Adding upstream version 1.37.0.upstream/1.37.0

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

1 files changed, 188 insertions, 117 deletions

diff --git a/libnetdata/dictionary/dictionary.h b/libnetdata/dictionary/dictionary.h
index fdb2088c0..0e7b3d39f 100644
--- a/libnetdata/dictionary/dictionary.h
+++ b/libnetdata/dictionary/dictionary.h
@@ -13,19 +13,19 @@
  * Names and Values in the dictionary can be cloned or linked.
  * In clone mode, the dictionary does all the memory management.
  * The default is clone for both names and values.
- * Set DICTIONARY_FLAG_NAME_LINK_DONT_CLONE to link names.
- * Set DICTIONARY_FLAG_VALUE_LINK_DONT_CLONE to link names.
+ * Set DICT_OPTION_NAME_LINK_DONT_CLONE to link names.
+ * Set DICT_OPTION_VALUE_LINK_DONT_CLONE to link names.
  *
  * ORDERED
  * Items are ordered in the order they are added (new items are appended at the end).
- * You may reverse the order by setting the flag DICTIONARY_FLAG_ADD_IN_FRONT.
+ * You may reverse the order by setting the flag DICT_OPTION_ADD_IN_FRONT.
  *
  * LOOKUP
  * The dictionary uses JudyHS to maintain a very fast randomly accessible hash table.
  *
  * MULTI-THREADED and SINGLE-THREADED
  * Each dictionary may be single threaded (no locks), or multi-threaded (multiple readers or one writer).
- * The default is multi-threaded. Add the flag DICTIONARY_FLAG_SINGLE_THREADED for single-threaded.
+ * The default is multi-threaded. Add the flag DICT_OPTION_SINGLE_THREADED for single-threaded.
  *
  * WALK-THROUGH and FOREACH traversal
  * The dictionary can be traversed on read or write mode, either with a callback (walkthrough) or with
@@ -35,110 +35,186 @@
  *
  */
 
+#ifdef DICTIONARY_INTERNALS
+#define DICTFE_CONST
+#define DICT_ITEM_CONST
+#else
+#define DICTFE_CONST const
+#define DICT_ITEM_CONST const
+#endif
+
 typedef struct dictionary DICTIONARY;
 typedef struct dictionary_item DICTIONARY_ITEM;
 
-typedef enum dictionary_flags {
-    DICTIONARY_FLAG_NONE                    = 0,        // the default is the opposite of all below
-    DICTIONARY_FLAG_SINGLE_THREADED         = (1 << 0), // don't use any locks (default: use locks)
-    DICTIONARY_FLAG_VALUE_LINK_DONT_CLONE   = (1 << 1), // don't copy the value, just point to the one provided (default: copy)
-    DICTIONARY_FLAG_NAME_LINK_DONT_CLONE    = (1 << 2), // don't copy the name, just point to the one provided (default: copy)
-    DICTIONARY_FLAG_DONT_OVERWRITE_VALUE    = (1 << 3), // don't overwrite values of dictionary items (default: overwrite)
-    DICTIONARY_FLAG_ADD_IN_FRONT            = (1 << 4), // add dictionary items at the front of the linked list (default: at the end)
-
-    // to change the value of the following, you also need to change the corresponding #defines in dictionary.c
-    DICTIONARY_FLAG_RESERVED1               = (1 << 29), // reserved for DICTIONARY_FLAG_EXCLUSIVE_ACCESS
-    DICTIONARY_FLAG_RESERVED2               = (1 << 30), // reserved for DICTIONARY_FLAG_DESTROYED
-    DICTIONARY_FLAG_RESERVED3               = (1 << 31), // reserved for DICTIONARY_FLAG_DEFER_ALL_DELETIONS
-} DICTIONARY_FLAGS;
+typedef enum dictionary_options {
+    DICT_OPTION_NONE                    = 0,        // the default is the opposite of all below
+    DICT_OPTION_SINGLE_THREADED         = (1 << 0), // don't use any locks (default: use locks)
+    DICT_OPTION_VALUE_LINK_DONT_CLONE   = (1 << 1), // don't copy the value, just point to the one provided (default: copy)
+    DICT_OPTION_NAME_LINK_DONT_CLONE    = (1 << 2), // don't copy the name, just point to the one provided (default: copy)
+    DICT_OPTION_DONT_OVERWRITE_VALUE    = (1 << 3), // don't overwrite values of dictionary items (default: overwrite)
+    DICT_OPTION_ADD_IN_FRONT            = (1 << 4), // add dictionary items at the front of the linked list (default: at the end)
+} DICT_OPTIONS;
+
+struct dictionary_stats {
+    const char *name;               // the name of the category
+
+    struct {
+        size_t active;              // the number of active dictionaries
+        size_t deleted;             // the number of dictionaries queued for destruction
+    } dictionaries;
+
+    struct {
+        long entries;               // active items in the dictionary
+        long pending_deletion;      // pending deletion items in the dictionary
+        long referenced;            // referenced items in the dictionary
+    } items;
+
+    struct {
+        size_t creations;           // dictionary creations
+        size_t destructions;        // dictionary destructions
+        size_t flushes;             // dictionary flushes
+        size_t traversals;          // dictionary foreach
+        size_t walkthroughs;        // dictionary walkthrough
+        size_t garbage_collections; // dictionary garbage collections
+        size_t searches;            // item searches
+        size_t inserts;             // item inserts
+        size_t resets;              // item resets
+        size_t deletes;             // item deletes
+    } ops;
+
+    struct {
+        size_t inserts;             // number of times the insert callback is called
+        size_t conflicts;           // number of times the conflict callback is called
+        size_t reacts;              // number of times the react callback is called
+        size_t deletes;             // number of times the delete callback is called
+    } callbacks;
+
+    // memory
+    struct {
+        long indexed;               // bytes of keys indexed (indication of the index size)
+        long values;                // bytes of caller structures
+        long dict;                  // bytes of the structures dictionary needs
+    } memory;
+
+    // spin locks
+    struct {
+        size_t use_spins;           // number of times a reference to item had to spin to acquire it or ignore it
+        size_t search_spins;        // number of times a successful search result had to be thrown away
+        size_t insert_spins;        // number of times an insertion to the hash table had to be repeated
+        size_t delete_spins;        // number of times a deletion had to spin to get a decision
+    } spin_locks;
+};
 
