gecko-dev/ipc/glue/CrossProcessSemaphore.h

104 строки
2.8 KiB
C++

/* -*- 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_CrossProcessSemaphore_h
#define mozilla_CrossProcessSemaphore_h
#include "base/process.h"
#include "mozilla/TimeStamp.h"
#include "mozilla/Maybe.h"
#if !defined(OS_WIN) && !defined(OS_MACOSX)
#include <pthread.h>
#include <semaphore.h>
#include "SharedMemoryBasic.h"
#include "mozilla/Atomics.h"
#endif
namespace IPC {
template<typename T>
struct ParamTraits;
} // namespace IPC
//
// Provides:
//
// - CrossProcessSemaphore, a semaphore that can be shared across processes
namespace mozilla {
#if defined(OS_WIN)
typedef HANDLE CrossProcessSemaphoreHandle;
#elif !defined(OS_MACOSX)
typedef mozilla::ipc::SharedMemoryBasic::Handle CrossProcessSemaphoreHandle;
#else
// Stub for other platforms. We can't use uintptr_t here since different
// processes could disagree on its size.
typedef uintptr_t CrossProcessSemaphoreHandle;
#endif
class CrossProcessSemaphore
{
public:
/**
* CrossProcessSemaphore
* @param name A name which can reference this lock (currently unused)
**/
static CrossProcessSemaphore* Create(const char* aName, uint32_t aInitialValue);
/**
* CrossProcessSemaphore
* @param handle A handle of an existing cross process semaphore that can be
* opened.
*/
static CrossProcessSemaphore* Create(CrossProcessSemaphoreHandle aHandle);
~CrossProcessSemaphore();
/**
* Decrements the current value of the semaphore. This will block if the
* current value of the semaphore is 0, up to a maximum of aWaitTime (if
* specified).
* Returns true if the semaphore was succesfully decremented, false otherwise.
**/
bool Wait(const Maybe<TimeDuration>& aWaitTime = Nothing());
/**
* Increments the current value of the semaphore.
**/
void Signal();
/**
* ShareToProcess
* 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
*/
CrossProcessSemaphoreHandle ShareToProcess(base::ProcessId aTargetPid);
void CloseHandle();
private:
friend struct IPC::ParamTraits<CrossProcessSemaphore>;
CrossProcessSemaphore();
CrossProcessSemaphore(const CrossProcessSemaphore&);
CrossProcessSemaphore &operator=(const CrossProcessSemaphore&);
#if defined(OS_WIN)
explicit CrossProcessSemaphore(HANDLE aSemaphore);
HANDLE mSemaphore;
#elif !defined(OS_MACOSX)
RefPtr<mozilla::ipc::SharedMemoryBasic> mSharedBuffer;
sem_t* mSemaphore;
mozilla::Atomic<int32_t>* mRefCount;
#endif
};
} // namespace mozilla
#endif