mirror of https://github.com/status-im/consul.git
120 lines
3.1 KiB
Go
120 lines
3.1 KiB
Go
/*
|
|
Copyright 2014 The Kubernetes Authors.
|
|
|
|
Licensed under the Apache License, Version 2.0 (the "License");
|
|
you may not use this file except in compliance with the License.
|
|
You may obtain a copy of the License at
|
|
|
|
http://www.apache.org/licenses/LICENSE-2.0
|
|
|
|
Unless required by applicable law or agreed to in writing, software
|
|
distributed under the License is distributed on an "AS IS" BASIS,
|
|
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
|
|
See the License for the specific language governing permissions and
|
|
limitations under the License.
|
|
*/
|
|
|
|
package watch
|
|
|
|
import (
|
|
"io"
|
|
"sync"
|
|
|
|
"github.com/golang/glog"
|
|
"k8s.io/apimachinery/pkg/runtime"
|
|
"k8s.io/apimachinery/pkg/util/net"
|
|
utilruntime "k8s.io/apimachinery/pkg/util/runtime"
|
|
)
|
|
|
|
// Decoder allows StreamWatcher to watch any stream for which a Decoder can be written.
|
|
type Decoder interface {
|
|
// Decode should return the type of event, the decoded object, or an error.
|
|
// An error will cause StreamWatcher to call Close(). Decode should block until
|
|
// it has data or an error occurs.
|
|
Decode() (action EventType, object runtime.Object, err error)
|
|
|
|
// Close should close the underlying io.Reader, signalling to the source of
|
|
// the stream that it is no longer being watched. Close() must cause any
|
|
// outstanding call to Decode() to return with an error of some sort.
|
|
Close()
|
|
}
|
|
|
|
// StreamWatcher turns any stream for which you can write a Decoder interface
|
|
// into a watch.Interface.
|
|
type StreamWatcher struct {
|
|
sync.Mutex
|
|
source Decoder
|
|
result chan Event
|
|
stopped bool
|
|
}
|
|
|
|
// NewStreamWatcher creates a StreamWatcher from the given decoder.
|
|
func 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
|
|
}
|
|
|
|
// ResultChan implements Interface.
|
|
func (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()
|
|
}
|
|
}
|
|
|
|
// stopping returns true if Stop() was called previously.
|
|
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.
|
|
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,
|
|
}
|
|
}
|
|
}
|