[2] == '\0')
+                        ) {
+                    debug(D_HEALTH, "CONFIG ignoring user-config directory '%s/%s'", udir, de->d_name);
+                    continue;
+                }
+
+                if(path_is_dir(udir, de->d_name)) {
+                    recursive_config_double_dir_load(udir, sdir, de->d_name, callback, data, depth + 1);
+                    continue;
+                }
+            }
+
+            if(de->d_type == DT_UNKNOWN || de->d_type == DT_REG || de->d_type == DT_LNK) {
+                size_t len = strlen(de->d_name);
+                if(path_is_file(udir, de->d_name) &&
+                   len > 5 && !strcmp(&de->d_name[len - 5], ".conf")) {
+                    char *filename = strdupz_path_subpath(udir, de->d_name);
+                    debug(D_HEALTH, "CONFIG calling callback for user file '%s'", filename);
+                    callback(filename, data);
+                    freez(filename);
+                    continue;
+                }
+            }
+
+            debug(D_HEALTH, "CONFIG ignoring user-config file '%s/%s' of type %d", udir, de->d_name, (int)de->d_type);
+        }
+
+        closedir(dir);
+    }
+
+    debug(D_HEALTH, "CONFIG traversing stock config directory '%s', user config directory '%s'", sdir, udir);
+
+    dir = opendir(sdir);
+    if (!dir) {
+        error("CONFIG cannot open stock config directory '%s'.", sdir);
+    }
+    else {
+        struct dirent *de = NULL;
+        while((de = readdir(dir))) {
+            if(de->d_type == DT_DIR || de->d_type == DT_LNK) {
+                if( !de->d_name[0] ||
+                    (de->d_name[0] == '.' && de->d_name[1] == '\0') ||
+                    (de->d_name[0] == '.' && de->d_name[1] == '.' && de->d_name[2] == '\0')
+                        ) {
+                    debug(D_HEALTH, "CONFIG ignoring stock config directory '%s/%s'", sdir, de->d_name);
+                    continue;
+                }
+
+                if(path_is_dir(sdir, de->d_name)) {
+                    // we recurse in stock subdirectory, only when there is no corresponding
+                    // user subdirectory - to avoid reading the files twice
+
+                    if(!path_is_dir(udir, de->d_name))
+                        recursive_config_double_dir_load(udir, sdir, de->d_name, callback, data, depth + 1);
+
+                    continue;
+                }
+            }
+
+            if(de->d_type == DT_UNKNOWN || de->d_type == DT_REG || de->d_type == DT_LNK) {
+                size_t len = strlen(de->d_name);
+                if(path_is_file(sdir, de->d_name) && !path_is_file(udir, de->d_name) &&
+                   len > 5 && !strcmp(&de->d_name[len - 5], ".conf")) {
+                    char *filename = strdupz_path_subpath(sdir, de->d_name);
+                    debug(D_HEALTH, "CONFIG calling callback for stock file '%s'", filename);
+                    callback(filename, data);
+                    freez(filename);
+                    continue;
+                }
+
+            }
+
+            debug(D_HEALTH, "CONFIG ignoring stock-config file '%s/%s' of type %d", udir, de->d_name, (int)de->d_type);
+        }
+
+        closedir(dir);
+    }
+
+    debug(D_HEALTH, "CONFIG done traversing user-config directory '%s', stock config directory '%s'", udir, sdir);
+
+    freez(udir);
+    freez(sdir);
+}
diff --git a/libnetdata/libnetdata.h b/libnetdata/libnetdata.h
new file mode 100644
index 0000000..8d9be33
--- /dev/null
+++ b/libnetdata/libnetdata.h
@@ -0,0 +1,308 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_LIB_H
+#define NETDATA_LIB_H 1
+
+#ifdef HAVE_CONFIG_H
+#include <config.h>
+#endif
+
+#define OS_LINUX   1
+#define OS_FREEBSD 2
+#define OS_MACOS   3
+
+
+// ----------------------------------------------------------------------------
+// system include files for all netdata C programs
+
+/* select the memory allocator, based on autoconf findings */
+#if defined(ENABLE_JEMALLOC)
+
+#if defined(HAVE_JEMALLOC_JEMALLOC_H)
+#include <jemalloc/jemalloc.h>
+#else // !defined(HAVE_JEMALLOC_JEMALLOC_H)
+#include <malloc.h>
+#endif // !defined(HAVE_JEMALLOC_JEMALLOC_H)
+
+#elif defined(ENABLE_TCMALLOC)
+
+#include <google/tcmalloc.h>
+
+#else /* !defined(ENABLE_JEMALLOC) && !defined(ENABLE_TCMALLOC) */
+
+#if !(defined(__FreeBSD__) || defined(__APPLE__))
+#include <malloc.h>
+#endif /* __FreeBSD__ || __APPLE__ */
+
+#endif /* !defined(ENABLE_JEMALLOC) && !defined(ENABLE_TCMALLOC) */
+
+// ----------------------------------------------------------------------------
+
+#if defined(__FreeBSD__)
+#include <pthread_np.h>
+#define NETDATA_OS_TYPE "freebsd"
+#elif defined(__APPLE__)
+#define NETDATA_OS_TYPE "macos"
+#else
+#define NETDATA_OS_TYPE "linux"
+#endif /* __FreeBSD__, __APPLE__*/
+
+#include <pthread.h>
+#include <errno.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <stdarg.h>
+#include <stddef.h>
+#include <ctype.h>
+#include <string.h>
+#include <strings.h>
+#include <arpa/inet.h>
+#include <netinet/tcp.h>
+#include <sys/ioctl.h>
+#include <libgen.h>
+#include <dirent.h>
+#include <fcntl.h>
+#include <getopt.h>
+#include <grp.h>
+#include <pwd.h>
+#include <locale.h>
+#include <net/if.h>
+#include <poll.h>
+#include <signal.h>
+#include <syslog.h>
+#include <sys/mman.h>
+#include <sys/resource.h>
+#include <sys/socket.h>
+#include <sys/syscall.h>
+#include <sys/time.h>
+#include <sys/types.h>
+#include <sys/wait.h>
+#include <sys/un.h>
+#include <time.h>
+#include <unistd.h>
+#include <uuid/uuid.h>
+
+#ifdef HAVE_NETINET_IN_H
+#include <netinet/in.h>
+#endif
+
+#ifdef HAVE_RESOLV_H
+#include <resolv.h>
+#endif
+
+#ifdef HAVE_NETDB_H
+#include <netdb.h>
+#endif
+
+#ifdef HAVE_SYS_PRCTL_H
+#include <sys/prctl.h>
+#endif
+
+#ifdef HAVE_SYS_STAT_H
+#include <sys/stat.h>
+#endif
+
+#ifdef HAVE_SYS_VFS_H
+#include <sys/vfs.h>
+#endif
+
+#ifdef HAVE_SYS_STATFS_H
+#include <sys/statfs.h>
+#endif
+
+#ifdef HAVE_SYS_MOUNT_H
+#include <sys/mount.h>
+#endif
+
+#ifdef HAVE_SYS_STATVFS_H
+#include <sys/statvfs.h>
+#endif
+
+// #1408
+#ifdef MAJOR_IN_MKDEV
+#include <sys/mkdev.h>
+#endif
+#ifdef MAJOR_IN_SYSMACROS
+#include <sys/sysmacros.h>
+#endif
+
+#ifdef STORAGE_WITH_MATH
+#include <math.h>
+#include <float.h>
+#endif
+
+#if defined(HAVE_INTTYPES_H)
+#include <inttypes.h>
+#elif defined(HAVE_STDINT_H)
+#include <stdint.h>
+#endif
+
+#ifdef NETDATA_WITH_ZLIB
+#include <zlib.h>
+#endif
+
+#ifdef HAVE_CAPABILITY
+#include <sys/capability.h>
+#endif
+
+
+// ----------------------------------------------------------------------------
+// netdata common definitions
+
+#if (SIZEOF_VOID_P == 8)
+#define ENVIRONMENT64
+#elif (SIZEOF_VOID_P == 4)
+#define ENVIRONMENT32
+#else
+#error "Cannot detect if this is a 32 or 64 bit CPU"
+#endif
+
+#ifdef __GNUC__
+#define GCC_VERSION (__GNUC__ * 10000 + __GNUC_MINOR__ * 100 + __GNUC_PATCHLEVEL__)
+#endif // __GNUC__
+
+#ifdef HAVE_FUNC_ATTRIBUTE_RETURNS_NONNULL
+#define NEVERNULL __attribute__((returns_nonnull))
+#else
+#define NEVERNULL
+#endif
+
+#ifdef HAVE_FUNC_ATTRIBUTE_NOINLINE
+#define NOINLINE __attribute__((noinline))
+#else
+#define NOINLINE
+#endif
+
+#ifdef HAVE_FUNC_ATTRIBUTE_MALLOC
+#define MALLOCLIKE __attribute__((malloc))
+#else
+#define MALLOCLIKE
+#endif
+
+#ifdef HAVE_FUNC_ATTRIBUTE_FORMAT
+#define PRINTFLIKE(f, a) __attribute__ ((format(__printf__, f, a)))
+#else
+#define PRINTFLIKE(f, a)
+#endif
+
+#ifdef HAVE_FUNC_ATTRIBUTE_NORETURN
+#define NORETURN __attribute__ ((noreturn))
+#else
+#define NORETURN
+#endif
+
+#ifdef HAVE_FUNC_ATTRIBUTE_WARN_UNUSED_RESULT
+#define WARNUNUSED __attribute__ ((warn_unused_result))
+#else
+#define WARNUNUSED
+#endif
+
+#ifdef abs
+#undef abs
+#endif
+#define abs(x) (((x) < 0)? (-(x)) : (x))
+
+#define GUID_LEN 36
+
+extern void netdata_fix_chart_id(char *s);
+extern void netdata_fix_chart_name(char *s);
+
+extern void strreverse(char* begin, char* end);
+extern char *mystrsep(char **ptr, char *s);
+extern char *trim(char *s); // remove leading and trailing spaces; may return NULL
+extern char *trim_all(char *buffer); // like trim(), but also remove duplicate spaces inside the string; may return NULL
+
+extern int  vsnprintfz(char *dst, size_t n, const char *fmt, va_list args);
+extern int  snprintfz(char *dst, size_t n, const char *fmt, ...) PRINTFLIKE(3, 4);
+
+// memory allocation functions that handle failures
+#ifdef NETDATA_LOG_ALLOCATIONS
+extern __thread size_t log_thread_memory_allocations;
+#define strdupz(s) strdupz_int(__FILE__, __FUNCTION__, __LINE__, s)
+#define callocz(nmemb, size) callocz_int(__FILE__, __FUNCTION__, __LINE__, nmemb, size)
+#define mallocz(size) mallocz_int(__FILE__, __FUNCTION__, __LINE__, size)
+#define reallocz(ptr, size) reallocz_int(__FILE__, __FUNCTION__, __LINE__, ptr, size)
+#define freez(ptr) freez_int(__FILE__, __FUNCTION__, __LINE__, ptr)
+
+extern char *strdupz_int(const char *file, const char *function, const unsigned long line, const char *s);
+extern void *callocz_int(const char *file, const char *function, const unsigned long line, size_t nmemb, size_t size);
+extern void *mallocz_int(const char *file, const char *function, const unsigned long line, size_t size);
+extern void *reallocz_int(const char *file, const char *function, const unsigned long line, void *ptr, size_t size);
+extern void freez_int(const char *file, const char *function, const unsigned long line, void *ptr);
+#else // NETDATA_LOG_ALLOCATIONS
+extern char *strdupz(const char *s) MALLOCLIKE NEVERNULL;
+extern void *callocz(size_t nmemb, size_t size) MALLOCLIKE NEVERNULL;
+extern void *mallocz(size_t size) MALLOCLIKE NEVERNULL;
+extern void *reallocz(void *ptr, size_t size) MALLOCLIKE NEVERNULL;
+extern void freez(void *ptr);
+#endif // NETDATA_LOG_ALLOCATIONS
+
+extern void json_escape_string(char *dst, const char *src, size_t size);
+extern void json_fix_string(char *s);
+
+extern void *mymmap(const char *filename, size_t size, int flags, int ksm);
+extern int memory_file_save(const char *filename, void *mem, size_t size);
+
+extern int fd_is_valid(int fd);
+
+extern struct rlimit rlimit_nofile;
+
+extern int enable_ksm;
+
+extern char *fgets_trim_len(char *buf, size_t buf_size, FILE *fp, size_t *len);
+
+extern int verify_netdata_host_prefix();
+
+extern int recursively_delete_dir(const char *path, const char *reason);
+
+extern volatile sig_atomic_t netdata_exit;
+extern const char *os_type;
+
+extern const char *program_version;
+
+extern char *strdupz_path_subpath(const char *path, const char *subpath);
+extern int path_is_dir(const char *path, const char *subpath);
+extern int path_is_file(const char *path, const char *subpath);
+extern void recursive_config_double_dir_load(
+        const char *user_path
+        , const char *stock_path
+        , const char *subpath
+        , int (*callback)(const char *filename, void *data)
+        , void *data
+        , size_t depth
+);
+
+/* fix for alpine linux */
+#ifndef RUSAGE_THREAD
+#ifdef RUSAGE_CHILDREN
+#define RUSAGE_THREAD RUSAGE_CHILDREN
+#endif
+#endif
+
+#define BITS_IN_A_KILOBIT 1000
+
+
+extern void netdata_cleanup_and_exit(int ret) NORETURN;
+extern void send_statistics(const char *action, const char *action_result, const char *action_data);
+extern char *netdata_configured_host_prefix;
+#include "os.h"
+#include "storage_number/storage_number.h"
+#include "threads/threads.h"
+#include "buffer/buffer.h"
+#include "locks/locks.h"
+#include "avl/avl.h"
+#include "inlined.h"
+#include "clocks/clocks.h"
+#include "popen/popen.h"
+#include "simple_pattern/simple_pattern.h"
+#include "socket/socket.h"
+#include "config/appconfig.h"
+#include "log/log.h"
+#include "procfile/procfile.h"
+#include "dictionary/dictionary.h"
+#include "eval/eval.h"
+#include "statistical/statistical.h"
+#include "adaptive_resortable_list/adaptive_resortable_list.h"
+#include "url/url.h"
+
+#endif // NETDATA_LIB_H
diff --git a/libnetdata/locks/Makefile.am b/libnetdata/locks/Makefile.am
new file mode 100644
index 0000000..1cb69ed
--- /dev/null
+++ b/libnetdata/locks/Makefile.am
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
+
+
+dist_noinst_DATA = \
+	README.md \
+	$(NULL)
diff --git a/libnetdata/locks/README.md b/libnetdata/locks/README.md
new file mode 100644
index 0000000..0f01e8c
--- /dev/null
+++ b/libnetdata/locks/README.md
@@ -0,0 +1,2 @@
+
+[![analytics](https://www.google-analytics.com/collect?v=1&aip=1&t=pageview&_s=1&ds=github&dr=https%3A%2F%2Fgithub.com%2Fnetdata%2Fnetdata&dl=https%3A%2F%2Fmy-netdata.io%2Fgithub%2Flibnetdata%2Flocks%2FREADME&_u=MAC~&cid=5792dfd7-8dc4-476b-af31-da2fdb9f93d2&tid=UA-64295674-3)]()
diff --git a/libnetdata/locks/locks.c b/libnetdata/locks/locks.c
new file mode 100644
index 0000000..91e2269
--- /dev/null
+++ b/libnetdata/locks/locks.c
@@ -0,0 +1,332 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../libnetdata.h"
+
+// ----------------------------------------------------------------------------
+// automatic thread cancelability management, based on locks
+
+static __thread int netdata_thread_first_cancelability = 0;
+static __thread int netdata_thread_lock_cancelability = 0;
+
+inline void netdata_thread_disable_cancelability(void) {
+    int old;
+    int ret = pthread_setcancelstate(PTHREAD_CANCEL_DISABLE, &old);
+    if(ret != 0)
+        error("THREAD_CANCELABILITY: pthread_setcancelstate() on thread %s returned error %d", netdata_thread_tag(), ret);
+    else {
+        if(!netdata_thread_lock_cancelability)
+            netdata_thread_first_cancelability = old;
+
+        netdata_thread_lock_cancelability++;
+    }
+}
+
+inline void netdata_thread_enable_cancelability(void) {
+    if(netdata_thread_lock_cancelability < 1) {
+        error("THREAD_CANCELABILITY: netdata_thread_enable_cancelability(): invalid thread cancelability count %d on thread %s - results will be undefined - please report this!", netdata_thread_lock_cancelability, netdata_thread_tag());
+    }
+    else if(netdata_thread_lock_cancelability == 1) {
+        int old = 1;
+        int ret = pthread_setcancelstate(netdata_thread_first_cancelability, &old);
+        if(ret != 0)
+            error("THREAD_CANCELABILITY: pthread_setcancelstate() on thread %s returned error %d", netdata_thread_tag(), ret);
+        else {
+            if(old != PTHREAD_CANCEL_DISABLE)
+                error("THREAD_CANCELABILITY: netdata_thread_enable_cancelability(): old thread cancelability on thread %s was changed, expected DISABLED (%d), found %s (%d) - please report this!", netdata_thread_tag(), PTHREAD_CANCEL_DISABLE, (old == PTHREAD_CANCEL_ENABLE)?"ENABLED":"UNKNOWN", old);
+        }
+
+        netdata_thread_lock_cancelability = 0;
+    }
+    else
+        netdata_thread_lock_cancelability--;
+}
+
+// ----------------------------------------------------------------------------
+// mutex
+
+int __netdata_mutex_init(netdata_mutex_t *mutex) {
+    int ret = pthread_mutex_init(mutex, NULL);
+    if(unlikely(ret != 0))
+        error("MUTEX_LOCK: failed to initialize (code %d).", ret);
+    return ret;
+}
+
+int __netdata_mutex_lock(netdata_mutex_t *mutex) {
+    netdata_thread_disable_cancelability();
+
+    int ret = pthread_mutex_lock(mutex);
+    if(unlikely(ret != 0)) {
+        netdata_thread_enable_cancelability();
+        error("MUTEX_LOCK: failed to get lock (code %d)", ret);
+    }
+    return ret;
+}
+
+int __netdata_mutex_trylock(netdata_mutex_t *mutex) {
+    netdata_thread_disable_cancelability();
+
+    int ret = pthread_mutex_trylock(mutex);
+    if(ret != 0)
+        netdata_thread_enable_cancelability();
+
+    return ret;
+}
+
+int __netdata_mutex_unlock(netdata_mutex_t *mutex) {
+    int ret = pthread_mutex_unlock(mutex);
+    if(unlikely(ret != 0))
+        error("MUTEX_LOCK: failed to unlock (code %d).", ret);
+    else
+        netdata_thread_enable_cancelability();
+
+    return ret;
+}
+
+int netdata_mutex_init_debug( const char *file, const char *function, const unsigned long line, netdata_mutex_t *mutex) {
+    usec_t start = 0;
+    (void)start;
+
+    if(unlikely(debug_flags & D_LOCKS)) {
+        start = now_boottime_usec();
+        debug(D_LOCKS, "MUTEX_LOCK: netdata_mutex_init(0x%p) from %lu@%s, %s()", mutex, line, file, function);
+    }
+
+    int ret = __netdata_mutex_init(mutex);
+
+    debug(D_LOCKS, "MUTEX_LOCK: netdata_mutex_init(0x%p) = %d in %llu usec, from %lu@%s, %s()", mutex, ret, now_boottime_usec() - start, line, file, function);
+
+    return ret;
+}
+
+int netdata_mutex_lock_debug( const char *file, const char *function, const unsigned long line, netdata_mutex_t *mutex) {
+    usec_t start = 0;
+    (void)start;
+
+    if(unlikely(debug_flags & D_LOCKS)) {
+        start = now_boottime_usec();
+        debug(D_LOCKS, "MUTEX_LOCK: netdata_mutex_lock(0x%p) from %lu@%s, %s()", mutex, line, file, function);
+    }
+
+    int ret = __netdata_mutex_lock(mutex);
+
+    debug(D_LOCKS, "MUTEX_LOCK: netdata_mutex_lock(0x%p) = %d in %llu usec, from %lu@%s, %s()", mutex, ret, now_boottime_usec() - start, line, file, function);
+
+    return ret;
+}
+
+int netdata_mutex_trylock_debug( const char *file, const char *function, const unsigned long line, netdata_mutex_t *mutex) {
+    usec_t start = 0;
+    (void)start;
+
+    if(unlikely(debug_flags & D_LOCKS)) {
+        start = now_boottime_usec();
+        debug(D_LOCKS, "MUTEX_LOCK: netdata_mutex_trylock(0x%p) from %lu@%s, %s()", mutex, line, file, function);
+    }
+
+    int ret = __netdata_mutex_trylock(mutex);
+
+    debug(D_LOCKS, "MUTEX_LOCK: netdata_mutex_trylock(0x%p) = %d in %llu usec, from %lu@%s, %s()", mutex, ret, now_boottime_usec() - start, line, file, function);
+
+    return ret;
+}
+
+int netdata_mutex_unlock_debug( const char *file, const char *function, const unsigned long line, netdata_mutex_t *mutex) {
+    usec_t start = 0;
+    (void)start;
+
+    if(unlikely(debug_flags & D_LOCKS)) {
+        start = now_boottime_usec();
+        debug(D_LOCKS, "MUTEX_LOCK: netdata_mutex_unlock(0x%p) from %lu@%s, %s()", mutex, line, file, function);
+    }
+
+    int ret = __netdata_mutex_unlock(mutex);
+
+    debug(D_LOCKS, "MUTEX_LOCK: netdata_mutex_unlock(0x%p) = %d in %llu usec, from %lu@%s, %s()", mutex, ret, now_boottime_usec() - start, line, file, function);
+
+    return ret;
+}
+
+
+// ----------------------------------------------------------------------------
+// r/w lock
+
+int __netdata_rwlock_destroy(netdata_rwlock_t *rwlock) {
+    int ret = pthread_rwlock_destroy(rwlock);
+    if(unlikely(ret != 0))
+        error("RW_LOCK: failed to destroy lock (code %d)", ret);
+    return ret;
+}
+
+int __netdata_rwlock_init(netdata_rwlock_t *rwlock) {
+    int ret = pthread_rwlock_init(rwlock, NULL);
+    if(unlikely(ret != 0))
+        error("RW_LOCK: failed to initialize lock (code %d)", ret);
+    return ret;
+}
+
+int __netdata_rwlock_rdlock(netdata_rwlock_t *rwlock) {
+    netdata_thread_disable_cancelability();
+
+    int ret = pthread_rwlock_rdlock(rwlock);
+    if(unlikely(ret != 0)) {
+        netdata_thread_enable_cancelability();
+        error("RW_LOCK: failed to obtain read lock (code %d)", ret);
+    }
+
+    return ret;
+}
+
+int __netdata_rwlock_wrlock(netdata_rwlock_t *rwlock) {
+    netdata_thread_disable_cancelability();
+
+    int ret = pthread_rwlock_wrlock(rwlock);
+    if(unlikely(ret != 0)) {
+        error("RW_LOCK: failed to obtain write lock (code %d)", ret);
+        netdata_thread_enable_cancelability();
+    }
+
+    return ret;
+}
+
+int __netdata_rwlock_unlock(netdata_rwlock_t *rwlock) {
+    int ret = pthread_rwlock_unlock(rwlock);
+    if(unlikely(ret != 0))
+        error("RW_LOCK: failed to release lock (code %d)", ret);
+    else
+        netdata_thread_enable_cancelability();
+
+    return ret;
+}
+
+int __netdata_rwlock_tryrdlock(netdata_rwlock_t *rwlock) {
+    netdata_thread_disable_cancelability();
+
+    int ret = pthread_rwlock_tryrdlock(rwlock);
+    if(ret != 0)
+        netdata_thread_enable_cancelability();
+
+    return ret;
+}
+
+int __netdata_rwlock_trywrlock(netdata_rwlock_t *rwlock) {
+    netdata_thread_disable_cancelability();
+
+    int ret = pthread_rwlock_trywrlock(rwlock);
+    if(ret != 0)
+        netdata_thread_enable_cancelability();
+
+    return ret;
+}
+
+
+int netdata_rwlock_destroy_debug( const char *file, const char *function, const unsigned long line, netdata_rwlock_t *rwlock) {
+    usec_t start = 0;
+    (void)start;
+
+    if(unlikely(debug_flags & D_LOCKS)) {
+        start = now_boottime_usec();
+        debug(D_LOCKS, "RW_LOCK: netdata_rwlock_destroy(0x%p) from %lu@%s, %s()", rwlock, line, file, function);
+    }
+
+    int ret = __netdata_rwlock_destroy(rwlock);
+
+    debug(D_LOCKS, "RW_LOCK: netdata_rwlock_destroy(0x%p) = %d in %llu usec, from %lu@%s, %s()", rwlock, ret, now_boottime_usec() - start, line, file, function);
+
+    return ret;
+}
+
+int netdata_rwlock_init_debug( const char *file, const char *function, const unsigned long line, netdata_rwlock_t *rwlock) {
+    usec_t start = 0;
+    (void)start;
+
+    if(unlikely(debug_flags & D_LOCKS)) {
+        start = now_boottime_usec();
+        debug(D_LOCKS, "RW_LOCK: netdata_rwlock_init(0x%p) from %lu@%s, %s()", rwlock, line, file, function);
+    }
+
+    int ret = __netdata_rwlock_init(rwlock);
+
+    debug(D_LOCKS, "RW_LOCK: netdata_rwlock_init(0x%p) = %d in %llu usec, from %lu@%s, %s()", rwlock, ret, now_boottime_usec() - start, line, file, function);
+
+    return ret;
+}
+
+int netdata_rwlock_rdlock_debug( const char *file, const char *function, const unsigned long line, netdata_rwlock_t *rwlock) {
+    usec_t start = 0;
+    (void)start;
+
+    if(unlikely(debug_flags & D_LOCKS)) {
+        start = now_boottime_usec();
+        debug(D_LOCKS, "RW_LOCK: netdata_rwlock_rdlock(0x%p) from %lu@%s, %s()", rwlock, line, file, function);
+    }
+
+    int ret = __netdata_rwlock_rdlock(rwlock);
+
+    debug(D_LOCKS, "RW_LOCK: netdata_rwlock_rdlock(0x%p) = %d in %llu usec, from %lu@%s, %s()", rwlock, ret, now_boottime_usec() - start, line, file, function);
+
+    return ret;
+}
+
+int netdata_rwlock_wrlock_debug( const char *file, const char *function, const unsigned long line, netdata_rwlock_t *rwlock) {
+    usec_t start = 0;
+    (void)start;
+
+    if(unlikely(debug_flags & D_LOCKS)) {
+        start = now_boottime_usec();
+        debug(D_LOCKS, "RW_LOCK: netdata_rwlock_wrlock(0x%p) from %lu@%s, %s()", rwlock, line, file, function);
+    }
+
+    int ret = __netdata_rwlock_wrlock(rwlock);
+
+    debug(D_LOCKS, "RW_LOCK: netdata_rwlock_wrlock(0x%p) = %d in %llu usec, from %lu@%s, %s()", rwlock, ret, now_boottime_usec() - start, line, file, function);
+
+    return ret;
+}
+
+int netdata_rwlock_unlock_debug( const char *file, const char *function, const unsigned long line, netdata_rwlock_t *rwlock) {
+    usec_t start = 0;
+    (void)start;
+
+    if(unlikely(debug_flags & D_LOCKS)) {
+        start = now_boottime_usec();
+        debug(D_LOCKS, "RW_LOCK: netdata_rwlock_unlock(0x%p) from %lu@%s, %s()", rwlock, line, file, function);
+    }
+
+    int ret = __netdata_rwlock_unlock(rwlock);
+
+    debug(D_LOCKS, "RW_LOCK: netdata_rwlock_unlock(0x%p) = %d in %llu usec, from %lu@%s, %s()", rwlock, ret, now_boottime_usec() - start, line, file, function);
+
+    return ret;
+}
+
+int netdata_rwlock_tryrdlock_debug( const char *file, const char *function, const unsigned long line, netdata_rwlock_t *rwlock) {
+    usec_t start = 0;
+    (void)start;
+
+    if(unlikely(debug_flags & D_LOCKS)) {
+        start = now_boottime_usec();
+        debug(D_LOCKS, "RW_LOCK: netdata_rwlock_tryrdlock(0x%p) from %lu@%s, %s()", rwlock, line, file, function);
+    }
+
+    int ret = __netdata_rwlock_tryrdlock(rwlock);
+
+    debug(D_LOCKS, "RW_LOCK: netdata_rwlock_tryrdlock(0x%p) = %d in %llu usec, from %lu@%s, %s()", rwlock, ret, now_boottime_usec() - start, line, file, function);
+
+    return ret;
+}
+
+int netdata_rwlock_trywrlock_debug( const char *file, const char *function, const unsigned long line, netdata_rwlock_t *rwlock) {
+    usec_t start = 0;
+    (void)start;
+
+    if(unlikely(debug_flags & D_LOCKS)) {
+        start = now_boottime_usec();
+        debug(D_LOCKS, "RW_LOCK: netdata_rwlock_trywrlock(0x%p) from %lu@%s, %s()", rwlock, line, file, function);
+    }
+
+    int ret = __netdata_rwlock_trywrlock(rwlock);
+
+    debug(D_LOCKS, "RW_LOCK: netdata_rwlock_trywrlock(0x%p) = %d in %llu usec, from %lu@%s, %s()", rwlock, ret, now_boottime_usec() - start, line, file, function);
+
+    return ret;
+}
diff --git a/libnetdata/locks/locks.h b/libnetdata/locks/locks.h
new file mode 100644
index 0000000..850dd7e
--- /dev/null
+++ b/libnetdata/locks/locks.h
@@ -0,0 +1,75 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_LOCKS_H
+#define NETDATA_LOCKS_H 1
+
+#include "../libnetdata.h"
+
+typedef pthread_mutex_t netdata_mutex_t;
+#define NETDATA_MUTEX_INITIALIZER PTHREAD_MUTEX_INITIALIZER
+
+typedef pthread_rwlock_t netdata_rwlock_t;
+#define NETDATA_RWLOCK_INITIALIZER PTHREAD_RWLOCK_INITIALIZER
+
+extern int __netdata_mutex_init(netdata_mutex_t *mutex);
+extern int __netdata_mutex_lock(netdata_mutex_t *mutex);
+extern int __netdata_mutex_trylock(netdata_mutex_t *mutex);
+extern int __netdata_mutex_unlock(netdata_mutex_t *mutex);
+
+extern int __netdata_rwlock_destroy(netdata_rwlock_t *rwlock);
+extern int __netdata_rwlock_init(netdata_rwlock_t *rwlock);
