Queue commands to the Os to start a video device.

content/browser/renderer_host/media/video_capture_manager.cc

 // 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.
 
 #include "content/browser/renderer_host/media/video_capture_manager.h"
 
 #include <set>
 
 #include "base/bind.h"
 #include "base/bind_helpers.h"
@@ skipping 100 matching lines @@
 
 VideoCaptureManager::VideoCaptureManager(
     scoped_ptr<media::VideoCaptureDeviceFactory> factory)
     : listener_(NULL),
       new_capture_session_id_(1),
       video_capture_device_factory_(factory.Pass()) {
 }
 
 VideoCaptureManager::~VideoCaptureManager() {
   DCHECK(devices_.empty());
+  DCHECK(device_start_queue_.empty());
 }
 
 void VideoCaptureManager::Register(
     MediaStreamProviderListener* listener,
     const scoped_refptr<base::SingleThreadTaskRunner>& device_task_runner) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DCHECK(!listener_);
   DCHECK(!device_task_runner_.get());
   listener_ = listener;
   device_task_runner_ = device_task_runner;
@@ skipping 78 matching lines @@
     DestroyDeviceEntryIfNoClients(existing_device);
   }
 
   // Notify listeners asynchronously, and forget the session.
   base::MessageLoop::current()->PostTask(FROM_HERE,
       base::Bind(&VideoCaptureManager::OnClosed, this, session_it->second.type,
                  capture_session_id));
   sessions_.erase(session_it);
 }
 
-void VideoCaptureManager::DoStartDeviceOnDeviceThread(
+VideoCaptureManager::CaptureDeviceStartRequest::CaptureDeviceStartRequest(
+    DeviceEntry* entry,
+    media::VideoCaptureSessionId session_id,
+    const media::VideoCaptureParams& params)
+    : entry(entry),
+      session_id(session_id),
+      params(params) {
+}
+
+void VideoCaptureManager::QueueStartDevice(
     media::VideoCaptureSessionId session_id,
     DeviceEntry* entry,
+    const media::VideoCaptureParams& params) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  device_start_queue_.push_back(
+      CaptureDeviceStartRequest(entry, session_id, params));
+  if (device_start_queue_.size() == 1)
+    HandleQueuedStartRequest();
+}
+
+void VideoCaptureManager::DoStopDevice(DeviceEntry* entry) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  DCHECK(std::find(devices_.begin(), devices_.end(), entry) != devices_.end());
+
+  // Check if the start request has not yet been sent to the device thread.
+  // If so, delete the request. The first request in the queue has already been
+  // sent the device thread for processing and will be erased in
+  // OnDeviceStarted.

[tommi (sloooow) - chröme, 2014/12/17 14:46:12]

I'm dcheck crazy :)  Can we dcheck that the first element (if any), has its
video_capture_device member not set?  Something like:

DCHECK(device_start_queue_.empty() ||
       !device_start_queue_.front()->video_capture_device.get());

[perkj_chrome, 2014/12/18 12:15:31]

I removed entry all together from the list. 

