hub

Documentation

Index

• Constants
• type Fields
  • func (f Fields) String() string
• type Hub
  • func New() *Hub
  • func (h *Hub) Close()
  • func (h *Hub) NonBlockingSubscribe(cap int, topics ...string) Subscription
  • func (h *Hub) Publish(m Message)
  • func (h *Hub) Subscribe(cap int, topics ...string) Subscription
  • func (h *Hub) Unsubscribe(sub Subscription)
  • func (h *Hub) With(f Fields) *Hub
• type Message
  • func (m *Message) Topic() string
• type Subscription

Constants

const AlertTopic = "hub.subscription.messageslost"

AlertTopic is used to notify when a nonblocking subscriber loose one message You can subscribe on this topic and log or send metrics.

Types

type Fields

type Fields map[string]interface{}

Fields is a [key]value storage for Messages values.

func (Fields) String

func (f Fields) String() string

type Hub

type Hub struct {
	// contains filtered or unexported fields
}

Hub is a component that provides publish and subscribe capabilities for messages. Every message has a Name used to route them to subscribers and this can be used like RabbitMQ topics exchanges. Where every word is separated by dots `.` and you can use `*` as a wildcard.

func New

func New() *Hub

New create and return a new empty hub.

func (*Hub) Close

func (h *Hub) Close()

Close will unsubscribe all the subscriptions and close them all.

func (*Hub) NonBlockingSubscribe

func (h *Hub) NonBlockingSubscribe(cap int, topics ...string) Subscription

NonBlockingSubscribe create a nonblocking subscription to receive events for a given topic. This subscriber will loose messages if the buffer reaches the max capability.

func (*Hub) Publish

func (h *Hub) Publish(m Message)

Publish will send an event to all the subscribers matching the event name.

func (*Hub) Subscribe

func (h *Hub) Subscribe(cap int, topics ...string) Subscription

Subscribe create a blocking subscription to receive events for a given topic. The cap param is used inside the subscriber and in this case used to create a channel. cap(1) = unbuffered channel.

func (*Hub) Unsubscribe

func (h *Hub) Unsubscribe(sub Subscription)

Unsubscribe remove and close the Subscription.

func (*Hub) With

func (h *Hub) With(f Fields) *Hub

With creates a child Hub with the fields added to it. When someone call Publish, this Fields will be added automatically into the message.

type Message

type Message struct {
	Name   string
	Body   []byte
	Fields Fields
}

Message represent some message/event passed into the hub It also contain some helper functions to convert the fields to primitive types.

func (*Message) Topic

func (m *Message) Topic() string

Topic return the message topic used when the message was sended.

type Subscription

type Subscription struct {
	Topics   []string
	Receiver <-chan Message
	// contains filtered or unexported fields
}

Subscription represents a topic subscription.