 // Create a dictionary
 #ifdef NETDATA_INTERNAL_CHECKS
-#define dictionary_create(flags) dictionary_create_advanced_with_trace(flags, 0, __FUNCTION__, __LINE__, __FILE__);
-#define dictionary_create_advanced(flags) dictionary_create_advanced_with_trace(flags, 0, __FUNCTION__, __LINE__, __FILE__);
-extern DICTIONARY *dictionary_create_advanced_with_trace(DICTIONARY_FLAGS flags, size_t scratchpad_size, const char *function, size_t line, const char *file);
+#define dictionary_create(options) dictionary_create_advanced_with_trace(options, NULL, __FUNCTION__, __LINE__, __FILE__)
+#define dictionary_create_advanced(options, stats) dictionary_create_advanced_with_trace(options, stats, __FUNCTION__, __LINE__, __FILE__)
+DICTIONARY *dictionary_create_advanced_with_trace(DICT_OPTIONS options, struct dictionary_stats *stats, const char *function, size_t line, const char *file);
 #else
-#define dictionary_create(flags) dictionary_create_advanced(flags, 0);
-extern DICTIONARY *dictionary_create_advanced(DICTIONARY_FLAGS flags, size_t scratchpad_size);
+#define dictionary_create(options) dictionary_create_advanced(options, NULL);
+DICTIONARY *dictionary_create_advanced(DICT_OPTIONS options, struct dictionary_stats *stats);
 #endif
 
-extern void *dictionary_scratchpad(DICTIONARY *dict);
+// Create a view on a dictionary
+#ifdef NETDATA_INTERNAL_CHECKS
+#define dictionary_create_view(master) dictionary_create_view_with_trace(master, __FUNCTION__, __LINE__, __FILE__)
+DICTIONARY *dictionary_create_view_with_trace(DICTIONARY *master, const char *function, size_t line, const char *file);
+#else
+DICTIONARY *dictionary_create_view(DICTIONARY *master);
+#endif
 
 // an insert callback to be called just after an item is added to the dictionary
 // this callback is called while the dictionary is write locked!
-extern void dictionary_register_insert_callback(DICTIONARY *dict, void (*ins_callback)(const char *name, void *value, void *data), void *data);
+void dictionary_register_insert_callback(DICTIONARY *dict, void (*ins_callback)(const DICTIONARY_ITEM *item, void *value, void *data), void *data);
 
