woodpecker/vendor/github.com/cncd/pubsub/pubsub.go
2017-03-05 18:56:08 +11:00

72 lines
2 KiB
Go

// Package pubsub implements a publish-subscriber messaging system.
package pubsub
import (
"context"
"errors"
)
// ErrNotFound is returned when the named topic does not exist.
var ErrNotFound = errors.New("topic not found")
// Message defines a published message.
type Message struct {
// ID identifies this message.
ID string `json:"id,omitempty"`
// Data is the actual data in the entry.
Data []byte `json:"data"`
// Labels represents the key-value pairs the entry is lebeled with.
Labels map[string]string `json:"labels,omitempty"`
}
// Receiver receives published messages.
type Receiver func(Message)
// Publisher defines a mechanism for communicating messages from a group
// of senders, called producers, to a group of consumers.
type Publisher interface {
// Create creates the named topic.
Create(c context.Context, topic string) error
// Publish publishes the message.
Publish(c context.Context, topic string, message Message) error
// Subscribe subscribes to the topic. The Receiver function is a callback
// function that receives published messages.
Subscribe(c context.Context, topic string, receiver Receiver) error
// Remove removes the named topic.
Remove(c context.Context, topic string) error
}
// // global instance of the queue.
// var global = New()
//
// // Set sets the global queue.
// func Set(p Publisher) {
// global = p
// }
//
// // Create creates the named topic.
// func Create(c context.Context, topic string) error {
// return global.Create(c, topic)
// }
//
// // Publish publishes the message.
// func Publish(c context.Context, topic string, message Message) error {
// return global.Publish(c, topic, message)
// }
//
// // Subscribe subscribes to the topic. The Receiver function is a callback
// // function that receives published messages.
// func Subscribe(c context.Context, topic string, receiver Receiver) error {
// return global.Subscribe(c, topic, receiver)
// }
//
// // Remove removes the topic.
// func Remove(c context.Context, topic string) error {
// return global.Remove(c, topic)
// }