+extern int __netdata_rwlock_rdlock(netdata_rwlock_t *rwlock);
+extern int __netdata_rwlock_wrlock(netdata_rwlock_t *rwlock);
+extern int __netdata_rwlock_unlock(netdata_rwlock_t *rwlock);
+extern int __netdata_rwlock_tryrdlock(netdata_rwlock_t *rwlock);
+extern int __netdata_rwlock_trywrlock(netdata_rwlock_t *rwlock);
+
+extern int netdata_mutex_init_debug( const char *file, const char *function, const unsigned long line, netdata_mutex_t *mutex);
+extern int netdata_mutex_lock_debug( const char *file, const char *function, const unsigned long line, netdata_mutex_t *mutex);
+extern int netdata_mutex_trylock_debug( const char *file, const char *function, const unsigned long line, netdata_mutex_t *mutex);
+extern int netdata_mutex_unlock_debug( const char *file, const char *function, const unsigned long line, netdata_mutex_t *mutex);
+
+extern int netdata_rwlock_destroy_debug( const char *file, const char *function, const unsigned long line, netdata_rwlock_t *rwlock);
+extern int netdata_rwlock_init_debug( const char *file, const char *function, const unsigned long line, netdata_rwlock_t *rwlock);
+extern int netdata_rwlock_rdlock_debug( const char *file, const char *function, const unsigned long line, netdata_rwlock_t *rwlock);
+extern int netdata_rwlock_wrlock_debug( const char *file, const char *function, const unsigned long line, netdata_rwlock_t *rwlock);
+extern int netdata_rwlock_unlock_debug( const char *file, const char *function, const unsigned long line, netdata_rwlock_t *rwlock);
+extern int netdata_rwlock_tryrdlock_debug( const char *file, const char *function, const unsigned long line, netdata_rwlock_t *rwlock);
+extern int netdata_rwlock_trywrlock_debug( const char *file, const char *function, const unsigned long line, netdata_rwlock_t *rwlock);
+
+extern void netdata_thread_disable_cancelability(void);
+extern void netdata_thread_enable_cancelability(void);
+
+#ifdef NETDATA_INTERNAL_CHECKS
+
+#define netdata_mutex_init(mutex)    netdata_mutex_init_debug(__FILE__, __FUNCTION__, __LINE__, mutex)
+#define netdata_mutex_lock(mutex)    netdata_mutex_lock_debug(__FILE__, __FUNCTION__, __LINE__, mutex)
+#define netdata_mutex_trylock(mutex) netdata_mutex_trylock_debug(__FILE__, __FUNCTION__, __LINE__, mutex)
+#define netdata_mutex_unlock(mutex)  netdata_mutex_unlock_debug(__FILE__, __FUNCTION__, __LINE__, mutex)
+
+#define netdata_rwlock_destroy(rwlock)   netdata_rwlock_destroy_debug(__FILE__, __FUNCTION__, __LINE__, rwlock)
+#define netdata_rwlock_init(rwlock)      netdata_rwlock_init_debug(__FILE__, __FUNCTION__, __LINE__, rwlock)
+#define netdata_rwlock_rdlock(rwlock)    netdata_rwlock_rdlock_debug(__FILE__, __FUNCTION__, __LINE__, rwlock)
+#define netdata_rwlock_wrlock(rwlock)    netdata_rwlock_wrlock_debug(__FILE__, __FUNCTION__, __LINE__, rwlock)
+#define netdata_rwlock_unlock(rwlock)    netdata_rwlock_unlock_debug(__FILE__, __FUNCTION__, __LINE__, rwlock)
+#define netdata_rwlock_tryrdlock(rwlock) netdata_rwlock_tryrdlock_debug(__FILE__, __FUNCTION__, __LINE__, rwlock)
+#define netdata_rwlock_trywrlock(rwlock) netdata_rwlock_trywrlock_debug(__FILE__, __FUNCTION__, __LINE__, rwlock)
+
+#else // !NETDATA_INTERNAL_CHECKS
+
+#define netdata_mutex_init(mutex)    __netdata_mutex_init(mutex)
+#define netdata_mutex_lock(mutex)    __netdata_mutex_lock(mutex)
+#define netdata_mutex_trylock(mutex) __netdata_mutex_trylock(mutex)
+#define netdata_mutex_unlock(mutex)  __netdata_mutex_unlock(mutex)
+
+#define netdata_rwlock_destroy(rwlock)    __netdata_rwlock_destroy(rwlock)
+#define netdata_rwlock_init(rwlock)       __netdata_rwlock_init(rwlock)
+#define netdata_rwlock_rdlock(rwlock)     __netdata_rwlock_rdlock(rwlock)
+#define netdata_rwlock_wrlock(rwlock)     __netdata_rwlock_wrlock(rwlock)
+#define netdata_rwlock_unlock(rwlock)     __netdata_rwlock_unlock(rwlock)
+#define netdata_rwlock_tryrdlock(rwlock)  __netdata_rwlock_tryrdlock(rwlock)
+#define netdata_rwlock_trywrlock(rwlock)  __netdata_rwlock_trywrlock(rwlock)
+
+#endif // NETDATA_INTERNAL_CHECKS
+
+#endif //NETDATA_LOCKS_H
diff --git a/libnetdata/log/Makefile.am b/libnetdata/log/Makefile.am
new file mode 100644
index 0000000..1cb69ed
--- /dev/null
+++ b/libnetdata/log/Makefile.am
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
+
+
+dist_noinst_DATA = \
+	README.md \
+	$(NULL)
diff --git a/libnetdata/log/README.md b/libnetdata/log/README.md
new file mode 100644
index 0000000..28e3c3f
--- /dev/null
+++ b/libnetdata/log/README.md
@@ -0,0 +1,2 @@
+
+[![analytics](https://www.google-analytics.com/collect?v=1&aip=1&t=pageview&_s=1&ds=github&dr=https%3A%2F%2Fgithub.com%2Fnetdata%2Fnetdata&dl=https%3A%2F%2Fmy-netdata.io%2Fgithub%2Flibnetdata%2Flog%2FREADME&_u=MAC~&cid=5792dfd7-8dc4-476b-af31-da2fdb9f93d2&tid=UA-64295674-3)]()
diff --git a/libnetdata/log/log.c b/libnetdata/log/log.c
new file mode 100644
index 0000000..66a923f
--- /dev/null
+++ b/libnetdata/log/log.c
@@ -0,0 +1,445 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include <daemon/main.h>
+#include "../libnetdata.h"
+
+int web_server_is_multithreaded = 1;
+
+const char *program_name = "";
+uint64_t debug_flags = DEBUG;
+
+int access_log_syslog = 1;
+int error_log_syslog = 1;
+int output_log_syslog = 1;  // debug log
+
+int stdaccess_fd = -1;
+FILE *stdaccess = NULL;
+
+const char *stdaccess_filename = NULL;
+const char *stderr_filename = NULL;
+const char *stdout_filename = NULL;
+
+void syslog_init(void) {
+    static int i = 0;
+
+    if(!i) {
+        openlog(program_name, LOG_PID, LOG_DAEMON);
+        i = 1;
+    }
+}
+
+#define LOG_DATE_LENGTH 26
+
+static inline void log_date(char *buffer, size_t len) {
+    if(unlikely(!buffer || !len))
+        return;
+
+    time_t t;
+    struct tm *tmp, tmbuf;
+
+    t = now_realtime_sec();
+    tmp = localtime_r(&t, &tmbuf);
+
+    if (tmp == NULL) {
+        buffer[0] = '\0';
+        return;
+    }
+
+    if (unlikely(strftime(buffer, len, "%Y-%m-%d %H:%M:%S", tmp) == 0))
+        buffer[0] = '\0';
+
+    buffer[len - 1] = '\0';
+}
+
+static netdata_mutex_t log_mutex = NETDATA_MUTEX_INITIALIZER;
+static inline void log_lock() {
+    netdata_mutex_lock(&log_mutex);
+}
+static inline void log_unlock() {
+    netdata_mutex_unlock(&log_mutex);
+}
+
+static FILE *open_log_file(int fd, FILE *fp, const char *filename, int *enabled_syslog, int is_stdaccess, int *fd_ptr) {
+    int f, devnull = 0;
+
+    if(!filename || !*filename || !strcmp(filename, "none") ||  !strcmp(filename, "/dev/null")) {
+        filename = "/dev/null";
+        devnull = 1;
+    }
+
+    if(!strcmp(filename, "syslog")) {
+        filename = "/dev/null";
+        devnull = 1;
+        syslog_init();
+        if(enabled_syslog) *enabled_syslog = 1;
+    }
+    else if(enabled_syslog) *enabled_syslog = 0;
+
+    // don't do anything if the user is willing
+    // to have the standard one
+    if(!strcmp(filename, "system")) {
+        if(fd != -1 && !is_stdaccess) {
+            if(fd_ptr) *fd_ptr = fd;
+            return fp;
+        }
+
+        filename = "stderr";
+    }
+
+    if(!strcmp(filename, "stdout"))
+        f = STDOUT_FILENO;
+
+    else if(!strcmp(filename, "stderr"))
+        f = STDERR_FILENO;
+
+    else {
+        f = open(filename, O_WRONLY | O_APPEND | O_CREAT, 0664);
+        if(f == -1) {
+            error("Cannot open file '%s'. Leaving %d to its default.", filename, fd);
+            if(fd_ptr) *fd_ptr = fd;
+            return fp;
+        }
+    }
+
+    // if there is a level-2 file pointer
+    // flush it before switching the level-1 fds
+    if(fp)
+        fflush(fp);
+
+    if(devnull && is_stdaccess) {
+        fd = -1;
+        fp = NULL;
+    }
+
+    if(fd != f && fd != -1) {
+        // it automatically closes
+        int t = dup2(f, fd);
+        if (t == -1) {
+            error("Cannot dup2() new fd %d to old fd %d for '%s'", f, fd, filename);
+            close(f);
+            if(fd_ptr) *fd_ptr = fd;
+            return fp;
+        }
+        // info("dup2() new fd %d to old fd %d for '%s'", f, fd, filename);
+        close(f);
+    }
+    else fd = f;
+
+    if(!fp) {
+        fp = fdopen(fd, "a");
+        if (!fp)
+            error("Cannot fdopen() fd %d ('%s')", fd, filename);
+        else {
+            if (setvbuf(fp, NULL, _IOLBF, 0) != 0)
+                error("Cannot set line buffering on fd %d ('%s')", fd, filename);
+        }
+    }
+
+    if(fd_ptr) *fd_ptr = fd;
+    return fp;
+}
+
+void reopen_all_log_files() {
+    if(stdout_filename)
+        open_log_file(STDOUT_FILENO, stdout, stdout_filename, &output_log_syslog, 0, NULL);
+
+    if(stderr_filename)
+        open_log_file(STDERR_FILENO, stderr, stderr_filename, &error_log_syslog, 0, NULL);
+
+    if(stdaccess_filename)
+         stdaccess = open_log_file(stdaccess_fd, stdaccess, stdaccess_filename, &access_log_syslog, 1, &stdaccess_fd);
+}
+
+void open_all_log_files() {
+    // disable stdin
+    open_log_file(STDIN_FILENO, stdin, "/dev/null", NULL, 0, NULL);
+
+    open_log_file(STDOUT_FILENO, stdout, stdout_filename, &output_log_syslog, 0, NULL);
+    open_log_file(STDERR_FILENO, stderr, stderr_filename, &error_log_syslog, 0, NULL);
+    stdaccess = open_log_file(stdaccess_fd, stdaccess, stdaccess_filename, &access_log_syslog, 1, &stdaccess_fd);
+}
+
+// ----------------------------------------------------------------------------
+// error log throttling
+
+time_t error_log_throttle_period = 1200;
+unsigned long error_log_errors_per_period = 200;
+unsigned long error_log_errors_per_period_backup = 0;
+
+int error_log_limit(int reset) {
+    static time_t start = 0;
+    static unsigned long counter = 0, prevented = 0;
+
+    // fprintf(stderr, "FLOOD: counter=%lu, allowed=%lu, backup=%lu, period=%llu\n", counter, error_log_errors_per_period, error_log_errors_per_period_backup, (unsigned long long)error_log_throttle_period);
+
+    // do not throttle if the period is 0
+    if(error_log_throttle_period == 0)
+        return 0;
+
+    // prevent all logs if the errors per period is 0
+    if(error_log_errors_per_period == 0)
+#ifdef NETDATA_INTERNAL_CHECKS
+        return 0;
+#else
+        return 1;
+#endif
+
+    time_t now = now_monotonic_sec();
+    if(!start) start = now;
+
+    if(reset) {
+        if(prevented) {
+            char date[LOG_DATE_LENGTH];
+            log_date(date, LOG_DATE_LENGTH);
+            fprintf(stderr, "%s: %s LOG FLOOD PROTECTION reset for process '%s' (prevented %lu logs in the last %ld seconds).\n"
+                    , date
+                    , program_name
+                    , program_name
+                    , prevented
+                    , now - start
+            );
+        }
+
+        start = now;
+        counter = 0;
+        prevented = 0;
+    }
+
+    // detect if we log too much
+    counter++;
+
+    if(now - start > error_log_throttle_period) {
+        if(prevented) {
+            char date[LOG_DATE_LENGTH];
+            log_date(date, LOG_DATE_LENGTH);
+            fprintf(stderr, "%s: %s LOG FLOOD PROTECTION resuming logging from process '%s' (prevented %lu logs in the last %ld seconds).\n"
+                    , date
+                    , program_name
+                    , program_name
+                    , prevented
+                    , error_log_throttle_period
+            );
+        }
+
+        // restart the period accounting
+        start = now;
+        counter = 1;
+        prevented = 0;
+
+        // log this error
+        return 0;
+    }
+
+    if(counter > error_log_errors_per_period) {
+        if(!prevented) {
+            char date[LOG_DATE_LENGTH];
+            log_date(date, LOG_DATE_LENGTH);
+            fprintf(stderr, "%s: %s LOG FLOOD PROTECTION too many logs (%lu logs in %ld seconds, threshold is set to %lu logs in %ld seconds). Preventing more logs from process '%s' for %ld seconds.\n"
+                    , date
+                    , program_name
+                    , counter
+                    , now - start
+                    , error_log_errors_per_period
+                    , error_log_throttle_period
+                    , program_name
+                    , start + error_log_throttle_period - now);
+        }
+
+        prevented++;
+
+        // prevent logging this error
+#ifdef NETDATA_INTERNAL_CHECKS
+        return 0;
+#else
+        return 1;
+#endif
+    }
+
+    return 0;
+}
+
+// ----------------------------------------------------------------------------
+// debug log
+
+void debug_int( const char *file, const char *function, const unsigned long line, const char *fmt, ... ) {
+    va_list args;
+
+    char date[LOG_DATE_LENGTH];
+    log_date(date, LOG_DATE_LENGTH);
+
+    va_start( args, fmt );
+    printf("%s: %s DEBUG : %s : (%04lu@%-10.10s:%-15.15s): ", date, program_name, netdata_thread_tag(), line, file, function);
+    vprintf(fmt, args);
+    va_end( args );
+    putchar('\n');
+
+    if(output_log_syslog) {
+        va_start( args, fmt );
+        vsyslog(LOG_ERR,  fmt, args );
+        va_end( args );
+    }
+
+    fflush(stdout);
+}
+
+// ----------------------------------------------------------------------------
+// info log
+
+void info_int( const char *file, const char *function, const unsigned long line, const char *fmt, ... )
+{
+    va_list args;
+
+    // prevent logging too much
+    if(error_log_limit(0)) return;
+
+    if(error_log_syslog) {
+        va_start( args, fmt );
+        vsyslog(LOG_INFO,  fmt, args );
+        va_end( args );
+    }
+
+    char date[LOG_DATE_LENGTH];
+    log_date(date, LOG_DATE_LENGTH);
+
+    log_lock();
+
+    va_start( args, fmt );
+    if(debug_flags) fprintf(stderr, "%s: %s INFO  : %s : (%04lu@%-10.10s:%-15.15s): ", date, program_name, netdata_thread_tag(), line, file, function);
+    else            fprintf(stderr, "%s: %s INFO  : %s : ", date, program_name, netdata_thread_tag());
+    vfprintf( stderr, fmt, args );
+    va_end( args );
+
+    fputc('\n', stderr);
+
+    log_unlock();
+}
+
+// ----------------------------------------------------------------------------
+// error log
+
+#if defined(STRERROR_R_CHAR_P)
+// GLIBC version of strerror_r
+static const char *strerror_result(const char *a, const char *b) { (void)b; return a; }
+#elif defined(HAVE_STRERROR_R)
+// POSIX version of strerror_r
+static const char *strerror_result(int a, const char *b) { (void)a; return b; }
+#elif defined(HAVE_C__GENERIC)
+
+// what a trick!
+// http://stackoverflow.com/questions/479207/function-overloading-in-c
+static const char *strerror_result_int(int a, const char *b) { (void)a; return b; }
+static const char *strerror_result_string(const char *a, const char *b) { (void)b; return a; }
+
+#define strerror_result(a, b) _Generic((a), \
+    int: strerror_result_int, \
+    char *: strerror_result_string \
+    )(a, b)
+
+#else
+#error "cannot detect the format of function strerror_r()"
+#endif
+
+void error_int( const char *prefix, const char *file, const char *function, const unsigned long line, const char *fmt, ... ) {
+    // save a copy of errno - just in case this function generates a new error
+    int __errno = errno;
+
+    va_list args;
+
+    // prevent logging too much
+    if(error_log_limit(0)) return;
+
+    if(error_log_syslog) {
+        va_start( args, fmt );
+        vsyslog(LOG_ERR,  fmt, args );
+        va_end( args );
+    }
+
+    char date[LOG_DATE_LENGTH];
+    log_date(date, LOG_DATE_LENGTH);
+
+    log_lock();
+
+    va_start( args, fmt );
+    if(debug_flags) fprintf(stderr, "%s: %s %-5.5s : %s : (%04lu@%-10.10s:%-15.15s): ", date, program_name, prefix, netdata_thread_tag(), line, file, function);
+    else            fprintf(stderr, "%s: %s %-5.5s : %s : ", date, program_name, prefix, netdata_thread_tag());
+    vfprintf( stderr, fmt, args );
+    va_end( args );
+
+    if(__errno) {
+        char buf[1024];
+        fprintf(stderr, " (errno %d, %s)\n", __errno, strerror_result(strerror_r(__errno, buf, 1023), buf));
+        errno = 0;
+    }
+    else
+        fputc('\n', stderr);
+
+    log_unlock();
+}
+
+void fatal_int( const char *file, const char *function, const unsigned long line, const char *fmt, ... ) {
+    // save a copy of errno - just in case this function generates a new error
+    int __errno = errno;
+    va_list args;
+
+    if(error_log_syslog) {
+        va_start( args, fmt );
+        vsyslog(LOG_CRIT,  fmt, args );
+        va_end( args );
+    }
+
+    char date[LOG_DATE_LENGTH];
+    log_date(date, LOG_DATE_LENGTH);
+
+    log_lock();
+
+    va_start( args, fmt );
+    if(debug_flags) fprintf(stderr, "%s: %s FATAL : %s : (%04lu@%-10.10s:%-15.15s): ", date, program_name, netdata_thread_tag(), line, file, function);
+    else            fprintf(stderr, "%s: %s FATAL : %s :", date, program_name, netdata_thread_tag());
+    vfprintf( stderr, fmt, args );
+    va_end( args );
+
+    perror(" # ");
+    fputc('\n', stderr);
+
+    log_unlock();
+
+    char action_data[70+1];
+	snprintfz(action_data, 70, "%04lu@%-10.10s:%-15.15s/%d", line, file, function, __errno);
+	char action_result[60+1];
+	snprintfz(action_result, 60, "%s:%s",program_name, netdata_thread_tag());
+	send_statistics("FATAL", action_result, action_data);
+
+    netdata_cleanup_and_exit(1);
+}
+
+// ----------------------------------------------------------------------------
+// access log
+
+void log_access( const char *fmt, ... ) {
+    va_list args;
+
+    if(access_log_syslog) {
+        va_start( args, fmt );
+        vsyslog(LOG_INFO,  fmt, args );
+        va_end( args );
+    }
+
+    if(stdaccess) {
+        static netdata_mutex_t access_mutex = NETDATA_MUTEX_INITIALIZER;
+
+        if(web_server_is_multithreaded)
+            netdata_mutex_lock(&access_mutex);
+
+        char date[LOG_DATE_LENGTH];
+        log_date(date, LOG_DATE_LENGTH);
+        fprintf(stdaccess, "%s: ", date);
+
+        va_start( args, fmt );
+        vfprintf( stdaccess, fmt, args );
+        va_end( args );
+        fputc('\n', stdaccess);
+
+        if(web_server_is_multithreaded)
+            netdata_mutex_unlock(&access_mutex);
+    }
+}
diff --git a/libnetdata/log/log.h b/libnetdata/log/log.h
new file mode 100644
index 0000000..44670f3
--- /dev/null
+++ b/libnetdata/log/log.h
@@ -0,0 +1,95 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_LOG_H
+#define NETDATA_LOG_H 1
+
+#include "../libnetdata.h"
+
+#define D_WEB_BUFFER        0x0000000000000001
+#define D_WEB_CLIENT        0x0000000000000002
+#define D_LISTENER          0x0000000000000004
+#define D_WEB_DATA          0x0000000000000008
+#define D_OPTIONS           0x0000000000000010
+#define D_PROCNETDEV_LOOP   0x0000000000000020
+#define D_RRD_STATS         0x0000000000000040
+#define D_WEB_CLIENT_ACCESS 0x0000000000000080
+#define D_TC_LOOP           0x0000000000000100
+#define D_DEFLATE           0x0000000000000200
+#define D_CONFIG            0x0000000000000400
+#define D_PLUGINSD          0x0000000000000800
+#define D_CHILDS            0x0000000000001000
+#define D_EXIT              0x0000000000002000
+#define D_CHECKS            0x0000000000004000
+#define D_NFACCT_LOOP       0x0000000000008000
+#define D_PROCFILE          0x0000000000010000
+#define D_RRD_CALLS         0x0000000000020000
+#define D_DICTIONARY        0x0000000000040000
+#define D_MEMORY            0x0000000000080000
+#define D_CGROUP            0x0000000000100000
+#define D_REGISTRY          0x0000000000200000
+#define D_VARIABLES         0x0000000000400000
+#define D_HEALTH            0x0000000000800000
+#define D_CONNECT_TO        0x0000000001000000
+#define D_RRDHOST           0x0000000002000000
+#define D_LOCKS             0x0000000004000000
+#define D_BACKEND           0x0000000008000000
+#define D_STATSD            0x0000000010000000
+#define D_POLLFD            0x0000000020000000
+#define D_STREAM            0x0000000040000000
+#define D_SYSTEM            0x8000000000000000
+
+//#define DEBUG (D_WEB_CLIENT_ACCESS|D_LISTENER|D_RRD_STATS)
+//#define DEBUG 0xffffffff
+#define DEBUG (0)
+
+extern int web_server_is_multithreaded;
+
+extern uint64_t debug_flags;
+
+extern const char *program_name;
+
+extern int stdaccess_fd;
+extern FILE *stdaccess;
+
+extern const char *stdaccess_filename;
+extern const char *stderr_filename;
+extern const char *stdout_filename;
+
+extern int access_log_syslog;
+extern int error_log_syslog;
+extern int output_log_syslog;
+
+extern time_t error_log_throttle_period;
+extern unsigned long error_log_errors_per_period, error_log_errors_per_period_backup;
+extern int error_log_limit(int reset);
+
+extern void open_all_log_files();
+extern void reopen_all_log_files();
+
+static inline void debug_dummy(void) {}
+
+#define error_log_limit_reset() do { error_log_errors_per_period = error_log_errors_per_period_backup; error_log_limit(1); } while(0)
+#define error_log_limit_unlimited() do { \
+        error_log_limit_reset(); \
+        error_log_errors_per_period = ((error_log_errors_per_period_backup * 10) < 10000) ? 10000 : (error_log_errors_per_period_backup * 10); \
+    } while(0)
+
+#ifdef NETDATA_INTERNAL_CHECKS
+#define debug(type, args...) do { if(unlikely(debug_flags & type)) debug_int(__FILE__, __FUNCTION__, __LINE__, ##args); } while(0)
+#else
+#define debug(type, args...) debug_dummy()
+#endif
+
+#define info(args...)    info_int(__FILE__, __FUNCTION__, __LINE__, ##args)
+#define infoerr(args...) error_int("INFO", __FILE__, __FUNCTION__, __LINE__, ##args)
+#define error(args...)   error_int("ERROR", __FILE__, __FUNCTION__, __LINE__, ##args)
+#define fatal(args...)   fatal_int(__FILE__, __FUNCTION__, __LINE__, ##args)
+
+extern void send_statistics(const char *action, const char *action_result, const char *action_data);
+extern void debug_int( const char *file, const char *function, const unsigned long line, const char *fmt, ... ) PRINTFLIKE(4, 5);
+extern void info_int( const char *file, const char *function, const unsigned long line, const char *fmt, ... ) PRINTFLIKE(4, 5);
+extern void error_int( const char *prefix, const char *file, const char *function, const unsigned long line, const char *fmt, ... ) PRINTFLIKE(5, 6);
+extern void fatal_int( const char *file, const char *function, const unsigned long line, const char *fmt, ... ) NORETURN PRINTFLIKE(4, 5);
+extern void log_access( const char *fmt, ... ) PRINTFLIKE(1, 2);
+
+#endif /* NETDATA_LOG_H */
diff --git a/libnetdata/os.c b/libnetdata/os.c
new file mode 100644
index 0000000..0248eb6
--- /dev/null
+++ b/libnetdata/os.c
@@ -0,0 +1,218 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "os.h"
+
+// ----------------------------------------------------------------------------
+// system functions
+// to retrieve settings of the system
+
+int processors = 1;
+long get_system_cpus(void) {
+    processors = 1;
+
+#ifdef __APPLE__
+    int32_t tmp_processors;
+
+        if (unlikely(GETSYSCTL_BY_NAME("hw.logicalcpu", tmp_processors))) {
+            error("Assuming system has %d processors.", processors);
+        } else {
+            processors = tmp_processors;
+        }
+
+        return processors;
+#elif __FreeBSD__
+    int32_t tmp_processors;
+
+        if (unlikely(GETSYSCTL_BY_NAME("hw.ncpu", tmp_processors))) {
+            error("Assuming system has %d processors.", processors);
+        } else {
+            processors = tmp_processors;
+        }
+
+        return processors;
+#else
+
+    char filename[FILENAME_MAX + 1];
+    snprintfz(filename, FILENAME_MAX, "%s/proc/stat", netdata_configured_host_prefix);
+
+    procfile *ff = procfile_open(filename, NULL, PROCFILE_FLAG_DEFAULT);
+    if(!ff) {
+        error("Cannot open file '%s'. Assuming system has %d processors.", filename, processors);
+        return processors;
+    }
+
+    ff = procfile_readall(ff);
+    if(!ff) {
+        error("Cannot open file '%s'. Assuming system has %d processors.", filename, processors);
+        return processors;
+    }
+
+    processors = 0;
+    unsigned int i;
+    for(i = 0; i < procfile_lines(ff); i++) {
+        if(!procfile_linewords(ff, i)) continue;
+
+        if(strncmp(procfile_lineword(ff, i, 0), "cpu", 3) == 0) processors++;
+    }
+    processors--;
+    if(processors < 1) processors = 1;
+
+    procfile_close(ff);
+
+    debug(D_SYSTEM, "System has %d processors.", processors);
+    return processors;
+
+#endif /* __APPLE__, __FreeBSD__ */
+}
+
+pid_t pid_max = 32768;
+pid_t get_system_pid_max(void) {
+#ifdef __APPLE__
+    // As we currently do not know a solution to query pid_max from the os
+        // we use the number defined in bsd/sys/proc_internal.h in XNU sources
+        pid_max = 99999;
+        return pid_max;
+#elif __FreeBSD__
+    int32_t tmp_pid_max;
+
+        if (unlikely(GETSYSCTL_BY_NAME("kern.pid_max", tmp_pid_max))) {
+            pid_max = 99999;
+            error("Assuming system's maximum pid is %d.", pid_max);
+        } else {
+            pid_max = tmp_pid_max;
+        }
+
+        return pid_max;
+#else
+
+    static char read = 0;
+    if(unlikely(read)) return pid_max;
+    read = 1;
+
+    char filename[FILENAME_MAX + 1];
+    snprintfz(filename, FILENAME_MAX, "%s/proc/sys/kernel/pid_max", netdata_configured_host_prefix);
+
+    unsigned long long max = 0;
+    if(read_single_number_file(filename, &max) != 0) {
+        error("Cannot open file '%s'. Assuming system supports %d pids.", filename, pid_max);
+        return pid_max;
+    }
+
