michael@0: /* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*-
michael@0:  * This Source Code Form is subject to the terms of the Mozilla Public
michael@0:  * License, v. 2.0. If a copy of the MPL was not distributed with this
michael@0:  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
michael@0: 
michael@0: #include "CrossProcessMutex.h"
michael@0: #include "mozilla/unused.h"
michael@0: #include "nsDebug.h"
michael@0: #include "nsISupportsImpl.h"
michael@0: 
michael@0: namespace {
michael@0: 
michael@0: struct MutexData {
michael@0:   pthread_mutex_t mMutex;
michael@0:   mozilla::Atomic<int32_t> mCount;
michael@0: };
michael@0: 
michael@0: }
michael@0: 
michael@0: namespace mozilla {
michael@0: 
michael@0: CrossProcessMutex::CrossProcessMutex(const char*)
michael@0:     : mSharedBuffer(nullptr)
michael@0:     , mMutex(nullptr)
michael@0:     , mCount(nullptr)
michael@0: {
michael@0:   mSharedBuffer = new ipc::SharedMemoryBasic;
michael@0:   if (!mSharedBuffer->Create(sizeof(MutexData))) {
michael@0:     MOZ_CRASH();
michael@0:   }
michael@0: 
michael@0:   if (!mSharedBuffer->Map(sizeof(MutexData))) {
michael@0:     MOZ_CRASH();
michael@0:   }
michael@0: 
michael@0:   MutexData* data = static_cast<MutexData*>(mSharedBuffer->memory());
michael@0: 
michael@0:   if (!data) {
michael@0:     MOZ_CRASH();
michael@0:   }
michael@0: 
michael@0:   mMutex = &(data->mMutex);
michael@0:   mCount = &(data->mCount);
michael@0: 
michael@0:   *mCount = 1;
michael@0: 
michael@0:   pthread_mutexattr_t mutexAttributes;
michael@0:   pthread_mutexattr_init(&mutexAttributes);
michael@0:   // Make the mutex reentrant so it behaves the same as a win32 mutex
michael@0:   if (pthread_mutexattr_settype(&mutexAttributes, PTHREAD_MUTEX_RECURSIVE)) {
michael@0:     MOZ_CRASH();
michael@0:   }
michael@0:   if (pthread_mutexattr_setpshared(&mutexAttributes, PTHREAD_PROCESS_SHARED)) {
michael@0:     MOZ_CRASH();
michael@0:   }
michael@0: 
michael@0:   if (pthread_mutex_init(mMutex, &mutexAttributes)) {
michael@0:     MOZ_CRASH();
michael@0:   }
michael@0: 
michael@0:   MOZ_COUNT_CTOR(CrossProcessMutex);
michael@0: }
michael@0: 
michael@0: CrossProcessMutex::CrossProcessMutex(CrossProcessMutexHandle aHandle)
michael@0:     : mSharedBuffer(nullptr)
michael@0:     , mMutex(nullptr)
michael@0:     , mCount(nullptr)
michael@0: {
michael@0:   if (!ipc::SharedMemoryBasic::IsHandleValid(aHandle)) {
michael@0:     MOZ_CRASH();
michael@0:   }
michael@0: 
michael@0:   mSharedBuffer = new ipc::SharedMemoryBasic(aHandle);
michael@0: 
michael@0:   if (!mSharedBuffer->Map(sizeof(MutexData))) {
michael@0:     MOZ_CRASH();
michael@0:   }
michael@0: 
michael@0:   MutexData* data = static_cast<MutexData*>(mSharedBuffer->memory());
michael@0: 
michael@0:   if (!data) {
michael@0:     MOZ_CRASH();
michael@0:   }
michael@0: 
michael@0:   mMutex = &(data->mMutex);
michael@0:   mCount = &(data->mCount);
michael@0:   (*mCount)++;
michael@0: 
michael@0:   MOZ_COUNT_CTOR(CrossProcessMutex);
michael@0: }
michael@0: 
michael@0: CrossProcessMutex::~CrossProcessMutex()
michael@0: {
michael@0:   int32_t count = --(*mCount);
michael@0: 
michael@0:   if (count == 0) {
michael@0:     // Nothing can be done if the destroy fails so ignore return code.
michael@0:     unused << pthread_mutex_destroy(mMutex);
michael@0:   }
michael@0: 
michael@0:   delete mSharedBuffer;
michael@0:   MOZ_COUNT_DTOR(CrossProcessMutex);
michael@0: }
michael@0: 
michael@0: void
michael@0: CrossProcessMutex::Lock()
michael@0: {
michael@0:   MOZ_ASSERT(*mCount > 0, "Attempting to lock mutex with zero ref count");
michael@0:   pthread_mutex_lock(mMutex);
michael@0: }
michael@0: 
michael@0: void
michael@0: CrossProcessMutex::Unlock()
michael@0: {
michael@0:   MOZ_ASSERT(*mCount > 0, "Attempting to unlock mutex with zero ref count");
michael@0:   pthread_mutex_unlock(mMutex);
michael@0: }
michael@0: 
michael@0: CrossProcessMutexHandle
michael@0: CrossProcessMutex::ShareToProcess(base::ProcessHandle aHandle)
michael@0: {
michael@0:   CrossProcessMutexHandle result = ipc::SharedMemoryBasic::NULLHandle();
michael@0: 
michael@0:   if (mSharedBuffer && !mSharedBuffer->ShareToProcess(aHandle, &result)) {
michael@0:     MOZ_CRASH();
michael@0:   }
michael@0: 
michael@0:   return result;
michael@0: }
michael@0: 
michael@0: }