+  if (device_start_queue_.size() > 1) {
+    for (DeviceStartQueue::iterator request = ++device_start_queue_.begin();
+         request != device_start_queue_.end(); ++request) {
+      if (request->entry == entry) {
+        device_start_queue_.erase(request);
+        DVLOG(3) << "DoStopDevice, aborting start request for device "
+                 << entry->id << ".";
+        return;
+      }
+    }
+  }
+
+  DVLOG(3) << "DoStopDevice. Send stop request for device " << entry->id << ".";
+  if (entry->video_capture_device.get()) {
+    // |entry->video_capture_device| can be null if creating the device fails.
+    device_task_runner_->PostTask(
+        FROM_HERE,
+        base::Bind(&VideoCaptureManager::DoStopDeviceOnDeviceThread, this,
+                   base::Passed(entry->video_capture_device.Pass())));
+  }
+}
+
+void VideoCaptureManager::HandleQueuedStartRequest() {
+  DCHECK(!device_start_queue_.empty());
+
+  const CaptureDeviceStartRequest* request = &(*device_start_queue_.begin());
+  DeviceEntry* entry = request->entry;
+  DCHECK(std::find(devices_.begin(), devices_.end(), request->entry) !=
+      devices_.end());
+
+  DVLOG(3) << "HandleQueuedStartRequest, Post start to device thread, device = "
+           << entry->id;
+  base::PostTaskAndReplyWithResult(
+      device_task_runner_.get(),
+      FROM_HERE,
+      base::Bind(
+          &VideoCaptureManager::DoStartDeviceOnDeviceThread,
+          this,
+          request->session_id,
+          entry->id,
+          entry->stream_type,
+          request->params,
+          base::Passed(entry->video_capture_controller->NewDeviceClient())),
+      base::Bind(&VideoCaptureManager::OnDeviceStarted, this, entry));
+}
+
+void VideoCaptureManager::OnDeviceStarted(
+    DeviceEntry* device_entry,
+    scoped_ptr<media::VideoCaptureDevice> device) {
+  DCHECK_CURRENTLY_ON(BrowserThread::IO);
+  DVLOG(3) << "OnDeviceStarted";
+
+  DCHECK(device_entry == device_start_queue_.begin()->entry);
+  device_start_queue_.pop_front();
+
+  DeviceEntries::iterator entry_it =
+      std::find(devices_.begin(), devices_.end(), device_entry);
+  if (entry_it == devices_.end()) {
+    // |device| can be null if creation failed in DoStartDeviceOnDeviceThread.
+    // The device is no longer wanted. Stop the device again.
+    media::VideoCaptureDevice* device_ptr = device.get();
+    base::Closure closure =
+        base::Bind(&VideoCaptureManager::DoStopDeviceOnDeviceThread, this,
+                   base::Passed(&device));
+    if (device_ptr && !device_task_runner_->PostTask(FROM_HERE, closure)) {
+      // PostTask failed. The device must be stopped anyway.
+      device_ptr->StopAndDeAllocate();
+    }
+  } else {
+    (*entry_it)->video_capture_device.swap(device);
+  }
+
+  if (!device_start_queue_.empty())
+    HandleQueuedStartRequest();
+}
+
+scoped_ptr<media::VideoCaptureDevice>
+VideoCaptureManager::DoStartDeviceOnDeviceThread(
+    media::VideoCaptureSessionId session_id,
+    const std::string& id,
+    MediaStreamType stream_type,
     const media::VideoCaptureParams& params,
     scoped_ptr<media::VideoCaptureDevice::Client> device_client) {
   SCOPED_UMA_HISTOGRAM_TIMER("Media.VideoCaptureManager.StartDeviceTime");
   DCHECK(IsOnDeviceThread());
 
   scoped_ptr<media::VideoCaptureDevice> video_capture_device;
-  switch (entry->stream_type) {
+  switch (stream_type) {
     case MEDIA_DEVICE_VIDEO_CAPTURE: {
       // We look up the device id from the renderer in our local enumeration
       // since the renderer does not have all the information that might be
       // held in the browser-side VideoCaptureDevice::Name structure.
       media::VideoCaptureDeviceInfo* found =
-          FindDeviceInfoById(entry->id, devices_info_cache_);
+          FindDeviceInfoById(id, devices_info_cache_);
       if (found) {
         video_capture_device =
             video_capture_device_factory_->Create(found->name);
       }
       break;
     }
     case MEDIA_TAB_VIDEO_CAPTURE: {
       video_capture_device.reset(
-          WebContentsVideoCaptureDevice::Create(entry->id));
+          WebContentsVideoCaptureDevice::Create(id));
       break;
     }
     case MEDIA_DESKTOP_VIDEO_CAPTURE: {
 #if defined(ENABLE_SCREEN_CAPTURE)
-      DesktopMediaID id = DesktopMediaID::Parse(entry->id);
+      DesktopMediaID desktop_id = DesktopMediaID::Parse(id);
 #if defined(USE_AURA)
-      if (id.type == DesktopMediaID::TYPE_AURA_WINDOW) {
-        video_capture_device.reset(DesktopCaptureDeviceAura::Create(id));
+      if (desktop_id.type == DesktopMediaID::TYPE_AURA_WINDOW) {
+        video_capture_device.reset(
+            DesktopCaptureDeviceAura::Create(desktop_id));
       } else
 #endif
-      if (id.type != DesktopMediaID::TYPE_NONE &&
-          id.type != DesktopMediaID::TYPE_AURA_WINDOW) {
-        video_capture_device = DesktopCaptureDevice::Create(id);
+      if (desktop_id.type != DesktopMediaID::TYPE_NONE &&
+          desktop_id.type != DesktopMediaID::TYPE_AURA_WINDOW) {
+        video_capture_device = DesktopCaptureDevice::Create(desktop_id);
         if (notification_window_ids_.find(session_id) !=
             notification_window_ids_.end()) {
           static_cast<DesktopCaptureDevice*>(video_capture_device.get())
               ->SetNotificationWindowId(notification_window_ids_[session_id]);
           VLOG(2) << "Screen capture notification window passed for session "
                   << session_id;
         }
       }
 #endif  // defined(ENABLE_SCREEN_CAPTURE)
       break;
     }
     default: {
       NOTIMPLEMENTED();
       break;
     }
   }
 