+    if(!max) {
+        error("Cannot parse file '%s'. Assuming system supports %d pids.", filename, pid_max);
+        return pid_max;
+    }
+
+    pid_max = (pid_t) max;
+    return pid_max;
+
+#endif /* __APPLE__, __FreeBSD__ */
+}
+
+unsigned int system_hz;
+void get_system_HZ(void) {
+    long ticks;
+
+    if ((ticks = sysconf(_SC_CLK_TCK)) == -1) {
+        error("Cannot get system clock ticks");
+    }
+
+    system_hz = (unsigned int) ticks;
+}
+
+// =====================================================================================================================
+// FreeBSD
+
+#if (TARGET_OS == OS_FREEBSD)
+
+int getsysctl_by_name(const char *name, void *ptr, size_t len) {
+    size_t nlen = len;
+
+    if (unlikely(sysctlbyname(name, ptr, &nlen, NULL, 0) == -1)) {
+        error("FREEBSD: sysctl(%s...) failed: %s", name, strerror(errno));
+        return 1;
+    }
+    if (unlikely(nlen != len)) {
+        error("FREEBSD: sysctl(%s...) expected %lu, got %lu", name, (unsigned long)len, (unsigned long)nlen);
+        return 1;
+    }
+    return 0;
+}
+
+int getsysctl_simple(const char *name, int *mib, size_t miblen, void *ptr, size_t len) {
+    size_t nlen = len;
+
+    if (unlikely(!mib[0]))
+        if (unlikely(getsysctl_mib(name, mib, miblen)))
+            return 1;
+
+    if (unlikely(sysctl(mib, miblen, ptr, &nlen, NULL, 0) == -1)) {
+        error("FREEBSD: sysctl(%s...) failed: %s", name, strerror(errno));
+        return 1;
+    }
+    if (unlikely(nlen != len)) {
+        error("FREEBSD: sysctl(%s...) expected %lu, got %lu", name, (unsigned long)len, (unsigned long)nlen);
+        return 1;
+    }
+
+    return 0;
+}
+
+int getsysctl(const char *name, int *mib, size_t miblen, void *ptr, size_t *len) {
+    size_t nlen = *len;
+
+    if (unlikely(!mib[0]))
+        if (unlikely(getsysctl_mib(name, mib, miblen)))
+            return 1;
+
+    if (unlikely(sysctl(mib, miblen, ptr, len, NULL, 0) == -1)) {
+        error("FREEBSD: sysctl(%s...) failed: %s", name, strerror(errno));
+        return 1;
+    }
+    if (unlikely(ptr != NULL && nlen != *len)) {
+        error("FREEBSD: sysctl(%s...) expected %lu, got %lu", name, (unsigned long)*len, (unsigned long)nlen);
+        return 1;
+    }
+
+    return 0;
+}
+
+int getsysctl_mib(const char *name, int *mib, size_t len) {
+    size_t nlen = len;
+
+    if (unlikely(sysctlnametomib(name, mib, &nlen) == -1)) {
+        error("FREEBSD: sysctl(%s...) failed: %s", name, strerror(errno));
+        return 1;
+    }
+    if (unlikely(nlen != len)) {
+        error("FREEBSD: sysctl(%s...) expected %lu, got %lu", name, (unsigned long)len, (unsigned long)nlen);
+        return 1;
+    }
+    return 0;
+}
+
+
+#endif
+
+
+// =====================================================================================================================
+// MacOS
+
+#if (TARGET_OS == OS_MACOS)
+
+int getsysctl_by_name(const char *name, void *ptr, size_t len) {
+    size_t nlen = len;
+
+    if (unlikely(sysctlbyname(name, ptr, &nlen, NULL, 0) == -1)) {
+        error("MACOS: sysctl(%s...) failed: %s", name, strerror(errno));
+        return 1;
+    }
+    if (unlikely(nlen != len)) {
+        error("MACOS: sysctl(%s...) expected %lu, got %lu", name, (unsigned long)len, (unsigned long)nlen);
+        return 1;
+    }
+    return 0;
+}
+
+#endif // (TARGET_OS == OS_MACOS)
+
diff --git a/libnetdata/os.h b/libnetdata/os.h
new file mode 100644
index 0000000..2494174
--- /dev/null
+++ b/libnetdata/os.h
@@ -0,0 +1,70 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_OS_H
+#define NETDATA_OS_H
+
+#include "libnetdata.h"
+
+// =====================================================================================================================
+// Linux
+
+#if (TARGET_OS == OS_LINUX)
+
+
+// =====================================================================================================================
+// FreeBSD
+
+#elif (TARGET_OS == OS_FREEBSD)
+
+#include <sys/sysctl.h>
+
+#define GETSYSCTL_BY_NAME(name, var) getsysctl_by_name(name, &(var), sizeof(var))
+extern int getsysctl_by_name(const char *name, void *ptr, size_t len);
+
+#define GETSYSCTL_MIB(name, mib) getsysctl_mib(name, mib, sizeof(mib)/sizeof(int))
+
+extern int getsysctl_mib(const char *name, int *mib, size_t len);
+
+#define GETSYSCTL_SIMPLE(name, mib, var) getsysctl_simple(name, mib, sizeof(mib)/sizeof(int), &(var), sizeof(var))
+#define GETSYSCTL_WSIZE(name, mib, var, size) getsysctl_simple(name, mib, sizeof(mib)/sizeof(int), var, size)
+
+extern int getsysctl_simple(const char *name, int *mib, size_t miblen, void *ptr, size_t len);
+
+#define GETSYSCTL_SIZE(name, mib, size) getsysctl(name, mib, sizeof(mib)/sizeof(int), NULL, &(size))
+#define GETSYSCTL(name, mib, var, size) getsysctl(name, mib, sizeof(mib)/sizeof(int), &(var), &(size))
+
+extern int getsysctl(const char *name, int *mib, size_t miblen, void *ptr, size_t *len);
+
+
+// =====================================================================================================================
+// MacOS
+
+#elif (TARGET_OS == OS_MACOS)
+
+#include <sys/sysctl.h>
+
+#define GETSYSCTL_BY_NAME(name, var) getsysctl_by_name(name, &(var), sizeof(var))
+extern int getsysctl_by_name(const char *name, void *ptr, size_t len);
+
+
+// =====================================================================================================================
+// unknown O/S
+
+#else
+#error unsupported operating system
+#endif
+
+
+// =====================================================================================================================
+// common for all O/S
+
+extern int processors;
+extern long get_system_cpus(void);
+
+extern pid_t pid_max;
+extern pid_t get_system_pid_max(void);
+
+extern unsigned int system_hz;
+extern void get_system_HZ(void);
+
+#endif //NETDATA_OS_H
diff --git a/libnetdata/popen/Makefile.am b/libnetdata/popen/Makefile.am
new file mode 100644
index 0000000..1cb69ed
--- /dev/null
+++ b/libnetdata/popen/Makefile.am
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
+
+
+dist_noinst_DATA = \
+	README.md \
+	$(NULL)
diff --git a/libnetdata/popen/README.md b/libnetdata/popen/README.md
new file mode 100644
index 0000000..5a83b60
--- /dev/null
+++ b/libnetdata/popen/README.md
@@ -0,0 +1,2 @@
+
+[![analytics](https://www.google-analytics.com/collect?v=1&aip=1&t=pageview&_s=1&ds=github&dr=https%3A%2F%2Fgithub.com%2Fnetdata%2Fnetdata&dl=https%3A%2F%2Fmy-netdata.io%2Fgithub%2Flibnetdata%2Fpopen%2FREADME&_u=MAC~&cid=5792dfd7-8dc4-476b-af31-da2fdb9f93d2&tid=UA-64295674-3)]()
diff --git a/libnetdata/popen/popen.c b/libnetdata/popen/popen.c
new file mode 100644
index 0000000..845363f
--- /dev/null
+++ b/libnetdata/popen/popen.c
@@ -0,0 +1,206 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../libnetdata.h"
+
+/*
+struct mypopen {
+    pid_t pid;
+    FILE *fp;
+    struct mypopen *next;
+    struct mypopen *prev;
+};
+
+static struct mypopen *mypopen_root = NULL;
+
+static void mypopen_add(FILE *fp, pid_t *pid) {
+    struct mypopen *mp = malloc(sizeof(struct mypopen));
+    if(!mp) {
+        fatal("Cannot allocate %zu bytes", sizeof(struct mypopen))
+        return;
+    }
+
+    mp->fp = fp;
+    mp->pid = pid;
+    mp->next = popen_root;
+    mp->prev = NULL;
+    if(mypopen_root) mypopen_root->prev = mp;
+    mypopen_root = mp;
+}
+
+static void mypopen_del(FILE *fp) {
+    struct mypopen *mp;
+
+    for(mp = mypopen_root; mp; mp = mp->next)
+        if(mp->fd == fp) break;
+
+    if(!mp) error("Cannot find mypopen() file pointer in open childs.");
+    else {
+        if(mp->next) mp->next->prev = mp->prev;
+        if(mp->prev) mp->prev->next = mp->next;
+        if(mypopen_root == mp) mypopen_root = mp->next;
+        free(mp);
+    }
+}
+*/
+#define PIPE_READ 0
+#define PIPE_WRITE 1
+
+FILE *mypopen(const char *command, volatile pid_t *pidptr)
+{
+    int pipefd[2];
+
+    if(pipe(pipefd) == -1) return NULL;
+
+    int pid = fork();
+    if(pid == -1) {
+        close(pipefd[PIPE_READ]);
+        close(pipefd[PIPE_WRITE]);
+        return NULL;
+    }
+    if(pid != 0) {
+        // the parent
+        *pidptr = pid;
+        close(pipefd[PIPE_WRITE]);
+        FILE *fp = fdopen(pipefd[PIPE_READ], "r");
+        /*mypopen_add(fp, pid);*/
+        return(fp);
+    }
+    // the child
+
+    // close all files
+    int i;
+    for(i = (int) (sysconf(_SC_OPEN_MAX) - 1); i >= 0; i--)
+        if(i != STDIN_FILENO && i != STDERR_FILENO && i != pipefd[PIPE_WRITE]) close(i);
+
+    // move the pipe to stdout
+    if(pipefd[PIPE_WRITE] != STDOUT_FILENO) {
+        dup2(pipefd[PIPE_WRITE], STDOUT_FILENO);
+        close(pipefd[PIPE_WRITE]);
+    }
+
+#ifdef DETACH_PLUGINS_FROM_NETDATA
+    // this was an attempt to detach the child and use the suspend mode charts.d
+    // unfortunatelly it does not work as expected.
+
+    // fork again to become session leader
+    pid = fork();
+    if(pid == -1)
+        error("pre-execution of command '%s' on pid %d: Cannot fork 2nd time.", command, getpid());
+
+    if(pid != 0) {
+        // the parent
+        exit(0);
+    }
+
+    // set a new process group id for just this child
+    if( setpgid(0, 0) != 0 )
+        error("pre-execution of command '%s' on pid %d: Cannot set a new process group.", command, getpid());
+
+    if( getpgid(0) != getpid() )
+        error("pre-execution of command '%s' on pid %d: Cannot set a new process group. Process group set is incorrect. Expected %d, found %d", command, getpid(), getpid(), getpgid(0));
+
+    if( setsid() != 0 )
+        error("pre-execution of command '%s' on pid %d: Cannot set session id.", command, getpid());
+
+    fprintf(stdout, "MYPID %d\n", getpid());
+    fflush(NULL);
+#endif
+
+    // reset all signals
+    signals_unblock();
+    signals_reset();
+
+    debug(D_CHILDS, "executing command: '%s' on pid %d.", command, getpid());
+    execl("/bin/sh", "sh", "-c", command, NULL);
+    exit(1);
+}
+
+FILE *mypopene(const char *command, volatile pid_t *pidptr, char **env) {
+    int pipefd[2];
+
+    if(pipe(pipefd) == -1)
+        return NULL;
+
+    int pid = fork();
+    if(pid == -1) {
+        close(pipefd[PIPE_READ]);
+        close(pipefd[PIPE_WRITE]);
+        return NULL;
+    }
+    if(pid != 0) {
+        // the parent
+        *pidptr = pid;
+        close(pipefd[PIPE_WRITE]);
+        FILE *fp = fdopen(pipefd[PIPE_READ], "r");
+        return(fp);
+    }
+    // the child
+
+    // close all files
+    int i;
+    for(i = (int) (sysconf(_SC_OPEN_MAX) - 1); i >= 0; i--)
+        if(i != STDIN_FILENO && i != STDERR_FILENO && i != pipefd[PIPE_WRITE]) close(i);
+
+    // move the pipe to stdout
+    if(pipefd[PIPE_WRITE] != STDOUT_FILENO) {
+        dup2(pipefd[PIPE_WRITE], STDOUT_FILENO);
+        close(pipefd[PIPE_WRITE]);
+    }
+
+    execle("/bin/sh", "sh", "-c", command, NULL, env);
+    exit(1);
+}
+
+int mypclose(FILE *fp, pid_t pid) {
+    debug(D_EXIT, "Request to mypclose() on pid %d", pid);
+
+    /*mypopen_del(fp);*/
+
+    // close the pipe fd
+    // this is required in musl
+    // without it the childs do not exit
+    close(fileno(fp));
+
+    // close the pipe file pointer
+    fclose(fp);
+
+    errno = 0;
+
+    siginfo_t info;
+    if(waitid(P_PID, (id_t) pid, &info, WEXITED) != -1) {
+        switch(info.si_code) {
+            case CLD_EXITED:
+                if(info.si_status)
+                    error("child pid %d exited with code %d.", info.si_pid, info.si_status);
+                return(info.si_status);
+
+            case CLD_KILLED:
+                error("child pid %d killed by signal %d.", info.si_pid, info.si_status);
+                return(-1);
+
+            case CLD_DUMPED:
+                error("child pid %d core dumped by signal %d.", info.si_pid, info.si_status);
+                return(-2);
+
+            case CLD_STOPPED:
+                error("child pid %d stopped by signal %d.", info.si_pid, info.si_status);
+                return(0);
+
+            case CLD_TRAPPED:
+                error("child pid %d trapped by signal %d.", info.si_pid, info.si_status);
+                return(-4);
+
+            case CLD_CONTINUED:
+                error("child pid %d continued by signal %d.", info.si_pid, info.si_status);
+                return(0);
+
+            default:
+                error("child pid %d gave us a SIGCHLD with code %d and status %d.", info.si_pid, info.si_code, info.si_status);
+                return(-5);
+        }
+    }
+    else
+        error("Cannot waitid() for pid %d", pid);
+    
+    return 0;
+}
diff --git a/libnetdata/popen/popen.h b/libnetdata/popen/popen.h
new file mode 100644
index 0000000..90d4b82
--- /dev/null
+++ b/libnetdata/popen/popen.h
@@ -0,0 +1,18 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_POPEN_H
+#define NETDATA_POPEN_H 1
+
+#include "../libnetdata.h"
+
+#define PIPE_READ 0
+#define PIPE_WRITE 1
+
+extern FILE *mypopen(const char *command, volatile pid_t *pidptr);
+extern FILE *mypopene(const char *command, volatile pid_t *pidptr, char **env);
+extern int mypclose(FILE *fp, pid_t pid);
+
+extern void signals_unblock(void);
+extern void signals_reset(void);
+
+#endif /* NETDATA_POPEN_H */
diff --git a/libnetdata/procfile/Makefile.am b/libnetdata/procfile/Makefile.am
new file mode 100644
index 0000000..1cb69ed
--- /dev/null
+++ b/libnetdata/procfile/Makefile.am
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
+
+
+dist_noinst_DATA = \
+	README.md \
+	$(NULL)
diff --git a/libnetdata/procfile/README.md b/libnetdata/procfile/README.md
new file mode 100644
index 0000000..7037dc4
--- /dev/null
+++ b/libnetdata/procfile/README.md
@@ -0,0 +1,63 @@
+
+# PROCFILE
+
+procfile is a library for reading text data files (i.e `/proc` files) in the fastest possible way.
+
+## How it works
+
+The library automatically adapts (through the iterations) its memory so that each file
+is read with single `read()` call.
+
+Then the library splits the file into words, using the supplied separators.
+The library also supported quoted words (i.e. strings within of which the separators are ignored).
+
+### Initialization
+
+Initially the caller: 
+
+- calls `procfile_open()` to open the file and allocate the structures needed.
+
+### Iterations
+
+For each iteration, the caller:
+
+- calls `procfile_readall()` to read updated contents.
+   This call also rewinds (`lseek()` to 0) before reading it.
+
+   For every file, a [BUFFER](../buffer/) is used that is automatically adjusted to fit
+   the entire file contents of the file. So the file is read with a single `read()` call
+   (providing atomicity / consistency when the data are read from the kernel).
+
+   Once the data are read, 2 arrays of pointers are updated:
+
+   - a `words` array, pointing to each word in the data read
+   - a `lines` array, pointing to the first word for each line
+
+   This is highly optimized. Both arrays are automatically adjusted to
+   fit all contents and are updated in a single pass on the data.
+   
+   The library provides a number of macros:
+   
+   - `procfile_lines()` returns the # of lines read
+   - `procfile_linewords()` returns the # of words in the given line
+   - `procfile_word()` returns a pointer the given word #
+   - `procfile_line()` returns a pointer to the first word of the given line #
+   - `procfile_lineword()` returns a pointer to the given word # of the given line #
+
+### Cleanup
+
+When the caller exits:
+
+- calls `procfile_free()` to close the file and free all memory used.
+
+### Performance
+
+- a **raspberry Pi 1** (the oldest single core one) can process 5.000+ `/proc` files per second.
+- a **J1900 Celeron** processor can process 23.000+ `/proc` files per second per core.
+
+To achieve this kind of performance, the library tries to work in batches so that the code
+and the data are inside the processor's caches.
+
+This library is extensively used in netdata and its plugins.
+
+[![analytics](https://www.google-analytics.com/collect?v=1&aip=1&t=pageview&_s=1&ds=github&dr=https%3A%2F%2Fgithub.com%2Fnetdata%2Fnetdata&dl=https%3A%2F%2Fmy-netdata.io%2Fgithub%2Flibnetdata%2Fprocfile%2FREADME&_u=MAC~&cid=5792dfd7-8dc4-476b-af31-da2fdb9f93d2&tid=UA-64295674-3)]()
diff --git a/libnetdata/procfile/procfile.c b/libnetdata/procfile/procfile.c
new file mode 100644
index 0000000..4a812ba
--- /dev/null
+++ b/libnetdata/procfile/procfile.c
@@ -0,0 +1,472 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../libnetdata.h"
+
+#define PF_PREFIX "PROCFILE"
+
+#define PFWORDS_INCREASE_STEP 200
+#define PFLINES_INCREASE_STEP 10
+#define PROCFILE_INCREMENT_BUFFER 512
+
+int procfile_open_flags = O_RDONLY;
+
+int procfile_adaptive_initial_allocation = 0;
+
+// if adaptive allocation is set, these store the
+// max values we have seen so far
+size_t procfile_max_lines = PFLINES_INCREASE_STEP;
+size_t procfile_max_words = PFWORDS_INCREASE_STEP;
+size_t procfile_max_allocation = PROCFILE_INCREMENT_BUFFER;
+
+
+// ----------------------------------------------------------------------------
+
+char *procfile_filename(procfile *ff) {
+    if(ff->filename[0]) return ff->filename;
+
+    char buffer[FILENAME_MAX + 1];
+    snprintfz(buffer, FILENAME_MAX, "/proc/self/fd/%d", ff->fd);
+
+    ssize_t l = readlink(buffer, ff->filename, FILENAME_MAX);
+    if(unlikely(l == -1))
+        snprintfz(ff->filename, FILENAME_MAX, "unknown filename for fd %d", ff->fd);
+    else
+        ff->filename[l] = '\0';
+
+    // on non-linux systems, something like this will be needed
+    // fcntl(ff->fd, F_GETPATH, ff->filename)
+
+    return ff->filename;
+}
+
+// ----------------------------------------------------------------------------
+// An array of words
+
+static inline void pfwords_add(procfile *ff, char *str) {
+    // debug(D_PROCFILE, PF_PREFIX ":   adding word No %d: '%s'", fw->len, str);
+
+    pfwords *fw = ff->words;
+    if(unlikely(fw->len == fw->size)) {
+        // debug(D_PROCFILE, PF_PREFIX ":   expanding words");
+
+        ff->words = fw = reallocz(fw, sizeof(pfwords) + (fw->size + PFWORDS_INCREASE_STEP) * sizeof(char *));
+        fw->size += PFWORDS_INCREASE_STEP;
+    }
+
+    fw->words[fw->len++] = str;
+}
+
+NEVERNULL
+static inline pfwords *pfwords_new(void) {
+    // debug(D_PROCFILE, PF_PREFIX ":   initializing words");
+
+    size_t size = (procfile_adaptive_initial_allocation) ? procfile_max_words : PFWORDS_INCREASE_STEP;
+
+    pfwords *new = mallocz(sizeof(pfwords) + size * sizeof(char *));
+    new->len = 0;
+    new->size = size;
+    return new;
+}
+
+static inline void pfwords_reset(pfwords *fw) {
+    // debug(D_PROCFILE, PF_PREFIX ":   reseting words");
+    fw->len = 0;
+}
+
+static inline void pfwords_free(pfwords *fw) {
+    // debug(D_PROCFILE, PF_PREFIX ":   freeing words");
+
+    freez(fw);
+}
+
+
+// ----------------------------------------------------------------------------
+// An array of lines
+
+NEVERNULL
+static inline size_t *pflines_add(procfile *ff) {
+    // debug(D_PROCFILE, PF_PREFIX ":   adding line %d at word %d", fl->len, first_word);
+
+    pflines *fl = ff->lines;
+    if(unlikely(fl->len == fl->size)) {
+        // debug(D_PROCFILE, PF_PREFIX ":   expanding lines");
+
+        ff->lines = fl = reallocz(fl, sizeof(pflines) + (fl->size + PFLINES_INCREASE_STEP) * sizeof(ffline));
+        fl->size += PFLINES_INCREASE_STEP;
+    }
+
+    ffline *ffl = &fl->lines[fl->len++];
+    ffl->words = 0;
+    ffl->first = ff->words->len;
+
+    return &ffl->words;
+}
+
+NEVERNULL
+static inline pflines *pflines_new(void) {
+    // debug(D_PROCFILE, PF_PREFIX ":   initializing lines");
+
+    size_t size = (unlikely(procfile_adaptive_initial_allocation)) ? procfile_max_words : PFLINES_INCREASE_STEP;
+
+    pflines *new = mallocz(sizeof(pflines) + size * sizeof(ffline));
+    new->len = 0;
+    new->size = size;
+    return new;
+}
+
+static inline void pflines_reset(pflines *fl) {
+    // debug(D_PROCFILE, PF_PREFIX ":   reseting lines");
+
+    fl->len = 0;
+}
+
+static inline void pflines_free(pflines *fl) {
+    // debug(D_PROCFILE, PF_PREFIX ":   freeing lines");
+
+    freez(fl);
+}
+
+
+// ----------------------------------------------------------------------------
+// The procfile
+
+void procfile_close(procfile *ff) {
+    if(unlikely(!ff)) return;
+
+    debug(D_PROCFILE, PF_PREFIX ": Closing file '%s'", procfile_filename(ff));
+
+    if(likely(ff->lines)) pflines_free(ff->lines);
+    if(likely(ff->words)) pfwords_free(ff->words);
+
+    if(likely(ff->fd != -1)) close(ff->fd);
+    freez(ff);
+}
+
+NOINLINE
+static void procfile_parser(procfile *ff) {
+    // debug(D_PROCFILE, PF_PREFIX ": Parsing file '%s'", ff->filename);
+
+    char  *s = ff->data                 // our current position
+        , *e = &ff->data[ff->len]       // the terminating null
+        , *t = ff->data;                // the first character of a word (or quoted / parenthesized string)
+
+                                        // the look up array to find our type of character
+    PF_CHAR_TYPE *separators = ff->separators;
+
+    char quote = 0;                     // the quote character - only when in quoted string
+    size_t opened = 0;                  // counts the number of open parenthesis
+
+    size_t *line_words = pflines_add(ff);
+
+    while(s < e) {
+        PF_CHAR_TYPE ct = separators[(unsigned char)(*s)];
+
+        // this is faster than a switch()
+        // read more here: http://lazarenko.me/switch/
+        if(likely(ct == PF_CHAR_IS_WORD)) {
+            s++;
+        }
+        else if(likely(ct == PF_CHAR_IS_SEPARATOR)) {
+            if(!quote && !opened) {
+                if (s != t) {
+                    // separator, but we have word before it
+                    *s = '\0';
+                    pfwords_add(ff, t);
+                    (*line_words)++;
+                    t = ++s;
+                }
+                else {
+                    // separator at the beginning
+                    // skip it
+                    t = ++s;
+                }
+            }
+            else {
+                // we are inside a quote or parenthesized string
+                s++;
+            }
+        }
+        else if(likely(ct == PF_CHAR_IS_NEWLINE)) {
+            // end of line
+
+            *s = '\0';
+            pfwords_add(ff, t);
+            (*line_words)++;
+            t = ++s;
+
+            // debug(D_PROCFILE, PF_PREFIX ":   ended line %d with %d words", l, ff->lines->lines[l].words);
+
+            line_words = pflines_add(ff);
+        }
+        else if(likely(ct == PF_CHAR_IS_QUOTE)) {
+            if(unlikely(!quote && s == t)) {
+                // quote opened at the beginning
+                quote = *s;
+                t = ++s;
+            }
+            else if(unlikely(quote && quote == *s)) {
+                // quote closed
+                quote = 0;
+
+                *s = '\0';
+                pfwords_add(ff, t);
+                (*line_words)++;
+                t = ++s;
+            }
+            else
+                s++;
+        }
+        else if(likely(ct == PF_CHAR_IS_OPEN)) {
+            if(s == t) {
+                opened++;
+                t = ++s;
+            }
+            else if(opened) {
+                opened++;
+                s++;
+            }
+            else
+                s++;
+        }
+        else if(likely(ct == PF_CHAR_IS_CLOSE)) {
+            if(opened) {
+                opened--;
+
+                if(!opened) {
+                    *s = '\0';
+                    pfwords_add(ff, t);
+                    (*line_words)++;
+                    t = ++s;
+                }
+                else
+                    s++;
+            }
+            else
+                s++;
+        }
+        else
+            fatal("Internal Error: procfile_readall() does not handle all the cases.");
+    }
+
+    if(likely(s > t && t < e)) {
+        // the last word
+        if(unlikely(ff->len >= ff->size)) {
+            // we are going to loose the last byte
+            s = &ff->data[ff->size - 1];
+        }
+
+        *s = '\0';
+        pfwords_add(ff, t);
+        (*line_words)++;
+        // t = ++s;
+    }
+}
+
+procfile *procfile_readall(procfile *ff) {
+    // debug(D_PROCFILE, PF_PREFIX ": Reading file '%s'.", ff->filename);
+
+    ff->len = 0;    // zero the used size
+    ssize_t r = 1;  // read at least once
+    while(r > 0) {
+        ssize_t s = ff->len;
+        ssize_t x = ff->size - s;
+
+        if(unlikely(!x)) {
+            debug(D_PROCFILE, PF_PREFIX ": Expanding data buffer for file '%s'.", procfile_filename(ff));
+            ff = reallocz(ff, sizeof(procfile) + ff->size + PROCFILE_INCREMENT_BUFFER);
+            ff->size += PROCFILE_INCREMENT_BUFFER;
+        }
+
+        debug(D_PROCFILE, "Reading file '%s', from position %zd with length %zd", procfile_filename(ff), s, (ssize_t)(ff->size - s));
+        r = read(ff->fd, &ff->data[s], ff->size - s);
+        if(unlikely(r == -1)) {
+            if(unlikely(!(ff->flags & PROCFILE_FLAG_NO_ERROR_ON_FILE_IO))) error(PF_PREFIX ": Cannot read from file '%s' on fd %d", procfile_filename(ff), ff->fd);
+            procfile_close(ff);
+            return NULL;
+        }
+
+        ff->len += r;
+    }
+
+    // debug(D_PROCFILE, "Rewinding file '%s'", ff->filename);
+    if(unlikely(lseek(ff->fd, 0, SEEK_SET) == -1)) {
