120 lines
2.9 KiB
Go
120 lines
2.9 KiB
Go
/*
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Copyright 2015 The Kubernetes Authors.
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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 threading
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import (
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"os"
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"sync"
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"time"
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"github.com/golang/glog"
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)
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type rwMutexToLockableAdapter struct {
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rw *sync.RWMutex
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}
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func (r *rwMutexToLockableAdapter) Lock() {
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r.rw.RLock()
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}
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func (r *rwMutexToLockableAdapter) Unlock() {
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r.rw.RUnlock()
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}
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type deadlockDetector struct {
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name string
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lock sync.Locker
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maxLockPeriod time.Duration
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exiter exiter
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exitChannelFn func() <-chan time.Time
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// Really only useful for testing
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stopChannel <-chan bool
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}
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// DeadlockWatchdogReadLock creates a watchdog on read/write mutex. If the mutex can not be acquired
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// for read access within 'maxLockPeriod', the program exits via glog.Exitf() or os.Exit() if that fails
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// 'name' is a semantic name that is useful for the user and is printed on exit.
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func DeadlockWatchdogReadLock(lock *sync.RWMutex, name string, maxLockPeriod time.Duration) {
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DeadlockWatchdog(&rwMutexToLockableAdapter{lock}, name, maxLockPeriod)
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}
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func DeadlockWatchdog(lock sync.Locker, name string, maxLockPeriod time.Duration) {
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if maxLockPeriod <= 0 {
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panic("maxLockPeriod is <= 0, that can't be what you wanted")
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}
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detector := &deadlockDetector{
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lock: lock,
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name: name,
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maxLockPeriod: maxLockPeriod,
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exitChannelFn: func() <-chan time.Time { return time.After(maxLockPeriod) },
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stopChannel: make(chan bool),
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}
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go detector.run()
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}
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// Useful for injecting tests
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type exiter interface {
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Exitf(format string, args ...interface{})
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}
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type realExiter struct{}
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func (realExiter) Exitf(format string, args ...interface{}) {
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func() {
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defer func() {
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// Let's just be extra sure we die, even if Exitf panics
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if r := recover(); r != nil {
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glog.Errorf(format, args...)
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os.Exit(2)
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}
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}()
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glog.Exitf(format, args...)
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}()
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}
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func (d *deadlockDetector) run() {
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for {
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if !d.runOnce() {
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return
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}
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time.Sleep(d.maxLockPeriod / 2)
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}
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}
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func (d *deadlockDetector) runOnce() bool {
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ch := make(chan bool, 1)
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go func() {
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d.lock.Lock()
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d.lock.Unlock()
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ch <- true
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}()
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exitCh := d.exitChannelFn()
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select {
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case <-exitCh:
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d.exiter.Exitf("Deadlock on %s, exiting", d.name)
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// return is here for when we use a fake exiter in testing
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return false
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case <-ch:
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glog.V(6).Infof("%s is not deadlocked", d.name)
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case <-d.stopChannel:
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glog.V(4).Infof("Stopping deadlock detector for %s", d.name)
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return false
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}
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return true
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}
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