   if (!video_capture_device) {
     device_client->OnError("Could not create capture device");
-    return;
+    return nullptr;
   }
 
   video_capture_device->AllocateAndStart(params, device_client.Pass());
-  entry->video_capture_device = video_capture_device.Pass();
+  return video_capture_device.Pass();
 }
 
 void VideoCaptureManager::StartCaptureForClient(
     media::VideoCaptureSessionId session_id,
     const media::VideoCaptureParams& params,
     base::ProcessHandle client_render_process,
     VideoCaptureControllerID client_id,
     VideoCaptureControllerEventHandler* client_handler,
     const DoneCB& done_cb) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DVLOG(1) << "VideoCaptureManager::StartCaptureForClient, "
            << params.requested_format.frame_size.ToString() << ", "
            << params.requested_format.frame_rate << ", #" << session_id << ")";
 
   DeviceEntry* entry = GetOrCreateDeviceEntry(session_id);
   if (!entry) {
     done_cb.Run(base::WeakPtr<VideoCaptureController>());
     return;
   }
 
   DCHECK(entry->video_capture_controller);
 
   LogVideoCaptureEvent(VIDEO_CAPTURE_START_CAPTURE);
 
   // First client starts the device.
   if (entry->video_capture_controller->GetActiveClientCount() == 0) {
     DVLOG(1) << "VideoCaptureManager starting device (type = "
              << entry->stream_type << ", id = " << entry->id << ")";
-
-    device_task_runner_->PostTask(
-        FROM_HERE,
-        base::Bind(
-            &VideoCaptureManager::DoStartDeviceOnDeviceThread,
-            this,
-            session_id,
-            entry,
-            params,
-            base::Passed(entry->video_capture_controller->NewDeviceClient())));
+    QueueStartDevice(session_id, entry, params);
   }
   // Run the callback first, as AddClient() may trigger OnFrameInfo().
   done_cb.Run(entry->video_capture_controller->GetWeakPtr());
   entry->video_capture_controller->AddClient(
       client_id, client_handler, client_render_process, session_id, params);
 }
 
 void VideoCaptureManager::StopCaptureForClient(
     VideoCaptureController* controller,
     VideoCaptureControllerID client_id,
@@ skipping 56 matching lines @@
   // We only pause the MEDIA_DEVICE_VIDEO_CAPTURE entry to release camera to
   // system.
   if (entry->stream_type != MEDIA_DEVICE_VIDEO_CAPTURE)
     return;
 
   controller->PauseOrResumeClient(client_id, client_handler, true);
   if (controller->GetActiveClientCount() != 0)
     return;
 
   // There is no more client, release the camera.
-  device_task_runner_->PostTask(
-      FROM_HERE,
-      base::Bind(&VideoCaptureManager::DoStopDeviceOnDeviceThread, this,
-                 base::Unretained(entry)));
+  DoStopDevice(entry);
 }
 
 void VideoCaptureManager::ResumeCaptureForClient(
     media::VideoCaptureSessionId session_id,
     const media::VideoCaptureParams& params,
     VideoCaptureController* controller,
     VideoCaptureControllerID client_id,
     VideoCaptureControllerEventHandler* client_handler) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DCHECK(controller);
   DCHECK(client_handler);
 
   DeviceEntry* entry = GetDeviceEntryForController(controller);
   if (!entry) {
     NOTREACHED();
     return;
   }
 
   // We only pause/resume the MEDIA_DEVICE_VIDEO_CAPTURE entry.
   if (entry->stream_type != MEDIA_DEVICE_VIDEO_CAPTURE)
     return;
 
   controller->PauseOrResumeClient(client_id, client_handler, false);
   if (controller->GetActiveClientCount() != 1)
     return;
 
   // This is first active client, allocate the camera.
-  device_task_runner_->PostTask(
-      FROM_HERE,
-      base::Bind(
-          &VideoCaptureManager::DoStartDeviceOnDeviceThread,
-          this,
-          session_id,
-          entry,
-          params,
-          base::Passed(entry->video_capture_controller->NewDeviceClient())));
+  QueueStartDevice(session_id, entry, params);
 }
 
 bool VideoCaptureManager::GetDeviceSupportedFormats(
     media::VideoCaptureSessionId capture_session_id,
     media::VideoCaptureFormats* supported_formats) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   DCHECK(supported_formats->empty());
 