+        if(unlikely(!(ff->flags & PROCFILE_FLAG_NO_ERROR_ON_FILE_IO))) error(PF_PREFIX ": Cannot rewind on file '%s'.", procfile_filename(ff));
+        procfile_close(ff);
+        return NULL;
+    }
+
+    pflines_reset(ff->lines);
+    pfwords_reset(ff->words);
+    procfile_parser(ff);
+
+    if(unlikely(procfile_adaptive_initial_allocation)) {
+        if(unlikely(ff->len > procfile_max_allocation)) procfile_max_allocation = ff->len;
+        if(unlikely(ff->lines->len > procfile_max_lines)) procfile_max_lines = ff->lines->len;
+        if(unlikely(ff->words->len > procfile_max_words)) procfile_max_words = ff->words->len;
+    }
+
+    // debug(D_PROCFILE, "File '%s' updated.", ff->filename);
+    return ff;
+}
+
+NOINLINE
+static void procfile_set_separators(procfile *ff, const char *separators) {
+    static PF_CHAR_TYPE def[256];
+    static char initilized = 0;
+
+    if(unlikely(!initilized)) {
+        // this is thread safe
+        // if initialized is zero, multiple threads may be executing
+        // this code at the same time, setting in def[] the exact same values
+        int i = 256;
+        while(i--) {
+            if(unlikely(i == '\n' || i == '\r'))
+                def[i] = PF_CHAR_IS_NEWLINE;
+
+            else if(unlikely(isspace(i) || !isprint(i)))
+                def[i] = PF_CHAR_IS_SEPARATOR;
+
+            else
+                def[i] = PF_CHAR_IS_WORD;
+        }
+
+        initilized = 1;
+    }
+
+    // copy the default
+    PF_CHAR_TYPE *ffs = ff->separators, *ffd = def, *ffe = &def[256];
+    while(ffd != ffe)
+        *ffs++ = *ffd++;
+
+    // set the separators
+    if(unlikely(!separators))
+        separators = " \t=|";
+
+    ffs = ff->separators;
+    const char *s = separators;
+    while(*s)
+        ffs[(int)*s++] = PF_CHAR_IS_SEPARATOR;
+}
+
+void procfile_set_quotes(procfile *ff, const char *quotes) {
+    PF_CHAR_TYPE *ffs = ff->separators;
+
+    // remove all quotes
+    int i = 256;
+    while(i--)
+        if(unlikely(ffs[i] == PF_CHAR_IS_QUOTE))
+            ffs[i] = PF_CHAR_IS_WORD;
+
+    // if nothing given, return
+    if(unlikely(!quotes || !*quotes))
+        return;
+
+    // set the quotes
+    const char *s = quotes;
+    while(*s)
+        ffs[(int)*s++] = PF_CHAR_IS_QUOTE;
+}
+
+void procfile_set_open_close(procfile *ff, const char *open, const char *close) {
+    PF_CHAR_TYPE *ffs = ff->separators;
+
+    // remove all open/close
+    int i = 256;
+    while(i--)
+        if(unlikely(ffs[i] == PF_CHAR_IS_OPEN || ffs[i] == PF_CHAR_IS_CLOSE))
+            ffs[i] = PF_CHAR_IS_WORD;
+
+    // if nothing given, return
+    if(unlikely(!open || !*open || !close || !*close))
+        return;
+
+    // set the openings
+    const char *s = open;
+    while(*s)
+        ffs[(int)*s++] = PF_CHAR_IS_OPEN;
+
+    // set the closings
+    s = close;
+    while(*s)
+        ffs[(int)*s++] = PF_CHAR_IS_CLOSE;
+}
+
+procfile *procfile_open(const char *filename, const char *separators, uint32_t flags) {
+    debug(D_PROCFILE, PF_PREFIX ": Opening file '%s'", filename);
+
+    int fd = open(filename, procfile_open_flags, 0666);
+    if(unlikely(fd == -1)) {
+        if(unlikely(!(flags & PROCFILE_FLAG_NO_ERROR_ON_FILE_IO))) error(PF_PREFIX ": Cannot open file '%s'", filename);
+        return NULL;
+    }
+
+    // info("PROCFILE: opened '%s' on fd %d", filename, fd);
+
+    size_t size = (unlikely(procfile_adaptive_initial_allocation)) ? procfile_max_allocation : PROCFILE_INCREMENT_BUFFER;
+    procfile *ff = mallocz(sizeof(procfile) + size);
+
+    //strncpyz(ff->filename, filename, FILENAME_MAX);
+    ff->filename[0] = '\0';
+
+    ff->fd = fd;
+    ff->size = size;
+    ff->len = 0;
+    ff->flags = flags;
+
+    ff->lines = pflines_new();
+    ff->words = pfwords_new();
+
+    procfile_set_separators(ff, separators);
+
+    debug(D_PROCFILE, "File '%s' opened.", filename);
+    return ff;
+}
+
+procfile *procfile_reopen(procfile *ff, const char *filename, const char *separators, uint32_t flags) {
+    if(unlikely(!ff)) return procfile_open(filename, separators, flags);
+
+    if(likely(ff->fd != -1)) {
+        // info("PROCFILE: closing fd %d", ff->fd);
+        close(ff->fd);
+    }
+
+    ff->fd = open(filename, procfile_open_flags, 0666);
+    if(unlikely(ff->fd == -1)) {
+        procfile_close(ff);
+        return NULL;
+    }
+
+    // info("PROCFILE: opened '%s' on fd %d", filename, ff->fd);
+
+    //strncpyz(ff->filename, filename, FILENAME_MAX);
+    ff->filename[0] = '\0';
+    ff->flags = flags;
+
+    // do not do the separators again if NULL is given
+    if(likely(separators)) procfile_set_separators(ff, separators);
+
+    return ff;
+}
+
+// ----------------------------------------------------------------------------
+// example parsing of procfile data
+
+void procfile_print(procfile *ff) {
+    size_t lines = procfile_lines(ff), l;
+    char *s;
+    (void)s;
+
+    debug(D_PROCFILE, "File '%s' with %zu lines and %zu words", procfile_filename(ff), ff->lines->len, ff->words->len);
+
+    for(l = 0; likely(l < lines) ;l++) {
+        size_t words = procfile_linewords(ff, l);
+
+        debug(D_PROCFILE, " line %zu starts at word %zu and has %zu words", l, ff->lines->lines[l].first, ff->lines->lines[l].words);
+
+        size_t w;
+        for(w = 0; likely(w < words) ;w++) {
+            s = procfile_lineword(ff, l, w);
+            debug(D_PROCFILE, "     [%zu.%zu] '%s'", l, w, s);
+        }
+    }
+}
diff --git a/libnetdata/procfile/procfile.h b/libnetdata/procfile/procfile.h
new file mode 100644
index 0000000..b107358
--- /dev/null
+++ b/libnetdata/procfile/procfile.h
@@ -0,0 +1,106 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_PROCFILE_H
+#define NETDATA_PROCFILE_H 1
+
+#include "../libnetdata.h"
+
+// ----------------------------------------------------------------------------
+// An array of words
+
+typedef struct {
+    size_t len;     // used entries
+    size_t size;    // capacity
+    char *words[];  // array of pointers
+} pfwords;
+
+
+// ----------------------------------------------------------------------------
+// An array of lines
+
+typedef struct {
+    size_t words;   // how many words this line has
+    size_t first;   // the id of the first word of this line
+                    // in the words array
+} ffline;
+
+typedef struct {
+    size_t len;     // used entries
+    size_t size;    // capacity
+    ffline lines[]; // array of lines
+} pflines;
+
+
+// ----------------------------------------------------------------------------
+// The procfile
+
+#define PROCFILE_FLAG_DEFAULT             0x00000000
+#define PROCFILE_FLAG_NO_ERROR_ON_FILE_IO 0x00000001
+
+typedef enum procfile_separator {
+    PF_CHAR_IS_SEPARATOR,
+    PF_CHAR_IS_NEWLINE,
+    PF_CHAR_IS_WORD,
+    PF_CHAR_IS_QUOTE,
+    PF_CHAR_IS_OPEN,
+    PF_CHAR_IS_CLOSE
+} PF_CHAR_TYPE;
+
+typedef struct {
+    char filename[FILENAME_MAX + 1]; // not populated until profile_filename() is called
+
+    uint32_t flags;
+    int fd;               // the file desriptor
+    size_t len;           // the bytes we have placed into data
+    size_t size;          // the bytes we have allocated for data
+    pflines *lines;
+    pfwords *words;
+    PF_CHAR_TYPE separators[256];
+    char data[];          // allocated buffer to keep file contents
+} procfile;
+
+// close the proc file and free all related memory
+extern void procfile_close(procfile *ff);
+
+// (re)read and parse the proc file
+extern procfile *procfile_readall(procfile *ff);
+
+// open a /proc or /sys file
+extern procfile *procfile_open(const char *filename, const char *separators, uint32_t flags);
+
+// re-open a file
+// if separators == NULL, the last separators are used
+extern procfile *procfile_reopen(procfile *ff, const char *filename, const char *separators, uint32_t flags);
+
+// example walk-through a procfile parsed file
+extern void procfile_print(procfile *ff);
+
+extern void procfile_set_quotes(procfile *ff, const char *quotes);
+extern void procfile_set_open_close(procfile *ff, const char *open, const char *close);
+
+extern char *procfile_filename(procfile *ff);
+
+// ----------------------------------------------------------------------------
+
+// set to the O_XXXX flags, to have procfile_open and procfile_reopen use them when opening proc files
+extern int procfile_open_flags;
+
+// set this to 1, to have procfile adapt its initial buffer allocation to the max allocation used so far
+extern int procfile_adaptive_initial_allocation;
+
+// return the number of lines present
+#define procfile_lines(ff) ((ff)->lines->len)
+
+// return the number of words of the Nth line
+#define procfile_linewords(ff, line) (((line) < procfile_lines(ff)) ? (ff)->lines->lines[(line)].words : 0)
+
+// return the Nth word of the file, or empty string
+#define procfile_word(ff, word) (((word) < (ff)->words->len) ? (ff)->words->words[(word)] : "")
+
+// return the first word of the Nth line, or empty string
+#define procfile_line(ff, line) (((line) < procfile_lines(ff)) ? procfile_word((ff), (ff)->lines->lines[(line)].first) : "")
+
+// return the Nth word of the current line
+#define procfile_lineword(ff, line, word) (((line) < procfile_lines(ff) && (word) < procfile_linewords((ff), (line))) ? procfile_word((ff), (ff)->lines->lines[(line)].first + (word)) : "")
+
+#endif /* NETDATA_PROCFILE_H */
diff --git a/libnetdata/simple_pattern/Makefile.am b/libnetdata/simple_pattern/Makefile.am
new file mode 100644
index 0000000..1cb69ed
--- /dev/null
+++ b/libnetdata/simple_pattern/Makefile.am
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
+
+
+dist_noinst_DATA = \
+	README.md \
+	$(NULL)
diff --git a/libnetdata/simple_pattern/README.md b/libnetdata/simple_pattern/README.md
new file mode 100644
index 0000000..79a7131
--- /dev/null
+++ b/libnetdata/simple_pattern/README.md
@@ -0,0 +1,38 @@
+## netdata simple patterns
+
+Unix prefers regular expressions. But they are just too hard, too cryptic
+to use, write and understand.
+
+So, netdata supports **simple patterns**.
+
+Simple patterns are a space separated list of words, that can have `*`
+as a wildcard. Each world may use any number of `*`. Simple patterns
+allow **negative** matches by prefixing a word with `!`.
+
+So, `pattern = !*bad* *` will match anything, except all those that
+contain the word `bad`. 
+
+Simple patterns are quite powerful: `pattern = *foobar* !foo* !*bar *`
+matches everything containing `foobar`, except strings that start
+with `foo` or end with `bar`.
+
+You can use the netdata command line to check simple patterns,
+like this:
+
+```sh
+# netdata -W simple-pattern '*foobar* !foo* !*bar *' 'hello world'
+RESULT: MATCHED - pattern '*foobar* !foo* !*bar *' matches 'hello world'
+
+# netdata -W simple-pattern '*foobar* !foo* !*bar *' 'hello world bar'
+RESULT: NOT MATCHED - pattern '*foobar* !foo* !*bar *' does not match 'hello world bar'
+
+# netdata -W simple-pattern '*foobar* !foo* !*bar *' 'hello world foobar'
+RESULT: MATCHED - pattern '*foobar* !foo* !*bar *' matches 'hello world foobar'
+```
+
+netdata stops processing to the first positive or negative match
+(left to right). If it is not matched by either positive or negative
+patterns, it is denied at the end.
+
+
+[![analytics](https://www.google-analytics.com/collect?v=1&aip=1&t=pageview&_s=1&ds=github&dr=https%3A%2F%2Fgithub.com%2Fnetdata%2Fnetdata&dl=https%3A%2F%2Fmy-netdata.io%2Fgithub%2Flibnetdata%2Fsimple_pattern%2FREADME&_u=MAC~&cid=5792dfd7-8dc4-476b-af31-da2fdb9f93d2&tid=UA-64295674-3)]()
diff --git a/libnetdata/simple_pattern/simple_pattern.c b/libnetdata/simple_pattern/simple_pattern.c
new file mode 100644
index 0000000..57b0aec
--- /dev/null
+++ b/libnetdata/simple_pattern/simple_pattern.c
@@ -0,0 +1,262 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../libnetdata.h"
+
+struct simple_pattern {
+    const char *match;
+    size_t len;
+
+    SIMPLE_PREFIX_MODE mode;
+    char negative;
+
+    struct simple_pattern *child;
+
+    struct simple_pattern *next;
+};
+
+static inline struct simple_pattern *parse_pattern(char *str, SIMPLE_PREFIX_MODE default_mode) {
+    // fprintf(stderr, "PARSING PATTERN: '%s'\n", str);
+
+    SIMPLE_PREFIX_MODE mode;
+    struct simple_pattern *child = NULL;
+
+    char *s = str, *c = str;
+
+    // skip asterisks in front
+    while(*c == '*') c++;
+
+    // find the next asterisk
+    while(*c && *c != '*') c++;
+
+    // do we have an asterisk in the middle?
+    if(*c == '*' && c[1] != '\0') {
+        // yes, we have
+        child = parse_pattern(c, default_mode);
+        c[1] = '\0';
+    }
+
+    // check what this one matches
+
+    size_t len = strlen(s);
+    if(len >= 2 && *s == '*' && s[len - 1] == '*') {
+        s[len - 1] = '\0';
+        s++;
+        mode = SIMPLE_PATTERN_SUBSTRING;
+    }
+    else if(len >= 1 && *s == '*') {
+        s++;
+        mode = SIMPLE_PATTERN_SUFFIX;
+    }
+    else if(len >= 1 && s[len - 1] == '*') {
+        s[len - 1] = '\0';
+        mode = SIMPLE_PATTERN_PREFIX;
+    }
+    else
+        mode = default_mode;
+
+    // allocate the structure
+    struct simple_pattern *m = callocz(1, sizeof(struct simple_pattern));
+    if(*s) {
+        m->match = strdupz(s);
+        m->len = strlen(m->match);
+        m->mode = mode;
+    }
+    else {
+        m->mode = SIMPLE_PATTERN_SUBSTRING;
+    }
+
+    m->child = child;
+
+    return m;
+}
+
+SIMPLE_PATTERN *simple_pattern_create(const char *list, const char *separators, SIMPLE_PREFIX_MODE default_mode) {
+    struct simple_pattern *root = NULL, *last = NULL;
+
+    if(unlikely(!list || !*list)) return root;
+
+    int isseparator[256] = {
+            [' '] = 1       // space
+            , ['\t'] = 1    // tab
+            , ['\r'] = 1    // carriage return
+            , ['\n'] = 1    // new line
+            , ['\f'] = 1    // form feed
+            , ['\v'] = 1    // vertical tab
+    };
+
+    if (unlikely(separators && *separators)) {
+        memset(&isseparator[0], 0, sizeof(isseparator));
+        while(*separators) isseparator[(unsigned char)*separators++] = 1;
+    }
+
+    char *buf = mallocz(strlen(list) + 1);
+    const char *s = list;
+
+    while(s && *s) {
+        buf[0] = '\0';
+        char *c = buf;
+
+        char negative = 0;
+
+        // skip all spaces
+        while(isseparator[(unsigned char)*s])
+            s++;
+
+        if(*s == '!') {
+            negative = 1;
+            s++;
+        }
+
+        // empty string
+        if(unlikely(!*s))
+            break;
+
+        // find the next space
+        char escape = 0;
+        while(*s) {
+            if(*s == '\\' && !escape) {
+                escape = 1;
+                s++;
+            }
+            else {
+                if (isseparator[(unsigned char)*s] && !escape) {
+                    s++;
+                    break;
+                }
+
+                *c++ = *s++;
+                escape = 0;
+            }
+        }
+
+        // terminate our string
+        *c = '\0';
+
+        // if we matched the empty string, skip it
+        if(unlikely(!*buf))
+            continue;
+
+        // fprintf(stderr, "FOUND PATTERN: '%s'\n", buf);
+        struct simple_pattern *m = parse_pattern(buf, default_mode);
+        m->negative = negative;
+
+        // link it at the end
+        if(unlikely(!root))
+            root = last = m;
+        else {
+            last->next = m;
+            last = m;
+        }
+    }
+
+    freez(buf);
+    return (SIMPLE_PATTERN *)root;
+}
+
+static inline char *add_wildcarded(const char *matched, size_t matched_size, char *wildcarded, size_t *wildcarded_size) {
+    //if(matched_size) {
+    //    char buf[matched_size + 1];
+    //    strncpyz(buf, matched, matched_size);
+    //    fprintf(stderr, "ADD WILDCARDED '%s' of length %zu\n", buf, matched_size);
+    //}
+
+    if(unlikely(wildcarded && *wildcarded_size && matched && *matched && matched_size)) {
+        size_t wss = *wildcarded_size - 1;
+        size_t len = (matched_size < wss)?matched_size:wss;
+        if(likely(len)) {
+            strncpyz(wildcarded, matched, len);
+
+            *wildcarded_size -= len;
+            return &wildcarded[len];
+        }
+    }
+
+    return wildcarded;
+}
+
+static inline int match_pattern(struct simple_pattern *m, const char *str, size_t len, char *wildcarded, size_t *wildcarded_size) {
+    char *s;
+
+    if(m->len <= len) {
+        switch(m->mode) {
+            case SIMPLE_PATTERN_SUBSTRING:
+                if(!m->len) return 1;
+                if((s = strstr(str, m->match))) {
+                    wildcarded = add_wildcarded(str, s - str, wildcarded, wildcarded_size);
+                    if(!m->child) {
+                        wildcarded = add_wildcarded(&s[m->len], len - (&s[m->len] - str), wildcarded, wildcarded_size);
+                        return 1;
+                    }
+                    return match_pattern(m->child, &s[m->len], len - (s - str) - m->len, wildcarded, wildcarded_size);
+                }
+                break;
+
+            case SIMPLE_PATTERN_PREFIX:
+                if(unlikely(strncmp(str, m->match, m->len) == 0)) {
+                    if(!m->child) {
+                        wildcarded = add_wildcarded(&str[m->len], len - m->len, wildcarded, wildcarded_size);
+                        return 1;
+                    }
+                    return match_pattern(m->child, &str[m->len], len - m->len, wildcarded, wildcarded_size);
+                }
+                break;
+
+            case SIMPLE_PATTERN_SUFFIX:
+                if(unlikely(strcmp(&str[len - m->len], m->match) == 0)) {
+                    wildcarded = add_wildcarded(str, len - m->len, wildcarded, wildcarded_size);
+                    if(!m->child) return 1;
+                    return 0;
+                }
+                break;
+
+            case SIMPLE_PATTERN_EXACT:
+            default:
+                if(unlikely(strcmp(str, m->match) == 0)) {
+                    if(!m->child) return 1;
+                    return 0;
+                }
+                break;
+        }
+    }
+
+    return 0;
+}
+
+int simple_pattern_matches_extract(SIMPLE_PATTERN *list, const char *str, char *wildcarded, size_t wildcarded_size) {
+    struct simple_pattern *m, *root = (struct simple_pattern *)list;
+
+    if(unlikely(!root || !str || !*str)) return 0;
+
+    size_t len = strlen(str);
+    for(m = root; m ; m = m->next) {
+        char *ws = wildcarded;
+        size_t wss = wildcarded_size;
+        if(unlikely(ws)) *ws = '\0';
+
+        if (match_pattern(m, str, len, ws, &wss)) {
+
+            //if(ws && wss)
+            //    fprintf(stderr, "FINAL WILDCARDED '%s' of length %zu\n", ws, strlen(ws));
+
+            if (m->negative) return 0;
+            return 1;
+        }
+    }
+
+    return 0;
+}
+
+static inline void free_pattern(struct simple_pattern *m) {
+    if(!m) return;
+
+    free_pattern(m->child);
+    free_pattern(m->next);
+    freez((void *)m->match);
+    freez(m);
+}
+
+void simple_pattern_free(SIMPLE_PATTERN *list) {
+    if(!list) return;
+
+    free_pattern(((struct simple_pattern *)list));
+}
diff --git a/libnetdata/simple_pattern/simple_pattern.h b/libnetdata/simple_pattern/simple_pattern.h
new file mode 100644
index 0000000..b96a018
--- /dev/null
+++ b/libnetdata/simple_pattern/simple_pattern.h
@@ -0,0 +1,33 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_SIMPLE_PATTERN_H
+#define NETDATA_SIMPLE_PATTERN_H
+
+#include "../libnetdata.h"
+
+
+typedef enum {
+    SIMPLE_PATTERN_EXACT,
+    SIMPLE_PATTERN_PREFIX,
+    SIMPLE_PATTERN_SUFFIX,
+    SIMPLE_PATTERN_SUBSTRING
+} SIMPLE_PREFIX_MODE;
+
+typedef void SIMPLE_PATTERN;
+
+// create a simple_pattern from the string given
+// default_mode is used in cases where EXACT matches, without an asterisk,
+// should be considered PREFIX matches.
+extern SIMPLE_PATTERN *simple_pattern_create(const char *list, const char *separators, SIMPLE_PREFIX_MODE default_mode);
+
+// test if string str is matched from the pattern and fill 'wildcarded' with the parts matched by '*'
+extern int simple_pattern_matches_extract(SIMPLE_PATTERN *list, const char *str, char *wildcarded, size_t wildcarded_size);
+
+// test if string str is matched from the pattern
+#define simple_pattern_matches(list, str) simple_pattern_matches_extract(list, str, NULL, 0)
+
+// free a simple_pattern that was created with simple_pattern_create()
+// list can be NULL, in which case, this does nothing.
+extern void simple_pattern_free(SIMPLE_PATTERN *list);
+
+#endif //NETDATA_SIMPLE_PATTERN_H
diff --git a/libnetdata/socket/Makefile.am b/libnetdata/socket/Makefile.am
new file mode 100644
index 0000000..1cb69ed
--- /dev/null
+++ b/libnetdata/socket/Makefile.am
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
+
+
+dist_noinst_DATA = \
+	README.md \
+	$(NULL)
diff --git a/libnetdata/socket/README.md b/libnetdata/socket/README.md
new file mode 100644
index 0000000..e427560
--- /dev/null
+++ b/libnetdata/socket/README.md
@@ -0,0 +1,2 @@
+
+[![analytics](https://www.google-analytics.com/collect?v=1&aip=1&t=pageview&_s=1&ds=github&dr=https%3A%2F%2Fgithub.com%2Fnetdata%2Fnetdata&dl=https%3A%2F%2Fmy-netdata.io%2Fgithub%2Flibnetdata%2Fsocket%2FREADME&_u=MAC~&cid=5792dfd7-8dc4-476b-af31-da2fdb9f93d2&tid=UA-64295674-3)]()
diff --git a/libnetdata/socket/socket.c b/libnetdata/socket/socket.c
new file mode 100644
index 0000000..6b0b3b6
--- /dev/null
+++ b/libnetdata/socket/socket.c
@@ -0,0 +1,1571 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../libnetdata.h"
+
+// --------------------------------------------------------------------------------------------------------------------
+// various library calls
+
+#ifdef __gnu_linux__
+#define LARGE_SOCK_SIZE 33554431 // don't ask why - I found it at brubeck source - I guess it is just a large number
+#else
+#define LARGE_SOCK_SIZE 4096
+#endif
+
+int sock_setnonblock(int fd) {
+    int flags;
+
+    flags = fcntl(fd, F_GETFL);
+    flags |= O_NONBLOCK;
+
+    int ret = fcntl(fd, F_SETFL, flags);
+    if(ret < 0)
+        error("Failed to set O_NONBLOCK on socket %d", fd);
+
+    return ret;
+}
+
+int sock_delnonblock(int fd) {
+    int flags;
+
+    flags = fcntl(fd, F_GETFL);
+    flags &= ~O_NONBLOCK;
+
+    int ret = fcntl(fd, F_SETFL, flags);
+    if(ret < 0)
+        error("Failed to remove O_NONBLOCK on socket %d", fd);
+
+    return ret;
+}
+
+int sock_setreuse(int fd, int reuse) {
+    int ret = setsockopt(fd, SOL_SOCKET, SO_REUSEADDR, &reuse, sizeof(reuse));
+
+    if(ret == -1)
+        error("Failed to set SO_REUSEADDR on socket %d", fd);
+
+    return ret;
+}
+
+int sock_setreuse_port(int fd, int reuse) {
+    int ret;
+
+#ifdef SO_REUSEPORT
+    ret = setsockopt(fd, SOL_SOCKET, SO_REUSEPORT, &reuse, sizeof(reuse));
+    if(ret == -1 && errno != ENOPROTOOPT)
+        error("failed to set SO_REUSEPORT on socket %d", fd);
+#else
+    ret = -1;
+#endif
+
+    return ret;
+}
+
+int sock_enlarge_in(int fd) {
+    int ret, bs = LARGE_SOCK_SIZE;
+
+    ret = setsockopt(fd, SOL_SOCKET, SO_RCVBUF, &bs, sizeof(bs));
+
+    if(ret == -1)
+        error("Failed to set SO_RCVBUF on socket %d", fd);
+
+    return ret;
+}
+
+int sock_enlarge_out(int fd) {
+    int ret, bs = LARGE_SOCK_SIZE;
+    ret = setsockopt(fd, SOL_SOCKET, SO_SNDBUF, &bs, sizeof(bs));
+
+    if(ret == -1)
+        error("Failed to set SO_SNDBUF on socket %d", fd);
+
+    return ret;
+}
+
+
+// --------------------------------------------------------------------------------------------------------------------
+
+char *strdup_client_description(int family, const char *protocol, const char *ip, uint16_t port) {
+    char buffer[100 + 1];
+
+    switch(family) {
+        case AF_INET:
+            snprintfz(buffer, 100, "%s:%s:%d", protocol, ip, port);
+            break;
+
+        case AF_INET6:
+        default:
+            snprintfz(buffer, 100, "%s:[%s]:%d", protocol, ip, port);
+            break;
+
+        case AF_UNIX:
+            snprintfz(buffer, 100, "%s:%s", protocol, ip);
+            break;
+    }
+
+    return strdupz(buffer);
+}
+
+// --------------------------------------------------------------------------------------------------------------------
+// listening sockets
+
+int create_listen_socket_unix(const char *path, int listen_backlog) {
+    int sock;
+
+    debug(D_LISTENER, "LISTENER: UNIX creating new listening socket on path '%s'", path);
+
+    sock = socket(AF_UNIX, SOCK_STREAM, 0);
+    if(sock < 0) {
+        error("LISTENER: UNIX socket() on path '%s' failed.", path);
+        return -1;
+    }
+
+    sock_setnonblock(sock);
+    sock_enlarge_in(sock);
+
+    struct sockaddr_un name;
+    memset(&name, 0, sizeof(struct sockaddr_un));
+    name.sun_family = AF_UNIX;
+    strncpy(name.sun_path, path, sizeof(name.sun_path)-1);
+
+    errno = 0;
+    if (unlink(path) == -1 && errno != ENOENT)
+        error("LISTENER: failed to remove existing (probably obsolete or left-over) file on UNIX socket path '%s'.", path);
+
+    if(bind (sock, (struct sockaddr *) &name, sizeof (name)) < 0) {
+        close(sock);
+        error("LISTENER: UNIX bind() on path '%s' failed.", path);
+        return -1;
+    }
+
+    // we have to chmod this to 0777 so that the client will be able
+    // to read from and write to this socket.
