зеркало из https://github.com/mozilla/gecko-dev.git
153 строки
3.4 KiB
C++
153 строки
3.4 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
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* This Source Code Form is subject to the terms of the Mozilla Public
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* License, v. 2.0. If a copy of the MPL was not distributed with this
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* file, You can obtain one at http://mozilla.org/MPL/2.0/. */
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#include "CrossProcessMutex.h"
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#include "mozilla/unused.h"
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#include "nsDebug.h"
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#include "nsISupportsImpl.h"
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#ifdef OS_MACOSX
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#include "nsCocoaFeatures.h"
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#endif
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namespace {
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struct MutexData {
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pthread_mutex_t mMutex;
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mozilla::Atomic<int32_t> mCount;
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};
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} // namespace
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namespace mozilla {
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static void
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InitMutex(pthread_mutex_t* mMutex)
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{
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pthread_mutexattr_t mutexAttributes;
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pthread_mutexattr_init(&mutexAttributes);
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// Make the mutex reentrant so it behaves the same as a win32 mutex
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if (pthread_mutexattr_settype(&mutexAttributes, PTHREAD_MUTEX_RECURSIVE)) {
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MOZ_CRASH();
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}
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if (pthread_mutexattr_setpshared(&mutexAttributes, PTHREAD_PROCESS_SHARED)) {
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MOZ_CRASH();
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}
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if (pthread_mutex_init(mMutex, &mutexAttributes)) {
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MOZ_CRASH();
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}
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}
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CrossProcessMutex::CrossProcessMutex(const char*)
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: mMutex(nullptr)
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, mCount(nullptr)
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{
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#ifdef OS_MACOSX
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if (!nsCocoaFeatures::OnLionOrLater()) {
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// Don't allow using the cross-process mutex before OS X 10.7 because it
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// probably doesn't work very well. See discussion in bug 1072093 for more
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// details.
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MOZ_CRASH();
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}
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#endif
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mSharedBuffer = new ipc::SharedMemoryBasic;
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if (!mSharedBuffer->Create(sizeof(MutexData))) {
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MOZ_CRASH();
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}
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if (!mSharedBuffer->Map(sizeof(MutexData))) {
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MOZ_CRASH();
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}
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MutexData* data = static_cast<MutexData*>(mSharedBuffer->memory());
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if (!data) {
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MOZ_CRASH();
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}
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mMutex = &(data->mMutex);
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mCount = &(data->mCount);
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*mCount = 1;
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InitMutex(mMutex);
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MOZ_COUNT_CTOR(CrossProcessMutex);
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}
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CrossProcessMutex::CrossProcessMutex(CrossProcessMutexHandle aHandle)
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: mMutex(nullptr)
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, mCount(nullptr)
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{
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if (!ipc::SharedMemoryBasic::IsHandleValid(aHandle)) {
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MOZ_CRASH();
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}
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mSharedBuffer = new ipc::SharedMemoryBasic(aHandle);
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if (!mSharedBuffer->Map(sizeof(MutexData))) {
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MOZ_CRASH();
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}
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MutexData* data = static_cast<MutexData*>(mSharedBuffer->memory());
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if (!data) {
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MOZ_CRASH();
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}
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mMutex = &(data->mMutex);
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mCount = &(data->mCount);
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int32_t count = (*mCount)++;
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if (count == 0) {
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// The other side has already let go of their CrossProcessMutex, so now
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// mMutex is garbage. We need to re-initialize it.
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InitMutex(mMutex);
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}
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MOZ_COUNT_CTOR(CrossProcessMutex);
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}
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CrossProcessMutex::~CrossProcessMutex()
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{
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int32_t count = --(*mCount);
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if (count == 0) {
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// Nothing can be done if the destroy fails so ignore return code.
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unused << pthread_mutex_destroy(mMutex);
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}
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MOZ_COUNT_DTOR(CrossProcessMutex);
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}
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void
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CrossProcessMutex::Lock()
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{
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MOZ_ASSERT(*mCount > 0, "Attempting to lock mutex with zero ref count");
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pthread_mutex_lock(mMutex);
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}
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void
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CrossProcessMutex::Unlock()
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{
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MOZ_ASSERT(*mCount > 0, "Attempting to unlock mutex with zero ref count");
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pthread_mutex_unlock(mMutex);
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}
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CrossProcessMutexHandle
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CrossProcessMutex::ShareToProcess(base::ProcessId aTargetPid)
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{
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CrossProcessMutexHandle result = ipc::SharedMemoryBasic::NULLHandle();
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if (mSharedBuffer && !mSharedBuffer->ShareToProcess(aTargetPid, &result)) {
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MOZ_CRASH();
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}
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return result;
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}
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} // namespace mozilla
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