msgbus

type JetStreamStreamerConfig struct {
	// AckWait is the duration to wait before Ack() is considered failed and JetStream knows to resend the value.
	AckWait time.Duration
}

type Msg interface {
	// Data returns the serialized data stored in the message.
	Data() []byte
	// Ack acknowledges the message.
	Ack() error
}

type MsgHandler func(msg Msg)

type PersistentSub interface {
	// Close the subscription, but allow future PersistentSubs to read from the sub starting after
	// the last acked message.
	Close() error
}

type Streamer interface {
	// PersistentSubscribe creates a persistent subscription on a subject, calling the message
	// handler callback on each message that arrives on the sub.
	//
	// Here persistence means that if the subscription closes or dies and later resumes,
	// the Subscription will continue from the earliest message that was not acked.
	//
	// This position in the stream will be tracked according to the (subject, persistentName) pair.
	// * If you need a new subscription to see all of the available stream messages, you can receive them
	//   by invoking PersistentSubscribe() on the same subject but a new persistentName.
	// * If you call PersistentSubscribe() with a new subject but an existing persistentName, the implementation
	//   should treat it as a new persistent subscription and send all data available on the subscription.
	//
	// Parallel callers of PersistentSubscribe that use the same subject + persistentName pair will be added
	// to the same WorkQueue: messages published on that subject will be assigned to one of
	// the callers. If the assigned caller does not Ack() a message within an implementation's
	// timeout, then the message will be reassigned to another worker.
	PersistentSubscribe(subject, persistentName string, cb MsgHandler) (PersistentSub, error)

	// Publish publishes the data to the specific subject.
	Publish(subject string, data []byte) error

	// PeekLatestMessage returns the last message published on a subject. If no messages
	// exist for the subject method returns `nil`.
	//
	// PeekLatestMessage does not care about the state of any Sub. It strictly returns the last message sent from a Publish()
	// call.
	PeekLatestMessage(subject string) (Msg, error)
}