Deliver webrtc-internals updates in bulk, every 500ms at most.

content/browser/media/webrtc_internals.h

 // Copyright (c) 2013 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 CONTENT_BROWSER_MEDIA_WEBRTC_INTERNALS_H_
 #define CONTENT_BROWSER_MEDIA_WEBRTC_INTERNALS_H_
 
+#include <queue>
+
 #include "base/containers/hash_tables.h"
 #include "base/gtest_prod_util.h"
 #include "base/lazy_instance.h"
 #include "base/memory/scoped_ptr.h"
+#include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "base/process/process.h"
+#include "base/threading/thread_checker.h"
 #include "base/values.h"
 #include "content/common/content_export.h"
 #include "content/public/browser/render_process_host_observer.h"
 #include "ui/shell_dialogs/select_file_dialog.h"
 
 namespace content {
 
 class PowerSaveBlocker;
 class WebContents;
 class WebRTCInternalsUIObserver;
@@ skipping 50 matching lines @@
   // is the constraints for the video.
   void OnGetUserMedia(int render_process_id,
                       base::ProcessId pid,
                       const std::string& origin,
                       bool audio,
                       bool video,
                       const std::string& audio_constraints,
                       const std::string& video_constraints);
 
   // Methods for adding or removing WebRTCInternalsUIObserver.
-  void AddObserver(WebRTCInternalsUIObserver *observer);
-  void RemoveObserver(WebRTCInternalsUIObserver *observer);
+  void AddObserver(WebRTCInternalsUIObserver* observer);
+  void RemoveObserver(WebRTCInternalsUIObserver* observer);
 
   // Sends all update data to |observer|.
   void UpdateObserver(WebRTCInternalsUIObserver* observer);
 
   // Enables or disables diagnostic audio recordings for debugging purposes.
   void EnableAudioDebugRecordings(content::WebContents* web_contents);
   void DisableAudioDebugRecordings();
 
   bool IsAudioDebugRecordingsEnabled() const;
   const base::FilePath& GetAudioDebugRecordingsFilePath() const;
 
   // Enables or disables diagnostic event log.
   void SetEventLogRecordings(bool enable, content::WebContents* web_contents);
 
   bool IsEventLogRecordingsEnabled() const;
   const base::FilePath& GetEventLogRecordingsFilePath() const;
 
-  void ResetForTesting();
+ protected:
+  // Constructor/Destructor are protected to allow tests to derive from the
+  // class and do per-instance testing without having to use the global
+  // instance.

[Henrik Grunell, 2016/02/09 11:47:48]

Maybe comment that 500 ms is the default used with ctor with no args?

[tommi (sloooow) - chröme, 2016/02/09 12:13:53]

Done.

+  WebRTCInternals();
+  explicit WebRTCInternals(int aggregate_updates_ms);
+  ~WebRTCInternals() override;
 
  private:
   friend struct base::DefaultLazyInstanceTraits<WebRTCInternals>;
   FRIEND_TEST_ALL_PREFIXES(WebRtcAudioDebugRecordingsBrowserTest,
                            CallWithAudioDebugRecordings);
   FRIEND_TEST_ALL_PREFIXES(WebRtcAudioDebugRecordingsBrowserTest,
                            CallWithAudioDebugRecordingsEnabledThenDisabled);
   FRIEND_TEST_ALL_PREFIXES(WebRtcAudioDebugRecordingsBrowserTest,
                            TwoCallsWithAudioDebugRecordings);
   FRIEND_TEST_ALL_PREFIXES(WebRtcInternalsTest,
                            AudioDebugRecordingsFileSelectionCanceled);
 
-  WebRTCInternals();
-  ~WebRTCInternals() override;
-
-  void SendUpdate(const std::string& command, base::Value* value);
+  void SendUpdate(const std::string& command, scoped_ptr<base::Value> value);
 
