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Diffstat (limited to 'dom/media/systemservices/CamerasChild.h')
| -rw-r--r-- | dom/media/systemservices/CamerasChild.h | 262 |
1 files changed, 262 insertions, 0 deletions
diff --git a/dom/media/systemservices/CamerasChild.h b/dom/media/systemservices/CamerasChild.h new file mode 100644 index 0000000000..18bdeec251 --- /dev/null +++ b/dom/media/systemservices/CamerasChild.h @@ -0,0 +1,262 @@ +/* -*- 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 <utility> + +#include "MediaEventSource.h" +#include "mozilla/Mutex.h" +#include "mozilla/camera/PCamerasChild.h" +#include "mozilla/camera/PCamerasParent.h" +#include "nsCOMPtr.h" + +// conflicts with #include of scoped_ptr.h +#undef FF +#include "modules/video_capture/video_capture_defines.h" + +namespace mozilla { + +namespace ipc { +class BackgroundChildImpl; +} // namespace ipc + +namespace camera { + +class FrameRelay { + public: + virtual int DeliverFrame( + uint8_t* buffer, const mozilla::camera::VideoFrameProperties& props) = 0; +}; + +struct CapturerElement { + CaptureEngine engine; + int id; + FrameRelay* 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: + static OffTheBooksMutex& Mutex() { return singleton().mCamerasMutex; } + + static CamerasChild*& Child() { + Mutex().AssertCurrentThreadOwns(); + return singleton().mCameras; + } + + static nsCOMPtr<nsIThread>& Thread() { + Mutex().AssertCurrentThreadOwns(); + return singleton().mCamerasChildThread; + } + // The mutex is not held because mCameras is known not to be modified + // concurrently when this is asserted. + static void AssertNoChild() { MOZ_ASSERT(!singleton().mCameras); } + + private: + CamerasSingleton(); + ~CamerasSingleton(); + + static CamerasSingleton& singleton() { + static CamerasSingleton camera; + return camera; + } + + // 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; +}; + +// 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)(std::forward<ARGS>(args)...); + } else { + return -1; + } +} + +class CamerasChild final : public PCamerasChild { + 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_THREADSAFE_REFCOUNTING(CamerasChild) + + // IPC messages recevied, received on the PBackground thread + // these are the actual callbacks with data + mozilla::ipc::IPCResult RecvDeliverFrame( + const CaptureEngine&, const int&, mozilla::ipc::Shmem&&, + const VideoFrameProperties& prop) override; + + mozilla::ipc::IPCResult RecvDeviceChange() override; + + // these are response messages to our outgoing requests + mozilla::ipc::IPCResult RecvReplyNumberOfCaptureDevices(const int&) override; + mozilla::ipc::IPCResult RecvReplyNumberOfCapabilities(const int&) override; + mozilla::ipc::IPCResult RecvReplyAllocateCapture(const int&) override; + mozilla::ipc::IPCResult RecvReplyGetCaptureCapability( + const VideoCaptureCapability& capability) override; + mozilla::ipc::IPCResult RecvReplyGetCaptureDevice( + const nsACString& device_name, const nsACString& device_id, + const bool& scary) override; + mozilla::ipc::IPCResult RecvReplyFailure(void) override; + mozilla::ipc::IPCResult RecvReplySuccess(void) override; + 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 ReleaseCapture(CaptureEngine aCapEngine, const int capture_id); + int StartCapture(CaptureEngine aCapEngine, const int capture_id, + const webrtc::VideoCaptureCapability& capability, + FrameRelay* func); + int FocusOnSelectedSource(CaptureEngine aCapEngine, const int capture_id); + int StopCapture(CaptureEngine aCapEngine, const int capture_id); + // Returns a non-negative capture identifier or -1 on failure. + int AllocateCapture(CaptureEngine aCapEngine, const char* unique_idUTF8, + uint64_t aWindowID); + int GetCaptureCapability(CaptureEngine aCapEngine, const char* unique_idUTF8, + const unsigned int capability_number, + webrtc::VideoCaptureCapability* 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); + int EnsureInitialized(CaptureEngine aCapEngine); + + template <typename This> + int ConnectDeviceListChangeListener(MediaEventListener* aListener, + AbstractThread* aTarget, This* aThis, + void (This::*aMethod)()) { + // According to the spec, if the script sets + // navigator.mediaDevices.ondevicechange and the permission state is + // "always granted", the User Agent MUST fires a devicechange event when + // a new media input device is made available, even the script never + // call getusermedia or enumerateDevices. + + // In order to detect the event, we need to init the camera engine. + // Currently EnsureInitialized(aCapEngine) is only called when one of + // CamerasParent api, e.g., RecvNumberOfCaptureDevices(), is called. + + // So here we setup camera engine via EnsureInitialized(aCapEngine) + + EnsureInitialized(CameraEngine); + *aListener = mDeviceListChangeEvent.Connect(aTarget, aThis, aMethod); + return IPC_OK(); + } + + FrameRelay* 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, + FrameRelay* render); + void RemoveCallback(const CaptureEngine aCapEngine, const int capture_id); + + nsTArray<CapturerElement> mCallbacks; + // Protects the callback arrays + Mutex mCallbackMutex MOZ_UNANNOTATED; + + 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 MOZ_UNANNOTATED; + // Hold to wait for an async response to our calls *and* until the + // user of LockAndDispatch<> has read the data out. This is done by + // keeping the LockAndDispatch object alive. + Monitor mReplyMonitor MOZ_UNANNOTATED; + // Async response valid? + bool mReceivedReply; + // Async responses data contents; + bool mReplySuccess; + const int mZero; + int mReplyInteger; + webrtc::VideoCaptureCapability* mReplyCapability = nullptr; + nsCString mReplyDeviceName; + nsCString mReplyDeviceID; + bool mReplyScary; + MediaEventProducer<void> mDeviceListChangeEvent; +}; + +} // namespace camera +} // namespace mozilla + +#endif // mozilla_CamerasChild_h |