+    if(chmod(path, 0777) == -1)
+        error("LISTENER: failed to chmod() socket file '%s'.", path);
+
+    if(listen(sock, listen_backlog) < 0) {
+        close(sock);
+        error("LISTENER: UNIX listen() on path '%s' failed.", path);
+        return -1;
+    }
+
+    debug(D_LISTENER, "LISTENER: Listening on UNIX path '%s'", path);
+    return sock;
+}
+
+int create_listen_socket4(int socktype, const char *ip, uint16_t port, int listen_backlog) {
+    int sock;
+
+    debug(D_LISTENER, "LISTENER: IPv4 creating new listening socket on ip '%s' port %d, socktype %d", ip, port, socktype);
+
+    sock = socket(AF_INET, socktype, 0);
+    if(sock < 0) {
+        error("LISTENER: IPv4 socket() on ip '%s' port %d, socktype %d failed.", ip, port, socktype);
+        return -1;
+    }
+
+    sock_setreuse(sock, 1);
+    sock_setreuse_port(sock, 1);
+    sock_setnonblock(sock);
+    sock_enlarge_in(sock);
+
+    struct sockaddr_in name;
+    memset(&name, 0, sizeof(struct sockaddr_in));
+    name.sin_family = AF_INET;
+    name.sin_port = htons (port);
+
+    int ret = inet_pton(AF_INET, ip, (void *)&name.sin_addr.s_addr);
+    if(ret != 1) {
+        error("LISTENER: Failed to convert IP '%s' to a valid IPv4 address.", ip);
+        close(sock);
+        return -1;
+    }
+
+    if(bind (sock, (struct sockaddr *) &name, sizeof (name)) < 0) {
+        close(sock);
+        error("LISTENER: IPv4 bind() on ip '%s' port %d, socktype %d failed.", ip, port, socktype);
+        return -1;
+    }
+
+    if(socktype == SOCK_STREAM && listen(sock, listen_backlog) < 0) {
+        close(sock);
+        error("LISTENER: IPv4 listen() on ip '%s' port %d, socktype %d failed.", ip, port, socktype);
+        return -1;
+    }
+
+    debug(D_LISTENER, "LISTENER: Listening on IPv4 ip '%s' port %d, socktype %d", ip, port, socktype);
+    return sock;
+}
+
+int create_listen_socket6(int socktype, uint32_t scope_id, const char *ip, int port, int listen_backlog) {
+    int sock;
+    int ipv6only = 1;
+
+    debug(D_LISTENER, "LISTENER: IPv6 creating new listening socket on ip '%s' port %d, socktype %d", ip, port, socktype);
+
+    sock = socket(AF_INET6, socktype, 0);
+    if (sock < 0) {
+        error("LISTENER: IPv6 socket() on ip '%s' port %d, socktype %d, failed.", ip, port, socktype);
+        return -1;
+    }
+
+    sock_setreuse(sock, 1);
+    sock_setreuse_port(sock, 1);
+    sock_setnonblock(sock);
+    sock_enlarge_in(sock);
+
+    /* IPv6 only */
+    if(setsockopt(sock, IPPROTO_IPV6, IPV6_V6ONLY, (void*)&ipv6only, sizeof(ipv6only)) != 0)
+        error("LISTENER: Cannot set IPV6_V6ONLY on ip '%s' port %d, socktype %d.", ip, port, socktype);
+
+    struct sockaddr_in6 name;
+    memset(&name, 0, sizeof(struct sockaddr_in6));
+    name.sin6_family = AF_INET6;
+    name.sin6_port = htons ((uint16_t) port);
+    name.sin6_scope_id = scope_id;
+
+    int ret = inet_pton(AF_INET6, ip, (void *)&name.sin6_addr.s6_addr);
+    if(ret != 1) {
+        error("LISTENER: Failed to convert IP '%s' to a valid IPv6 address.", ip);
+        close(sock);
+        return -1;
+    }
+
+    name.sin6_scope_id = scope_id;
+
+    if (bind (sock, (struct sockaddr *) &name, sizeof (name)) < 0) {
+        close(sock);
+        error("LISTENER: IPv6 bind() on ip '%s' port %d, socktype %d failed.", ip, port, socktype);
+        return -1;
+    }
+
+    if (socktype == SOCK_STREAM && listen(sock, listen_backlog) < 0) {
+        close(sock);
+        error("LISTENER: IPv6 listen() on ip '%s' port %d, socktype %d failed.", ip, port, socktype);
+        return -1;
+    }
+
+    debug(D_LISTENER, "LISTENER: Listening on IPv6 ip '%s' port %d, socktype %d", ip, port, socktype);
+    return sock;
+}
+
+static inline int listen_sockets_add(LISTEN_SOCKETS *sockets, int fd, int family, int socktype, const char *protocol, const char *ip, uint16_t port, int acl_flags) {
+    if(sockets->opened >= MAX_LISTEN_FDS) {
+        error("LISTENER: Too many listening sockets. Failed to add listening %s socket at ip '%s' port %d, protocol %s, socktype %d", protocol, ip, port, protocol, socktype);
+        close(fd);
+        return -1;
+    }
+
+    sockets->fds[sockets->opened] = fd;
+    sockets->fds_types[sockets->opened] = socktype;
+    sockets->fds_families[sockets->opened] = family;
+    sockets->fds_names[sockets->opened] = strdup_client_description(family, protocol, ip, port);
+    sockets->fds_acl_flags[sockets->opened] = acl_flags;
+
+    sockets->opened++;
+    return 0;
+}
+
+int listen_sockets_check_is_member(LISTEN_SOCKETS *sockets, int fd) {
+    size_t i;
+    for(i = 0; i < sockets->opened ;i++)
+        if(sockets->fds[i] == fd) return 1;
+
+    return 0;
+}
+
+static inline void listen_sockets_init(LISTEN_SOCKETS *sockets) {
+    size_t i;
+    for(i = 0; i < MAX_LISTEN_FDS ;i++) {
+        sockets->fds[i] = -1;
+        sockets->fds_names[i] = NULL;
+        sockets->fds_types[i] = -1;
+    }
+
+    sockets->opened = 0;
+    sockets->failed = 0;
+}
+
+void listen_sockets_close(LISTEN_SOCKETS *sockets) {
+    size_t i;
+    for(i = 0; i < sockets->opened ;i++) {
+        close(sockets->fds[i]);
+        sockets->fds[i] = -1;
+
+        freez(sockets->fds_names[i]);
+        sockets->fds_names[i] = NULL;
+
+        sockets->fds_types[i] = -1;
+    }
+
+    sockets->opened = 0;
+    sockets->failed = 0;
+}
+
+WEB_CLIENT_ACL read_acl(char *st) {
+    if (!strcmp(st,"dashboard")) return WEB_CLIENT_ACL_DASHBOARD;
+    if (!strcmp(st,"registry")) return WEB_CLIENT_ACL_REGISTRY;
+    if (!strcmp(st,"badges")) return WEB_CLIENT_ACL_BADGE;
+    if (!strcmp(st,"management")) return WEB_CLIENT_ACL_MGMT;
+    if (!strcmp(st,"streaming")) return WEB_CLIENT_ACL_STREAMING;
+    if (!strcmp(st,"netdata.conf")) return WEB_CLIENT_ACL_NETDATACONF;
+    return WEB_CLIENT_ACL_NONE;
+}
+
+static inline int bind_to_this(LISTEN_SOCKETS *sockets, const char *definition, uint16_t default_port, int listen_backlog) {
+    int added = 0;
+    WEB_CLIENT_ACL acl_flags = WEB_CLIENT_ACL_NONE;
+
+    struct addrinfo hints;
+    struct addrinfo *result = NULL, *rp = NULL;
+
+    char buffer[strlen(definition) + 1];
+    strcpy(buffer, definition);
+
+    char buffer2[10 + 1];
+    snprintfz(buffer2, 10, "%d", default_port);
+
+    char *ip = buffer, *port = buffer2, *interface = "", *portconfig;;
+
+    int protocol = IPPROTO_TCP, socktype = SOCK_STREAM;
+    const char *protocol_str = "tcp";
+
+    if(strncmp(ip, "tcp:", 4) == 0) {
+        ip += 4;
+        protocol = IPPROTO_TCP;
+        socktype = SOCK_STREAM;
+        protocol_str = "tcp";
+    }
+    else if(strncmp(ip, "udp:", 4) == 0) {
+        ip += 4;
+        protocol = IPPROTO_UDP;
+        socktype = SOCK_DGRAM;
+        protocol_str = "udp";
+    }
+    else if(strncmp(ip, "unix:", 5) == 0) {
+        char *path = ip + 5;
+        socktype = SOCK_STREAM;
+        protocol_str = "unix";
+        int fd = create_listen_socket_unix(path, listen_backlog);
+        if (fd == -1) {
+            error("LISTENER: Cannot create unix socket '%s'", path);
+            sockets->failed++;
+        } else {
+            acl_flags = WEB_CLIENT_ACL_DASHBOARD | WEB_CLIENT_ACL_REGISTRY | WEB_CLIENT_ACL_BADGE | WEB_CLIENT_ACL_MGMT | WEB_CLIENT_ACL_NETDATACONF | WEB_CLIENT_ACL_STREAMING;
+            listen_sockets_add(sockets, fd, AF_UNIX, socktype, protocol_str, path, 0, acl_flags);
+            added++;
+        }
+        return added;
+    }
+
+    char *e = ip;
+    if(*e == '[') {
+        e = ++ip;
+        while(*e && *e != ']') e++;
+        if(*e == ']') {
+            *e = '\0';
+            e++;
+        }
+    }
+    else {
+        while(*e && *e != ':' && *e != '%' && *e != '=') e++;
+    }
+
+    if(*e == '%') {
+        *e = '\0';
+        e++;
+        interface = e;
+        while(*e && *e != ':' && *e != '=') e++;
+    }
+
+    if(*e == ':') {
+        port = e + 1;
+        *e = '\0';
+        e++;
+        while(*e && *e != '=') e++;
+    }
+
+    if(*e == '=') {
+        *e='\0';
+        e++;
+        portconfig = e;
+        while (*e != '\0') {
+            if (*e == '|') {
+                *e = '\0';
+                acl_flags |= read_acl(portconfig);
+                e++;
+                portconfig = e;
+                continue;
+            }
+            e++;
+        }
+        acl_flags |= read_acl(portconfig);
+    } else {
+        acl_flags = WEB_CLIENT_ACL_DASHBOARD | WEB_CLIENT_ACL_REGISTRY | WEB_CLIENT_ACL_BADGE | WEB_CLIENT_ACL_MGMT | WEB_CLIENT_ACL_NETDATACONF | WEB_CLIENT_ACL_STREAMING;
+    }
+
+    uint32_t scope_id = 0;
+    if(*interface) {
+        scope_id = if_nametoindex(interface);
+        if(!scope_id)
+            error("LISTENER: Cannot find a network interface named '%s'. Continuing with limiting the network interface", interface);
+    }
+
+    if(!*ip || *ip == '*' || !strcmp(ip, "any") || !strcmp(ip, "all"))
+        ip = NULL;
+
+    if(!*port)
+        port = buffer2;
+
+    memset(&hints, 0, sizeof(hints));
+    hints.ai_family = AF_UNSPEC;  /* Allow IPv4 or IPv6 */
+    hints.ai_socktype = socktype;
+    hints.ai_flags = AI_PASSIVE;  /* For wildcard IP address */
+    hints.ai_protocol = protocol;
+    hints.ai_canonname = NULL;
+    hints.ai_addr = NULL;
+    hints.ai_next = NULL;
+
+    int r = getaddrinfo(ip, port, &hints, &result);
+    if (r != 0) {
+        error("LISTENER: getaddrinfo('%s', '%s'): %s\n", ip, port, gai_strerror(r));
+        return -1;
+    }
+
+    for (rp = result; rp != NULL; rp = rp->ai_next) {
+        int fd = -1;
+        int family;
+
+        char rip[INET_ADDRSTRLEN + INET6_ADDRSTRLEN] = "INVALID";
+        uint16_t rport = default_port;
+
+        family = rp->ai_addr->sa_family;
+        switch (family) {
+            case AF_INET: {
+                struct sockaddr_in *sin = (struct sockaddr_in *) rp->ai_addr;
+                inet_ntop(AF_INET, &sin->sin_addr, rip, INET_ADDRSTRLEN);
+                rport = ntohs(sin->sin_port);
+                // info("Attempting to listen on IPv4 '%s' ('%s'), port %d ('%s'), socktype %d", rip, ip, rport, port, socktype);
+                fd = create_listen_socket4(socktype, rip, rport, listen_backlog);
+                break;
+            }
+
+            case AF_INET6: {
+                struct sockaddr_in6 *sin6 = (struct sockaddr_in6 *) rp->ai_addr;
+                inet_ntop(AF_INET6, &sin6->sin6_addr, rip, INET6_ADDRSTRLEN);
+                rport = ntohs(sin6->sin6_port);
+                // info("Attempting to listen on IPv6 '%s' ('%s'), port %d ('%s'), socktype %d", rip, ip, rport, port, socktype);
+                fd = create_listen_socket6(socktype, scope_id, rip, rport, listen_backlog);
+                break;
+            }
+
+            default:
+                debug(D_LISTENER, "LISTENER: Unknown socket family %d", family);
+                break;
+        }
+
+        if (fd == -1) {
+            error("LISTENER: Cannot bind to ip '%s', port %d", rip, rport);
+            sockets->failed++;
+        }
+        else {
+            listen_sockets_add(sockets, fd, family, socktype, protocol_str, rip, rport, acl_flags);
+            added++;
+        }
+    }
+
+    freeaddrinfo(result);
+
+    return added;
+}
+
+int listen_sockets_setup(LISTEN_SOCKETS *sockets) {
+    listen_sockets_init(sockets);
+
+    sockets->backlog = (int) appconfig_get_number(sockets->config, sockets->config_section, "listen backlog", sockets->backlog);
+
+    long long int old_port = sockets->default_port;
+    long long int new_port = appconfig_get_number(sockets->config, sockets->config_section, "default port", sockets->default_port);
+    if(new_port < 1 || new_port > 65535) {
+        error("LISTENER: Invalid listen port %lld given. Defaulting to %lld.", new_port, old_port);
+        sockets->default_port = (uint16_t) appconfig_set_number(sockets->config, sockets->config_section, "default port", old_port);
+    }
+    else sockets->default_port = (uint16_t)new_port;
+
+    debug(D_OPTIONS, "LISTENER: Default listen port set to %d.", sockets->default_port);
+
+    char *s = appconfig_get(sockets->config, sockets->config_section, "bind to", sockets->default_bind_to);
+    while(*s) {
+        char *e = s;
+
+        // skip separators, moving both s(tart) and e(nd)
+        while(isspace(*e) || *e == ',') s = ++e;
+
+        // move e(nd) to the first separator
+        while(*e && !isspace(*e) && *e != ',') e++;
+
+        // is there anything?
+        if(!*s || s == e) break;
+
+        char buf[e - s + 1];
+        strncpyz(buf, s, e - s);
+        bind_to_this(sockets, buf, sockets->default_port, sockets->backlog);
+
+        s = e;
+    }
+
+    if(sockets->failed) {
+        size_t i;
+        for(i = 0; i < sockets->opened ;i++)
+            info("LISTENER: Listen socket %s opened successfully.", sockets->fds_names[i]);
+    }
+
+    return (int)sockets->opened;
+}
+
+
+// --------------------------------------------------------------------------------------------------------------------
+// connect to another host/port
+
+// connect_to_this_unix()
+// path        the path of the unix socket
+// timeout     the timeout for establishing a connection
+
+static inline int connect_to_unix(const char *path, struct timeval *timeout) {
+    int fd = socket(AF_UNIX, SOCK_STREAM, 0);
+    if(fd == -1) {
+        error("Failed to create UNIX socket() for '%s'", path);
+        return -1;
+    }
+
+    if(timeout) {
+        if(setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, (char *) timeout, sizeof(struct timeval)) < 0)
+            error("Failed to set timeout on UNIX socket '%s'", path);
+    }
+
+    struct sockaddr_un addr;
+    memset(&addr, 0, sizeof(addr));
+    addr.sun_family = AF_UNIX;
+    strncpy(addr.sun_path, path, sizeof(addr.sun_path)-1);
+
+    if (connect(fd, (struct sockaddr*)&addr, sizeof(addr)) == -1) {
+        error("Cannot connect to UNIX socket on path '%s'.", path);
+        close(fd);
+        return -1;
+    }
+
+    debug(D_CONNECT_TO, "Connected to UNIX socket on path '%s'.", path);
+
+    return fd;
+}
+
+// connect_to_this_ip46()
+// protocol    IPPROTO_TCP, IPPROTO_UDP
+// socktype    SOCK_STREAM, SOCK_DGRAM
+// host        the destination hostname or IP address (IPv4 or IPv6) to connect to
+//             if it resolves to many IPs, all are tried (IPv4 and IPv6)
+// scope_id    the if_index id of the interface to use for connecting (0 = any)
+//             (used only under IPv6)
+// service     the service name or port to connect to
+// timeout     the timeout for establishing a connection
+
+static inline int connect_to_this_ip46(int protocol, int socktype, const char *host, uint32_t scope_id, const char *service, struct timeval *timeout) {
+    struct addrinfo hints;
+    struct addrinfo *ai_head = NULL, *ai = NULL;
+
+    memset(&hints, 0, sizeof(hints));
+    hints.ai_family   = PF_UNSPEC;   /* Allow IPv4 or IPv6 */
+    hints.ai_socktype = socktype;
+    hints.ai_protocol = protocol;
+
+    int ai_err = getaddrinfo(host, service, &hints, &ai_head);
+    if (ai_err != 0) {
+        error("Cannot resolve host '%s', port '%s': %s", host, service, gai_strerror(ai_err));
+        return -1;
+    }
+
+    int fd = -1;
+    for (ai = ai_head; ai != NULL && fd == -1; ai = ai->ai_next) {
+
+        if (ai->ai_family == PF_INET6) {
+            struct sockaddr_in6 *pSadrIn6 = (struct sockaddr_in6 *) ai->ai_addr;
+            if(pSadrIn6->sin6_scope_id == 0) {
+                pSadrIn6->sin6_scope_id = scope_id;
+            }
+        }
+
+        char hostBfr[NI_MAXHOST + 1];
+        char servBfr[NI_MAXSERV + 1];
+
+        getnameinfo(ai->ai_addr,
+                    ai->ai_addrlen,
+                    hostBfr,
+                    sizeof(hostBfr),
+                    servBfr,
+                    sizeof(servBfr),
+                    NI_NUMERICHOST | NI_NUMERICSERV);
+
+        debug(D_CONNECT_TO, "Address info: host = '%s', service = '%s', ai_flags = 0x%02X, ai_family = %d (PF_INET = %d, PF_INET6 = %d), ai_socktype = %d (SOCK_STREAM = %d, SOCK_DGRAM = %d), ai_protocol = %d (IPPROTO_TCP = %d, IPPROTO_UDP = %d), ai_addrlen = %lu (sockaddr_in = %lu, sockaddr_in6 = %lu)",
+              hostBfr,
+              servBfr,
+              (unsigned int)ai->ai_flags,
+              ai->ai_family,
+              PF_INET,
+              PF_INET6,
+              ai->ai_socktype,
+              SOCK_STREAM,
+              SOCK_DGRAM,
+              ai->ai_protocol,
+              IPPROTO_TCP,
+              IPPROTO_UDP,
+              (unsigned long)ai->ai_addrlen,
+              (unsigned long)sizeof(struct sockaddr_in),
+              (unsigned long)sizeof(struct sockaddr_in6));
+
+        switch (ai->ai_addr->sa_family) {
+            case PF_INET: {
+                struct sockaddr_in *pSadrIn = (struct sockaddr_in *)ai->ai_addr;
+                (void)pSadrIn;
+
+                debug(D_CONNECT_TO, "ai_addr = sin_family: %d (AF_INET = %d, AF_INET6 = %d), sin_addr: '%s', sin_port: '%s'",
+                      pSadrIn->sin_family,
+                      AF_INET,
+                      AF_INET6,
+                      hostBfr,
+                      servBfr);
+                break;
+            }
+
+            case PF_INET6: {
+                struct sockaddr_in6 *pSadrIn6 = (struct sockaddr_in6 *) ai->ai_addr;
+                (void)pSadrIn6;
+
+                debug(D_CONNECT_TO,"ai_addr = sin6_family: %d (AF_INET = %d, AF_INET6 = %d), sin6_addr: '%s', sin6_port: '%s', sin6_flowinfo: %u, sin6_scope_id: %u",
+                      pSadrIn6->sin6_family,
+                      AF_INET,
+                      AF_INET6,
+                      hostBfr,
+                      servBfr,
+                      pSadrIn6->sin6_flowinfo,
+                      pSadrIn6->sin6_scope_id);
+                break;
+            }
+
+            default: {
+                debug(D_CONNECT_TO, "Unknown protocol family %d.", ai->ai_family);
+                continue;
+            }
+        }
+
+        fd = socket(ai->ai_family, ai->ai_socktype, ai->ai_protocol);
+        if(fd != -1) {
+            if(timeout) {
+                if(setsockopt(fd, SOL_SOCKET, SO_SNDTIMEO, (char *) timeout, sizeof(struct timeval)) < 0)
+                    error("Failed to set timeout on the socket to ip '%s' port '%s'", hostBfr, servBfr);
+            }
+
+            errno = 0;
+            if(connect(fd, ai->ai_addr, ai->ai_addrlen) < 0) {
+                if(errno == EALREADY || errno == EINPROGRESS) {
+                    info("Waiting for connection to ip %s port %s to be established", hostBfr, servBfr);
+
+                    fd_set fds;
+                    FD_ZERO(&fds);
+                    FD_SET(0, &fds);
+                    int rc = select (1, NULL, &fds, NULL, timeout);
+
+                    if(rc > 0 && FD_ISSET(fd, &fds)) {
+                        info("connect() to ip %s port %s completed successfully", hostBfr, servBfr);
+                    }
+                    else if(rc == -1) {
+                        error("Failed to connect to '%s', port '%s'. select() returned %d", hostBfr, servBfr, rc);
+                        close(fd);
+                        fd = -1;
+                    }
+                    else {
+                        error("Timed out while connecting to '%s', port '%s'. select() returned %d", hostBfr, servBfr, rc);
+                        close(fd);
+                        fd = -1;
+                    }
+                }
+                else {
+                    error("Failed to connect to '%s', port '%s'", hostBfr, servBfr);
+                    close(fd);
+                    fd = -1;
+                }
+            }
+
+            if(fd != -1)
+                debug(D_CONNECT_TO, "Connected to '%s' on port '%s'.", hostBfr, servBfr);
+        }
+    }
+
+    freeaddrinfo(ai_head);
+
+    return fd;
+}
+
+// connect_to_this()
+//
+// definition format:
+//
+//    [PROTOCOL:]IP[%INTERFACE][:PORT]
+//
+// PROTOCOL  = tcp or udp
+// IP        = IPv4 or IPv6 IP or hostname, optionally enclosed in [] (required for IPv6)
+// INTERFACE = for IPv6 only, the network interface to use
+// PORT      = port number or service name
+
+int connect_to_this(const char *definition, int default_port, struct timeval *timeout) {
+    char buffer[strlen(definition) + 1];
+    strcpy(buffer, definition);
+
+    char default_service[10 + 1];
+    snprintfz(default_service, 10, "%d", default_port);
+
+    char *host = buffer, *service = default_service, *interface = "";
+    int protocol = IPPROTO_TCP, socktype = SOCK_STREAM;
+    uint32_t scope_id = 0;
+
+    if(strncmp(host, "tcp:", 4) == 0) {
+        host += 4;
+        protocol = IPPROTO_TCP;
+        socktype = SOCK_STREAM;
+    }
+    else if(strncmp(host, "udp:", 4) == 0) {
+        host += 4;
+        protocol = IPPROTO_UDP;
+        socktype = SOCK_DGRAM;
+    }
+    else if(strncmp(host, "unix:", 5) == 0) {
+        char *path = host + 5;
+        return connect_to_unix(path, timeout);
+    }
+
+    char *e = host;
+    if(*e == '[') {
+        e = ++host;
+        while(*e && *e != ']') e++;
+        if(*e == ']') {
+            *e = '\0';
+            e++;
+        }
+    }
+    else {
+        while(*e && *e != ':' && *e != '%') e++;
+    }
+
+    if(*e == '%') {
+        *e = '\0';
+        e++;
+        interface = e;
+        while(*e && *e != ':') e++;
+    }
+
+    if(*e == ':') {
+        *e = '\0';
+        e++;
+        service = e;
+    }
+
+    debug(D_CONNECT_TO, "Attempting connection to host = '%s', service = '%s', interface = '%s', protocol = %d (tcp = %d, udp = %d)", host, service, interface, protocol, IPPROTO_TCP, IPPROTO_UDP);
+
+    if(!*host) {
+        error("Definition '%s' does not specify a host.", definition);
+        return -1;
+    }
+
+    if(*interface) {
+        scope_id = if_nametoindex(interface);
+        if(!scope_id)
+            error("Cannot find a network interface named '%s'. Continuing with limiting the network interface", interface);
+    }
+
+    if(!*service)
+        service = default_service;
+
+
+    return connect_to_this_ip46(protocol, socktype, host, scope_id, service, timeout);
+}
+
+int connect_to_one_of(const char *destination, int default_port, struct timeval *timeout, size_t *reconnects_counter, char *connected_to, size_t connected_to_size) {
+    int sock = -1;
+
+    const char *s = destination;
+    while(*s) {
+        const char *e = s;
+
+        // skip separators, moving both s(tart) and e(nd)
+        while(isspace(*e) || *e == ',') s = ++e;
+
+        // move e(nd) to the first separator
+        while(*e && !isspace(*e) && *e != ',') e++;
+
+        // is there anything?
