fix default metrics collection after metrics.clear

CHANGELOG.md

@@ -5,6 +5,8 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
 ## [Unreleased]
+### Fixed
+- metrics.clear() disables default metrics
 
 ## [0.5.0] - 2020-09-18
 ### Added

metrics/utils.lua

@@ -1,22 +1,16 @@
 local metrics = require('metrics')
 
-local gauges_storage = {}
-
 local TNT_PREFIX = 'tnt_'
 
 local function prefix_name(name)
     return TNT_PREFIX .. name
 end
 
 local function set_gauge(name, description, value, labels)
-    if (gauges_storage[name] == nil) then
-        gauges_storage[name] = metrics.gauge(prefix_name(name), description)
-    end
-
-    gauges_storage[name]:set(value, labels or {})
+    local gauge = metrics.gauge(prefix_name(name), description)
+    gauge:set(value, labels or {})
 end
 
-
 local function box_is_configured()
     return type(box.cfg) ~= 'function'
 end
@@ -25,4 +19,4 @@ return {
     set_gauge = set_gauge,
     box_is_configured = box_is_configured,
     prefix_name = prefix_name,
-}
+}

test/default_metrics_test.lua

@@ -0,0 +1,34 @@
+#!/usr/bin/env tarantool
+
+require('strict').on()
+
+local t = require('luatest')
+local g = t.group('default_metrics')
+
+local metrics = require('metrics')
+
+g.before_all(function()
+    box.cfg{}
+    metrics.clear()
+end)
+
+g.after_each(function()
+    -- Delete all collectors and global labels
+    metrics.clear()
+end)
+
+g.test_default_metrics_clear = function()
+    metrics.clear()
+    metrics.enable_default_metrics()
+    t.assert_equals(#metrics.collect(), 0)
+
+    metrics.invoke_callbacks()
+    t.assert(#metrics.collect() > 0)
+
+    metrics.clear()
+    t.assert_equals(#metrics.collect(), 0)
+
+    metrics.enable_default_metrics()
+    metrics.invoke_callbacks()
+    t.assert(#metrics.collect() > 0)
+end