mirror of https://github.com/docker/docs.git
125 lines
2.8 KiB
Go
125 lines
2.8 KiB
Go
package api
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import (
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"fmt"
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"io"
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"net/http"
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"sync"
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"time"
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"github.com/docker/swarm/cluster"
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)
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const eventFmt string = "{%q:%q,%q:%q,%q:%q,%q:%d,%q:{%q:%q,%q:%q,%q:%q,%q:%q}}\n"
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// EventsHandler broadcasts events to multiple client listeners.
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type eventsHandler struct {
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sync.RWMutex
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ws map[string]io.Writer
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cs map[string]chan struct{}
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}
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// NewEventsHandler creates a new EventsHandler for a cluster.
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// The new eventsHandler is initialized with no writers or channels.
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func newEventsHandler() *eventsHandler {
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return &eventsHandler{
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ws: make(map[string]io.Writer),
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cs: make(map[string]chan struct{}),
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}
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}
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// Add adds the writer and a new channel for the remote address.
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func (eh *eventsHandler) Add(remoteAddr string, w io.Writer) {
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eh.Lock()
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eh.ws[remoteAddr] = w
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eh.cs[remoteAddr] = make(chan struct{})
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eh.Unlock()
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}
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// Wait waits on a signal from the remote address.
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func (eh *eventsHandler) Wait(remoteAddr string, until int64) {
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timer := time.NewTimer(0)
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timer.Stop()
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if until > 0 {
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dur := time.Unix(until, 0).Sub(time.Now())
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timer = time.NewTimer(dur)
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}
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// subscribe to http client close event
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w := eh.ws[remoteAddr]
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var closeNotify <-chan bool
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if closeNotifier, ok := w.(http.CloseNotifier); ok {
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closeNotify = closeNotifier.CloseNotify()
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}
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select {
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case <-eh.cs[remoteAddr]:
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case <-closeNotify:
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case <-timer.C: // `--until` timeout
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close(eh.cs[remoteAddr])
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}
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eh.cleanupHandler(remoteAddr)
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}
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func (eh *eventsHandler) cleanupHandler(remoteAddr string) {
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eh.Lock()
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// the maps are expected to have the same keys
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delete(eh.cs, remoteAddr)
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delete(eh.ws, remoteAddr)
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eh.Unlock()
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}
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// Handle writes information about a cluster event to each remote address in the cluster that has been added to the events handler.
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// After an unsuccessful write to a remote address, the associated channel is closed and the address is removed from the events handler.
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func (eh *eventsHandler) Handle(e *cluster.Event) error {
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eh.RLock()
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str := fmt.Sprintf(eventFmt,
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"status", e.Status,
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"id", e.Id,
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"from", e.From+" node:"+e.Engine.Name,
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"time", e.Time,
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"node",
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"Name", e.Engine.Name,
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"Id", e.Engine.ID,
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"Addr", e.Engine.Addr,
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"Ip", e.Engine.IP)
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var failed []string
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for key, w := range eh.ws {
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if _, err := fmt.Fprintf(w, str); err != nil {
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// collect them to handle later under Lock
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failed = append(failed, key)
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continue
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}
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if f, ok := w.(http.Flusher); ok {
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f.Flush()
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}
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}
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eh.RUnlock()
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eh.Lock()
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if len(failed) > 0 {
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for _, key := range failed {
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if ch, ok := eh.cs[key]; ok {
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close(ch)
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}
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delete(eh.cs, key)
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}
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}
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eh.Unlock()
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return nil
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}
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// Size returns the number of remote addresses that the events handler currently contains.
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func (eh *eventsHandler) Size() int {
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eh.RLock()
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defer eh.RUnlock()
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return len(eh.ws)
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}
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