Database engine (#5282)

* Database engine prototype version 0

* Database engine initial integration with netdata POC

* Scalable database engine with file and memory management.

* Database engine integration with netdata

* Added MIN MAX definitions to fix alpine build of travis CI

* Bugfix for backends and new DB engine, remove useless rrdset_time2slot() calls and erroneous checks

* DB engine disk protocol correction

* Moved DB engine storage file location to /var/cache/netdata/{host}/dbengine

* Fix configure to require openSSL for DB engine

* Fix netdata daemon health not holding read lock when iterating chart dimensions

* Optimized query API for new DB engine and old netdata DB fallback code-path

* netdata database internal query API improvements and cleanup

* Bugfix for DB engine queries returning empty values

* Added netdata internal check for data queries for old and new DB

* Added statistics to DB engine and fixed memory corruption bug

* Added preliminary charts for DB engine statistics

* Changed DB engine ratio statistics to incremental

* Added netdata statistics charts for DB engine internal statistics

* Fix for netdata not compiling successfully when missing dbengine dependencies

* Added DB engine functional test to netdata unittest command parameter

* Implemented DB engine dataset generator based on example.random chart

* Fix build error in CI

* Support older versions of libuv1

* Fixes segmentation fault when using multiple DB engine instances concurrently

* Fix memory corruption bug

* Fixed createdataset advanced option not exiting

* Fix for DB engine not working on FreeBSD

* Support FreeBSD library paths of new dependencies

* Workaround for unsupported O_DIRECT in OS X

* Fix unittest crashing during cleanup

* Disable DB engine FS caching in Apple OS X since O_DIRECT is not available

* Fix segfault when unittest and DB engine dataset generator don't have permissions to create temporary host

* Modified DB engine dataset generator to create multiple files

* Toned down overzealous page cache prefetcher

* Reduce internal memory fragmentation for page-cache data pages

* Added documentation describing the DB engine

* Documentation bugfixes

* Fixed unit tests compilation errors since last rebase

* Added note to back-up the DB engine files in documentation

* Added codacy fix.

* Support old gcc versions for atomic counters in DB engine

1 files changed, 8 insertions, 1 deletions

diff --git a/database/rrd.c b/database/rrd.c
index 119efa62ea..2457cac011 100644
--- a/database/rrd.c
+++ b/database/rrd.c
@@ -38,6 +38,9 @@ inline const char *rrd_memory_mode_name(RRD_MEMORY_MODE id) {
 
         case RRD_MEMORY_MODE_ALLOC:
             return RRD_MEMORY_MODE_ALLOC_NAME;
+
+        case RRD_MEMORY_MODE_DBENGINE:
+            return RRD_MEMORY_MODE_DBENGINE_NAME;
     }
 
     return RRD_MEMORY_MODE_SAVE_NAME;
@@ -56,6 +59,9 @@ RRD_MEMORY_MODE rrd_memory_mode_id(const char *name) {
     else if(unlikely(!strcmp(name, RRD_MEMORY_MODE_ALLOC_NAME)))
         return RRD_MEMORY_MODE_ALLOC;
 
+    else if(unlikely(!strcmp(name, RRD_MEMORY_MODE_DBENGINE_NAME)))
+        return RRD_MEMORY_MODE_DBENGINE;
+
     return RRD_MEMORY_MODE_SAVE;
 }
 
@@ -140,7 +146,8 @@ char *rrdset_cache_dir(RRDHOST *host, const char *id, const char *config_section
     snprintfz(n, FILENAME_MAX, "%s/%s", host->cache_dir, b);
     ret = config_get(config_section, "cache directory", n);
 
-    if(host->rrd_memory_mode == RRD_MEMORY_MODE_MAP || host->rrd_memory_mode == RRD_MEMORY_MODE_SAVE) {
+    if(host->rrd_memory_mode == RRD_MEMORY_MODE_MAP || host->rrd_memory_mode == RRD_MEMORY_MODE_SAVE ||
+       host->rrd_memory_mode == RRD_MEMORY_MODE_DBENGINE) {
         int r = mkdir(ret, 0775);
         if(r != 0 && errno != EEXIST)
             error("Cannot create directory '%s'", ret);