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: #ifndef mozilla_CrossProcessMutex_h
michael@0: #define mozilla_CrossProcessMutex_h
michael@0: 
michael@0: #include "base/process.h"
michael@0: #include "mozilla/Mutex.h"
michael@0: 
michael@0: #if defined(OS_LINUX)
michael@0: #include <pthread.h>
michael@0: #include "SharedMemoryBasic.h"
michael@0: #include "mozilla/Atomics.h"
michael@0: #endif
michael@0: 
michael@0: namespace IPC {
michael@0: template<typename T>
michael@0: struct ParamTraits;
michael@0: }
michael@0: 
michael@0: //
michael@0: // Provides:
michael@0: //
michael@0: //  - CrossProcessMutex, a non-recursive mutex that can be shared across processes
michael@0: //  - CrossProcessMutexAutoLock, an RAII class for ensuring that Mutexes are
michael@0: //    properly locked and unlocked
michael@0: //
michael@0: // Using CrossProcessMutexAutoLock/CrossProcessMutexAutoUnlock is MUCH
michael@0: // preferred to making bare calls to CrossProcessMutex.Lock and Unlock.
michael@0: //
michael@0: namespace mozilla {
michael@0: #ifdef XP_WIN
michael@0: typedef HANDLE CrossProcessMutexHandle;
michael@0: #elif defined(OS_LINUX)
michael@0: typedef mozilla::ipc::SharedMemoryBasic::Handle CrossProcessMutexHandle;
michael@0: #else
michael@0: // Stub for other platforms. We can't use uintptr_t here since different
michael@0: // processes could disagree on its size.
michael@0: typedef uintptr_t CrossProcessMutexHandle;
michael@0: #endif
michael@0: 
michael@0: class NS_COM_GLUE CrossProcessMutex
michael@0: {
michael@0: public:
michael@0:   /**
michael@0:    * CrossProcessMutex
michael@0:    * @param name A name which can reference this lock (currently unused)
michael@0:    **/
michael@0:   CrossProcessMutex(const char* aName);
michael@0:   /**
michael@0:    * CrossProcessMutex
michael@0:    * @param handle A handle of an existing cross process mutex that can be
michael@0:    *               opened.
michael@0:    */
michael@0:   CrossProcessMutex(CrossProcessMutexHandle aHandle);
michael@0: 
michael@0:   /**
michael@0:    * ~CrossProcessMutex
michael@0:    **/
michael@0:   ~CrossProcessMutex();
michael@0: 
michael@0:   /**
michael@0:    * Lock
michael@0:    * This will lock the mutex. Any other thread in any other process that
michael@0:    * has access to this mutex calling lock will block execution until the
michael@0:    * initial caller of lock has made a call to Unlock.
michael@0:    *
michael@0:    * If the owning process is terminated unexpectedly the mutex will be
michael@0:    * released.
michael@0:    **/
michael@0:   void Lock();
michael@0: 
michael@0:   /**
michael@0:    * Unlock
michael@0:    * This will unlock the mutex. A single thread currently waiting on a lock
michael@0:    * call will resume execution and aquire ownership of the lock. No
michael@0:    * guarantees are made as to the order in which waiting threads will resume
michael@0:    * execution.
michael@0:    **/
michael@0:   void Unlock();
michael@0: 
michael@0:   /**
michael@0:    * ShareToProcess
michael@0:    * This function is called to generate a serializable structure that can
michael@0:    * be sent to the specified process and opened on the other side.
michael@0:    *
michael@0:    * @returns A handle that can be shared to another process
michael@0:    */
michael@0:   CrossProcessMutexHandle ShareToProcess(base::ProcessHandle aTarget);
michael@0: 
michael@0: private:
michael@0:   friend struct IPC::ParamTraits<CrossProcessMutex>;
michael@0: 
michael@0:   CrossProcessMutex();
michael@0:   CrossProcessMutex(const CrossProcessMutex&);
michael@0:   CrossProcessMutex &operator=(const CrossProcessMutex&);
michael@0: 
michael@0: #ifdef XP_WIN
michael@0:   HANDLE mMutex;
michael@0: #elif defined(OS_LINUX)
michael@0:   mozilla::ipc::SharedMemoryBasic* mSharedBuffer;
michael@0:   pthread_mutex_t* mMutex;
michael@0:   mozilla::Atomic<int32_t>* mCount;
michael@0: #endif
michael@0: };
michael@0: 
michael@0: typedef BaseAutoLock<CrossProcessMutex> CrossProcessMutexAutoLock;
michael@0: typedef BaseAutoUnlock<CrossProcessMutex> CrossProcessMutexAutoUnlock;
michael@0: 
michael@0: }
michael@0: #endif