mirror of https://github.com/k3s-io/k3s
102 lines
2.2 KiB
Go
102 lines
2.2 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 proc
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import (
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"fmt"
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"sync"
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"time"
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)
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type errorOnce struct {
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once sync.Once
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err chan error
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abort <-chan struct{}
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}
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// NewErrorOnce creates an ErrorOnce that aborts blocking func calls once
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// the given abort chan has closed.
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func NewErrorOnce(abort <-chan struct{}) ErrorOnce {
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return &errorOnce{
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err: make(chan error, 1),
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abort: abort,
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}
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}
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func (b *errorOnce) Err() <-chan error {
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return b.err
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}
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func (b *errorOnce) Reportf(msg string, args ...interface{}) {
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b.Report(fmt.Errorf(msg, args...))
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}
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func (b *errorOnce) Report(err error) {
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b.once.Do(func() {
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select {
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case b.err <- err:
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default:
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}
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})
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}
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func (b *errorOnce) Send(errIn <-chan error) ErrorOnce {
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if errIn == nil {
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// don't execute this in a goroutine; save resources AND the caller
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// likely wants this executed ASAP because some of some operation
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// ordering semantics. forward() will not block here on a nil input
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// so this is safe to do.
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b.forward(nil)
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} else {
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go b.forward(errIn)
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}
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return b
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}
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func (b *errorOnce) forward(errIn <-chan error) {
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if errIn == nil {
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// important: nil never blocks; Report(nil) is guaranteed to be a
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// non-blocking operation.
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b.Report(nil)
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return
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}
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select {
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case err, _ := <-errIn:
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b.Report(err)
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case <-b.abort:
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// double-check that errIn was blocked: don't falsely return
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// errProcessTerminated if errIn was really ready
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select {
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case err, _ := <-errIn:
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b.Report(err)
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default:
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b.Report(errProcessTerminated)
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}
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}
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}
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func (b *errorOnce) WaitFor(d time.Duration) (error, bool) {
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t := time.NewTimer(d)
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select {
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case err, _ := <-b.err:
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t.Stop()
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return err, true
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case <-t.C:
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return nil, false
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}
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}
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