modularized all source code (#4391)

* modularized all external plugins

* added README.md in plugins

* fixed title

* fixed typo

* relative link to external plugins

* external plugins configuration README

* added plugins link

* remove plugins link

* plugin names are links

* added links to external plugins

* removed unecessary spacing

* list to table

* added language

* fixed typo

* list to table on internal plugins

* added more documentation to internal plugins

* moved python, node, and bash code and configs into the external plugins

* added statsd README

* fix bug with corrupting config.h every 2nd compilation

* moved all config files together with their code

* more documentation

* diskspace info

* fixed broken links in apps.plugin

* added backends docs

* updated plugins readme

* move nc-backend.sh to backends

* created daemon directory

* moved all code outside src/

* fixed readme identation

* renamed plugins.d.plugin to plugins.d

* updated readme

* removed linux- from linux plugins

* updated readme

* updated readme

* updated readme

* updated readme

* updated readme

* updated readme

* fixed README.md links

* fixed netdata tree links

* updated codacy, codeclimate and lgtm excluded paths

* update CMakeLists.txt

* updated automake options at top directory

* libnetdata slit into directories

* updated READMEs

* updated READMEs

* updated ARL docs

* updated ARL docs

* moved /plugins to /collectors

* moved all external plugins outside plugins.d

* updated codacy, codeclimate, lgtm

* updated README

* updated url

* updated readme

* updated readme

* updated readme

* updated readme

* moved api and web into webserver

* web/api web/gui web/server

* modularized webserver

* removed web/gui/version.txt

4 files changed, 351 insertions, 0 deletions

diff --git a/libnetdata/dictionary/Makefile.am b/libnetdata/dictionary/Makefile.am
new file mode 100644
index 0000000000..1cb69ed99a
--- /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 0000000000..e69de29bb2
--- /dev/null
+++ b/libnetdata/dictionary/README.md
diff --git a/libnetdata/dictionary/dictionary.c b/libnetdata/dictionary/dictionary.c
new file mode 100644
index 0000000000..dd94a801dc
--- /dev/null
+++ b/libnetdata/dictionary/dictionary.c
@@ -0,0 +1,294 @@
+// 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;
+}
diff --git a/libnetdata/dictionary/dictionary.h b/libnetdata/dictionary/dictionary.h
new file mode 100644
index 0000000000..61b9bfc615
--- /dev/null
+++ b/libnetdata/dictionary/dictionary.h
@@ -0,0 +1,48 @@
+// 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);
+
+#endif /* NETDATA_DICTIONARY_H */