import FIREFOX_52_6_0esr_RELEASE from mozilla-esr52 hg repo

dom/media/systemservices/CamerasChild.h

@@ -0,0 +1,250 @@
+/* -*- Mode: C++; tab-width: 8; indent-tabs-mode: nil; c-basic-offset: 2 -*- */
+/* vim: set sw=2 ts=8 et ft=cpp : */
+/* 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_CamerasChild_h
+#define mozilla_CamerasChild_h
+
+#include "mozilla/Move.h"
+#include "mozilla/Pair.h"
+#include "mozilla/dom/ContentChild.h"
+#include "mozilla/camera/PCamerasChild.h"
+#include "mozilla/camera/PCamerasParent.h"
+#include "mozilla/media/DeviceChangeCallback.h"
+#include "mozilla/Mutex.h"
+#include "base/singleton.h"
+#include "nsCOMPtr.h"
+
+// conflicts with #include of scoped_ptr.h
+#undef FF
+#include "webrtc/common.h"
+// Video Engine
+#include "webrtc/video_engine/include/vie_base.h"
+#include "webrtc/video_engine/include/vie_capture.h"
+#include "webrtc/video_engine/include/vie_render.h"
+
+namespace mozilla {
+
+namespace ipc {
+class BackgroundChildImpl;
+}
+
+namespace camera {
+
+struct CapturerElement {
+  CaptureEngine engine;
+  int id;
+  webrtc::ExternalRenderer* callback;
+};
+
+// Forward declaration so we can work with pointers to it.
+class CamerasChild;
+// Helper class in impl that we friend.
+template <class T> class LockAndDispatch;
+
+// We emulate the sync webrtc.org API with the help of singleton
+// CamerasSingleton, which manages a pointer to an IPC object, a thread
+// where IPC operations should run on, and a mutex.
+// The static function Cameras() will use that Singleton to set up,
+// if needed, both the thread and the associated IPC objects and return
+// a pointer to the IPC object. Users can then do IPC calls on that object
+// after dispatching them to aforementioned thread.
+
+// 2 Threads are involved in this code:
+// - the MediaManager thread, which will call the (static, sync API) functions
+//   through MediaEngineRemoteVideoSource
+// - the Cameras IPC thread, which will be doing our IPC to the parent process
+//   via PBackground
+
+// Our main complication is that we emulate a sync API while (having to do)
+// async messaging. We dispatch the messages to another thread to send them
+// async and hold a Monitor to wait for the result to be asynchronously received
+// again. The requirement for async messaging originates on the parent side:
+// it's not reasonable to block all PBackground IPC there while waiting for
+// something like device enumeration to complete.
+
+class CamerasSingleton {
+public:
+  CamerasSingleton();
+  ~CamerasSingleton();
+
+  static OffTheBooksMutex& Mutex() {
+    return gTheInstance.get()->mCamerasMutex;
+  }
+
+  static CamerasChild*& Child() {
+    Mutex().AssertCurrentThreadOwns();
+    return gTheInstance.get()->mCameras;
+  }
+
+  static nsCOMPtr<nsIThread>& Thread() {
+    Mutex().AssertCurrentThreadOwns();
+    return gTheInstance.get()->mCamerasChildThread;
+  }
+
+  static nsCOMPtr<nsIThread>& FakeDeviceChangeEventThread() {
+    Mutex().AssertCurrentThreadOwns();
+    return gTheInstance.get()->mFakeDeviceChangeEventThread;
+  }
+
+private:
+  static Singleton<CamerasSingleton> gTheInstance;
+
+  // Reinitializing CamerasChild will change the pointers below.
+  // We don't want this to happen in the middle of preparing IPC.
+  // We will be alive on destruction, so this needs to be off the books.
+  mozilla::OffTheBooksMutex mCamerasMutex;
+
+  // This is owned by the IPC code, and the same code controls the lifetime.
+  // It will set and clear this pointer as appropriate in setup/teardown.
+  // We'd normally make this a WeakPtr but unfortunately the IPC code already
+  // uses the WeakPtr mixin in a protected base class of CamerasChild, and in
+  // any case the object becomes unusable as soon as IPC is tearing down, which
+  // will be before actual destruction.
+  CamerasChild* mCameras;
+  nsCOMPtr<nsIThread> mCamerasChildThread;
+  nsCOMPtr<nsIThread> mFakeDeviceChangeEventThread;
+};
+
+// Get a pointer to a CamerasChild object we can use to do IPC with.
+// This does everything needed to set up, including starting the IPC
+// channel with PBackground, blocking until thats done, and starting the
+// thread to do IPC on. This will fail if we're in shutdown. On success
+// it will set up the CamerasSingleton.
+CamerasChild* GetCamerasChild();
+
+CamerasChild* GetCamerasChildIfExists();
+
+// Shut down the IPC channel and everything associated, like WebRTC.
+// This is a static call because the CamerasChild object may not even
+// be alive when we're called.
+void Shutdown(void);
+
+// Obtain the CamerasChild object (if possible, i.e. not shutting down),
+// and maintain a grip on the object for the duration of the call.
