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/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
* 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 "CrossProcessMutex.h"
#include "mozilla/unused.h"
#include "nsDebug.h"
#include "nsISupportsImpl.h"
namespace {
struct MutexData {
pthread_mutex_t mMutex;
mozilla::Atomic<int32_t> mCount;
};
}
namespace mozilla {
CrossProcessMutex::CrossProcessMutex(const char*)
: mSharedBuffer(nullptr)
, mMutex(nullptr)
, mCount(nullptr)
{
mSharedBuffer = new ipc::SharedMemoryBasic;
if (!mSharedBuffer->Create(sizeof(MutexData))) {
MOZ_CRASH();
}
if (!mSharedBuffer->Map(sizeof(MutexData))) {
MOZ_CRASH();
}
MutexData* data = static_cast<MutexData*>(mSharedBuffer->memory());
if (!data) {
MOZ_CRASH();
}
mMutex = &(data->mMutex);
mCount = &(data->mCount);
*mCount = 1;
pthread_mutexattr_t mutexAttributes;
pthread_mutexattr_init(&mutexAttributes);
// Make the mutex reentrant so it behaves the same as a win32 mutex
if (pthread_mutexattr_settype(&mutexAttributes, PTHREAD_MUTEX_RECURSIVE)) {
MOZ_CRASH();
}
if (pthread_mutexattr_setpshared(&mutexAttributes, PTHREAD_PROCESS_SHARED)) {
MOZ_CRASH();
}
if (pthread_mutex_init(mMutex, &mutexAttributes)) {
MOZ_CRASH();
}
MOZ_COUNT_CTOR(CrossProcessMutex);
}
CrossProcessMutex::CrossProcessMutex(CrossProcessMutexHandle aHandle)
: mSharedBuffer(nullptr)
, mMutex(nullptr)
, mCount(nullptr)
{
if (!ipc::SharedMemoryBasic::IsHandleValid(aHandle)) {
MOZ_CRASH();
}
mSharedBuffer = new ipc::SharedMemoryBasic(aHandle);
if (!mSharedBuffer->Map(sizeof(MutexData))) {
MOZ_CRASH();
}
MutexData* data = static_cast<MutexData*>(mSharedBuffer->memory());
if (!data) {
MOZ_CRASH();
}
mMutex = &(data->mMutex);
mCount = &(data->mCount);
(*mCount)++;
MOZ_COUNT_CTOR(CrossProcessMutex);
}
CrossProcessMutex::~CrossProcessMutex()
{
int32_t count = --(*mCount);
if (count == 0) {
// Nothing can be done if the destroy fails so ignore return code.
unused << pthread_mutex_destroy(mMutex);
}
delete mSharedBuffer;
MOZ_COUNT_DTOR(CrossProcessMutex);
}
void
CrossProcessMutex::Lock()
{
MOZ_ASSERT(*mCount > 0, "Attempting to lock mutex with zero ref count");
pthread_mutex_lock(mMutex);
}
void
CrossProcessMutex::Unlock()
{
MOZ_ASSERT(*mCount > 0, "Attempting to unlock mutex with zero ref count");
pthread_mutex_unlock(mMutex);
}
CrossProcessMutexHandle
CrossProcessMutex::ShareToProcess(base::ProcessHandle aHandle)
{
CrossProcessMutexHandle result = ipc::SharedMemoryBasic::NULLHandle();
if (mSharedBuffer && !mSharedBuffer->ShareToProcess(aHandle, &result)) {
MOZ_CRASH();
}
return result;
}
}
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