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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
/* vim: set ts=8 sts=2 et sw=2 tw=80: */
/* 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 http://mozilla.org/MPL/2.0/. */
#include "threading/Mutex.h"
using namespace js;
#ifdef DEBUG
MOZ_THREAD_LOCAL(js::Mutex*) js::Mutex::HeldMutexStack;
/* static */
bool js::Mutex::Init() { return HeldMutexStack.init(); }
void js::Mutex::lock() {
preLockChecks();
impl_.lock();
postLockChecks();
}
bool js::Mutex::tryLock() {
preLockChecks();
if (!impl_.tryLock()) {
return false;
}
postLockChecks();
return true;
}
void js::Mutex::preLockChecks() const {
Mutex* prev = HeldMutexStack.get();
if (prev) {
if (id_.order <= prev->id_.order) {
fprintf(stderr,
"Attempt to acquire mutex %s with order %u while holding %s with "
"order %u\n",
id_.name, id_.order, prev->id_.name, prev->id_.order);
MOZ_CRASH("Mutex ordering violation");
}
}
}
void js::Mutex::postLockChecks() {
MOZ_ASSERT(!owningThread_);
owningThread_ = ThreadId::ThisThreadId();
MOZ_ASSERT(prev_ == nullptr);
prev_ = HeldMutexStack.get();
HeldMutexStack.set(this);
}
void js::Mutex::unlock() {
preUnlockChecks();
impl_.unlock();
}
void js::Mutex::preUnlockChecks() {
Mutex* stack = HeldMutexStack.get();
MOZ_ASSERT(stack == this);
HeldMutexStack.set(prev_);
prev_ = nullptr;
MOZ_ASSERT(ThreadId::ThisThreadId() == owningThread_);
owningThread_ = ThreadId();
}
void js::Mutex::assertOwnedByCurrentThread() const {
// This check is only thread-safe if it succeeds.
MOZ_ASSERT(ThreadId::ThisThreadId() == owningThread_);
// Check the mutex is on the mutex stack.
for (Mutex* mutex = HeldMutexStack.get(); mutex; mutex = mutex->prev_) {
if (mutex == this) {
return;
}
}
MOZ_CRASH("Mutex not found on the stack of held mutexes");
}
#endif
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