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util.go
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/
util.go
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// Copyright (C) 2014 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at https://mozilla.org/MPL/2.0/.
package model
import (
"fmt"
"sync"
"time"
)
type Holdable interface {
Holders() string
}
func newDeadlockDetector(timeout time.Duration) *deadlockDetector {
return &deadlockDetector{
timeout: timeout,
lockers: make(map[string]sync.Locker),
}
}
type deadlockDetector struct {
timeout time.Duration
lockers map[string]sync.Locker
}
func (d *deadlockDetector) Watch(name string, mut sync.Locker) {
d.lockers[name] = mut
go func() {
for {
time.Sleep(d.timeout / 4)
ok := make(chan bool, 2)
go func() {
mut.Lock()
_ = 1 // empty critical section
mut.Unlock()
ok <- true
}()
go func() {
time.Sleep(d.timeout)
ok <- false
}()
if r := <-ok; !r {
msg := fmt.Sprintf("deadlock detected at %s", name)
for otherName, otherMut := range d.lockers {
if otherHolder, ok := otherMut.(Holdable); ok {
msg += "\n===" + otherName + "===\n" + otherHolder.Holders()
}
}
panic(msg)
}
}
}()
}