Merge pull request #933 from mfaizanse/backoff_sub_opt

Added BackOff helper method to set backoff through subOpts

example_test.go

@@ -620,6 +620,11 @@ func ExampleSubOpt() {
 	js.Subscribe("foo", func(msg *nats.Msg) {
 		fmt.Printf("Received a message: %s\n", string(msg.Data))
 	}, nats.StartTime(time.Now().Add(-2*time.Hour)))
+
+	// Start delivering messages with delay based on BackOff array of time durations.
+	js.Subscribe("foo", func(msg *nats.Msg) {
+		fmt.Printf("Received a message: %s\n", string(msg.Data))
+	}, nats.ManualAck(), nats.MaxDeliver(2), nats.BackOff([]time.Duration{50 * time.Millisecond, 250 * time.Millisecond}))
 }
 
 func ExampleMaxWait() {

js.go

@@ -2259,6 +2259,14 @@ func RateLimit(n uint64) SubOpt {
 	})
 }
 
+// BackOff is an array of time durations that represent the time to delay based on delivery count.
+func BackOff(backOff []time.Duration) SubOpt {
+	return subOptFn(func(opts *subOpts) error {
+		opts.cfg.BackOff = backOff
+		return nil
+	})
+}
+
 // BindStream binds a consumer to a stream explicitly based on a name.
 // When a stream name is not specified, the library uses the subscribe
 // subject as a way to find the stream name. It is done by making a request