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Diffstat (limited to 'chromium/media/audio/cross_process_notification.h')
| -rw-r--r-- | chromium/media/audio/cross_process_notification.h | 172 |
1 files changed, 0 insertions, 172 deletions
diff --git a/chromium/media/audio/cross_process_notification.h b/chromium/media/audio/cross_process_notification.h deleted file mode 100644 index 16f2fc07fcf..00000000000 --- a/chromium/media/audio/cross_process_notification.h +++ /dev/null @@ -1,172 +0,0 @@ -// Copyright (c) 2012 The Chromium Authors. All rights reserved. -// Use of this source code is governed by a BSD-style license that can be -// found in the LICENSE file. - -#ifndef MEDIA_AUDIO_CROSS_PROCESS_NOTIFICATION_H_ -#define MEDIA_AUDIO_CROSS_PROCESS_NOTIFICATION_H_ - -#include <vector> - -#include "base/basictypes.h" -#include "base/process/process.h" -#include "base/threading/non_thread_safe.h" -#include "media/base/media_export.h" - -#if defined(OS_WIN) -#include "base/win/scoped_handle.h" -#else -#include "base/file_descriptor_posix.h" -#include "base/sync_socket.h" -#endif - -// A mechanism to synchronize access to a shared resource between two parties -// when the usage pattern resembles that of two players playing a game of chess. -// Each end has an instance of CrossProcessNotification and calls Signal() when -// it has finished using the shared resource. -// Before accessing the resource, it must call Wait() in order to know when the -// other end has called Signal(). -// -// Here's some pseudo code for how this class can be used: -// -// This method is used by both processes as it's a general way to use the -// shared resource and then grant the privilege to the other process: -// -// void WriteToSharedMemory(CrossProcessNotification* notification, -// SharedMemory* mem, -// const char my_char) { -// notification->Wait(); // Wait for the other process to yield access. -// reinterpret_cast<char*>(mem->memory())[0] = my_char; -// notification->Signal(); // Grant the other process access. -// } -// -// Process A: -// -// class A { -// public: -// void Initialize(base::ProcessHandle process_b) { -// mem_.CreateNamed("foo", false, 1024); -// -// CrossProcessNotification other; -// CHECK(CrossProcessNotification::InitializePair(¬ification_, &other)); -// CrossProcessNotification::IPCHandle handle_1, handle_2; -// CHECK(other.ShareToProcess(process_b, &handle_1, &handle_2)); -// // This could be implemented by using some IPC mechanism -// // such as MessageLoop. -// SendToProcessB(mem_, handle_1, handle_2); -// // Allow process B the first chance to write to the memory: -// notification_.Signal(); -// // Once B is done, we'll write 'A' to the shared memory. -// WriteToSharedMemory(¬ification_, &mem_, 'A'); -// } -// -// CrossProcessNotification notification_; -// SharedMemory mem_; -// }; -// -// Process B: -// -// class B { -// public: -// // Called when we receive the IPC message from A. -// void Initialize(SharedMemoryHandle mem, -// CrossProcessNotification::IPCHandle handle_1, -// CrossProcessNotification::IPCHandle handle_2) { -// mem_.reset(new SharedMemory(mem, false)); -// notification_.reset(new CrossProcessNotification(handle_1, handle_2)); -// WriteToSharedMemory(¬ification_, &mem_, 'B'); -// } -// -// CrossProcessNotification notification_; -// scoped_ptr<SharedMemory> mem_; -// }; -// -class MEDIA_EXPORT CrossProcessNotification { - public: -#if defined(OS_WIN) - typedef HANDLE IPCHandle; -#else - typedef base::FileDescriptor IPCHandle; -#endif - - typedef std::vector<CrossProcessNotification*> Notifications; - - // Default ctor. Initializes a NULL notification. User must call - // InitializePair() to initialize the instance along with a connected one. - CrossProcessNotification(); - - // Ctor for the user that does not call InitializePair but instead receives - // handles from the one that did. These handles come from a call to - // ShareToProcess. - CrossProcessNotification(IPCHandle handle_1, IPCHandle handle_2); - ~CrossProcessNotification(); - - // Raises a signal that the shared resource now can be accessed by the other - // party. - // NOTE: Calling Signal() more than once without calling Wait() in between - // is not a supported scenario and will result in undefined behavior (and - // different depending on platform). - void Signal(); - - // Waits for the other party to finish using the shared resource. - // NOTE: As with Signal(), you must not call Wait() more than once without - // calling Signal() in between. - void Wait(); - - bool IsValid() const; - - // Copies the internal handles to the output parameters, |handle_1| and - // |handle_2|. The operation can fail, so the caller must be prepared to - // handle that case. - bool ShareToProcess(base::ProcessHandle process, IPCHandle* handle_1, - IPCHandle* handle_2); - - // Initializes a pair of CrossProcessNotification instances. Note that this - // can fail (e.g. due to EMFILE on Linux). - static bool InitializePair(CrossProcessNotification* a, - CrossProcessNotification* b); - - // Use an instance of this class when you have to repeatedly wait for multiple - // notifications on the same thread. The class will store information about - // which notification was last signaled and try to distribute the signals so - // that all notifications get a chance to be processed in times of high load - // and a busy one won't starve the others. - // TODO(tommi): Support a way to abort the wait. - class MEDIA_EXPORT WaitForMultiple : - public NON_EXPORTED_BASE(base::NonThreadSafe) { - public: - // Caller must make sure that the lifetime of the array is greater than - // that of the WaitForMultiple instance. - explicit WaitForMultiple(const Notifications* notifications); - - // Waits for any of the notifications to be signaled. Returns the 0 based - // index of a signaled notification. - int Wait(); - - // Call when the array changes. This should be called on the same thread - // as Wait() is called on and the array must never change while a Wait() - // is in progress. - void Reset(const Notifications* notifications); - - private: - const Notifications* notifications_; - size_t wait_offset_; - }; - - private: - // Only called by the WaitForMultiple class. See documentation - // for WaitForMultiple and comments inside WaitMultiple for details. - static int WaitMultiple(const Notifications& notifications, - size_t wait_offset); - -#if defined(OS_WIN) - base::win::ScopedHandle mine_; - base::win::ScopedHandle other_; -#else - typedef base::CancelableSyncSocket SocketClass; - SocketClass socket_; -#endif - - DISALLOW_COPY_AND_ASSIGN(CrossProcessNotification); -}; - -#endif // MEDIA_AUDIO_CROSS_PROCESS_NOTIFICATION_H_ |