 // a delete callback to be called just before an item is deleted forever
 // this callback is called while the dictionary is write locked!
-extern void dictionary_register_delete_callback(DICTIONARY *dict, void (*del_callback)(const char *name, void *value, void *data), void *data);
+void dictionary_register_delete_callback(DICTIONARY *dict, void (*del_callback)(const DICTIONARY_ITEM *item, void *value, void *data), void *data);
 
-// a merge callback to be called when DICTIONARY_FLAG_DONT_OVERWRITE_VALUE
+// a merge callback to be called when DICT_OPTION_DONT_OVERWRITE_VALUE
 // and an item is already found in the dictionary - the dictionary does nothing else in this case
 // the old_value will remain in the dictionary - the new_value is ignored
-extern void dictionary_register_conflict_callback(DICTIONARY *dict, void (*conflict_callback)(const char *name, void *old_value, void *new_value, void *data), void *data);
+// The callback should return true if the value has been updated (it increases the dictionary version).
+void dictionary_register_conflict_callback(DICTIONARY *dict, bool (*conflict_callback)(const DICTIONARY_ITEM *item, void *old_value, void *new_value, void *data), void *data);
 
 // a reaction callback to be called after every item insertion or conflict
 // after the constructors have finished and the items are fully available for use
 // and the dictionary is not write locked anymore
-extern void dictionary_register_react_callback(DICTIONARY *dict, void (*react_callback)(const char *name, void *value, void *data), void *data);
+void dictionary_register_react_callback(DICTIONARY *dict, void (*react_callback)(const DICTIONARY_ITEM *item, void *value, void *data), void *data);
 
 // Destroy a dictionary
-// returns the number of bytes freed
-// the returned value will not include name and value sizes if DICTIONARY_FLAG_WITH_STATISTICS is not set
-extern size_t dictionary_destroy(DICTIONARY *dict);
+// Returns the number of bytes freed
+// The returned value will not include name/key sizes
+// Registered delete callbacks will be run for each item in the dictionary.
+size_t dictionary_destroy(DICTIONARY *dict);
 
+// Empties a dictionary
+// Referenced items will survive, but are not offered anymore.
+// Registered delete callbacks will be run for each item in the dictionary.
+void dictionary_flush(DICTIONARY *dict);
+
+void dictionary_version_increment(DICTIONARY *dict);
+
+// ----------------------------------------------------------------------------
 // Set an item in the dictionary
+//
 // - if an item with the same name does not exist, create one
 // - if an item with the same name exists, then:
-//        a) if DICTIONARY_FLAG_DONT_OVERWRITE_VALUE is set, just return the existing value (ignore the new value)
+//        a) if DICT_OPTION_DONT_OVERWRITE_VALUE is set, just return the existing value (ignore the new value)
 //   else b) reset the value to the new value passed at the call
 //
-// When DICTIONARY_FLAG_VALUE_LINK_DONT_CLONE is set, the value is linked, otherwise it is copied
-// When DICTIONARY_FLAG_NAME_LINK_DONT_CLONE is set, the name is linked, otherwise it is copied
+// When DICT_OPTION_VALUE_LINK_DONT_CLONE is set, the value is linked, otherwise it is copied
+// When DICT_OPTION_NAME_LINK_DONT_CLONE is set, the name is linked, otherwise it is copied
 //
-// When neither DICTIONARY_FLAG_VALUE_LINK_DONT_CLONE nor DICTIONARY_FLAG_NAME_LINK_DONT_CLONE are set, all the
+// When neither DICT_OPTION_VALUE_LINK_DONT_CLONE nor DICT_OPTION_NAME_LINK_DONT_CLONE are set, all the
 // memory management for names and values is done by the dictionary.
 //
 // Passing NULL as value, the dictionary will callocz() the newly allocated value, otherwise it will copy it.
 // Passing 0 as value_len, the dictionary will set the value to NULL (no allocations for value will be made).
-extern void *dictionary_set(DICTIONARY *dict, const char *name, void *value, size_t value_len);
+#define dictionary_set(dict, name, value, value_len) dictionary_set_advanced(dict, name, -1, value, value_len, NULL)
+void *dictionary_set_advanced(DICTIONARY *dict, const char *name, ssize_t name_len, void *value, size_t value_len, void *constructor_data);
+
+#define dictionary_set_and_acquire_item(dict, name, value, value_len) dictionary_set_and_acquire_item_advanced(dict, name, -1, value, value_len, NULL)
+DICT_ITEM_CONST DICTIONARY_ITEM *dictionary_set_and_acquire_item_advanced(DICTIONARY *dict, const char *name, ssize_t name_len, void *value, size_t value_len, void *constructor_data);
 
