123 lines
2.8 KiB
Go
123 lines
2.8 KiB
Go
/*
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Copyright 2015 The Kubernetes Authors All rights reserved.
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Licensed under the Apache License, Version 2.0 (the "License");
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you may not use this file except in compliance with the License.
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You may obtain a copy of the License at
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http://www.apache.org/licenses/LICENSE-2.0
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Unless required by applicable law or agreed to in writing, software
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distributed under the License is distributed on an "AS IS" BASIS,
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WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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See the License for the specific language governing permissions and
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limitations under the License.
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*/
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package runtime
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import (
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"os"
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"sync"
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"time"
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"k8s.io/kubernetes/pkg/util"
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)
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type Signal <-chan struct{}
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// return a func that will close the signal chan.
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// multiple invocations of the returned func will not generate a panic.
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// two funcs from separate invocations of Closer() (on the same sig chan) will cause a panic if both invoked.
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// for example:
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// // good
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// x := runtime.After(func() { ... })
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// f := x.Closer()
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// f()
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// f()
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//
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// // bad
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// x := runtime.After(func() { ... })
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// f := x.Closer()
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// g := x.Closer()
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// f()
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// g() // this will panic
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func Closer(sig chan<- struct{}) func() {
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var once sync.Once
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return func() {
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once.Do(func() { close(sig) })
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}
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}
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// upon receiving signal sig invoke function f and immediately return a signal
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// that indicates f's completion. used to chain handler funcs, for example:
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// On(job.Done(), response.Send).Then(wg.Done)
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func (sig Signal) Then(f func()) Signal {
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if sig == nil {
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return nil
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}
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return On(sig, f)
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}
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// execute a callback function after the specified signal chan closes.
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// immediately returns a signal that indicates f's completion.
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func On(sig <-chan struct{}, f func()) Signal {
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if sig == nil {
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return nil
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}
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return After(func() {
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<-sig
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if f != nil {
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f()
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}
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})
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}
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func OnOSSignal(sig <-chan os.Signal, f func(os.Signal)) Signal {
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if sig == nil {
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return nil
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}
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return After(func() {
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if s, ok := <-sig; ok && f != nil {
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f(s)
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}
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})
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}
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// spawn a goroutine to execute a func, immediately returns a chan that closes
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// upon completion of the func. returns a nil signal chan if the given func is nil.
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func After(f func()) Signal {
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ch := make(chan struct{})
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go func() {
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defer close(ch)
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defer util.HandleCrash()
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if f != nil {
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f()
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}
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}()
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return Signal(ch)
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}
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// periodically execute the given function, stopping once stopCh is closed.
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// this func blocks until stopCh is closed, it's intended to be run as a goroutine.
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func Until(f func(), period time.Duration, stopCh <-chan struct{}) {
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if f == nil {
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return
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}
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for {
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select {
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case <-stopCh:
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return
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default:
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}
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func() {
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defer util.HandleCrash()
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f()
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}()
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select {
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case <-stopCh:
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case <-time.After(period):
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}
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}
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}
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