Merging upstream version 1.11.0+dfsg.

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

5 files changed, 984 insertions, 0 deletions

diff --git a/libnetdata/adaptive_resortable_list/Makefile.am b/libnetdata/adaptive_resortable_list/Makefile.am
new file mode 100644
index 000000000..1cb69ed99
--- /dev/null
+++ b/libnetdata/adaptive_resortable_list/Makefile.am
@@ -0,0 +1,9 @@
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diff --git a/libnetdata/adaptive_resortable_list/Makefile.in b/libnetdata/adaptive_resortable_list/Makefile.in
new file mode 100644
index 000000000..229511083
--- /dev/null
+++ b/libnetdata/adaptive_resortable_list/Makefile.in
@@ -0,0 +1,464 @@
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diff --git a/libnetdata/adaptive_resortable_list/README.md b/libnetdata/adaptive_resortable_list/README.md
new file mode 100644
index 000000000..0ba3ec9b5
--- /dev/null
+++ b/libnetdata/adaptive_resortable_list/README.md
@@ -0,0 +1,93 @@
+
+# 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. 
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 000000000..7f4c6c53d
--- /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 000000000..011ee73d9
--- /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