+// set an item in a dictionary view
+#define dictionary_view_set_and_acquire_item(dict, name, master_item) dictionary_view_set_and_acquire_item_advanced(dict, name, -1, master_item)
+DICT_ITEM_CONST DICTIONARY_ITEM *dictionary_view_set_and_acquire_item_advanced(DICTIONARY *dict, const char *name, ssize_t name_len, DICTIONARY_ITEM *master_item);
+#define dictionary_view_set(dict, name, master_item) dictionary_view_set_advanced(dict, name, -1, master_item)
+void *dictionary_view_set_advanced(DICTIONARY *dict, const char *name, ssize_t name_len, DICT_ITEM_CONST DICTIONARY_ITEM *master_item);
+
+// ----------------------------------------------------------------------------
 // Get an item from the dictionary
 // If it returns NULL, the item is not found
-extern void *dictionary_get(DICTIONARY *dict, const char *name);
 
+#define dictionary_get(dict, name) dictionary_get_advanced(dict, name, -1)
+void *dictionary_get_advanced(DICTIONARY *dict, const char *name, ssize_t name_len);
+
+#define dictionary_get_and_acquire_item(dict, name) dictionary_get_and_acquire_item_advanced(dict, name, -1)
+DICT_ITEM_CONST DICTIONARY_ITEM *dictionary_get_and_acquire_item_advanced(DICTIONARY *dict, const char *name, ssize_t name_len);
+
+
+// ----------------------------------------------------------------------------
 // Delete an item from the dictionary
-// returns 0 if the item was found and has been deleted
-// returns -1 if the item was not found in the index
-extern int dictionary_del(DICTIONARY *dict, const char *name);
+// returns true if the item was found and has been deleted
+// returns false if the item was not found in the index
 
-extern DICTIONARY_ITEM *dictionary_get_and_acquire_item_unsafe(DICTIONARY *dict, const char *name);
-extern DICTIONARY_ITEM *dictionary_get_and_acquire_item(DICTIONARY *dict, const char *name);
+#define dictionary_del(dict, name) dictionary_del_advanced(dict, name, -1)
+bool dictionary_del_advanced(DICTIONARY *dict, const char *name, ssize_t name_len);
 
-extern DICTIONARY_ITEM *dictionary_set_and_acquire_item_unsafe(DICTIONARY *dict, const char *name, void *value, size_t value_len);
-extern DICTIONARY_ITEM *dictionary_set_and_acquire_item(DICTIONARY *dict, const char *name, void *value, size_t value_len);
+// ----------------------------------------------------------------------------
+// reference counters management
 
-extern void dictionary_acquired_item_release_unsafe(DICTIONARY *dict, DICTIONARY_ITEM *item);
-extern void dictionary_acquired_item_release(DICTIONARY *dict, DICTIONARY_ITEM *item);
+void dictionary_acquired_item_release(DICTIONARY *dict, DICT_ITEM_CONST DICTIONARY_ITEM *item);
 
-extern DICTIONARY_ITEM *dictionary_acquired_item_dup(DICTIONARY_ITEM *item);
-extern const char *dictionary_acquired_item_name(DICTIONARY_ITEM *item);
-extern void *dictionary_acquired_item_value(DICTIONARY_ITEM *item);
+DICT_ITEM_CONST DICTIONARY_ITEM *dictionary_acquired_item_dup(DICTIONARY *dict, DICT_ITEM_CONST DICTIONARY_ITEM *item);
 
-// UNSAFE functions, without locks
-// to be used when the user is traversing with the right lock type
-// Read lock is acquired by dictionary_walktrhough_read() and dfe_start_read()
-// Write lock is acquired by dictionary_walktrhough_write() and dfe_start_write()
-// For code readability, please use these macros:
-#define dictionary_get_having_read_lock(dict, name) dictionary_get_unsafe(dict, name)
-#define dictionary_get_having_write_lock(dict, name) dictionary_get_unsafe(dict, name)
-#define dictionary_set_having_write_lock(dict, name, value, value_len) dictionary_set_unsafe(dict, name, value, value_len)
-#define dictionary_del_having_write_lock(dict, name) dictionary_del_unsafe(dict, name)
+const char *dictionary_acquired_item_name(DICT_ITEM_CONST DICTIONARY_ITEM *item);
+void *dictionary_acquired_item_value(DICT_ITEM_CONST DICTIONARY_ITEM *item);
 