+template <class MEM_FUN, class... ARGS>
+int GetChildAndCall(MEM_FUN&& f, ARGS&&... args)
+{
+  OffTheBooksMutexAutoLock lock(CamerasSingleton::Mutex());
+  CamerasChild* child = GetCamerasChild();
+  if (child) {
+    return (child->*f)(mozilla::Forward<ARGS>(args)...);
+  } else {
+    return -1;
+  }
+}
+
+class CamerasChild final : public PCamerasChild
+                          ,public DeviceChangeCallback
+{
+  friend class mozilla::ipc::BackgroundChildImpl;
+  template <class T> friend class mozilla::camera::LockAndDispatch;
+
+public:
+  // We are owned by the PBackground thread only. CamerasSingleton
+  // takes a non-owning reference.
+  NS_INLINE_DECL_REFCOUNTING(CamerasChild)
+
+  // IPC messages recevied, received on the PBackground thread
+  // these are the actual callbacks with data
+  virtual bool RecvDeliverFrame(const CaptureEngine&, const int&, mozilla::ipc::Shmem&&,
+                                const size_t&, const uint32_t&, const int64_t&,
+                                const int64_t&) override;
+  virtual bool RecvFrameSizeChange(const CaptureEngine&, const int&,
+                                   const int& w, const int& h) override;
+
+  virtual bool RecvDeviceChange() override;
+  virtual int AddDeviceChangeCallback(DeviceChangeCallback* aCallback) override;
+  int SetFakeDeviceChangeEvents();
+
+  // these are response messages to our outgoing requests
+  virtual bool RecvReplyNumberOfCaptureDevices(const int&) override;
+  virtual bool RecvReplyNumberOfCapabilities(const int&) override;
+  virtual bool RecvReplyAllocateCaptureDevice(const int&) override;
+  virtual bool RecvReplyGetCaptureCapability(const CaptureCapability& capability) override;
+  virtual bool RecvReplyGetCaptureDevice(const nsCString& device_name,
+                                         const nsCString& device_id,
+                                         const bool& scary) override;
+  virtual bool RecvReplyFailure(void) override;
+  virtual bool RecvReplySuccess(void) override;
+  virtual void ActorDestroy(ActorDestroyReason aWhy) override;
+
+  // the webrtc.org ViECapture calls are mirrored here, but with access
+  // to a specific PCameras instance to communicate over. These also
+  // run on the MediaManager thread
+  int NumberOfCaptureDevices(CaptureEngine aCapEngine);
+  int NumberOfCapabilities(CaptureEngine aCapEngine,
+                           const char* deviceUniqueIdUTF8);
+  int ReleaseCaptureDevice(CaptureEngine aCapEngine,
+                           const int capture_id);
+  int StartCapture(CaptureEngine aCapEngine,
+                   const int capture_id, webrtc::CaptureCapability& capability,
+                   webrtc::ExternalRenderer* func);
+  int StopCapture(CaptureEngine aCapEngine, const int capture_id);
+  int AllocateCaptureDevice(CaptureEngine aCapEngine,
+                            const char* unique_idUTF8,
+                            const unsigned int unique_idUTF8Length,
+                            int& capture_id,
+                            const nsACString& aOrigin);
+  int GetCaptureCapability(CaptureEngine aCapEngine,
+                           const char* unique_idUTF8,
+                           const unsigned int capability_number,
+                           webrtc::CaptureCapability& capability);
+  int GetCaptureDevice(CaptureEngine aCapEngine,
+                       unsigned int list_number, char* device_nameUTF8,
+                       const unsigned int device_nameUTF8Length,
+                       char* unique_idUTF8,
+                       const unsigned int unique_idUTF8Length,
+                       bool* scary = nullptr);
+  void ShutdownAll();
+  int EnsureInitialized(CaptureEngine aCapEngine);
+
+  webrtc::ExternalRenderer* Callback(CaptureEngine aCapEngine, int capture_id);
+
+private:
+  CamerasChild();
+  ~CamerasChild();
+  // Dispatch a Runnable to the PCamerasParent, by executing it on the
+  // decidecated Cameras IPC/PBackground thread.
+  bool DispatchToParent(nsIRunnable* aRunnable,
+                        MonitorAutoLock& aMonitor);
+  void AddCallback(const CaptureEngine aCapEngine, const int capture_id,
+                   webrtc::ExternalRenderer* render);
+  void RemoveCallback(const CaptureEngine aCapEngine, const int capture_id);
+  void ShutdownParent();
+  void ShutdownChild();
+
+  nsTArray<CapturerElement> mCallbacks;
+  // Protects the callback arrays
+  Mutex mCallbackMutex;
+
+  bool mIPCIsAlive;
+
+  // Hold to prevent multiple outstanding requests. We don't use
+  // request IDs so we only support one at a time. Don't want try
+  // to use the webrtc.org API from multiple threads simultanously.
+  // The monitor below isn't sufficient for this, as it will drop
+  // the lock when Wait-ing for a response, allowing us to send a new
+  // request. The Notify on receiving the response will then unblock
+  // both waiters and one will be guaranteed to get the wrong result.
+  // Take this one before taking mReplyMonitor.
+  Mutex mRequestMutex;
+  // Hold to wait for an async response to our calls
+  Monitor mReplyMonitor;
+  // Async response valid?
+  bool mReceivedReply;
+  // Async responses data contents;
+  bool mReplySuccess;
+  int mReplyInteger;
+  webrtc::CaptureCapability mReplyCapability;
+  nsCString mReplyDeviceName;
+  nsCString mReplyDeviceID;
+  bool mReplyScary;
+};
+
+} // namespace camera
+} // namespace mozilla
+
+#endif  // mozilla_CamerasChild_h