kubernetes源码之watch包streamwatcher.go阅读理解五

这是watcher包中最后一个文件了

streamwatcher.go先看数据结构

type Decoder interface {    Decode() (action EventType, object runtime.Object, err error)    Close()}type StreamWatcher struct {    sync.Mutex    source  Decoder    result  chan Event    stopped bool}

再看看方法

StreamWatcher 有两 ResultChan()个stop()方法，实现Interfacefunc (sw *StreamWatcher) ResultChan() <-chan Event {    return sw.result}// Stop implements Interface.func (sw *StreamWatcher) Stop() {    // Call Close() exactly once by locking and setting a flag.    sw.Lock()    defer sw.Unlock()    if !sw.stopped {        sw.stopped = true        sw.source.Close()    }}实例化一个StreamWatcher并且有一个goroutinefunc NewStreamWatcher(d Decoder) *StreamWatcher {    sw := &StreamWatcher{        source: d,        // It's easy for a consumer to add buffering via an extra        // goroutine/channel, but impossible for them to remove it,        // so nonbuffered is better.        result: make(chan Event),    }    go sw.receive()    return sw}func (sw *StreamWatcher) stopping() bool {    sw.Lock()    defer sw.Unlock()    return sw.stopped}// receive reads result from the decoder in a loop and sends down the result channel.receive方法循环读取decoder的结果，然后发送到结果通道。receive方法从decoder中使用Decode方法获取(action EventType, object runtime.Object, err error)func (sw *StreamWatcher) receive() {    defer close(sw.result)    defer sw.Stop()    defer utilruntime.HandleCrash()    for {        action, obj, err := sw.source.Decode()        if err != nil {            // Ignore expected error.            if sw.stopping() {                return            }            switch err {            case io.EOF:                // watch closed normally            case io.ErrUnexpectedEOF:                glog.V(1).Infof("Unexpected EOF during watch stream event decoding: %v", err)            default:                msg := "Unable to decode an event from the watch stream: %v"                if net.IsProbableEOF(err) {                    glog.V(5).Infof(msg, err)                } else {                    glog.Errorf(msg, err)                }            }            return        }        sw.result <- Event{            Type:   action,            Object: obj,        }    }}

总结

说白了就是从Decoder读取数据然后发送给resulttype StreamWatcher struct {    sync.Mutex    source  Decoder    result  chan Event    stopped bool    

拓展，看看使用了NewStreamWatcher的文件

k8s.io\client-go\rest\request.go 中694行使用了这个函数 回头在仔细阅读以下这个文件return watch.NewStreamWatcher(restclientwatch.NewDecoder(decoder, r.serializers.Decoder)), nil