   SessionMap::iterator it = sessions_.find(capture_session_id);
   if (it == sessions_.end())
@@ skipping 65 matching lines @@
   }
 
   device_task_runner_->PostTask(
       FROM_HERE,
       base::Bind(&VideoCaptureManager::SetDesktopCaptureWindowIdOnDeviceThread,
                  this,
                  existing_device,
                  window_id));
 }
 
-void VideoCaptureManager::DoStopDeviceOnDeviceThread(DeviceEntry* entry) {
+void VideoCaptureManager::DoStopDeviceOnDeviceThread(
+    scoped_ptr<media::VideoCaptureDevice> device) {
   SCOPED_UMA_HISTOGRAM_TIMER("Media.VideoCaptureManager.StopDeviceTime");
   DCHECK(IsOnDeviceThread());
-  if (entry->video_capture_device) {
-    entry->video_capture_device->StopAndDeAllocate();
-  }
-  entry->video_capture_device.reset();
+  device->StopAndDeAllocate();
+  DVLOG(3) << "DoStopDeviceOnDeviceThread";
 }
 
 void VideoCaptureManager::OnOpened(
     MediaStreamType stream_type,
     media::VideoCaptureSessionId capture_session_id) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   if (!listener_) {
     // Listener has been removed.
     return;
   }
@@ skipping 109 matching lines @@
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
   // Removal of the last client stops the device.
   if (entry->video_capture_controller->GetClientCount() == 0) {
     DVLOG(1) << "VideoCaptureManager stopping device (type = "
              << entry->stream_type << ", id = " << entry->id << ")";
 
     // The DeviceEntry is removed from |devices_| immediately. The controller is
     // deleted immediately, and the device is freed asynchronously. After this
     // point, subsequent requests to open this same device ID will create a new
     // DeviceEntry, VideoCaptureController, and VideoCaptureDevice.
-    devices_.erase(entry);
-    entry->video_capture_controller.reset();
-    device_task_runner_->PostTask(
-        FROM_HERE,
-        base::Bind(&VideoCaptureManager::DoStopDeviceOnDeviceThread, this,
-                   base::Owned(entry)));
+    DoStopDevice(entry);
+    DeviceEntries::iterator device_it = std::find(devices_.begin(),
+                                                  devices_.end(),
+                                                  entry);
+    devices_.erase(device_it);
   }
 }
 
 VideoCaptureManager::DeviceEntry* VideoCaptureManager::GetOrCreateDeviceEntry(
     media::VideoCaptureSessionId capture_session_id) {
   DCHECK_CURRENTLY_ON(BrowserThread::IO);
 
   SessionMap::iterator session_it = sessions_.find(capture_session_id);
   if (session_it == sessions_.end()) {
     return NULL;
   }
   const MediaStreamDevice& device_info = session_it->second;
 
   // Check if another session has already opened this device. If so, just
   // use that opened device.
   DeviceEntry* const existing_device =
       GetDeviceEntryForMediaStreamDevice(device_info);
   if (existing_device) {
     DCHECK_EQ(device_info.type, existing_device->stream_type);
     return existing_device;
   }
 
   const int max_buffers = device_info.type == MEDIA_TAB_VIDEO_CAPTURE ?
       kMaxNumberOfBuffersForTabCapture : kMaxNumberOfBuffers;
   scoped_ptr<VideoCaptureController> video_capture_controller(
       new VideoCaptureController(max_buffers));
   DeviceEntry* new_device = new DeviceEntry(device_info.type,
                                             device_info.id,
                                             video_capture_controller.Pass());
-  devices_.insert(new_device);
+  devices_.push_back(new_device);
   return new_device;
 }
 
 media::VideoCaptureDeviceInfo* VideoCaptureManager::FindDeviceInfoById(
     const std::string& id,
     media::VideoCaptureDeviceInfos& device_vector) {
   for (auto& it : device_vector) {
     if (it.name.id() == id)
       return &(it);
   }
@@ skipping 18 matching lines @@
     gfx::NativeViewId window_id) {
   DCHECK(IsOnDeviceThread());
   DCHECK(notification_window_ids_.find(session_id) ==
          notification_window_ids_.end());
   notification_window_ids_[session_id] = window_id;
   VLOG(2) << "Screen capture notification window saved for session "
           << session_id << " on device thread.";
 }
 
 }  // namespace content