Alerting: Ticker to support stopping (#48142)

* add stop for ticker
* stop ticker when scheduler stops
* stop ticker when legacy engine stops

pkg/services/ngalert/CHANGELOG.md

@@ -59,6 +59,7 @@ Scopes must have an order to ensure consistency and ease of search, this helps u
 - [BUGFIX] RBAC: replace create\update\delete actions for notification policies by alert.notifications:write #49185
 - [BUGFIX] Fix access to alerts for Viewer role with editor permissions in folder #49270
 - [FEATURE] Alert rules with associated panels will take screenshots. #49293 #49338 #49374 #49377 #49378 #49379 #49381 #49385 #49439 #49445
+- [ENHANCEMENT] Scheduler: ticker to support stopping #48142
 
 ## 8.5.3
 
@@ -81,4 +82,3 @@ Scopes must have an order to ensure consistency and ease of search, this helps u
 - [BUGFIX] (Legacy) Templates: Parse notification templates using all the matches of the alert rule when going from `Alerting` to `OK` in legacy alerting #47355
 - [BUGFIX] Scheduler: Fix state manager to support OK option of `AlertRule.ExecErrState` #47670
 - [ENHANCEMENT] Templates: Enable the use of classic condition values in templates #46971
-

pkg/services/ngalert/schedule/schedule.go

@@ -156,6 +156,8 @@ func (sch *schedule) Run(ctx context.Context) error {
 	var wg sync.WaitGroup
 	wg.Add(2)
 
+	defer sch.ticker.Stop()
+
 	go func() {
 		defer wg.Done()
 		if err := sch.schedulePeriodic(ctx); err != nil {
@@ -652,6 +654,7 @@ func (sch *schedule) saveAlertStates(ctx context.Context, states []*state.State)
 func (sch *schedule) overrideCfg(cfg SchedulerCfg) {
 	sch.clock = cfg.C
 	sch.baseInterval = cfg.BaseInterval
+	sch.ticker.Stop()
 	sch.ticker = alerting.NewTicker(cfg.C, cfg.BaseInterval, cfg.Metrics.Ticker)
 	sch.evalAppliedFunc = cfg.EvalAppliedFunc
 	sch.stopAppliedFunc = cfg.StopAppliedFunc