Add deadline to syncRequest

- syncer will drop a request if its deadline has been exceeded

processor.go

@@ -208,7 +208,7 @@ func (p *processor) exec() {
 				return
 			case <-ctx.Done():
 				p.logger.Debugf("Retrying task. task id=%s", msg.ID) // TODO: Improve this log message and above
-				p.retryOrKill(msg, ctx.Err())
+				p.retryOrKill(ctx, msg, ctx.Err())
 				return
 			case resErr := <-resCh:
 				// Note: One of three things should happen.
@@ -219,10 +219,10 @@ func (p *processor) exec() {
 					if p.errHandler != nil {
 						p.errHandler.HandleError(task, resErr, msg.Retried, msg.Retry)
 					}
-					p.retryOrKill(msg, resErr)
+					p.retryOrKill(ctx, msg, resErr)
 					return
 				}
-				p.markAsDone(msg)
+				p.markAsDone(ctx, msg)
 			}
 		}()
 	}
@@ -237,55 +237,70 @@ func (p *processor) requeue(msg *base.TaskMessage) {
 	}
 }
 
-func (p *processor) markAsDone(msg *base.TaskMessage) {
+func (p *processor) markAsDone(ctx context.Context, msg *base.TaskMessage) {
 	err := p.broker.Done(msg)
 	if err != nil {
 		errMsg := fmt.Sprintf("Could not remove task id=%s type=%q from %q err: %+v", msg.ID, msg.Type, base.InProgressQueue, err)
+		deadline, ok := ctx.Deadline()
+		if !ok {
+			panic("asynq: internal error: missing deadline in context")
+		}
 		p.logger.Warnf("%s; Will retry syncing", errMsg)
 		p.syncRequestCh <- &syncRequest{
 			fn: func() error {
 				return p.broker.Done(msg)
 			},
-			errMsg: errMsg,
+			errMsg:   errMsg,
+			deadline: deadline,
 		}
 	}
 }
 
-func (p *processor) retryOrKill(msg *base.TaskMessage, err error) {
+func (p *processor) retryOrKill(ctx context.Context, msg *base.TaskMessage, err error) {
 	if msg.Retried >= msg.Retry {
-		p.kill(msg, err)
+		p.kill(ctx, msg, err)
 	} else {
-		p.retry(msg, err)
+		p.retry(ctx, msg, err)
 	}
 }
 
-func (p *processor) retry(msg *base.TaskMessage, e error) {
+func (p *processor) retry(ctx context.Context, msg *base.TaskMessage, e error) {
 	d := p.retryDelayFunc(msg.Retried, e, NewTask(msg.Type, msg.Payload))
 	retryAt := time.Now().Add(d)
 	err := p.broker.Retry(msg, retryAt, e.Error())
 	if err != nil {
 		errMsg := fmt.Sprintf("Could not move task id=%s from %q to %q", msg.ID, base.InProgressQueue, base.RetryQueue)
+		deadline, ok := ctx.Deadline()
+		if !ok {
+			panic("asynq: internal error: missing deadline in context")
+		}
 		p.logger.Warnf("%s; Will retry syncing", errMsg)
 		p.syncRequestCh <- &syncRequest{
 			fn: func() error {
 				return p.broker.Retry(msg, retryAt, e.Error())
 			},
-			errMsg: errMsg,
+			errMsg:   errMsg,
+			deadline: deadline,
 		}
 	}
 }
 
-func (p *processor) kill(msg *base.TaskMessage, e error) {
+func (p *processor) kill(ctx context.Context, msg *base.TaskMessage, e error) {
 	p.logger.Warnf("Retry exhausted for task id=%s", msg.ID)
 	err := p.broker.Kill(msg, e.Error())
 	if err != nil {
 		errMsg := fmt.Sprintf("Could not move task id=%s from %q to %q", msg.ID, base.InProgressQueue, base.DeadQueue)
+		deadline, ok := ctx.Deadline()
+		if !ok {
+			panic("asynq: internal error: missing deadline in context")
+		}
 		p.logger.Warnf("%s; Will retry syncing", errMsg)
 		p.syncRequestCh <- &syncRequest{
 			fn: func() error {
 				return p.broker.Kill(msg, e.Error())
 			},
-			errMsg: errMsg,
+			errMsg:   errMsg,
+			deadline: deadline,
 		}
 	}
 }

syncer.go

@@ -26,8 +26,9 @@ type syncer struct {
 }
 
 type syncRequest struct {
-	fn     func() error // sync operation
+	fn       func() error // sync operation
-	errMsg string       // error message
+	errMsg   string       // error message
+	deadline time.Time    // request should be dropped if deadline has been exceeded
 }
 
 type syncerParams struct {
@@ -72,6 +73,9 @@ func (s *syncer) start(wg *sync.WaitGroup) {
 			case <-time.After(s.interval):
 				var temp []*syncRequest
 				for _, req := range requests {
+					if req.deadline.Before(time.Now()) {
+						continue // drop stale request
+					}
 					if err := req.fn(); err != nil {
 						temp = append(temp, req)
 					}

syncer_test.go

@@ -42,6 +42,7 @@ func TestSyncer(t *testing.T) {
 			fn: func() error {
 				return rdbClient.Done(m)
 			},
+			deadline: time.Now().Add(5 * time.Minute),
 		}
 	}
 
@@ -85,8 +86,9 @@ func TestSyncerRetry(t *testing.T) {
 	}
 
 	syncRequestCh <- &syncRequest{
-		fn:     requestFunc,
+		fn:       requestFunc,
-		errMsg: "error",
+		errMsg:   "error",
+		deadline: time.Now().Add(5 * time.Minute),
 	}
 
 	// allow syncer to retry
@@ -98,3 +100,41 @@ func TestSyncerRetry(t *testing.T) {
 	}
 	mu.Unlock()
 }
+
+func TestSyncerDropsStaleRequests(t *testing.T) {
+	const interval = time.Second
+	syncRequestCh := make(chan *syncRequest)
+	syncer := newSyncer(syncerParams{
+		logger:     testLogger,
+		requestsCh: syncRequestCh,
+		interval:   interval,
+	})
+	var wg sync.WaitGroup
+	syncer.start(&wg)
+
+	var (
+		mu sync.Mutex
+		n  int // number of times request has been processed
+	)
+
+	for i := 0; i < 10; i++ {
+		syncRequestCh <- &syncRequest{
+			fn: func() error {
+				mu.Lock()
+				n++
+				mu.Unlock()
+				return nil
+			},
+			deadline: time.Now().Add(time.Duration(-i) * time.Second), // already exceeded deadline
+		}
+	}
+
+	time.Sleep(2 * interval) // ensure that syncer runs at least once
+	syncer.terminate()
+
+	mu.Lock()
+	if n != 0 {
+		t.Errorf("requests has been processed %d times, want 0", n)
+	}
+	mu.Unlock()
+}