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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/. */
#ifndef mozilla_CrossProcessMutex_h
#define mozilla_CrossProcessMutex_h
#include "base/process.h"
#include "mozilla/Mutex.h"
#if defined(XP_WIN)
# include "mozilla/UniquePtrExtensions.h"
#endif
#if !defined(XP_WIN) && !defined(XP_NETBSD) && !defined(XP_OPENBSD)
# include <pthread.h>
# include "mozilla/ipc/SharedMemoryMapping.h"
# include "mozilla/Atomics.h"
#endif
namespace IPC {
template <typename T>
struct ParamTraits;
} // namespace IPC
//
// Provides:
//
// - CrossProcessMutex, a non-recursive mutex that can be shared across
// processes
// - CrossProcessMutexAutoLock, an RAII class for ensuring that Mutexes are
// properly locked and unlocked
//
// Using CrossProcessMutexAutoLock/CrossProcessMutexAutoUnlock is MUCH
// preferred to making bare calls to CrossProcessMutex.Lock and Unlock.
//
namespace mozilla {
#if defined(XP_WIN)
typedef mozilla::UniqueFileHandle CrossProcessMutexHandle;
#elif !defined(XP_NETBSD) && !defined(XP_OPENBSD)
typedef mozilla::ipc::MutableSharedMemoryHandle CrossProcessMutexHandle;
#else
// Stub for other platforms. We can't use uintptr_t here since different
// processes could disagree on its size.
typedef uintptr_t CrossProcessMutexHandle;
#endif
class CrossProcessMutex {
public:
/**
* CrossProcessMutex
* @param name A name which can reference this lock (currently unused)
**/
explicit CrossProcessMutex(const char* aName);
/**
* CrossProcessMutex
* @param handle A handle of an existing cross process mutex that can be
* opened.
*/
explicit CrossProcessMutex(CrossProcessMutexHandle aHandle);
/**
* ~CrossProcessMutex
**/
~CrossProcessMutex();
/**
* Lock
* This will lock the mutex. Any other thread in any other process that
* has access to this mutex calling lock will block execution until the
* initial caller of lock has made a call to Unlock.
*
* If the owning process is terminated unexpectedly the mutex will be
* released.
**/
void Lock();
/**
* Unlock
* This will unlock the mutex. A single thread currently waiting on a lock
* call will resume execution and aquire ownership of the lock. No
* guarantees are made as to the order in which waiting threads will resume
* execution.
**/
void Unlock();
/**
* CloneHandle
* This function is called to generate a serializable structure that can
* be sent to the specified process and opened on the other side.
*
* @returns A handle that can be shared to another process
*/
CrossProcessMutexHandle CloneHandle();
private:
friend struct IPC::ParamTraits<CrossProcessMutex>;
CrossProcessMutex();
CrossProcessMutex(const CrossProcessMutex&);
CrossProcessMutex& operator=(const CrossProcessMutex&);
#if defined(XP_WIN)
HANDLE mMutex;
#elif !defined(XP_NETBSD) && !defined(XP_OPENBSD)
mozilla::ipc::SharedMemoryMappingWithHandle mSharedBuffer;
pthread_mutex_t* mMutex;
mozilla::Atomic<int32_t>* mCount;
#endif
};
typedef detail::BaseAutoLock<CrossProcessMutex&> CrossProcessMutexAutoLock;
typedef detail::BaseAutoUnlock<CrossProcessMutex&> CrossProcessMutexAutoUnlock;
} // namespace mozilla
#endif
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