-extern void *dictionary_get_unsafe(DICTIONARY *dict, const char *name);
-extern void *dictionary_set_unsafe(DICTIONARY *dict, const char *name, void *value, size_t value_len);
-extern int dictionary_del_unsafe(DICTIONARY *dict, const char *name);
+size_t dictionary_acquired_item_references(DICT_ITEM_CONST DICTIONARY_ITEM *item);
 
+// ----------------------------------------------------------------------------
 // Traverse (walk through) the items of the dictionary.
 // The order of traversal is currently the order of insertion.
 //
@@ -153,12 +229,15 @@ extern int dictionary_del_unsafe(DICTIONARY *dict, const char *name);
 //
 #define dictionary_walkthrough_read(dict, callback, data) dictionary_walkthrough_rw(dict, 'r', callback, data)
 #define dictionary_walkthrough_write(dict, callback, data) dictionary_walkthrough_rw(dict, 'w', callback, data)
-extern int dictionary_walkthrough_rw(DICTIONARY *dict, char rw, int (*callback)(const char *name, void *value, void *data), void *data);
+int dictionary_walkthrough_rw(DICTIONARY *dict, char rw, int (*callback)(const DICTIONARY_ITEM *item, void *value, void *data), void *data);
 
-#define dictionary_sorted_walkthrough_read(dict, callback, data) dictionary_sorted_walkthrough_rw(dict, 'r', callback, data)
-#define dictionary_sorted_walkthrough_write(dict, callback, data) dictionary_sorted_walkthrough_rw(dict, 'w', callback, data)
-int dictionary_sorted_walkthrough_rw(DICTIONARY *dict, char rw, int (*callback)(const char *name, void *entry, void *data), void *data);
+typedef int (*dictionary_sorted_compar)(const DICTIONARY_ITEM **item1, const DICTIONARY_ITEM **item2);
 
+#define dictionary_sorted_walkthrough_read(dict, callback, data) dictionary_sorted_walkthrough_rw(dict, 'r', callback, data, NULL)
+#define dictionary_sorted_walkthrough_write(dict, callback, data) dictionary_sorted_walkthrough_rw(dict, 'w', callback, data, NULL)
+int dictionary_sorted_walkthrough_rw(DICTIONARY *dict, char rw, int (*callback)(const DICTIONARY_ITEM *item, void *entry, void *data), void *data, dictionary_sorted_compar compar);
+
+// ----------------------------------------------------------------------------
 // Traverse with foreach
 //
 // Use like this:
@@ -173,80 +252,72 @@ int dictionary_sorted_walkthrough_rw(DICTIONARY *dict, char rw, int (*callback)(
 // You can only delete the current item from inside a dfe_start_write() - you can add as many as you want.
 //
 
-#ifdef DICTIONARY_INTERNALS
-#define DICTFE_CONST
-#else
-#define DICTFE_CONST const
-#endif
+#define DICTIONARY_LOCK_READ      'r'
+#define DICTIONARY_LOCK_WRITE     'w'
+#define DICTIONARY_LOCK_REENTRANT 'z'
 
-#define DICTIONARY_LOCK_READ  'r'
-#define DICTIONARY_LOCK_WRITE 'w'
-#define DICTIONARY_LOCK_NONE  'u'
+void dictionary_write_lock(DICTIONARY *dict);
+void dictionary_write_unlock(DICTIONARY *dict);
 
 typedef DICTFE_CONST struct dictionary_foreach {
+    DICTIONARY *dict;           // the dictionary upon we work
+
+    DICTIONARY_ITEM *item;      // the item we work on, to remember the position we are at
+                                // this can be used with dictionary_acquired_item_dup() to
+                                // acquire the currently working item.
+
     DICTFE_CONST char *name;    // the dictionary name of the last item used
     void *value;                // the dictionary value of the last item used
                                 // same as the return value of dictfe_start() and dictfe_next()
 
-    // the following are for internal use only - to keep track of the point we are
+    size_t counter;             // counts the number of iterations made, starting from zero
+
     char rw;                    // the lock mode 'r' or 'w'
-    usec_t started_ut;          // the time the caller started iterating (now_realtime_usec())
-    DICTIONARY *dict;           // the dictionary upon we work
-    void *last_item;            // the item we work on, to remember the position we are at
 } DICTFE;
 
