Fix data race for leaderelection package

Kubernetes-commit: 8eda5521c041bbcd5ad19b3cfff49202e7eb5d22

tools/leaderelection/leaderelection.go

@@ -56,6 +56,7 @@ import (
 	"bytes"
 	"context"
 	"fmt"
+	"sync"
 	"time"
 
 	"k8s.io/apimachinery/pkg/api/errors"
@@ -187,6 +188,9 @@ type LeaderElector struct {
 	// clock is wrapper around time to allow for less flaky testing
 	clock clock.Clock
 
+	// used to lock the observedRecord
+	observedRecordLock sync.Mutex
+
 	metrics leaderMetricsAdapter
 }
 
@@ -224,13 +228,14 @@ func RunOrDie(ctx context.Context, lec LeaderElectionConfig) {
 
 // GetLeader returns the identity of the last observed leader or returns the empty string if
 // no leader has yet been observed.
+// This function is for informational purposes. (e.g. monitoring, logs, etc.)
 func (le *LeaderElector) GetLeader() string {
-	return le.observedRecord.HolderIdentity
+	return le.getObservedRecord().HolderIdentity
 }
 
 // IsLeader returns true if the last observed leader was this client else returns false.
 func (le *LeaderElector) IsLeader() bool {
-	return le.observedRecord.HolderIdentity == le.config.Lock.Identity()
+	return le.getObservedRecord().HolderIdentity == le.config.Lock.Identity()
 }
 
 // acquire loops calling tryAcquireOrRenew and returns true immediately when tryAcquireOrRenew succeeds.
@@ -301,8 +306,8 @@ func (le *LeaderElector) release() bool {
 		klog.Errorf("Failed to release lock: %v", err)
 		return false
 	}
-	le.observedRecord = leaderElectionRecord
+
-	le.observedTime = le.clock.Now()
+	le.setObservedRecord(&leaderElectionRecord)
 	return true
 }
 
@@ -329,16 +334,17 @@ func (le *LeaderElector) tryAcquireOrRenew(ctx context.Context) bool {
 			klog.Errorf("error initially creating leader election record: %v", err)
 			return false
 		}
-		le.observedRecord = leaderElectionRecord
+
-		le.observedTime = le.clock.Now()
+		le.setObservedRecord(&leaderElectionRecord)
+
 		return true
 	}
 
 	// 2. Record obtained, check the Identity & Time
 	if !bytes.Equal(le.observedRawRecord, oldLeaderElectionRawRecord) {
-		le.observedRecord = *oldLeaderElectionRecord
+		le.setObservedRecord(oldLeaderElectionRecord)
+
 		le.observedRawRecord = oldLeaderElectionRawRecord
-		le.observedTime = le.clock.Now()
 	}
 	if len(oldLeaderElectionRecord.HolderIdentity) > 0 &&
 		le.observedTime.Add(le.config.LeaseDuration).After(now.Time) &&
@@ -362,8 +368,7 @@ func (le *LeaderElector) tryAcquireOrRenew(ctx context.Context) bool {
 		return false
 	}
 
-	le.observedRecord = leaderElectionRecord
+	le.setObservedRecord(&leaderElectionRecord)
-	le.observedTime = le.clock.Now()
 	return true
 }
 
@@ -392,3 +397,22 @@ func (le *LeaderElector) Check(maxTolerableExpiredLease time.Duration) error {
 
 	return nil
 }
+
+// setObservedRecord will set a new observedRecord and update observedTime to the current time.
+// Protect critical sections with lock.
+func (le *LeaderElector) setObservedRecord(observedRecord *rl.LeaderElectionRecord) {
+	le.observedRecordLock.Lock()
+	defer le.observedRecordLock.Unlock()
+
+	le.observedRecord = *observedRecord
+	le.observedTime = le.clock.Now()
+}
+
+// getObservedRecord returns observersRecord.
+// Protect critical sections with lock.
+func (le *LeaderElector) getObservedRecord() rl.LeaderElectionRecord {
+	le.observedRecordLock.Lock()
+	defer le.observedRecordLock.Unlock()
+
+	return le.observedRecord
+}