+        if(!*s || s == e) break;
+
+        char buf[e - s + 1];
+        strncpyz(buf, s, e - s);
+        if(reconnects_counter) *reconnects_counter += 1;
+        sock = connect_to_this(buf, default_port, timeout);
+        if(sock != -1) {
+            if(connected_to && connected_to_size) {
+                strncpy(connected_to, buf, connected_to_size);
+                connected_to[connected_to_size - 1] = '\0';
+            }
+            break;
+        }
+        s = e;
+    }
+
+    return sock;
+}
+
+
+// --------------------------------------------------------------------------------------------------------------------
+// helpers to send/receive data in one call, in blocking mode, with a timeout
+
+ssize_t recv_timeout(int sockfd, void *buf, size_t len, int flags, int timeout) {
+    for(;;) {
+        struct pollfd fd = {
+                .fd = sockfd,
+                .events = POLLIN,
+                .revents = 0
+        };
+
+        errno = 0;
+        int retval = poll(&fd, 1, timeout * 1000);
+
+        if(retval == -1) {
+            // failed
+
+            if(errno == EINTR || errno == EAGAIN)
+                continue;
+
+            return -1;
+        }
+
+        if(!retval) {
+            // timeout
+            return 0;
+        }
+
+        if(fd.events & POLLIN) break;
+    }
+
+    return recv(sockfd, buf, len, flags);
+}
+
+ssize_t send_timeout(int sockfd, void *buf, size_t len, int flags, int timeout) {
+    for(;;) {
+        struct pollfd fd = {
+                .fd = sockfd,
+                .events = POLLOUT,
+                .revents = 0
+        };
+
+        errno = 0;
+        int retval = poll(&fd, 1, timeout * 1000);
+
+        if(retval == -1) {
+            // failed
+
+            if(errno == EINTR || errno == EAGAIN)
+                continue;
+
+            return -1;
+        }
+
+        if(!retval) {
+            // timeout
+            return 0;
+        }
+
+        if(fd.events & POLLOUT) break;
+    }
+
+    return send(sockfd, buf, len, flags);
+}
+
+
+// --------------------------------------------------------------------------------------------------------------------
+// accept4() replacement for systems that do not have one
+
+#ifndef HAVE_ACCEPT4
+int accept4(int sock, struct sockaddr *addr, socklen_t *addrlen, int flags) {
+    int fd = accept(sock, addr, addrlen);
+    int newflags = 0;
+
+    if (fd < 0) return fd;
+
+    if (flags & SOCK_NONBLOCK) {
+        newflags |= O_NONBLOCK;
+        flags &= ~SOCK_NONBLOCK;
+    }
+
+#ifdef SOCK_CLOEXEC
+#ifdef O_CLOEXEC
+    if (flags & SOCK_CLOEXEC) {
+        newflags |= O_CLOEXEC;
+        flags &= ~SOCK_CLOEXEC;
+    }
+#endif
+#endif
+
+    if (flags) {
+        close(fd);
+        errno = EINVAL;
+        return -1;
+    }
+
+    if (fcntl(fd, F_SETFL, newflags) < 0) {
+        int saved_errno = errno;
+        close(fd);
+        errno = saved_errno;
+        return -1;
+    }
+
+    return fd;
+}
+#endif
+
+
+// --------------------------------------------------------------------------------------------------------------------
+// accept_socket() - accept a socket and store client IP and port
+
+int accept_socket(int fd, int flags, char *client_ip, size_t ipsize, char *client_port, size_t portsize, SIMPLE_PATTERN *access_list) {
+    struct sockaddr_storage sadr;
+    socklen_t addrlen = sizeof(sadr);
+
+    int nfd = accept4(fd, (struct sockaddr *)&sadr, &addrlen, flags);
+    if (likely(nfd >= 0)) {
+        if (getnameinfo((struct sockaddr *)&sadr, addrlen, client_ip, (socklen_t)ipsize, client_port, (socklen_t)portsize, NI_NUMERICHOST | NI_NUMERICSERV) != 0) {
+            error("LISTENER: cannot getnameinfo() on received client connection.");
+            strncpyz(client_ip, "UNKNOWN", ipsize - 1);
+            strncpyz(client_port, "UNKNOWN", portsize - 1);
+        }
+
+        client_ip[ipsize - 1] = '\0';
+        client_port[portsize - 1] = '\0';
+
+        switch (((struct sockaddr *)&sadr)->sa_family) {
+            case AF_UNIX:
+                debug(D_LISTENER, "New UNIX domain web client from %s on socket %d.", client_ip, fd);
+                // set the port - certain versions of libc return garbage on unix sockets
+                strncpy(client_port, "UNIX", portsize);
+                client_port[portsize - 1] = '\0';
+                break;
+
+            case AF_INET:
+                debug(D_LISTENER, "New IPv4 web client from %s port %s on socket %d.", client_ip, client_port, fd);
+                break;
+
+            case AF_INET6:
+                if (strncmp(client_ip, "::ffff:", 7) == 0) {
+                    memmove(client_ip, &client_ip[7], strlen(&client_ip[7]) + 1);
+                    debug(D_LISTENER, "New IPv4 web client from %s port %s on socket %d.", client_ip, client_port, fd);
+                }
+                else
+                    debug(D_LISTENER, "New IPv6 web client from %s port %s on socket %d.", client_ip, client_port, fd);
+                break;
+
+            default:
+                debug(D_LISTENER, "New UNKNOWN web client from %s port %s on socket %d.", client_ip, client_port, fd);
+                break;
+        }
+
+        if(access_list) {
+            if(!strcmp(client_ip, "127.0.0.1") || !strcmp(client_ip, "::1")) {
+                strncpy(client_ip, "localhost", ipsize);
+                client_ip[ipsize - 1] = '\0';
+            }
+
+            if(unlikely(!simple_pattern_matches(access_list, client_ip))) {
+                errno = 0;
+                debug(D_LISTENER, "Permission denied for client '%s', port '%s'", client_ip, client_port);
+                error("DENIED ACCESS to client '%s'", client_ip);
+                close(nfd);
+                nfd = -1;
+                errno = EPERM;
+            }
+        }
+    }
+#ifdef HAVE_ACCEPT4
+    else if(errno == ENOSYS)
+        error("netdata has been compiled with the assumption that the system has the accept4() call, but it is not here. Recompile netdata like this: ./configure --disable-accept4 ...");
+#endif
+
+    return nfd;
+}
+
+
+// --------------------------------------------------------------------------------------------------------------------
+// poll() based listener
+// this should be the fastest possible listener for up to 100 sockets
+// above 100, an epoll() interface is needed on Linux
+
+#define POLL_FDS_INCREASE_STEP 10
+
+inline POLLINFO *poll_add_fd(POLLJOB *p
+                             , int fd
+                             , int socktype
+                             , WEB_CLIENT_ACL port_acl
+                             , uint32_t flags
+                             , const char *client_ip
+                             , const char *client_port
+                             , void *(*add_callback)(POLLINFO * /*pi*/, short int * /*events*/, void * /*data*/)
+                             , void  (*del_callback)(POLLINFO * /*pi*/)
+                             , int   (*rcv_callback)(POLLINFO * /*pi*/, short int * /*events*/)
+                             , int   (*snd_callback)(POLLINFO * /*pi*/, short int * /*events*/)
+                             , void *data
+) {
+    debug(D_POLLFD, "POLLFD: ADD: request to add fd %d, slots = %zu, used = %zu, min = %zu, max = %zu, next free = %zd", fd, p->slots, p->used, p->min, p->max, p->first_free?(ssize_t)p->first_free->slot:(ssize_t)-1);
+
+    if(unlikely(fd < 0)) return NULL;
+
+    //if(p->limit && p->used >= p->limit) {
+    //    info("Max sockets limit reached (%zu sockets), dropping connection", p->used);
+    //    close(fd);
+    //    return NULL;
+    //}
+
+    if(unlikely(!p->first_free)) {
+        size_t new_slots = p->slots + POLL_FDS_INCREASE_STEP;
+        debug(D_POLLFD, "POLLFD: ADD: increasing size (current = %zu, new = %zu, used = %zu, min = %zu, max = %zu)", p->slots, new_slots, p->used, p->min, p->max);
+
+        p->fds = reallocz(p->fds, sizeof(struct pollfd) * new_slots);
+        p->inf = reallocz(p->inf, sizeof(POLLINFO) * new_slots);
+
+        // reset all the newly added slots
+        ssize_t i;
+        for(i = new_slots - 1; i >= (ssize_t)p->slots ; i--) {
+            debug(D_POLLFD, "POLLFD: ADD: resetting new slot %zd", i);
+            p->fds[i].fd = -1;
+            p->fds[i].events = 0;
+            p->fds[i].revents = 0;
+
+            p->inf[i].p = p;
+            p->inf[i].slot = (size_t)i;
+            p->inf[i].flags = 0;
+            p->inf[i].socktype = -1;
+            p->inf[i].port_acl = -1;
+
+            p->inf[i].client_ip = NULL;
+            p->inf[i].client_port = NULL;
+            p->inf[i].del_callback = p->del_callback;
+            p->inf[i].rcv_callback = p->rcv_callback;
+            p->inf[i].snd_callback = p->snd_callback;
+            p->inf[i].data = NULL;
+
+            // link them so that the first free will be earlier in the array
+            // (we loop decrementing i)
+            p->inf[i].next = p->first_free;
+            p->first_free = &p->inf[i];
+        }
+
+        p->slots = new_slots;
+    }
+
+    POLLINFO *pi = p->first_free;
+    p->first_free = p->first_free->next;
+
+    debug(D_POLLFD, "POLLFD: ADD: selected slot %zu, next free is %zd", pi->slot, p->first_free?(ssize_t)p->first_free->slot:(ssize_t)-1);
+
+    struct pollfd *pf = &p->fds[pi->slot];
+    pf->fd = fd;
+    pf->events = POLLIN;
+    pf->revents = 0;
+
+    pi->fd = fd;
+    pi->p = p;
+    pi->socktype = socktype;
+    pi->port_acl = port_acl;
+    pi->flags = flags;
+    pi->next = NULL;
+    pi->client_ip = strdupz(client_ip);
+    pi->client_port = strdupz(client_port);
+
+    pi->del_callback = del_callback;
+    pi->rcv_callback = rcv_callback;
+    pi->snd_callback = snd_callback;
+
+    pi->connected_t = now_boottime_sec();
+    pi->last_received_t = 0;
+    pi->last_sent_t = 0;
+    pi->last_sent_t = 0;
+    pi->recv_count = 0;
+    pi->send_count = 0;
+
+    netdata_thread_disable_cancelability();
+    p->used++;
+    if(unlikely(pi->slot > p->max))
+        p->max = pi->slot;
+
+    if(pi->flags & POLLINFO_FLAG_CLIENT_SOCKET) {
+        pi->data = add_callback(pi, &pf->events, data);
+    }
+
+    if(pi->flags & POLLINFO_FLAG_SERVER_SOCKET) {
+        p->min = pi->slot;
+    }
+    netdata_thread_enable_cancelability();
+
+    debug(D_POLLFD, "POLLFD: ADD: completed, slots = %zu, used = %zu, min = %zu, max = %zu, next free = %zd", p->slots, p->used, p->min, p->max, p->first_free?(ssize_t)p->first_free->slot:(ssize_t)-1);
+
+    return pi;
+}
+
+inline void poll_close_fd(POLLINFO *pi) {
+    POLLJOB *p = pi->p;
+
+    struct pollfd *pf = &p->fds[pi->slot];
+    debug(D_POLLFD, "POLLFD: DEL: request to clear slot %zu (fd %d), old next free was %zd", pi->slot, pf->fd, p->first_free?(ssize_t)p->first_free->slot:(ssize_t)-1);
+
+    if(unlikely(pf->fd == -1)) return;
+
+    netdata_thread_disable_cancelability();
+
+    if(pi->flags & POLLINFO_FLAG_CLIENT_SOCKET) {
+        pi->del_callback(pi);
+
+        if(likely(!(pi->flags & POLLINFO_FLAG_DONT_CLOSE))) {
+            if(close(pf->fd) == -1)
+                error("Failed to close() poll_events() socket %d", pf->fd);
+        }
+    }
+
+    pf->fd = -1;
+    pf->events = 0;
+    pf->revents = 0;
+
+    pi->fd = -1;
+    pi->socktype = -1;
+    pi->flags = 0;
+    pi->data = NULL;
+
+    pi->del_callback = NULL;
+    pi->rcv_callback = NULL;
+    pi->snd_callback = NULL;
+
+    freez(pi->client_ip);
+    pi->client_ip = NULL;
+
+    freez(pi->client_port);
+    pi->client_port = NULL;
+
+    pi->next = p->first_free;
+    p->first_free = pi;
+
+    p->used--;
+    if(unlikely(p->max == pi->slot)) {
+        p->max = p->min;
+        ssize_t i;
+        for(i = (ssize_t)pi->slot; i > (ssize_t)p->min ;i--) {
+            if (unlikely(p->fds[i].fd != -1)) {
+                p->max = (size_t)i;
+                break;
+            }
+        }
+    }
+    netdata_thread_enable_cancelability();
+
+    debug(D_POLLFD, "POLLFD: DEL: completed, slots = %zu, used = %zu, min = %zu, max = %zu, next free = %zd", p->slots, p->used, p->min, p->max, p->first_free?(ssize_t)p->first_free->slot:(ssize_t)-1);
+}
+
+void *poll_default_add_callback(POLLINFO *pi, short int *events, void *data) {
+    (void)pi;
+    (void)events;
+    (void)data;
+
+    // error("POLLFD: internal error: poll_default_add_callback() called");
+
+    return NULL;
+}
+
+void poll_default_del_callback(POLLINFO *pi) {
+    if(pi->data)
+        error("POLLFD: internal error: del_callback_default() called with data pointer - possible memory leak");
+}
+
+int poll_default_rcv_callback(POLLINFO *pi, short int *events) {
+    *events |= POLLIN;
+
+    char buffer[1024 + 1];
+
+    ssize_t rc;
+    do {
+        rc = recv(pi->fd, buffer, 1024, MSG_DONTWAIT);
+        if (rc < 0) {
+            // read failed
+            if (errno != EWOULDBLOCK && errno != EAGAIN) {
+                error("POLLFD: poll_default_rcv_callback(): recv() failed with %zd.", rc);
+                return -1;
+            }
+        } else if (rc) {
+            // data received
+            info("POLLFD: internal error: poll_default_rcv_callback() is discarding %zd bytes received on socket %d", rc, pi->fd);
+        }
+    } while (rc != -1);
+
+    return 0;
+}
+
+int poll_default_snd_callback(POLLINFO *pi, short int *events) {
+    *events &= ~POLLOUT;
+
+    info("POLLFD: internal error: poll_default_snd_callback(): nothing to send on socket %d", pi->fd);
+    return 0;
+}
+
+void poll_default_tmr_callback(void *timer_data) {
+    (void)timer_data;
+}
+
+static void poll_events_cleanup(void *data) {
+    POLLJOB *p = (POLLJOB *)data;
+
+    size_t i;
+    for(i = 0 ; i <= p->max ; i++) {
+        POLLINFO *pi = &p->inf[i];
+        poll_close_fd(pi);
+    }
+
+    freez(p->fds);
+    freez(p->inf);
+}
+
+static void poll_events_process(POLLJOB *p, POLLINFO *pi, struct pollfd *pf, short int revents, time_t now) {
+    short int events = pf->events;
+    int fd = pf->fd;
+    pf->revents = 0;
+    size_t i = pi->slot;
+
+    if(unlikely(fd == -1)) {
+        debug(D_POLLFD, "POLLFD: LISTENER: ignoring slot %zu, it does not have an fd", i);
+        return;
+    }
+
+    debug(D_POLLFD, "POLLFD: LISTENER: processing events for slot %zu (events = %d, revents = %d)", i, events, revents);
+
+    if(revents & POLLIN || revents & POLLPRI) {
+        // receiving data
+
+        pi->last_received_t = now;
+        pi->recv_count++;
+
+        if(likely(pi->flags & POLLINFO_FLAG_CLIENT_SOCKET)) {
+            // read data from client TCP socket
+            debug(D_POLLFD, "POLLFD: LISTENER: reading data from TCP client slot %zu (fd %d)", i, fd);
+
+            pf->events = 0;
+            if (pi->rcv_callback(pi, &pf->events) == -1) {
+                poll_close_fd(&p->inf[i]);
+                return;
+            }
+            pf = &p->fds[i];
+            pi = &p->inf[i];
+
+#ifdef NETDATA_INTERNAL_CHECKS
+            // this is common - it is used for web server file copies
+            if(unlikely(!(pf->events & (POLLIN|POLLOUT)))) {
+                error("POLLFD: LISTENER: after reading, client slot %zu (fd %d) from %s port %s was left without expecting input or output. ", i, fd, pi->client_ip?pi->client_ip:"<undefined-ip>", pi->client_port?pi->client_port:"<undefined-port>");
+                //poll_close_fd(pi);
+                //return;
+            }
+#endif
+        }
+        else if(likely(pi->flags & POLLINFO_FLAG_SERVER_SOCKET)) {
+            // new connection
+            // debug(D_POLLFD, "POLLFD: LISTENER: accepting connections from slot %zu (fd %d)", i, fd);
+
+            switch(pi->socktype) {
+                case SOCK_STREAM: {
+                    // a TCP socket
+                    // we accept the connection
+
+                    int nfd;
+                    do {
+                        char client_ip[NI_MAXHOST + 1];
+                        char client_port[NI_MAXSERV + 1];
+
+                        debug(D_POLLFD, "POLLFD: LISTENER: calling accept4() slot %zu (fd %d)", i, fd);
+                        nfd = accept_socket(fd, SOCK_NONBLOCK, client_ip, NI_MAXHOST + 1, client_port, NI_MAXSERV + 1, p->access_list);
+                        if (unlikely(nfd < 0)) {
+                            // accept failed
+
+                            debug(D_POLLFD, "POLLFD: LISTENER: accept4() slot %zu (fd %d) failed.", i, fd);
+
+                            if(unlikely(errno == EMFILE)) {
+                                error("POLLFD: LISTENER: too many open files - sleeping for 1ms - used by this thread %zu, max for this thread %zu", p->used, p->limit);
+                                usleep(1000); // 10ms
+                            }
+                            else if(unlikely(errno != EWOULDBLOCK && errno != EAGAIN))
+                                error("POLLFD: LISTENER: accept() failed.");
+
+                            break;
+                        }
+                        else {
+                            // accept ok
+                            // info("POLLFD: LISTENER: client '[%s]:%s' connected to '%s' on fd %d", client_ip, client_port, sockets->fds_names[i], nfd);
+                            poll_add_fd(p
+                                        , nfd
+                                        , SOCK_STREAM
+                                        , pi->port_acl
+                                        , POLLINFO_FLAG_CLIENT_SOCKET
+                                        , client_ip
+                                        , client_port
+                                        , p->add_callback
+                                        , p->del_callback
+                                        , p->rcv_callback
+                                        , p->snd_callback
+                                        , NULL
+                            );
+
+                            // it may have reallocated them, so refresh our pointers
+                            pf = &p->fds[i];
+                            pi = &p->inf[i];
+                        }
+                    } while (nfd >= 0 && (!p->limit || p->used < p->limit));
+                    break;
+                }
+
+                case SOCK_DGRAM: {
+                    // a UDP socket
+                    // we read data from the server socket
+
+                    debug(D_POLLFD, "POLLFD: LISTENER: reading data from UDP slot %zu (fd %d)", i, fd);
+
+                    // TODO: access_list is not applied to UDP
+                    // but checking the access list on every UDP packet will destroy
+                    // performance, especially for statsd.
+
+                    pf->events = 0;
+                    pi->rcv_callback(pi, &pf->events);
+                    break;
+                }
+
+                default: {
+                    error("POLLFD: LISTENER: Unknown socktype %d on slot %zu", pi->socktype, pi->slot);
+                    break;
+                }
+            }
+        }
+    }
+
+    if(unlikely(revents & POLLOUT)) {
+        // sending data
+        debug(D_POLLFD, "POLLFD: LISTENER: sending data to socket on slot %zu (fd %d)", i, fd);
+
+        pi->last_sent_t = now;
+        pi->send_count++;
+
+        pf->events = 0;
+        if (pi->snd_callback(pi, &pf->events) == -1) {
+            poll_close_fd(&p->inf[i]);
+            return;
+        }
+        pf = &p->fds[i];
+        pi = &p->inf[i];
+
+#ifdef NETDATA_INTERNAL_CHECKS
+        // this is common - it is used for streaming
+        if(unlikely(pi->flags & POLLINFO_FLAG_CLIENT_SOCKET && !(pf->events & (POLLIN|POLLOUT)))) {
+            error("POLLFD: LISTENER: after sending, client slot %zu (fd %d) from %s port %s was left without expecting input or output. ", i, fd, pi->client_ip?pi->client_ip:"<undefined-ip>", pi->client_port?pi->client_port:"<undefined-port>");
+            //poll_close_fd(pi);
+            //return;
+        }
+#endif
+    }
+
+    if(unlikely(revents & POLLERR)) {
+        error("POLLFD: LISTENER: processing POLLERR events for slot %zu fd %d (events = %d, revents = %d)", i, events, revents, fd);
+        pf->events = 0;
+        poll_close_fd(pi);
+        return;
+    }
+
+    if(unlikely(revents & POLLHUP)) {
+        error("POLLFD: LISTENER: processing POLLHUP events for slot %zu fd %d (events = %d, revents = %d)", i, events, revents, fd);
+        pf->events = 0;
+        poll_close_fd(pi);
+        return;
+    }
+
+    if(unlikely(revents & POLLNVAL)) {
+        error("POLLFD: LISTENER: processing POLLNVAL events for slot %zu fd %d (events = %d, revents = %d)", i, events, revents, fd);
+        pf->events = 0;
+        poll_close_fd(pi);
+        return;
+    }
+}
+
+void poll_events(LISTEN_SOCKETS *sockets
+        , void *(*add_callback)(POLLINFO * /*pi*/, short int * /*events*/, void * /*data*/)
+        , void  (*del_callback)(POLLINFO * /*pi*/)
+        , int   (*rcv_callback)(POLLINFO * /*pi*/, short int * /*events*/)
+        , int   (*snd_callback)(POLLINFO * /*pi*/, short int * /*events*/)
+        , void  (*tmr_callback)(void * /*timer_data*/)
+        , SIMPLE_PATTERN *access_list
+        , void *data
+        , time_t tcp_request_timeout_seconds
+        , time_t tcp_idle_timeout_seconds
+        , time_t timer_milliseconds
+        , void *timer_data
+        , size_t max_tcp_sockets
+) {
+    if(!sockets || !sockets->opened) {
+        error("POLLFD: internal error: no listening sockets are opened");
+        return;
+    }
+
+    if(timer_milliseconds <= 0) timer_milliseconds = 0;
+
+    int retval;
+
+    POLLJOB p = {
+            .slots = 0,
+            .used = 0,
+            .max = 0,
+            .limit = max_tcp_sockets,
+            .fds = NULL,
+            .inf = NULL,
+            .first_free = NULL,
+
+            .complete_request_timeout = tcp_request_timeout_seconds,
+            .idle_timeout = tcp_idle_timeout_seconds,
+            .checks_every = (tcp_idle_timeout_seconds / 3) + 1,
+
+            .access_list = access_list,
+
+            .timer_milliseconds = timer_milliseconds,
+            .timer_data = timer_data,
+
+            .add_callback = add_callback?add_callback:poll_default_add_callback,
+            .del_callback = del_callback?del_callback:poll_default_del_callback,
+            .rcv_callback = rcv_callback?rcv_callback:poll_default_rcv_callback,
+            .snd_callback = snd_callback?snd_callback:poll_default_snd_callback,
+            .tmr_callback = tmr_callback?tmr_callback:poll_default_tmr_callback
+    };
+
+    size_t i;
+    for(i = 0; i < sockets->opened ;i++) {
+
+        POLLINFO *pi = poll_add_fd(&p
+                                   , sockets->fds[i]
+                                   , sockets->fds_types[i]
+                                   , sockets->fds_acl_flags[i]
+                                   , POLLINFO_FLAG_SERVER_SOCKET
+                                   , (sockets->fds_names[i])?sockets->fds_names[i]:"UNKNOWN"
+                                   , ""
+                                   , p.add_callback
+                                   , p.del_callback
+                                   , p.rcv_callback
+                                   , p.snd_callback
+                                   , NULL
+        );
+
+        pi->data = data;
+        info("POLLFD: LISTENER: listening on '%s'", (sockets->fds_names[i])?sockets->fds_names[i]:"UNKNOWN");
+    }
+
+    int listen_sockets_active = 1;
+
+    int timeout_ms = 1000; // in milliseconds
+    time_t last_check = now_boottime_sec();
+
+    usec_t timer_usec = timer_milliseconds * USEC_PER_MS;
+    usec_t now_usec = 0, next_timer_usec = 0, last_timer_usec = 0;
+    (void)last_timer_usec;
+
+    if(unlikely(timer_usec)) {
+        now_usec = now_boottime_usec();
+        next_timer_usec = now_usec - (now_usec % timer_usec) + timer_usec;
+    }
+
+    netdata_thread_cleanup_push(poll_events_cleanup, &p);
+
+    while(!netdata_exit) {
+        if(unlikely(timer_usec)) {
+            now_usec = now_boottime_usec();
+
+            if(unlikely(timer_usec && now_usec >= next_timer_usec)) {
+                debug(D_POLLFD, "Calling timer callback after %zu usec", (size_t)(now_usec - last_timer_usec));
+                last_timer_usec = now_usec;
+                p.tmr_callback(p.timer_data);
+                now_usec = now_boottime_usec();
+                next_timer_usec = now_usec - (now_usec % timer_usec) + timer_usec;
+            }
+
+            usec_t dt_usec = next_timer_usec - now_usec;
+            if(dt_usec < 1000 * USEC_PER_MS)
+                timeout_ms = 1000;
+            else
+                timeout_ms = (int)(dt_usec / USEC_PER_MS);
+        }
+
+        // enable or disable the TCP listening sockets, based on the current number of sockets used and the limit set
+        if((listen_sockets_active && (p.limit && p.used >= p.limit)) || (!listen_sockets_active && (!p.limit || p.used < p.limit))) {
+            listen_sockets_active = !listen_sockets_active;
+            info("%s listening sockets (used TCP sockets %zu, max allowed for this worker %zu)", (listen_sockets_active)?"ENABLING":"DISABLING", p.used, p.limit);
+            for (i = 0; i <= p.max; i++) {
+                if(p.inf[i].flags & POLLINFO_FLAG_SERVER_SOCKET && p.inf[i].socktype == SOCK_STREAM) {
+                    p.fds[i].events = (short int) ((listen_sockets_active) ? POLLIN : 0);
+                }
+            }
+        }
+
+        debug(D_POLLFD, "POLLFD: LISTENER: Waiting on %zu sockets for %zu ms...", p.max + 1, (size_t)timeout_ms);
+        retval = poll(p.fds, p.max + 1, timeout_ms);
+        time_t now = now_boottime_sec();
+
+        if(unlikely(retval == -1)) {
+            error("POLLFD: LISTENER: poll() failed while waiting on %zu sockets.", p.max + 1);
+            break;
+        }
+        else if(unlikely(!retval)) {
+            debug(D_POLLFD, "POLLFD: LISTENER: poll() timeout.");
+        }
+        else {
+            for (i = 0; i <= p.max; i++) {
+                struct pollfd *pf     = &p.fds[i];
+                short int     revents = pf->revents;
+                if (unlikely(revents))
+                    poll_events_process(&p, &p.inf[i], pf, revents, now);
+            }
+        }
+
+        if(unlikely(p.checks_every > 0 && now - last_check > p.checks_every)) {
+            last_check = now;
+
+            // security checks
+            for(i = 0; i <= p.max; i++) {
+                POLLINFO *pi = &p.inf[i];
+
+                if(likely(pi->flags & POLLINFO_FLAG_CLIENT_SOCKET)) {
+                    if (unlikely(pi->send_count == 0 && p.complete_request_timeout > 0 && (now - pi->connected_t) >= p.complete_request_timeout)) {
+                        info("POLLFD: LISTENER: client slot %zu (fd %d) from %s port %s has not sent a complete request in %zu seconds - closing it. "
+                              , i
+                              , pi->fd
