db: fix TestCleanupManagerCloseWithPacing

This test is ineffective because the `FreeSpaceThresholdBytes` option
disables pacing. Fix by setting that option to 1 byte.

We also remove the extra checking of `stopCh` - if it is closed, we
will exit the pacing loop right away so there's no need for this
special check.

Author: RaduBerinde

obsolete_files.go

@@ -185,12 +185,7 @@ func (cm *cleanupManager) mainLoop() {
 	// Use a token bucket with 1 token / second refill rate and 1 token burst.
 	tb.Init(1.0, 1.0)
 	for job := range cm.jobsCh {
-		select {
-		case <-cm.stopCh:
-			cm.deleteObsoleteFilesInJob(job, nil, nil)
-		default:
-			cm.deleteObsoleteFilesInJob(job, &tb, paceTimer)
-		}
+		cm.deleteObsoleteFilesInJob(job, &tb, paceTimer)
 		cm.mu.Lock()
 		cm.mu.completedJobs++
 		cm.mu.completedStats.Add(job.stats)
@@ -247,6 +242,7 @@ func (cm *cleanupManager) maybePace(
 		select {
 		case <-paceTimer.C:
 		case <-cm.stopCh:
+			// The cleanup manager is being closed. Delete without pacing.
 			return
 		}
 	}

obsolete_files_test.go

@@ -145,8 +145,9 @@ func TestCleaner(t *testing.T) {
 func TestCleanupManagerCloseWithPacing(t *testing.T) {
 	mem := vfs.NewMem()
 	opts := &Options{
-		FS:                     mem,
-		TargetByteDeletionRate: 1024, // 1 KB/s - slow pacing
+		FS:                      mem,
+		FreeSpaceThresholdBytes: 1,
+		TargetByteDeletionRate:  1024, // 1 KB/s - slow pacing
 	}
 	opts.EnsureDefaults()
 
@@ -160,6 +161,7 @@ func TestCleanupManagerCloseWithPacing(t *testing.T) {
 	getDeletePacerInfo := func() deletionPacerInfo {
 		return deletionPacerInfo{
 			freeBytes: 10 << 30,
+			liveBytes: 10 << 30,
 		}
 	}