Add Unregister method to Scheduler

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Added
+
+- `Unregister` method is added to `Scheduler` to remove a registered entry.
+
 ## [0.15.0] - 2021-01-31
 
 **IMPORTATNT**: All `Inspector` related code are moved to subpackage "github.com/hibiken/asynq/inspeq"
@@ -15,7 +19,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - `Inspector` related code are moved to subpackage "github.com/hibken/asynq/inspeq".
 - `RedisConnOpt` interface has changed slightly. If you have been passing `RedisClientOpt`, `RedisFailoverClientOpt`, or `RedisClusterClientOpt` as a pointer,
-   update your code to pass as a value.
+  update your code to pass as a value.
 - `ErrorMsg` field in `RetryTask` and `ArchivedTask` was renamed to `LastError`.
 
 ### Added

scheduler.go

@@ -30,6 +30,10 @@ type Scheduler struct {
 	done       chan struct{}
 	wg         sync.WaitGroup
 	errHandler func(task *Task, opts []Option, err error)
+	// idmap maps Scheduler's entry ID to cron.EntryID
+	// to avoid using cron.EntryID as the public API of
+	// the Scheduler.
+	idmap map[string]cron.EntryID
 }
 
 // NewScheduler returns a new Scheduler instance given the redis connection option.
@@ -65,6 +69,7 @@ func NewScheduler(r RedisConnOpt, opts *SchedulerOpts) *Scheduler {
 		location:   loc,
 		done:       make(chan struct{}),
 		errHandler: opts.EnqueueErrorHandler,
+		idmap:      make(map[string]cron.EntryID),
 	}
 }
 
@@ -145,12 +150,25 @@ func (s *Scheduler) Register(cronspec string, task *Task, opts ...Option) (entry
 		logger:     s.logger,
 		errHandler: s.errHandler,
 	}
-	if _, err = s.cron.AddJob(cronspec, job); err != nil {
+	cronID, err := s.cron.AddJob(cronspec, job)
+	if err != nil {
 		return "", err
 	}
+	s.idmap[job.id.String()] = cronID
 	return job.id.String(), nil
 }
 
+// Unregister removes a registered entry by entry ID.
+// Unregister returns a non-nil error if no entries were found for the given entryID.
+func (s *Scheduler) Unregister(entryID string) error {
+	cronID, ok := s.idmap[entryID]
+	if !ok {
+		return fmt.Errorf("asynq: no scheduler entry found")
+	}
+	s.cron.Remove(cronID)
+	return nil
+}
+
 // Run starts the scheduler until an os signal to exit the program is received.
 // It returns an error if scheduler is already running or has been stopped.
 func (s *Scheduler) Run() error {

scheduler_test.go

@@ -14,7 +14,7 @@ import (
 	"github.com/hibiken/asynq/internal/base"
 )
 
-func TestScheduler(t *testing.T) {
+func TestSchedulerRegister(t *testing.T) {
 	tests := []struct {
 		cronspec string
 		task     *Task
@@ -116,3 +116,47 @@ func TestSchedulerWhenRedisDown(t *testing.T) {
 	}
 	mu.Unlock()
 }
+
+func TestSchedulerUnregister(t *testing.T) {
+	tests := []struct {
+		cronspec string
+		task     *Task
+		opts     []Option
+		wait     time.Duration
+		queue    string
+	}{
+		{
+			cronspec: "@every 3s",
+			task:     NewTask("task1", nil),
+			opts:     []Option{MaxRetry(10)},
+			wait:     10 * time.Second,
+			queue:    "default",
+		},
+	}
+
+	r := setup(t)
+
+	for _, tc := range tests {
+		scheduler := NewScheduler(getRedisConnOpt(t), nil)
+		entryID, err := scheduler.Register(tc.cronspec, tc.task, tc.opts...)
+		if err != nil {
+			t.Fatal(err)
+		}
+		if err := scheduler.Unregister(entryID); err != nil {
+			t.Fatal(err)
+		}
+
+		if err := scheduler.Start(); err != nil {
+			t.Fatal(err)
+		}
+		time.Sleep(tc.wait)
+		if err := scheduler.Stop(); err != nil {
+			t.Fatal(err)
+		}
+
+		got := asynqtest.GetPendingMessages(t, r, tc.queue)
+		if len(got) != 0 {
+			t.Errorf("%d tasks were enqueued, want zero", len(got))
+		}
+	}
+}