Export DefaultRetryDelayFunc

CHANGELOG.md

@@ -18,6 +18,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ### Added
 
+- `DefaultRetryDelayFunc` is now a public API, which can be used in the custom `RetryDelayFunc`.
 - `SkipRetry` error is added to be used as a return value from `Handler`.
 - `Servers` method is added to `Inspector`
 - `CancelActiveTask` method is added to `Inspector`.

processor.go

@@ -33,7 +33,7 @@ type processor struct {
 	// orderedQueues is set only in strict-priority mode.
 	orderedQueues []string
 
-	retryDelayFunc retryDelayFunc
+	retryDelayFunc RetryDelayFunc
 
 	errHandler ErrorHandler
 
@@ -67,12 +67,10 @@ type processor struct {
 	finished chan<- *base.TaskMessage
 }
 
-type retryDelayFunc func(n int, err error, task *Task) time.Duration
-
 type processorParams struct {
 	logger          *log.Logger
 	broker          base.Broker
-	retryDelayFunc  retryDelayFunc
+	retryDelayFunc  RetryDelayFunc
 	syncCh          chan<- *syncRequest
 	cancelations    *base.Cancelations
 	concurrency     int

processor_test.go

@@ -96,7 +96,7 @@ func TestProcessorSuccessWithSingleQueue(t *testing.T) {
 		p := newProcessor(processorParams{
 			logger:          testLogger,
 			broker:          rdbClient,
-			retryDelayFunc:  defaultDelayFunc,
+			retryDelayFunc:  DefaultRetryDelayFunc,
 			syncCh:          syncCh,
 			cancelations:    base.NewCancelations(),
 			concurrency:     10,
@@ -187,7 +187,7 @@ func TestProcessorSuccessWithMultipleQueues(t *testing.T) {
 		p := newProcessor(processorParams{
 			logger:         testLogger,
 			broker:         rdbClient,
-			retryDelayFunc: defaultDelayFunc,
+			retryDelayFunc: DefaultRetryDelayFunc,
 			syncCh:         syncCh,
 			cancelations:   base.NewCancelations(),
 			concurrency:    10,
@@ -268,7 +268,7 @@ func TestProcessTasksWithLargeNumberInPayload(t *testing.T) {
 		p := newProcessor(processorParams{
 			logger:          testLogger,
 			broker:          rdbClient,
-			retryDelayFunc:  defaultDelayFunc,
+			retryDelayFunc:  DefaultRetryDelayFunc,
 			syncCh:          syncCh,
 			cancelations:    base.NewCancelations(),
 			concurrency:     10,
@@ -478,7 +478,7 @@ func TestProcessorQueues(t *testing.T) {
 		p := newProcessor(processorParams{
 			logger:          testLogger,
 			broker:          nil,
-			retryDelayFunc:  defaultDelayFunc,
+			retryDelayFunc:  DefaultRetryDelayFunc,
 			syncCh:          nil,
 			cancelations:    base.NewCancelations(),
 			concurrency:     10,
@@ -569,7 +569,7 @@ func TestProcessorWithStrictPriority(t *testing.T) {
 		p := newProcessor(processorParams{
 			logger:          testLogger,
 			broker:          rdbClient,
-			retryDelayFunc:  defaultDelayFunc,
+			retryDelayFunc:  DefaultRetryDelayFunc,
 			syncCh:          syncCh,
 			cancelations:    base.NewCancelations(),
 			concurrency:     1, // Set concurrency to 1 to make sure tasks are processed one at a time.

recoverer.go

@@ -16,7 +16,7 @@ import (
 type recoverer struct {
 	logger         *log.Logger
 	broker         base.Broker
-	retryDelayFunc retryDelayFunc
+	retryDelayFunc RetryDelayFunc
 
 	// channel to communicate back to the long running "recoverer" goroutine.
 	done chan struct{}
@@ -33,7 +33,7 @@ type recovererParams struct {
 	broker         base.Broker
 	queues         []string
 	interval       time.Duration
-	retryDelayFunc retryDelayFunc
+	retryDelayFunc RetryDelayFunc
 }
 
 func newRecoverer(params recovererParams) *recoverer {

server.go

@@ -60,11 +60,7 @@ type Config struct {
 	// Function to calculate retry delay for a failed task.
 	//
 	// By default, it uses exponential backoff algorithm to calculate the delay.
-	//
-	// n is the number of times the task has been retried.
-	// e is the error returned by the task handler.
-	// t is the task in question.
-	RetryDelayFunc func(n int, e error, t *Task) time.Duration
+	RetryDelayFunc RetryDelayFunc
 
 	// List of queues to process with given priority value. Keys are the names of the
 	// queues and values are associated priority value.
@@ -153,6 +149,14 @@ func (fn ErrorHandlerFunc) HandleError(ctx context.Context, task *Task, err erro
 	fn(ctx, task, err)
 }
 
+// RetryDelayFunc calculates the retry delay duration for a failed task given
+// the retry count, error, and the task.
+//
+// n is the number of times the task has been retried.
+// e is the error returned by the task handler.
+// t is the task in question.
+type RetryDelayFunc func(n int, e error, t *Task) time.Duration
+
 // Logger supports logging at various log levels.
 type Logger interface {
 	// Debug logs a message at Debug level.
@@ -253,9 +257,11 @@ func toInternalLogLevel(l LogLevel) log.Level {
 	panic(fmt.Sprintf("asynq: unexpected log level: %v", l))
 }
 
-// Formula taken from https://github.com/mperham/sidekiq.
-func defaultDelayFunc(n int, e error, t *Task) time.Duration {
+// DefaultRetryDelayFunc is the default RetryDelayFunc used if one is not specified in Config.
+// It uses exponential back-off strategy to calculate the retry delay.
+func DefaultRetryDelayFunc(n int, e error, t *Task) time.Duration {
 	r := rand.New(rand.NewSource(time.Now().UnixNano()))
+	// Formula taken from https://github.com/mperham/sidekiq.
 	s := int(math.Pow(float64(n), 4)) + 15 + (r.Intn(30) * (n + 1))
 	return time.Duration(s) * time.Second
 }
@@ -279,7 +285,7 @@ func NewServer(r RedisConnOpt, cfg Config) *Server {
 	}
 	delayFunc := cfg.RetryDelayFunc
 	if delayFunc == nil {
-		delayFunc = defaultDelayFunc
+		delayFunc = DefaultRetryDelayFunc
 	}
 	queues := make(map[string]int)
 	for qname, p := range cfg.Queues {
@@ -291,7 +297,7 @@ func NewServer(r RedisConnOpt, cfg Config) *Server {
 		queues = defaultQueueConfig
 	}
 	var qnames []string
-	for q, _ := range queues {
+	for q := range queues {
 		qnames = append(qnames, q)
 	}
 	shutdownTimeout := cfg.ShutdownTimeout