   // RenderProcessHostObserver implementation.
   void RenderProcessHostDestroyed(RenderProcessHost* host) override;
 
   // ui::SelectFileDialog::Listener implementation.
   void FileSelected(const base::FilePath& path,
                     int index,
                     void* unused_params) override;
   void FileSelectionCanceled(void* params) override;
 
   // Called when a renderer exits (including crashes).
   void OnRendererExit(int render_process_id);
 
 #if defined(ENABLE_WEBRTC)
   // Enables diagnostic audio recordings on all render process hosts using
   // |audio_debug_recordings_file_path_|.
   void EnableAudioDebugRecordingsOnAllRenderProcessHosts();
 
   // Enables event log recordings on all render process hosts using
   // |event_log_recordings_file_path_|.
   void EnableEventLogRecordingsOnAllRenderProcessHosts();
 #endif
 
   // Called whenever an element is added to or removed from
   // |peer_connection_data_| to impose/release a block on suspending the current
   // application for power-saving.
   void CreateOrReleasePowerSaveBlocker();
 
+  // Called on a timer to deliver updates to javascript.
+  // We throttle and bulk together updates to avoid DOS like scenarios where
+  // a page uses a lot of peerconnection instances with many event
+  // notifications.
+  void ProcessPendingUpdates();
+
   base::ObserverList<WebRTCInternalsUIObserver> observers_;
 
   // |peer_connection_data_| is a list containing all the PeerConnection
   // updates.
   // Each item of the list represents the data for one PeerConnection, which
   // contains these fields:
   // "rid" -- the renderer id.
   // "pid" -- OS process id of the renderer that creates the PeerConnection.
   // "lid" -- local Id assigned to the PeerConnection.
   // "url" -- url of the web page that created the PeerConnection.
@@ skipping 26 matching lines @@
   bool selecting_event_log_;
   base::FilePath event_log_recordings_file_path_;
 
   // While |peer_connection_data_| is non-empty, hold an instance of
   // PowerSaveBlocker.  This prevents the application from being suspended while
   // remoting.
   scoped_ptr<PowerSaveBlocker> power_save_blocker_;
 
   // Set of render process hosts that |this| is registered as an observer on.
   base::hash_set<int> render_process_id_set_;
+
+  // Used to bulk up updates that we send to javascript.
+  // The class owns the value/dictionary and command name of an update.
+  // For each update, a PendingUpdate is stored in the |pending_updates_| queue
+  // and deleted as soon as the update has been delivered.
+  // The class is moveble and not copyable to avoid copying while still allowing
+  // us to use an stl container while not having to wrap it in a scoped_ptr or

[Henrik Grunell, 2016/02/09 11:47:47]

Hard to read this sentence. Repeated "while". (Pun not intended.)

[tommi (sloooow) - chröme, 2016/02/09 12:13:53]

Done.

+  // similar.
+  // The class is single threaded, so must be

[Henrik Grunell, 2016/02/09 11:47:48]

Incomplete... :)

[tommi (sloooow) - chröme, 2016/02/09 12:13:53]

Done.  I was working over an extremely slow connection and kept context
switching :) It shows.

+  class PendingUpdate {
+   public:
+    PendingUpdate(const std::string& command, scoped_ptr<base::Value> value);
+    PendingUpdate(PendingUpdate&& other);
+    ~PendingUpdate();
+
+    const std::string& command() const;
+    const base::Value* value() const;
+
+   private:
+    base::ThreadChecker thread_checker_;
+    std::string command_;
+    scoped_ptr<base::Value> value_;
+    DISALLOW_COPY_AND_ASSIGN(PendingUpdate);
+  };
+
+  std::queue<PendingUpdate> pending_updates_;
+  const int aggregate_updates_ms_;
+
+  // Weak factory for this object that we use for bulking up updates.
+  base::WeakPtrFactory<WebRTCInternals> weak_factory_;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_BROWSER_MEDIA_WEBRTC_INTERNALS_H_