Fixes timer resources leak in CountdownToGenesis (#7175)

* fixes timer leak in CountdownToGenesis
* Merge branch 'master' into fix-unclosed-timer-in-countdown
* Merge refs/heads/master into fix-unclosed-timer-in-countdown

shared/slotutil/BUILD.bazel

@@ -24,12 +24,14 @@ go_test(
         "countdown_test.go",
         "slotticker_test.go",
         "slottime_test.go",
+        "slotutil_test.go",
     ],
     embed = [":go_default_library"],
     deps = [
         "//shared/params:go_default_library",
         "//shared/roughtime:go_default_library",
         "//shared/testutil/require:go_default_library",
+        "@com_github_sirupsen_logrus//:go_default_library",
         "@com_github_sirupsen_logrus//hooks/test:go_default_library",
     ],
 )

shared/slotutil/countdown.go

@@ -18,33 +18,38 @@ var log = logrus.WithField("prefix", "slotutil")
 // of genesis validators.
 func CountdownToGenesis(ctx context.Context, genesisTime time.Time, genesisValidatorCount uint64) {
 	ticker := time.NewTicker(params.BeaconConfig().GenesisCountdownInterval)
-	timeTillGenesis := genesisTime.Sub(roughtime.Now())
+	defer func() {
+		// Used in anonymous function to make sure that updated (per second) ticker is stopped.
+		ticker.Stop()
+	}()
 	logFields := logrus.Fields{
 		"genesisValidators": fmt.Sprintf("%d", genesisValidatorCount),
 		"genesisTime":       fmt.Sprintf("%v", genesisTime),
 	}
+	secondTimerActivated := false
 	for {
-		select {
-		case <-time.After(timeTillGenesis):
+		currentTime := roughtime.Now()
+		if currentTime.After(genesisTime) {
 			log.WithFields(logFields).Info("Chain genesis time reached")
 			return
+		}
+		timeRemaining := genesisTime.Sub(currentTime)
+		if !secondTimerActivated && timeRemaining <= 2*time.Minute {
+			ticker.Stop()
+			// Replace ticker with a one having higher granularity.
+			ticker = time.NewTicker(time.Second)
+			secondTimerActivated = true
+		}
+		select {
 		case <-ticker.C:
-			currentTime := roughtime.Now()
-			if currentTime.After(genesisTime) {
-				log.WithFields(logFields).Info("Chain genesis time reached")
-				return
-			}
-			timeRemaining := genesisTime.Sub(currentTime)
-			if timeRemaining <= 2*time.Minute {
-				ticker = time.NewTicker(time.Second)
-			}
 			if timeRemaining >= time.Second {
 				log.WithFields(logFields).Infof(
 					"%s until chain genesis",
 					timeRemaining.Truncate(time.Second),
 				)
 			}
 		case <-ctx.Done():
+			log.Debug("Context closed, exiting routine")
 			return
 		}
 	}

shared/slotutil/countdown_test.go

@@ -18,13 +18,34 @@ func TestCountdownToGenesis(t *testing.T) {
 	config.GenesisCountdownInterval = time.Millisecond * 500
 	params.OverrideBeaconConfig(config)
 
-	firstStringResult := "1s until chain genesis"
-	genesisReached := "Chain genesis time reached"
-	CountdownToGenesis(
-		context.Background(),
-		roughtime.Now().Add(2*time.Second),
-		params.BeaconConfig().MinGenesisActiveValidatorCount,
-	)
-	require.LogsContain(t, hook, firstStringResult)
-	require.LogsContain(t, hook, genesisReached)
+	t.Run("normal countdown", func(t *testing.T) {
+		defer hook.Reset()
+		firstStringResult := "1s until chain genesis"
+		genesisReached := "Chain genesis time reached"
+		CountdownToGenesis(
+			context.Background(),
+			roughtime.Now().Add(2*time.Second),
+			params.BeaconConfig().MinGenesisActiveValidatorCount,
+		)
+		require.LogsContain(t, hook, firstStringResult)
+		require.LogsContain(t, hook, genesisReached)
+	})
+
+	t.Run("close context", func(t *testing.T) {
+		defer hook.Reset()
+		ctx, cancel := context.WithCancel(context.Background())
+		go func() {
+			time.AfterFunc(1500*time.Millisecond, func() {
+				cancel()
+			})
+		}()
+		CountdownToGenesis(
+			ctx,
+			roughtime.Now().Add(5*time.Second),
+			params.BeaconConfig().MinGenesisActiveValidatorCount,
+		)
+		require.LogsContain(t, hook, "4s until chain genesis")
+		require.LogsContain(t, hook, "Context closed, exiting routine")
+		require.LogsDoNotContain(t, hook, "Chain genesis time reached")
+	})
 }

shared/slotutil/slotutil_test.go

@@ -0,0 +1,16 @@
+package slotutil
+
+import (
+	"io/ioutil"
+	"os"
+	"testing"
+
+	"github.com/sirupsen/logrus"
+)
+
+func TestMain(m *testing.M) {
+	logrus.SetLevel(logrus.DebugLevel)
+	logrus.SetOutput(ioutil.Discard)
+
+	os.Exit(m.Run())
+}