go-events package简介

go-events实现了一种处理event的机制，其核心概念是Sink（定义在event.go）：

// Event marks items that can be sent as events.
type Event interface{}

// Sink accepts and sends events.
type Sink interface {
    // Write an event to the Sink. If no error is returned, the caller will
    // assume that all events have been committed to the sink. If an error is
    // received, the caller may retry sending the event.
    Write(event Event) error

    // Close the sink, possibly waiting for pending events to flush.
    Close() error
}

可以把Sink想象成一个“池子”，它提供了2个方法：Write往“池子”里发消息，Close是不用时关闭这个“池子”。 其它几个文件其实都是围绕Sink做文章，构造出各种功能。举个例子：

package main

import (
    "fmt"
    "github.com/docker/go-events"
    "time"
)

type eventRecv struct {
    name string
}

func (e *eventRecv)Write(event events.Event) error {
    fmt.Printf("%s receives %d\n", e.name, event.(int))
    return nil
}

func (e *eventRecv)Close() error {
    return nil
}

func createEventRecv(name string) *eventRecv {
    return &eventRecv{name}
}

func main() {
    e1 := createEventRecv("Foo")
    e2 := createEventRecv("Bar")

    bc := events.NewBroadcaster(e1, e2)
    bc.Write(1)
    bc.Write(2)
    time.Sleep(time.Second)
}

执行结果如下：

Foo receives 1
Bar receives 1
Foo receives 2
Bar receives 2

NewBroadcaster作用是把一个event发送到多个Sink。

再看一个使用NewQueue的例子：

package main

import (
    "fmt"
    "github.com/docker/go-events"
    "time"
)

type eventRecv struct {
    name string
}

func (e *eventRecv)Write(event events.Event) error {
    fmt.Printf("%s receives %d\n", e.name, event)
    return nil
}

func (e *eventRecv)Close() error {
    return nil
}

func createEventRecv(name string) *eventRecv {
    return &eventRecv{name}
}

func main() {
    q := events.NewQueue(createEventRecv("Foo"))
    q.Write(1)
    q.Write(2)
    time.Sleep(time.Second)
}

执行结果如下：

Foo receives 1
Foo receives 2