 #define dfe_start_read(dict, value) dfe_start_rw(dict, value, DICTIONARY_LOCK_READ)
 #define dfe_start_write(dict, value) dfe_start_rw(dict, value, DICTIONARY_LOCK_WRITE)
-#define dfe_start_rw(dict, value, mode) \
-        do { \
-            DICTFE value ## _dfe = {};  \
-            const char *value ## _name; (void)(value ## _name); (void)value; \
-            for((value) = dictionary_foreach_start_rw(&value ## _dfe, (dict), (mode)), ( value ## _name ) = value ## _dfe.name; \
-                (value ## _dfe.name) ;\
-                (value) = dictionary_foreach_next(&value ## _dfe), ( value ## _name ) = value ## _dfe.name) \
+#define dfe_start_reentrant(dict, value) dfe_start_rw(dict, value, DICTIONARY_LOCK_REENTRANT)
+
+#define dfe_start_rw(dict, value, mode)                                                             \
+        do {                                                                                        \
+            DICTFE value ## _dfe = {};                                                              \
+            (void)(value); /* needed to avoid warning when looping without using this */            \
+            for((value) = dictionary_foreach_start_rw(&value ## _dfe, (dict), (mode));              \
+                (value ## _dfe.item) ;                                                              \
+                (value) = dictionary_foreach_next(&value ## _dfe))                                  \
             {
 
-#define dfe_done(value) \
-            }           \
-            dictionary_foreach_done(&value ## _dfe); \
+#define dfe_done(value)                                                                             \
+            }                                                                                       \
+            dictionary_foreach_done(&value ## _dfe);                                                \
         } while(0)
 
-extern void * dictionary_foreach_start_rw(DICTFE *dfe, DICTIONARY *dict, char rw);
-extern void * dictionary_foreach_next(DICTFE *dfe);
-extern usec_t dictionary_foreach_done(DICTFE *dfe);
+void *dictionary_foreach_start_rw(DICTFE *dfe, DICTIONARY *dict, char rw);
+void *dictionary_foreach_next(DICTFE *dfe);
+void  dictionary_foreach_done(DICTFE *dfe);
 
+// ----------------------------------------------------------------------------
 // Get statistics about the dictionary
-extern long int dictionary_stats_allocated_memory(DICTIONARY *dict);
-extern long int dictionary_stats_entries(DICTIONARY *dict);
-extern size_t dictionary_stats_version(DICTIONARY *dict);
-extern size_t dictionary_stats_inserts(DICTIONARY *dict);
-extern size_t dictionary_stats_searches(DICTIONARY *dict);
-extern size_t dictionary_stats_deletes(DICTIONARY *dict);
-extern size_t dictionary_stats_resets(DICTIONARY *dict);
-extern size_t dictionary_stats_walkthroughs(DICTIONARY *dict);
-extern size_t dictionary_stats_referenced_items(DICTIONARY *dict);
-
-extern int dictionary_unittest(size_t entries);
 
-// ----------------------------------------------------------------------------
-// STRING implementation
+size_t dictionary_version(DICTIONARY *dict);
+size_t dictionary_entries(DICTIONARY *dict);
+size_t dictionary_referenced_items(DICTIONARY *dict);
+long int dictionary_stats_for_registry(DICTIONARY *dict);
 
-typedef struct netdata_string STRING;
-extern STRING *string_strdupz(const char *str);
-extern STRING *string_dup(STRING *string);
-extern void string_freez(STRING *string);
-extern size_t string_length(STRING *string);
-extern const char *string2str(STRING *string) NEVERNULL;
+// for all cases that the caller does not provide a stats structure, this is where they are accumulated.
+extern struct dictionary_stats dictionary_stats_category_other;
 
-// keep common prefix/suffix and replace everything else with [x]
-extern STRING *string_2way_merge(STRING *a, STRING *b);
+int dictionary_unittest(size_t entries);
+
+// ----------------------------------------------------------------------------
+// THREAD CACHE
 
-static inline int string_cmp(STRING *s1, STRING *s2) {
-    // STRINGs are deduplicated, so the same strings have the same pointer
-    if(unlikely(s1 == s2)) return 0;
+void *thread_cache_entry_get_or_set(void *key,
+                                    ssize_t key_length,
+                                    void *value,
+                                    void *(*transform_the_value_before_insert)(void *key, size_t key_length, void *value));
 
-    // they differ, do the typical comparison
-    return strcmp(string2str(s1), string2str(s2));
-}
+void thread_cache_destroy(void);
 
 #endif /* NETDATA_DICTIONARY_H */