Event stream updates (#1981)

- auto and manual acking
- retry limits

events/options.go

@@ -35,6 +35,17 @@ type SubscribeOptions struct {
 	// StartAtTime is the time from which the messages should be consumed from. If not provided then
 	// the messages will be consumed starting from the moment the Subscription starts.
 	StartAtTime time.Time
+	// AutoAck if true (default true), automatically acknowledges every message so it will not be redelivered.
+	// If false specifies that each message need ts to be manually acknowledged by the subscriber.
+	// If processing is successful the message should be ack'ed to remove the message from the stream.
+	// If processing is unsuccessful the message should be nack'ed (negative acknowledgement) which will mean it will
+	// remain on the stream to be processed again.
+	AutoAck bool
+	AckWait time.Duration
+	// RetryLimit indicates number of times a message is retried
+	RetryLimit int
+	// CustomRetries indicates whether to use RetryLimit
+	CustomRetries bool
 }
 
 // SubscribeOption sets attributes on SubscribeOptions
@@ -54,6 +65,31 @@ func WithStartAtTime(t time.Time) SubscribeOption {
 	}
 }
 
+// WithAutoAck sets the AutoAck field on SubscribeOptions and an ackWait duration after which if no ack is received
+// the message is requeued in case auto ack is turned off
+func WithAutoAck(ack bool, ackWait time.Duration) SubscribeOption {
+	return func(o *SubscribeOptions) {
+		o.AutoAck = ack
+		o.AckWait = ackWait
+	}
+}
+
+// WithRetryLimit sets the RetryLimit field on SubscribeOptions.
+// Set to -1 for infinite retries (default)
+func WithRetryLimit(retries int) SubscribeOption {
+	return func(o *SubscribeOptions) {
+		o.RetryLimit = retries
+		o.CustomRetries = true
+	}
+}
+
+func (s SubscribeOptions) GetRetryLimit() int {
+	if !s.CustomRetries {
+		return -1
+	}
+	return s.RetryLimit
+}
+
 // WriteOptions contains all the options which can be provided when writing an event to a store
 type WriteOptions struct {
 	// TTL is the duration the event should be recorded for, a zero value TTL indicates the event should