+                              , pi->client_ip ? pi->client_ip : "<undefined-ip>"
+                              , pi->client_port ? pi->client_port : "<undefined-port>"
+                              , (size_t) p.complete_request_timeout
+                        );
+                        poll_close_fd(pi);
+                    }
+                    else if(unlikely(pi->recv_count && p.idle_timeout > 0 && now - ((pi->last_received_t > pi->last_sent_t) ? pi->last_received_t : pi->last_sent_t) >= p.idle_timeout )) {
+                        info("POLLFD: LISTENER: client slot %zu (fd %d) from %s port %s is idle for more than %zu seconds - closing it. "
+                              , i
+                              , pi->fd
+                              , pi->client_ip ? pi->client_ip : "<undefined-ip>"
+                              , pi->client_port ? pi->client_port : "<undefined-port>"
+                              , (size_t) p.idle_timeout
+                        );
+                        poll_close_fd(pi);
+                    }
+                }
+            }
+        }
+    }
+
+    netdata_thread_cleanup_pop(1);
+    debug(D_POLLFD, "POLLFD: LISTENER: cleanup completed");
+}
diff --git a/libnetdata/socket/socket.h b/libnetdata/socket/socket.h
new file mode 100644
index 0000000..c69d489
--- /dev/null
+++ b/libnetdata/socket/socket.h
@@ -0,0 +1,188 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_SOCKET_H
+#define NETDATA_SOCKET_H
+
+#include "../libnetdata.h"
+
+#ifndef MAX_LISTEN_FDS
+#define MAX_LISTEN_FDS 50
+#endif
+
+typedef enum web_client_acl {
+    WEB_CLIENT_ACL_NONE        = 0,
+    WEB_CLIENT_ACL_NOCHECK     = 0,
+    WEB_CLIENT_ACL_DASHBOARD   = 1 << 0,
+    WEB_CLIENT_ACL_REGISTRY    = 1 << 1,
+    WEB_CLIENT_ACL_BADGE       = 1 << 2,
+    WEB_CLIENT_ACL_MGMT        = 1 << 3,
+    WEB_CLIENT_ACL_STREAMING   = 1 << 4,
+    WEB_CLIENT_ACL_NETDATACONF = 1 << 5
+} WEB_CLIENT_ACL;
+
+#define web_client_can_access_dashboard(w) ((w)->acl & WEB_CLIENT_ACL_DASHBOARD)
+#define web_client_can_access_registry(w) ((w)->acl & WEB_CLIENT_ACL_REGISTRY)
+#define web_client_can_access_badges(w) ((w)->acl & WEB_CLIENT_ACL_BADGE)
+#define web_client_can_access_mgmt(w) ((w)->acl & WEB_CLIENT_ACL_MGMT)
+#define web_client_can_access_stream(w) ((w)->acl & WEB_CLIENT_ACL_STREAMING)
+#define web_client_can_access_netdataconf(w) ((w)->acl & WEB_CLIENT_ACL_NETDATACONF)
+
+typedef struct listen_sockets {
+    struct config *config;              // the config file to use
+    const char *config_section;         // the netdata configuration section to read settings from
+    const char *default_bind_to;        // the default bind to configuration string
+    uint16_t default_port;              // the default port to use
+    int backlog;                        // the default listen backlog to use
+
+    size_t opened;                      // the number of sockets opened
+    size_t failed;                      // the number of sockets attempted to open, but failed
+    int fds[MAX_LISTEN_FDS];            // the open sockets
+    char *fds_names[MAX_LISTEN_FDS];    // descriptions for the open sockets
+    int fds_types[MAX_LISTEN_FDS];      // the socktype for the open sockets (SOCK_STREAM, SOCK_DGRAM)
+    int fds_families[MAX_LISTEN_FDS];   // the family of the open sockets (AF_UNIX, AF_INET, AF_INET6)
+    WEB_CLIENT_ACL fds_acl_flags[MAX_LISTEN_FDS];  // the acl to apply to the open sockets (dashboard, badges, streaming, netdata.conf, management)
+} LISTEN_SOCKETS;
+
+extern char *strdup_client_description(int family, const char *protocol, const char *ip, uint16_t port);
+
+extern int listen_sockets_setup(LISTEN_SOCKETS *sockets);
+extern void listen_sockets_close(LISTEN_SOCKETS *sockets);
+
+extern int connect_to_this(const char *definition, int default_port, struct timeval *timeout);
+extern int connect_to_one_of(const char *destination, int default_port, struct timeval *timeout, size_t *reconnects_counter, char *connected_to, size_t connected_to_size);
+
+extern ssize_t recv_timeout(int sockfd, void *buf, size_t len, int flags, int timeout);
+extern ssize_t send_timeout(int sockfd, void *buf, size_t len, int flags, int timeout);
+
+extern int sock_setnonblock(int fd);
+extern int sock_delnonblock(int fd);
+extern int sock_setreuse(int fd, int reuse);
+extern int sock_setreuse_port(int fd, int reuse);
+extern int sock_enlarge_in(int fd);
+extern int sock_enlarge_out(int fd);
+
+extern int accept_socket(int fd, int flags, char *client_ip, size_t ipsize, char *client_port, size_t portsize, SIMPLE_PATTERN *access_list);
+
+#ifndef HAVE_ACCEPT4
+extern int accept4(int sock, struct sockaddr *addr, socklen_t *addrlen, int flags);
+
+#ifndef SOCK_NONBLOCK
+#define SOCK_NONBLOCK 00004000
+#endif  /* #ifndef SOCK_NONBLOCK */
+
+#ifndef SOCK_CLOEXEC
+#define SOCK_CLOEXEC 02000000
+#endif /* #ifndef SOCK_CLOEXEC */
+
+#endif /* #ifndef HAVE_ACCEPT4 */
+
+
+// ----------------------------------------------------------------------------
+// poll() based listener
+
+#define POLLINFO_FLAG_SERVER_SOCKET 0x00000001
+#define POLLINFO_FLAG_CLIENT_SOCKET 0x00000002
+#define POLLINFO_FLAG_DONT_CLOSE    0x00000004
+
+typedef struct poll POLLJOB;
+
+typedef struct pollinfo {
+    POLLJOB *p;             // the parent
+    size_t slot;            // the slot id
+
+    int fd;                 // the file descriptor
+    int socktype;           // the client socket type
+    WEB_CLIENT_ACL port_acl; // the access lists permitted on this web server port (it's -1 for client sockets)
+    char *client_ip;        // the connected client IP
+    char *client_port;      // the connected client port
+
+    time_t connected_t;     // the time the socket connected
+    time_t last_received_t; // the time the socket last received data
+    time_t last_sent_t;     // the time the socket last sent data
+
+    size_t recv_count;      // the number of times the socket was ready for inbound traffic
+    size_t send_count;      // the number of times the socket was ready for outbound traffic
+
+    uint32_t flags;         // internal flags
+
+    // callbacks for this socket
+    void  (*del_callback)(struct pollinfo *pi);
+    int   (*rcv_callback)(struct pollinfo *pi, short int *events);
+    int   (*snd_callback)(struct pollinfo *pi, short int *events);
+
+    // the user data
+    void *data;
+
+    // linking of free pollinfo structures
+    // for quickly finding the next available
+    // this is like a stack, it grows and shrinks
+    // (with gaps - lower empty slots are preferred)
+    struct pollinfo *next;
+} POLLINFO;
+
+struct poll {
+    size_t slots;
+    size_t used;
+    size_t min;
+    size_t max;
+
+    size_t limit;
+
+    time_t complete_request_timeout;
+    time_t idle_timeout;
+    time_t checks_every;
+
+    time_t timer_milliseconds;
+    void *timer_data;
+
+    struct pollfd *fds;
+    struct pollinfo *inf;
+    struct pollinfo *first_free;
+
+    SIMPLE_PATTERN *access_list;
+
+    void *(*add_callback)(POLLINFO *pi, short int *events, void *data);
+    void  (*del_callback)(POLLINFO *pi);
+    int   (*rcv_callback)(POLLINFO *pi, short int *events);
+    int   (*snd_callback)(POLLINFO *pi, short int *events);
+    void  (*tmr_callback)(void *timer_data);
+};
+
+#define pollinfo_from_slot(p, slot) (&((p)->inf[(slot)]))
+
+extern int poll_default_snd_callback(POLLINFO *pi, short int *events);
+extern int poll_default_rcv_callback(POLLINFO *pi, short int *events);
+extern void poll_default_del_callback(POLLINFO *pi);
+extern void *poll_default_add_callback(POLLINFO *pi, short int *events, void *data);
+
+extern POLLINFO *poll_add_fd(POLLJOB *p
+                             , int fd
+                             , int socktype
+                             , WEB_CLIENT_ACL port_acl
+                             , uint32_t flags
+                             , const char *client_ip
+                             , const char *client_port
+                             , void *(*add_callback)(POLLINFO *pi, short int *events, void *data)
+                             , void  (*del_callback)(POLLINFO *pi)
+                             , int   (*rcv_callback)(POLLINFO *pi, short int *events)
+                             , int   (*snd_callback)(POLLINFO *pi, short int *events)
+                             , void *data
+);
+extern void poll_close_fd(POLLINFO *pi);
+
+extern void poll_events(LISTEN_SOCKETS *sockets
+        , void *(*add_callback)(POLLINFO *pi, short int *events, void *data)
+        , void  (*del_callback)(POLLINFO *pi)
+        , int   (*rcv_callback)(POLLINFO *pi, short int *events)
+        , int   (*snd_callback)(POLLINFO *pi, short int *events)
+        , void  (*tmr_callback)(void *timer_data)
+        , SIMPLE_PATTERN *access_list
+        , void *data
+        , time_t tcp_request_timeout_seconds
+        , time_t tcp_idle_timeout_seconds
+        , time_t timer_milliseconds
+        , void *timer_data
+        , size_t max_tcp_sockets
+);
+
+#endif //NETDATA_SOCKET_H
diff --git a/libnetdata/statistical/Makefile.am b/libnetdata/statistical/Makefile.am
new file mode 100644
index 0000000..1cb69ed
--- /dev/null
+++ b/libnetdata/statistical/Makefile.am
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
+
+
+dist_noinst_DATA = \
+	README.md \
+	$(NULL)
diff --git a/libnetdata/statistical/README.md b/libnetdata/statistical/README.md
new file mode 100644
index 0000000..184f82b
--- /dev/null
+++ b/libnetdata/statistical/README.md
@@ -0,0 +1,2 @@
+
+[![analytics](https://www.google-analytics.com/collect?v=1&aip=1&t=pageview&_s=1&ds=github&dr=https%3A%2F%2Fgithub.com%2Fnetdata%2Fnetdata&dl=https%3A%2F%2Fmy-netdata.io%2Fgithub%2Flibnetdata%2Fstatistical%2FREADME&_u=MAC~&cid=5792dfd7-8dc4-476b-af31-da2fdb9f93d2&tid=UA-64295674-3)]()
diff --git a/libnetdata/statistical/statistical.c b/libnetdata/statistical/statistical.c
new file mode 100644
index 0000000..15792fd
--- /dev/null
+++ b/libnetdata/statistical/statistical.c
@@ -0,0 +1,452 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../libnetdata.h"
+
+LONG_DOUBLE default_single_exponential_smoothing_alpha = 0.1;
+
+void log_series_to_stderr(LONG_DOUBLE *series, size_t entries, calculated_number result, const char *msg) {
+    const LONG_DOUBLE *value, *end = &series[entries];
+
+    fprintf(stderr, "%s of %zu entries [ ", msg, entries);
+    for(value = series; value < end ;value++) {
+        if(value != series) fprintf(stderr, ", ");
+        fprintf(stderr, "%" LONG_DOUBLE_MODIFIER, *value);
+    }
+    fprintf(stderr, " ] results in " CALCULATED_NUMBER_FORMAT "\n", result);
+}
+
+// --------------------------------------------------------------------------------------------------------------------
+
+inline LONG_DOUBLE sum_and_count(const LONG_DOUBLE *series, size_t entries, size_t *count) {
+    const LONG_DOUBLE *value, *end = &series[entries];
+    LONG_DOUBLE sum = 0;
+    size_t c = 0;
+
+    for(value = series; value < end ; value++) {
+        if(isnormal(*value)) {
+            sum += *value;
+            c++;
+        }
+    }
+
+    if(unlikely(!c)) sum = NAN;
+    if(likely(count)) *count = c;
+
+    return sum;
+}
+
+inline LONG_DOUBLE sum(const LONG_DOUBLE *series, size_t entries) {
+    return sum_and_count(series, entries, NULL);
+}
+
+inline LONG_DOUBLE average(const LONG_DOUBLE *series, size_t entries) {
+    size_t count = 0;
+    LONG_DOUBLE sum = sum_and_count(series, entries, &count);
+
+    if(unlikely(!count)) return NAN;
+    return sum / (LONG_DOUBLE)count;
+}
+
+// --------------------------------------------------------------------------------------------------------------------
+
+LONG_DOUBLE moving_average(const LONG_DOUBLE *series, size_t entries, size_t period) {
+    if(unlikely(period <= 0))
+        return 0.0;
+
+    size_t i, count;
+    LONG_DOUBLE sum = 0, avg = 0;
+    LONG_DOUBLE p[period];
+
+    for(count = 0; count < period ; count++)
+        p[count] = 0.0;
+
+    for(i = 0, count = 0; i < entries; i++) {
+        LONG_DOUBLE value = series[i];
+        if(unlikely(!isnormal(value))) continue;
+
+        if(unlikely(count < period)) {
+            sum += value;
+            avg = (count == period - 1) ? sum / (LONG_DOUBLE)period : 0;
+        }
+        else {
+            sum = sum - p[count % period] + value;
+            avg = sum / (LONG_DOUBLE)period;
+        }
+
+        p[count % period] = value;
+        count++;
+    }
+
+    return avg;
+}
+
+// --------------------------------------------------------------------------------------------------------------------
+
+static int qsort_compare(const void *a, const void *b) {
+    LONG_DOUBLE *p1 = (LONG_DOUBLE *)a, *p2 = (LONG_DOUBLE *)b;
+    LONG_DOUBLE n1 = *p1, n2 = *p2;
+
+    if(unlikely(isnan(n1) || isnan(n2))) {
+        if(isnan(n1) && !isnan(n2)) return -1;
+        if(!isnan(n1) && isnan(n2)) return 1;
+        return 0;
+    }
+    if(unlikely(isinf(n1) || isinf(n2))) {
+        if(!isinf(n1) && isinf(n2)) return -1;
+        if(isinf(n1) && !isinf(n2)) return 1;
+        return 0;
+    }
+
+    if(unlikely(n1 < n2)) return -1;
+    if(unlikely(n1 > n2)) return 1;
+    return 0;
+}
+
+inline void sort_series(LONG_DOUBLE *series, size_t entries) {
+    qsort(series, entries, sizeof(LONG_DOUBLE), qsort_compare);
+}
+
+inline LONG_DOUBLE *copy_series(const LONG_DOUBLE *series, size_t entries) {
+    LONG_DOUBLE *copy = mallocz(sizeof(LONG_DOUBLE) * entries);
+    memcpy(copy, series, sizeof(LONG_DOUBLE) * entries);
+    return copy;
+}
+
+LONG_DOUBLE median_on_sorted_series(const LONG_DOUBLE *series, size_t entries) {
+    if(unlikely(entries == 0)) return NAN;
+    if(unlikely(entries == 1)) return series[0];
+    if(unlikely(entries == 2)) return (series[0] + series[1]) / 2;
+
+    LONG_DOUBLE average;
+    if(entries % 2 == 0) {
+        size_t m = entries / 2;
+        average = (series[m] + series[m + 1]) / 2;
+    }
+    else {
+        average = series[entries / 2];
+    }
+
+    return average;
+}
+
+LONG_DOUBLE median(const LONG_DOUBLE *series, size_t entries) {
+    if(unlikely(entries == 0)) return NAN;
+    if(unlikely(entries == 1)) return series[0];
+
+    if(unlikely(entries == 2))
+        return (series[0] + series[1]) / 2;
+
+    LONG_DOUBLE *copy = copy_series(series, entries);
+    sort_series(copy, entries);
+
+    LONG_DOUBLE avg = median_on_sorted_series(copy, entries);
+
+    freez(copy);
+    return avg;
+}
+
+// --------------------------------------------------------------------------------------------------------------------
+
+LONG_DOUBLE moving_median(const LONG_DOUBLE *series, size_t entries, size_t period) {
+    if(entries <= period)
+        return median(series, entries);
+
+    LONG_DOUBLE *data = copy_series(series, entries);
+
+    size_t i;
+    for(i = period; i < entries; i++) {
+        data[i - period] = median(&series[i - period], period);
+    }
+
+    LONG_DOUBLE avg = median(data, entries - period);
+    freez(data);
+    return avg;
+}
+
+// --------------------------------------------------------------------------------------------------------------------
+
+// http://stackoverflow.com/a/15150143/4525767
+LONG_DOUBLE running_median_estimate(const LONG_DOUBLE *series, size_t entries) {
+    LONG_DOUBLE median = 0.0f;
+    LONG_DOUBLE average = 0.0f;
+    size_t i;
+
+    for(i = 0; i < entries ; i++) {
+        LONG_DOUBLE value = series[i];
+        if(unlikely(!isnormal(value))) continue;
+
+        average += ( value - average ) * 0.1f; // rough running average.
+        median += copysignl( average * 0.01, value - median );
+    }
+
+    return median;
+}
+
+// --------------------------------------------------------------------------------------------------------------------
+
+LONG_DOUBLE standard_deviation(const LONG_DOUBLE *series, size_t entries) {
+    if(unlikely(entries == 0)) return NAN;
+    if(unlikely(entries == 1)) return series[0];
+
+    const LONG_DOUBLE *value, *end = &series[entries];
+    size_t count;
+    LONG_DOUBLE sum;
+
+    for(count = 0, sum = 0, value = series ; value < end ;value++) {
+        if(likely(isnormal(*value))) {
+            count++;
+            sum += *value;
+        }
+    }
+
+    if(unlikely(count == 0)) return NAN;
+    if(unlikely(count == 1)) return sum;
+
+    LONG_DOUBLE average = sum / (LONG_DOUBLE)count;
+
+    for(count = 0, sum = 0, value = series ; value < end ;value++) {
+        if(isnormal(*value)) {
+            count++;
+            sum += powl(*value - average, 2);
+        }
+    }
+
+    if(unlikely(count == 0)) return NAN;
+    if(unlikely(count == 1)) return average;
+
+    LONG_DOUBLE variance = sum / (LONG_DOUBLE)(count); // remove -1 from count to have a population stddev
+    LONG_DOUBLE stddev = sqrtl(variance);
+    return stddev;
+}
+
+// --------------------------------------------------------------------------------------------------------------------
+
+LONG_DOUBLE single_exponential_smoothing(const LONG_DOUBLE *series, size_t entries, LONG_DOUBLE alpha) {
+    if(unlikely(entries == 0))
+        return NAN;
+
+    if(unlikely(isnan(alpha)))
+        alpha = default_single_exponential_smoothing_alpha;
+
+    const LONG_DOUBLE *value = series, *end = &series[entries];
+    LONG_DOUBLE level = (1.0 - alpha) * (*value);
+
+    for(value++ ; value < end; value++) {
+        if(likely(isnormal(*value)))
+            level = alpha * (*value) + (1.0 - alpha) * level;
+    }
+
+    return level;
+}
+
+LONG_DOUBLE single_exponential_smoothing_reverse(const LONG_DOUBLE *series, size_t entries, LONG_DOUBLE alpha) {
+    if(unlikely(entries == 0))
+        return NAN;
+
+    if(unlikely(isnan(alpha)))
+        alpha = default_single_exponential_smoothing_alpha;
+
+    const LONG_DOUBLE *value = &series[entries -1];
+    LONG_DOUBLE level = (1.0 - alpha) * (*value);
+
+    for(value++ ; value >= series; value--) {
+        if(likely(isnormal(*value)))
+            level = alpha * (*value) + (1.0 - alpha) * level;
+    }
+
+    return level;
+}
+
+// --------------------------------------------------------------------------------------------------------------------
+
+// http://grisha.org/blog/2016/02/16/triple-exponential-smoothing-forecasting-part-ii/
+LONG_DOUBLE double_exponential_smoothing(const LONG_DOUBLE *series, size_t entries, LONG_DOUBLE alpha, LONG_DOUBLE beta, LONG_DOUBLE *forecast) {
+    if(unlikely(entries == 0))
+        return NAN;
+
+    LONG_DOUBLE level, trend;
+
+    if(unlikely(isnan(alpha)))
+        alpha = 0.3;
+
+    if(unlikely(isnan(beta)))
+        beta = 0.05;
+
+    level = series[0];
+
+    if(likely(entries > 1))
+        trend = series[1] - series[0];
+    else
+        trend = 0;
+
+    const LONG_DOUBLE *value = series;
+    for(value++ ; value >= series; value--) {
+        if(likely(isnormal(*value))) {
+
+            LONG_DOUBLE last_level = level;
+            level = alpha * *value + (1.0 - alpha) * (level + trend);
+            trend = beta * (level - last_level) + (1.0 - beta) * trend;
+
+        }
+    }
+
+    if(forecast)
+        *forecast = level + trend;
+
+    return level;
+}
+
+// --------------------------------------------------------------------------------------------------------------------
+
+/*
+ * Based on th R implementation
+ *
+ * a: level component
+ * b: trend component
+ * s: seasonal component
+ *
+ * Additive:
+ *
+ *   Yhat[t+h] = a[t] + h * b[t] + s[t + 1 + (h - 1) mod p],
+ *   a[t] = α (Y[t] - s[t-p]) + (1-α) (a[t-1] + b[t-1])
+ *   b[t] = β (a[t] - a[t-1]) + (1-β) b[t-1]
+ *   s[t] = γ (Y[t] - a[t]) + (1-γ) s[t-p]
+ *
+ * Multiplicative:
+ *
+ *   Yhat[t+h] = (a[t] + h * b[t]) * s[t + 1 + (h - 1) mod p],
+ *   a[t] = α (Y[t] / s[t-p]) + (1-α) (a[t-1] + b[t-1])
+ *   b[t] = β (a[t] - a[t-1]) + (1-β) b[t-1]
+ *   s[t] = γ (Y[t] / a[t]) + (1-γ) s[t-p]
+ */
+static int __HoltWinters(
+        const LONG_DOUBLE *series,
+        int          entries,      // start_time + h
+
+        LONG_DOUBLE alpha,        // alpha parameter of Holt-Winters Filter.
+        LONG_DOUBLE beta,         // beta  parameter of Holt-Winters Filter. If set to 0, the function will do exponential smoothing.
+        LONG_DOUBLE gamma,        // gamma parameter used for the seasonal component. If set to 0, an non-seasonal model is fitted.
+
+        const int *seasonal,
+        const int *period,
+        const LONG_DOUBLE *a,      // Start value for level (a[0]).
+        const LONG_DOUBLE *b,      // Start value for trend (b[0]).
+        LONG_DOUBLE *s,            // Vector of start values for the seasonal component (s_1[0] ... s_p[0])
+
+        /* return values */
+        LONG_DOUBLE *SSE,          // The final sum of squared errors achieved in optimizing
+        LONG_DOUBLE *level,        // Estimated values for the level component (size entries - t + 2)
+        LONG_DOUBLE *trend,        // Estimated values for the trend component (size entries - t + 2)
+        LONG_DOUBLE *season        // Estimated values for the seasonal component (size entries - t + 2)
+)
+{
+    if(unlikely(entries < 4))
+        return 0;
+
+    int start_time = 2;
+
+    LONG_DOUBLE res = 0, xhat = 0, stmp = 0;
+    int i, i0, s0;
+
+    /* copy start values to the beginning of the vectors */
+    level[0] = *a;
+    if(beta > 0) trend[0] = *b;
+    if(gamma > 0) memcpy(season, s, *period * sizeof(LONG_DOUBLE));
+
+    for(i = start_time - 1; i < entries; i++) {
+        /* indices for period i */
+        i0 = i - start_time + 2;
+        s0 = i0 + *period - 1;
+
+        /* forecast *for* period i */
+        xhat = level[i0 - 1] + (beta > 0 ? trend[i0 - 1] : 0);
+        stmp = gamma > 0 ? season[s0 - *period] : (*seasonal != 1);
+        if (*seasonal == 1)
+            xhat += stmp;
+        else
+            xhat *= stmp;
+
+        /* Sum of Squared Errors */
+        res   = series[i] - xhat;
+        *SSE += res * res;
+
+        /* estimate of level *in* period i */
+        if (*seasonal == 1)
+            level[i0] = alpha       * (series[i] - stmp)
+                        + (1 - alpha) * (level[i0 - 1] + trend[i0 - 1]);
+        else
+            level[i0] = alpha       * (series[i] / stmp)
+                        + (1 - alpha) * (level[i0 - 1] + trend[i0 - 1]);
+
+        /* estimate of trend *in* period i */
+        if (beta > 0)
+            trend[i0] = beta        * (level[i0] - level[i0 - 1])
+                        + (1 - beta)  * trend[i0 - 1];
+
+        /* estimate of seasonal component *in* period i */
+        if (gamma > 0) {
+            if (*seasonal == 1)
+                season[s0] = gamma       * (series[i] - level[i0])
+                             + (1 - gamma) * stmp;
+            else
+                season[s0] = gamma       * (series[i] / level[i0])
+                             + (1 - gamma) * stmp;
+        }
+    }
+
+    return 1;
+}
+
+LONG_DOUBLE holtwinters(const LONG_DOUBLE *series, size_t entries, LONG_DOUBLE alpha, LONG_DOUBLE beta, LONG_DOUBLE gamma, LONG_DOUBLE *forecast) {
+    if(unlikely(isnan(alpha)))
+        alpha = 0.3;
+
+    if(unlikely(isnan(beta)))
+        beta = 0.05;
+
+    if(unlikely(isnan(gamma)))
+        gamma = 0;
+
+    int seasonal = 0;
+    int period = 0;
+    LONG_DOUBLE a0 = series[0];
+    LONG_DOUBLE b0 = 0;
+    LONG_DOUBLE s[] = {};
+
+    LONG_DOUBLE errors = 0.0;
+    size_t nb_computations = entries;
+    LONG_DOUBLE *estimated_level  = callocz(nb_computations, sizeof(LONG_DOUBLE));
+    LONG_DOUBLE *estimated_trend  = callocz(nb_computations, sizeof(LONG_DOUBLE));
+    LONG_DOUBLE *estimated_season = callocz(nb_computations, sizeof(LONG_DOUBLE));
+
+    int ret = __HoltWinters(
+            series,
+            (int)entries,
+            alpha,
+            beta,
+            gamma,
+            &seasonal,
+            &period,
+            &a0,
+            &b0,
+            s,
+            &errors,
+            estimated_level,
+            estimated_trend,
+            estimated_season
+    );
+
+    LONG_DOUBLE value = estimated_level[nb_computations - 1];
+
+    if(forecast)
+        *forecast = 0.0;
+
+    freez(estimated_level);
+    freez(estimated_trend);
+    freez(estimated_season);
+
+    if(!ret)
+        return 0.0;
+
+    return value;
+}
diff --git a/libnetdata/statistical/statistical.h b/libnetdata/statistical/statistical.h
new file mode 100644
index 0000000..586c6b3
--- /dev/null
+++ b/libnetdata/statistical/statistical.h
@@ -0,0 +1,30 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_STATISTICAL_H
+#define NETDATA_STATISTICAL_H 1
+
+#include "../libnetdata.h"
+
+#ifndef isnormal
+#define isnormal(x) (fpclassify(x) == FP_NORMAL)
+#endif
+
+extern void log_series_to_stderr(LONG_DOUBLE *series, size_t entries, calculated_number result, const char *msg);
+
+extern LONG_DOUBLE average(const LONG_DOUBLE *series, size_t entries);
+extern LONG_DOUBLE moving_average(const LONG_DOUBLE *series, size_t entries, size_t period);
+extern LONG_DOUBLE median(const LONG_DOUBLE *series, size_t entries);
+extern LONG_DOUBLE moving_median(const LONG_DOUBLE *series, size_t entries, size_t period);
+extern LONG_DOUBLE running_median_estimate(const LONG_DOUBLE *series, size_t entries);
+extern LONG_DOUBLE standard_deviation(const LONG_DOUBLE *series, size_t entries);
+extern LONG_DOUBLE single_exponential_smoothing(const LONG_DOUBLE *series, size_t entries, LONG_DOUBLE alpha);
+extern LONG_DOUBLE single_exponential_smoothing_reverse(const LONG_DOUBLE *series, size_t entries, LONG_DOUBLE alpha);
+extern LONG_DOUBLE double_exponential_smoothing(const LONG_DOUBLE *series, size_t entries, LONG_DOUBLE alpha, LONG_DOUBLE beta, LONG_DOUBLE *forecast);
+extern LONG_DOUBLE holtwinters(const LONG_DOUBLE *series, size_t entries, LONG_DOUBLE alpha, LONG_DOUBLE beta, LONG_DOUBLE gamma, LONG_DOUBLE *forecast);
+extern LONG_DOUBLE sum_and_count(const LONG_DOUBLE *series, size_t entries, size_t *count);
+extern LONG_DOUBLE sum(const LONG_DOUBLE *series, size_t entries);
+extern LONG_DOUBLE median_on_sorted_series(const LONG_DOUBLE *series, size_t entries);
+extern LONG_DOUBLE *copy_series(const LONG_DOUBLE *series, size_t entries);
+extern void sort_series(LONG_DOUBLE *series, size_t entries);
+
+#endif //NETDATA_STATISTICAL_H
diff --git a/libnetdata/storage_number/Makefile.am b/libnetdata/storage_number/Makefile.am
new file mode 100644
index 0000000..1cb69ed
--- /dev/null
+++ b/libnetdata/storage_number/Makefile.am
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
+
+
+dist_noinst_DATA = \
+	README.md \
+	$(NULL)
diff --git a/libnetdata/storage_number/README.md b/libnetdata/storage_number/README.md
new file mode 100644
index 0000000..5c2c0b0
--- /dev/null
+++ b/libnetdata/storage_number/README.md
@@ -0,0 +1,12 @@
+# netdata storage number
+
+Although `netdata` does all its calculations using `long double`, it stores all values using
+a **custom-made 32-bit number**.
