Allow user to define a max retry count for a task

client.go

@@ -3,8 +3,8 @@ package asynq
 import (
 	"time"
 
-	"github.com/rs/xid"
 	"github.com/hibiken/asynq/internal/rdb"
+	"github.com/rs/xid"
 )
 
 // A Client is responsible for scheduling tasks.
@@ -23,17 +23,59 @@ func NewClient(cfg *RedisConfig) *Client {
 	return &Client{r}
 }
 
+// Option configures the behavior of task processing.
+type Option interface{}
+
+// max number of times a task will be retried.
+type retryOption int
+
+// MaxRetry returns an option to specify the max number of times
+// a task will be retried.
+//
+// Negative retry count is treated as zero retry.
+func MaxRetry(n int) Option {
+	if n < 0 {
+		n = 0
+	}
+	return retryOption(n)
+}
+
+type option struct {
+	retry int
+}
+
+func composeOptions(opts ...Option) option {
+	res := option{
+		retry: defaultMaxRetry,
+	}
+	for _, opt := range opts {
+		switch opt := opt.(type) {
+		case retryOption:
+			res.retry = int(opt)
+		default:
+			// ignore unexpected option
+		}
+	}
+	return res
+}
+
+const (
+	// Max retry count by default
+	defaultMaxRetry = 25
+)
+
 // Process registers a task to be processed at the specified time.
 //
 // Process returns nil if the task is registered successfully,
 // otherwise returns non-nil error.
-func (c *Client) Process(task *Task, processAt time.Time) error {
+func (c *Client) Process(task *Task, processAt time.Time, opts ...Option) error {
+	opt := composeOptions(opts...)
 	msg := &rdb.TaskMessage{
 		ID:      xid.New(),
 		Type:    task.Type,
 		Payload: task.Payload,
 		Queue:   "default",
-		Retry:   defaultMaxRetry,
+		Retry:   opt.retry,
 	}
 	return c.enqueue(msg, processAt)
 }