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