+
+This custom-made number can store in 29 bits values from `-167772150000000.0` to  `167772150000000.0`
+with a precision of 0.00001 (yes, it's a floating point number, meaning that higher integer values
+have less decimal precision) and 3 bits for flags.
+
+This provides an extremely optimized memory footprint with just 0.0001% max accuracy loss.
+
+[![analytics](https://www.google-analytics.com/collect?v=1&aip=1&t=pageview&_s=1&ds=github&dr=https%3A%2F%2Fgithub.com%2Fnetdata%2Fnetdata&dl=https%3A%2F%2Fmy-netdata.io%2Fgithub%2Flibnetdata%2Fstorage_number%2FREADME&_u=MAC~&cid=5792dfd7-8dc4-476b-af31-da2fdb9f93d2&tid=UA-64295674-3)]()
diff --git a/libnetdata/storage_number/storage_number.c b/libnetdata/storage_number/storage_number.c
new file mode 100644
index 0000000..6825fa7
--- /dev/null
+++ b/libnetdata/storage_number/storage_number.c
@@ -0,0 +1,248 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../libnetdata.h"
+
+storage_number pack_storage_number(calculated_number value, uint32_t flags) {
+    // bit 32 = sign 0:positive, 1:negative
+    // bit 31 = 0:divide, 1:multiply
+    // bit 30, 29, 28 = (multiplier or divider) 0-7 (8 total)
+    // bit 27 SN_EXISTS_100
+    // bit 26 SN_EXISTS_RESET
+    // bit 25 SN_EXISTS
+    // bit 24 to bit 1 = the value
+
+    storage_number r = get_storage_number_flags(flags);
+    if(!value) return r;
+
+    int m = 0;
+    calculated_number n = value, factor = 10;
+
+    // if the value is negative
+    // add the sign bit and make it positive
+    if(n < 0) {
+        r += (1 << 31); // the sign bit 32
+        n = -n;
+    }
+
+    if(n / 10000000.0 > 0x00ffffff) {
+        factor = 100;
+        r |= SN_EXISTS_100;
+    }
+
+    // make its integer part fit in 0x00ffffff
+    // by dividing it by 10 up to 7 times
+    // and increasing the multiplier
+    while(m < 7 && n > (calculated_number)0x00ffffff) {
+        n /= factor;
+        m++;
+    }
+
+    if(m) {
+        // the value was too big and we divided it
+        // so we add a multiplier to unpack it
+        r += (1 << 30) + (m << 27); // the multiplier m
+
+        if(n > (calculated_number)0x00ffffff) {
+            #ifdef NETDATA_INTERNAL_CHECKS
+            error("Number " CALCULATED_NUMBER_FORMAT " is too big.", value);
+            #endif
+            r += 0x00ffffff;
+            return r;
+        }
+    }
+    else {
+        // 0x0019999e is the number that can be multiplied
+        // by 10 to give 0x00ffffff
+        // while the value is below 0x0019999e we can
+        // multiply it by 10, up to 7 times, increasing
+        // the multiplier
+        while(m < 7 && n < (calculated_number)0x0019999e) {
+            n *= 10;
+            m++;
+        }
+
+        // the value was small enough and we multiplied it
+        // so we add a divider to unpack it
+        r += (0 << 30) + (m << 27); // the divider m
+    }
+
+#ifdef STORAGE_WITH_MATH
+    // without this there are rounding problems
+    // example: 0.9 becomes 0.89
+    r += lrint((double) n);
+#else
+    r += (storage_number)n;
+#endif
+
+    return r;
+}
+
+calculated_number unpack_storage_number(storage_number value) {
+    if(!value) return 0;
+
+    int sign = 0, exp = 0;
+    int factor = 10;
+
+    // bit 32 = 0:positive, 1:negative
+    if(unlikely(value & (1 << 31)))
+        sign = 1;
+
+    // bit 31 = 0:divide, 1:multiply
+    if(unlikely(value & (1 << 30)))
+        exp = 1;
+
+    // bit 27 SN_EXISTS_100
+    if(unlikely(value & (1 << 26)))
+        factor = 100;
+
+    // bit 26 SN_EXISTS_RESET
+    // bit 25 SN_EXISTS
+
+    // bit 30, 29, 28 = (multiplier or divider) 0-7 (8 total)
+    int mul = (value & ((1<<29)|(1<<28)|(1<<27))) >> 27;
+
+    // bit 24 to bit 1 = the value, so remove all other bits
+    value ^= value & ((1<<31)|(1<<30)|(1<<29)|(1<<28)|(1<<27)|(1<<26)|(1<<25)|(1<<24));
+
+    calculated_number n = value;
+
+    // fprintf(stderr, "UNPACK: %08X, sign = %d, exp = %d, mul = %d, factor = %d, n = " CALCULATED_NUMBER_FORMAT "\n", value, sign, exp, mul, factor, n);
+
+    if(exp) {
+        for(; mul; mul--)
+            n *= factor;
+    }
+    else {
+        for( ; mul ; mul--)
+            n /= 10;
+    }
+
+    if(sign) n = -n;
+    return n;
+}
+
+/*
+int print_calculated_number(char *str, calculated_number value)
+{
+    char *wstr = str;
+
+    int sign = (value < 0) ? 1 : 0;
+    if(sign) value = -value;
+
+#ifdef STORAGE_WITH_MATH
+    // without llrintl() there are rounding problems
+    // for example 0.9 becomes 0.89
+    unsigned long long uvalue = (unsigned long long int) llrintl(value * (calculated_number)100000);
+#else
+    unsigned long long uvalue = value * (calculated_number)100000;
+#endif
+
+    wstr = print_number_llu_r_smart(str, uvalue);
+
+    // make sure we have 6 bytes at least
+    while((wstr - str) < 6) *wstr++ = '0';
+
+    // put the sign back
+    if(sign) *wstr++ = '-';
+
+    // reverse it
+    char *begin = str, *end = --wstr, aux;
+    while (end > begin) aux = *end, *end-- = *begin, *begin++ = aux;
+    // wstr--;
+    // strreverse(str, wstr);
+
+    // remove trailing zeros
+    int decimal = 5;
+    while(decimal > 0 && *wstr == '0') {
+        *wstr-- = '\0';
+        decimal--;
+    }
+
+    // terminate it, one position to the right
+    // to let space for a dot
+    wstr[2] = '\0';
+
+    // make space for the dot
+    int i;
+    for(i = 0; i < decimal ;i++) {
+        wstr[1] = wstr[0];
+        wstr--;
+    }
+
+    // put the dot
+    if(wstr[2] == '\0') { wstr[1] = '\0'; decimal--; }
+    else wstr[1] = '.';
+
+    // return the buffer length
+    return (int) ((wstr - str) + 2 + decimal );
+}
+*/
+
+int print_calculated_number(char *str, calculated_number value) {
+    // info("printing number " CALCULATED_NUMBER_FORMAT, value);
+    char integral_str[50], fractional_str[50];
+
+    char *wstr = str;
+
+    if(unlikely(value < 0)) {
+        *wstr++ = '-';
+        value = -value;
+    }
+
+    calculated_number integral, fractional;
+
+#ifdef STORAGE_WITH_MATH
+    fractional = calculated_number_modf(value, &integral) * 10000000.0;
+#else
+    fractional = ((unsigned long long)(value * 10000000ULL) % 10000000ULL);
+#endif
+
+    unsigned long long integral_int = (unsigned long long)integral;
+    unsigned long long fractional_int = (unsigned long long)calculated_number_llrint(fractional);
+    if(unlikely(fractional_int >= 10000000)) {
+        integral_int += 1;
+        fractional_int -= 10000000;
+    }
+
+    // info("integral " CALCULATED_NUMBER_FORMAT " (%llu), fractional " CALCULATED_NUMBER_FORMAT " (%llu)", integral, integral_int, fractional, fractional_int);
+
+    char *istre;
+    if(unlikely(integral_int == 0)) {
+        integral_str[0] = '0';
+        istre = &integral_str[1];
+    }
+    else
+        // convert the integral part to string (reversed)
+        istre = print_number_llu_r_smart(integral_str, integral_int);
+
+    // copy reversed the integral string
+    istre--;
+    while( istre >= integral_str ) *wstr++ = *istre--;
+
+    if(likely(fractional_int != 0)) {
+        // add a dot
+        *wstr++ = '.';
+
+        // convert the fractional part to string (reversed)
+        char *fstre = print_number_llu_r_smart(fractional_str, fractional_int);
+
+        // prepend zeros to reach 7 digits length
+        int decimal = 7;
+        int len = (int)(fstre - fractional_str);
+        while(len < decimal) {
+            *wstr++ = '0';
+            len++;
+        }
+
+        char *begin = fractional_str;
+        while(begin < fstre && *begin == '0') begin++;
+
+        // copy reversed the fractional string
+        fstre--;
+        while( fstre >= begin ) *wstr++ = *fstre--;
+    }
+
+    *wstr = '\0';
+    // info("printed number '%s'", str);
+    return (int)(wstr - str);
+}
diff --git a/libnetdata/storage_number/storage_number.h b/libnetdata/storage_number/storage_number.h
new file mode 100644
index 0000000..af7d29f
--- /dev/null
+++ b/libnetdata/storage_number/storage_number.h
@@ -0,0 +1,88 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_STORAGE_NUMBER_H
+#define NETDATA_STORAGE_NUMBER_H 1
+
+#include "../libnetdata.h"
+
+#ifdef NETDATA_WITHOUT_LONG_DOUBLE
+
+#define powl pow
+#define modfl modf
+#define llrintl llrint
+#define roundl round
+#define sqrtl sqrt
+#define copysignl copysign
+#define strtold strtod
+
+typedef double calculated_number;
+#define CALCULATED_NUMBER_FORMAT "%0.7f"
+#define CALCULATED_NUMBER_FORMAT_ZERO "%0.0f"
+#define CALCULATED_NUMBER_FORMAT_AUTO "%f"
+
+#define LONG_DOUBLE_MODIFIER "f"
+typedef double LONG_DOUBLE;
+
+#else // NETDATA_WITHOUT_LONG_DOUBLE
+
+typedef long double calculated_number;
+#define CALCULATED_NUMBER_FORMAT "%0.7Lf"
+#define CALCULATED_NUMBER_FORMAT_ZERO "%0.0Lf"
+#define CALCULATED_NUMBER_FORMAT_AUTO "%Lf"
+
+#define LONG_DOUBLE_MODIFIER "Lf"
+typedef long double LONG_DOUBLE;
+
+#endif // NETDATA_WITHOUT_LONG_DOUBLE
+
+//typedef long long calculated_number;
+//#define CALCULATED_NUMBER_FORMAT "%lld"
+
+typedef long long collected_number;
+#define COLLECTED_NUMBER_FORMAT "%lld"
+
+/*
+typedef long double collected_number;
+#define COLLECTED_NUMBER_FORMAT "%0.7Lf"
+*/
+
+#define calculated_number_modf(x, y) modfl(x, y)
+#define calculated_number_llrint(x) llrintl(x)
+#define calculated_number_round(x) roundl(x)
+#define calculated_number_fabs(x) fabsl(x)
+#define calculated_number_pow(x, y) powl(x, y)
+#define calculated_number_epsilon (calculated_number)0.0000001
+
+#define calculated_number_equal(a, b) (calculated_number_fabs((a) - (b)) < calculated_number_epsilon)
+
+typedef uint32_t storage_number;
+#define STORAGE_NUMBER_FORMAT "%u"
+
+#define SN_EXISTS           (1 << 24) // the value exists
+#define SN_EXISTS_RESET     (1 << 25) // the value has been overflown
+#define SN_EXISTS_100       (1 << 26) // very large value (multipler is 100 instead of 10)
+
+// extract the flags
+#define get_storage_number_flags(value) ((((storage_number)(value)) & (1 << 24)) | (((storage_number)(value)) & (1 << 25)) | (((storage_number)(value)) & (1 << 26)))
+#define SN_EMPTY_SLOT 0x00000000
+
+// checks
+#define does_storage_number_exist(value) ((get_storage_number_flags(value) != 0)?1:0)
+#define did_storage_number_reset(value)  ((get_storage_number_flags(value) == SN_EXISTS_RESET)?1:0)
+
+storage_number pack_storage_number(calculated_number value, uint32_t flags);
+calculated_number unpack_storage_number(storage_number value);
+
+int print_calculated_number(char *str, calculated_number value);
+
+//                                          sign       div/mul    <--- multiplier / divider --->     10/100       RESET      EXISTS     VALUE
+#define STORAGE_NUMBER_POSITIVE_MAX_RAW (storage_number)( (0 << 31) | (1 << 30) | (1 << 29) | (1 << 28) | (1<<27) | (1 << 26) | (0 << 25) | (1 << 24) | 0x00ffffff )
+#define STORAGE_NUMBER_POSITIVE_MIN_RAW (storage_number)( (0 << 31) | (0 << 30) | (1 << 29) | (1 << 28) | (1<<27) | (0 << 26) | (0 << 25) | (1 << 24) | 0x00000001 )
+#define STORAGE_NUMBER_NEGATIVE_MAX_RAW (storage_number)( (1 << 31) | (0 << 30) | (1 << 29) | (1 << 28) | (1<<27) | (0 << 26) | (0 << 25) | (1 << 24) | 0x00000001 )
+#define STORAGE_NUMBER_NEGATIVE_MIN_RAW (storage_number)( (1 << 31) | (1 << 30) | (1 << 29) | (1 << 28) | (1<<27) | (1 << 26) | (0 << 25) | (1 << 24) | 0x00ffffff )
+
+// accepted accuracy loss
+#define ACCURACY_LOSS_ACCEPTED_PERCENT 0.0001
+#define accuracy_loss(t1, t2) (((t1) == (t2) || (t1) == 0.0 || (t2) == 0.0) ? 0.0 : (100.0 - (((t1) > (t2)) ? ((t2) * 100.0 / (t1) ) : ((t1) * 100.0 / (t2)))))
+
+#endif /* NETDATA_STORAGE_NUMBER_H */
diff --git a/libnetdata/threads/Makefile.am b/libnetdata/threads/Makefile.am
new file mode 100644
index 0000000..1cb69ed
--- /dev/null
+++ b/libnetdata/threads/Makefile.am
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
+
+
+dist_noinst_DATA = \
+	README.md \
+	$(NULL)
diff --git a/libnetdata/threads/README.md b/libnetdata/threads/README.md
new file mode 100644
index 0000000..9f98ba1
--- /dev/null
+++ b/libnetdata/threads/README.md
@@ -0,0 +1,2 @@
+
+[![analytics](https://www.google-analytics.com/collect?v=1&aip=1&t=pageview&_s=1&ds=github&dr=https%3A%2F%2Fgithub.com%2Fnetdata%2Fnetdata&dl=https%3A%2F%2Fmy-netdata.io%2Fgithub%2Flibnetdata%2Fthreads%2FREADME&_u=MAC~&cid=5792dfd7-8dc4-476b-af31-da2fdb9f93d2&tid=UA-64295674-3)]()
diff --git a/libnetdata/threads/threads.c b/libnetdata/threads/threads.c
new file mode 100644
index 0000000..133d9a5
--- /dev/null
+++ b/libnetdata/threads/threads.c
@@ -0,0 +1,183 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../libnetdata.h"
+
+static size_t default_stacksize = 0, wanted_stacksize = 0;
+static pthread_attr_t *attr = NULL;
+
+// ----------------------------------------------------------------------------
+// per thread data
+
+typedef struct {
+    void *arg;
+    pthread_t *thread;
+    const char *tag;
+    void *(*start_routine) (void *);
+    NETDATA_THREAD_OPTIONS options;
+} NETDATA_THREAD;
+
+static __thread NETDATA_THREAD *netdata_thread = NULL;
+
+const char *netdata_thread_tag(void) {
+    return ((netdata_thread && netdata_thread->tag && *netdata_thread->tag)?netdata_thread->tag:"MAIN");
+}
+
+// ----------------------------------------------------------------------------
+// compatibility library functions
+
+pid_t gettid(void) {
+#ifdef __FreeBSD__
+
+    return (pid_t)pthread_getthreadid_np();
+
+#elif defined(__APPLE__)
+
+    #if (defined __MAC_OS_X_VERSION_MIN_REQUIRED && __MAC_OS_X_VERSION_MIN_REQUIRED >= 1060)
+        uint64_t curthreadid;
+        pthread_threadid_np(NULL, &curthreadid);
+        return (pid_t)curthreadid;
+    #else /* __MAC_OS_X_VERSION_MIN_REQUIRED */
+        return (pid_t)pthread_self;
+    #endif /* __MAC_OS_X_VERSION_MIN_REQUIRED */
+
+#else /* __APPLE__*/
+
+    return (pid_t)syscall(SYS_gettid);
+
+#endif /* __FreeBSD__, __APPLE__*/
+}
+
+// ----------------------------------------------------------------------------
+// early initialization
+
+size_t netdata_threads_init(void) {
+    int i;
+
+    // --------------------------------------------------------------------
+    // get the required stack size of the threads of netdata
+
+    attr = callocz(1, sizeof(pthread_attr_t));
+    i = pthread_attr_init(attr);
+    if(i != 0)
+        fatal("pthread_attr_init() failed with code %d.", i);
+
+    i = pthread_attr_getstacksize(attr, &default_stacksize);
+    if(i != 0)
+        fatal("pthread_attr_getstacksize() failed with code %d.", i);
+    else
+        debug(D_OPTIONS, "initial pthread stack size is %zu bytes", default_stacksize);
+
+    return default_stacksize;
+}
+
+// ----------------------------------------------------------------------------
+// late initialization
+
+void netdata_threads_init_after_fork(size_t stacksize) {
+    wanted_stacksize = stacksize;
+    int i;
+
+    // ------------------------------------------------------------------------
+    // set default pthread stack size
+
+    if(attr && default_stacksize < wanted_stacksize && wanted_stacksize > 0) {
+        i = pthread_attr_setstacksize(attr, wanted_stacksize);
+        if(i != 0)
+            fatal("pthread_attr_setstacksize() to %zu bytes, failed with code %d.", wanted_stacksize, i);
+        else
+            debug(D_SYSTEM, "Successfully set pthread stacksize to %zu bytes", wanted_stacksize);
+    }
+}
+
+
+// ----------------------------------------------------------------------------
+// netdata_thread_create
+
+static void thread_cleanup(void *ptr) {
+    if(netdata_thread != ptr) {
+        NETDATA_THREAD *info = (NETDATA_THREAD *)ptr;
+        error("THREADS: internal error - thread local variable does not match the one passed to this function. Expected thread '%s', passed thread '%s'", netdata_thread->tag, info->tag);
+    }
+
+    if(!(netdata_thread->options & NETDATA_THREAD_OPTION_DONT_LOG_CLEANUP))
+        info("thread with task id %d finished", gettid());
+
+    freez((void *)netdata_thread->tag);
+    netdata_thread->tag = NULL;
+
+    freez(netdata_thread);
+    netdata_thread = NULL;
+}
+
+static void *thread_start(void *ptr) {
+    netdata_thread = (NETDATA_THREAD *)ptr;
+
+    if(!(netdata_thread->options & NETDATA_THREAD_OPTION_DONT_LOG_STARTUP))
+        info("thread created with task id %d", gettid());
+
+    if(pthread_setcanceltype(PTHREAD_CANCEL_DEFERRED, NULL) != 0)
+        error("cannot set pthread cancel type to DEFERRED.");
+
+    if(pthread_setcancelstate(PTHREAD_CANCEL_ENABLE, NULL) != 0)
+        error("cannot set pthread cancel state to ENABLE.");
+
+    void *ret = NULL;
+    pthread_cleanup_push(thread_cleanup, ptr);
+            ret = netdata_thread->start_routine(netdata_thread->arg);
+    pthread_cleanup_pop(1);
+
+    return ret;
+}
+
+int netdata_thread_create(netdata_thread_t *thread, const char *tag, NETDATA_THREAD_OPTIONS options, void *(*start_routine) (void *), void *arg) {
+    NETDATA_THREAD *info = mallocz(sizeof(NETDATA_THREAD));
+    info->arg = arg;
+    info->thread = thread;
+    info->tag = strdupz(tag);
+    info->start_routine = start_routine;
+    info->options = options;
+
+    int ret = pthread_create(thread, attr, thread_start, info);
+    if(ret != 0)
+        error("failed to create new thread for %s. pthread_create() failed with code %d", tag, ret);
+
+    else {
+        if (!(options & NETDATA_THREAD_OPTION_JOINABLE)) {
+            int ret2 = pthread_detach(*thread);
+            if (ret2 != 0)
+                error("cannot request detach of newly created %s thread. pthread_detach() failed with code %d", tag, ret2);
+        }
+    }
+
+    return ret;
+}
+
+// ----------------------------------------------------------------------------
+// netdata_thread_cancel
+
+int netdata_thread_cancel(netdata_thread_t thread) {
+    int ret = pthread_cancel(thread);
+    if(ret != 0)
+        error("cannot cancel thread. pthread_cancel() failed with code %d.", ret);
+
+    return ret;
+}
+
+// ----------------------------------------------------------------------------
+// netdata_thread_join
+
+int netdata_thread_join(netdata_thread_t thread, void **retval) {
+    int ret = pthread_join(thread, retval);
+    if(ret != 0)
+        error("cannot join thread. pthread_join() failed with code %d.", ret);
+
+    return ret;
+}
+
+int netdata_thread_detach(pthread_t thread) {
+    int ret = pthread_detach(thread);
+    if(ret != 0)
+        error("cannot detach thread. pthread_detach() failed with code %d.", ret);
+
+    return ret;
+}
diff --git a/libnetdata/threads/threads.h b/libnetdata/threads/threads.h
new file mode 100644
index 0000000..eec6ad0
--- /dev/null
+++ b/libnetdata/threads/threads.h
@@ -0,0 +1,37 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_THREADS_H
+#define NETDATA_THREADS_H 1
+
+#include "../libnetdata.h"
+
+extern pid_t gettid(void);
+
+typedef enum {
+    NETDATA_THREAD_OPTION_DEFAULT          = 0 << 0,
+    NETDATA_THREAD_OPTION_JOINABLE         = 1 << 0,
+    NETDATA_THREAD_OPTION_DONT_LOG_STARTUP = 1 << 1,
+    NETDATA_THREAD_OPTION_DONT_LOG_CLEANUP = 1 << 2,
+    NETDATA_THREAD_OPTION_DONT_LOG         = NETDATA_THREAD_OPTION_DONT_LOG_STARTUP|NETDATA_THREAD_OPTION_DONT_LOG_CLEANUP,
+} NETDATA_THREAD_OPTIONS;
+
+#define netdata_thread_cleanup_push(func, arg) pthread_cleanup_push(func, arg)
+#define netdata_thread_cleanup_pop(execute) pthread_cleanup_pop(execute)
+
+typedef pthread_t netdata_thread_t;
+
+#define NETDATA_THREAD_TAG_MAX 100
+extern const char *netdata_thread_tag(void);
+
+extern size_t netdata_threads_init(void);
+extern void netdata_threads_init_after_fork(size_t stacksize);
+
+extern int netdata_thread_create(netdata_thread_t *thread, const char *tag, NETDATA_THREAD_OPTIONS options, void *(*start_routine) (void *), void *arg);
+extern int netdata_thread_cancel(netdata_thread_t thread);
+extern int netdata_thread_join(netdata_thread_t thread, void **retval);
+extern int netdata_thread_detach(pthread_t thread);
+
+#define netdata_thread_self pthread_self
+#define netdata_thread_testcancel pthread_testcancel
+
+#endif //NETDATA_THREADS_H
diff --git a/libnetdata/url/Makefile.am b/libnetdata/url/Makefile.am
new file mode 100644
index 0000000..1cb69ed
--- /dev/null
+++ b/libnetdata/url/Makefile.am
@@ -0,0 +1,9 @@
+# SPDX-License-Identifier: GPL-3.0-or-later
+
+AUTOMAKE_OPTIONS = subdir-objects
+MAINTAINERCLEANFILES = $(srcdir)/Makefile.in
+
+
+dist_noinst_DATA = \
+	README.md \
+	$(NULL)
diff --git a/libnetdata/url/README.md b/libnetdata/url/README.md
new file mode 100644
index 0000000..7562ffb
--- /dev/null
+++ b/libnetdata/url/README.md
@@ -0,0 +1,2 @@
+
+[![analytics](https://www.google-analytics.com/collect?v=1&aip=1&t=pageview&_s=1&ds=github&dr=https%3A%2F%2Fgithub.com%2Fnetdata%2Fnetdata&dl=https%3A%2F%2Fmy-netdata.io%2Fgithub%2Flibnetdata%2Furl%2FREADME&_u=MAC~&cid=5792dfd7-8dc4-476b-af31-da2fdb9f93d2&tid=UA-64295674-3)]()
diff --git a/libnetdata/url/url.c b/libnetdata/url/url.c
new file mode 100644
index 0000000..07a9f80
--- /dev/null
+++ b/libnetdata/url/url.c
@@ -0,0 +1,81 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#include "../libnetdata.h"
+
+// ----------------------------------------------------------------------------
+// URL encode / decode
+// code from: http://www.geekhideout.com/urlcode.shtml
+
+/* Converts a hex character to its integer value */
+char from_hex(char ch) {
+    return (char)(isdigit(ch) ? ch - '0' : tolower(ch) - 'a' + 10);
+}
+
+/* Converts an integer value to its hex character*/
+char to_hex(char code) {
+    static char hex[] = "0123456789abcdef";
+    return hex[code & 15];
+}
+
+/* Returns a url-encoded version of str */
+/* IMPORTANT: be sure to free() the returned string after use */
+char *url_encode(char *str) {
+    char *buf, *pbuf;
+
+    pbuf = buf = mallocz(strlen(str) * 3 + 1);
+
+    while (*str) {
+        if (isalnum(*str) || *str == '-' || *str == '_' || *str == '.' || *str == '~')
+            *pbuf++ = *str;
+
+        else if (*str == ' ')
+            *pbuf++ = '+';
+
+        else
+            *pbuf++ = '%', *pbuf++ = to_hex(*str >> 4), *pbuf++ = to_hex(*str & 15);
+
+        str++;
+    }
+    *pbuf = '\0';
+
+    pbuf = strdupz(buf);
+    freez(buf);
+    return pbuf;
+}
+
+/* Returns a url-decoded version of str */
+/* IMPORTANT: be sure to free() the returned string after use */
+char *url_decode(char *str) {
+    size_t size = strlen(str) + 1;
+
+    char *buf = mallocz(size);
+    return url_decode_r(buf, str, size);
+}
+
+char *url_decode_r(char *to, char *url, size_t size) {
+    char *s = url,           // source
+         *d = to,            // destination
+         *e = &to[size - 1]; // destination end
+
+    while(*s && d < e) {
+        if(unlikely(*s == '%')) {
+            if(likely(s[1] && s[2])) {
+                char t = from_hex(s[1]) << 4 | from_hex(s[2]);
+                // avoid HTTP header injection
+                *d++ = (char)((isprint(t))? t : ' ');
+                s += 2;
+            }
+        }
+        else if(unlikely(*s == '+'))
+            *d++ = ' ';
+
+        else
+            *d++ = *s;
+
+        s++;
+    }
+
+    *d = '\0';
+
+    return to;
+}
diff --git a/libnetdata/url/url.h b/libnetdata/url/url.h
new file mode 100644
index 0000000..6cef6d7
--- /dev/null
+++ b/libnetdata/url/url.h
@@ -0,0 +1,28 @@
+// SPDX-License-Identifier: GPL-3.0-or-later
+
+#ifndef NETDATA_URL_H
+#define NETDATA_URL_H 1
+
+#include "../libnetdata.h"
+
+// ----------------------------------------------------------------------------
+// URL encode / decode
+// code from: http://www.geekhideout.com/urlcode.shtml
+
+/* Converts a hex character to its integer value */
+extern char from_hex(char ch);
+
+/* Converts an integer value to its hex character*/
+extern char to_hex(char code);
+
+/* Returns a url-encoded version of str */
+/* IMPORTANT: be sure to free() the returned string after use */
+extern char *url_encode(char *str);
+
+/* Returns a url-decoded version of str */
+/* IMPORTANT: be sure to free() the returned string after use */
+extern char *url_decode(char *str);
+
+extern char *url_decode_r(char *to, char *url, size_t size);
+
+#endif /* NETDATA_URL_H */