forked from mirrors/gecko-dev
118 lines
3.2 KiB
C++
118 lines
3.2 KiB
C++
/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
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/* vim: set ts=8 sts=2 et sw=2 tw=80: */
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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_CrossProcessSemaphore_h
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#define mozilla_CrossProcessSemaphore_h
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#include "base/process.h"
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#include "mozilla/TimeStamp.h"
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#include "mozilla/Maybe.h"
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#if defined(OS_WIN)
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# include "mozilla/UniquePtrExtensions.h"
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#endif
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#if !defined(OS_WIN) && !defined(OS_MACOSX)
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# include <pthread.h>
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# include <semaphore.h>
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# include "mozilla/ipc/SharedMemoryBasic.h"
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# include "mozilla/Atomics.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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} // namespace IPC
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//
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// Provides:
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//
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// - CrossProcessSemaphore, a semaphore that can be shared across processes
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namespace mozilla {
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template <typename T>
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inline bool IsHandleValid(const T& handle) {
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return bool(handle);
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}
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#if defined(OS_WIN)
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typedef mozilla::UniqueFileHandle CrossProcessSemaphoreHandle;
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#elif !defined(OS_MACOSX)
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typedef mozilla::ipc::SharedMemoryBasic::Handle CrossProcessSemaphoreHandle;
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template <>
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inline bool IsHandleValid<CrossProcessSemaphoreHandle>(
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const CrossProcessSemaphoreHandle& handle) {
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return !(handle == mozilla::ipc::SharedMemoryBasic::NULLHandle());
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}
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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 CrossProcessSemaphoreHandle;
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#endif
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class CrossProcessSemaphore {
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public:
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/**
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* CrossProcessSemaphore
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* @param name A name which can reference this lock (currently unused)
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**/
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static CrossProcessSemaphore* Create(const char* aName,
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uint32_t aInitialValue);
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/**
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* CrossProcessSemaphore
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* @param handle A handle of an existing cross process semaphore that can be
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* opened.
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*/
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static CrossProcessSemaphore* Create(CrossProcessSemaphoreHandle aHandle);
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~CrossProcessSemaphore();
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/**
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* Decrements the current value of the semaphore. This will block if the
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* current value of the semaphore is 0, up to a maximum of aWaitTime (if
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* specified).
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* Returns true if the semaphore was succesfully decremented, false otherwise.
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**/
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bool Wait(const Maybe<TimeDuration>& aWaitTime = Nothing());
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/**
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* Increments the current value of the semaphore.
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**/
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void Signal();
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/**
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* CloneHandle
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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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CrossProcessSemaphoreHandle CloneHandle();
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void CloseHandle();
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private:
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friend struct IPC::ParamTraits<CrossProcessSemaphore>;
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CrossProcessSemaphore();
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CrossProcessSemaphore(const CrossProcessSemaphore&);
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CrossProcessSemaphore& operator=(const CrossProcessSemaphore&);
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#if defined(OS_WIN)
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explicit CrossProcessSemaphore(HANDLE aSemaphore);
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HANDLE mSemaphore;
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#elif !defined(OS_MACOSX)
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RefPtr<mozilla::ipc::SharedMemoryBasic> mSharedBuffer;
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sem_t* mSemaphore;
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mozilla::Atomic<int32_t>* mRefCount;
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#endif
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};
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} // namespace mozilla
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#endif
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