Properly close channel when monitor exits.

Signed-off-by: Lantao Liu <lantaol@google.com>

pkg/logcounter/log_counter.go

@@ -63,11 +63,15 @@ func NewJournaldLogCounter(options *options.LogCounterOptions) (types.LogCounter
 	}, nil
 }
 
-func (e *logCounter) Count() (count int) {
+func (e *logCounter) Count() (count int, err error) {
 	start := e.clock.Now()
 	for {
 		select {
-		case log := <-e.logCh:
+		case log, ok := <-e.logCh:
+			if !ok {
+				err = fmt.Errorf("log channel closed unexpectedly")
+				return
+			}
 			// We only want to count events up until the time at which we started.
 			// Otherwise we would run forever
 			if start.Before(log.Timestamp) {

pkg/logcounter/log_counter_test.go

@@ -120,7 +120,10 @@ func TestCount(t *testing.T) {
 					fakeClock.Step(2 * timeout)
 				}
 			}(tc.logs, logCh)
-			actualCount := counter.Count()
+			actualCount, err := counter.Count()
+			if err != nil {
+				t.Errorf("unexpected error %v", err)
+			}
 			if actualCount != tc.expectedCount {
 				t.Errorf("got %d; expected %d", actualCount, tc.expectedCount)
 			}

pkg/logcounter/types/types.go

@@ -17,5 +17,5 @@ limitations under the License.
 package types
 
 type LogCounter interface {
-	Count() int
+	Count() (int, error)
 }