Cast: Implemented size limiting and event filtering in EncodingEventSubscriber.

media/cast/logging/encoding_event_subscriber.h

 // Copyright 2014 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_CAST_LOGGING_ENCODING_EVENT_SUBSCRIBER_H_
 #define MEDIA_CAST_LOGGING_ENCODING_EVENT_SUBSCRIBER_H_
 
 #include <map>
 
 #include "base/memory/linked_ptr.h"
 #include "base/threading/thread_checker.h"
+#include "media/cast/logging/logging_defines.h"
 #include "media/cast/logging/proto/raw_events.pb.h"
 #include "media/cast/logging/raw_event_subscriber.h"
 
 namespace media {
 namespace cast {
 
 typedef std::map<RtpTimestamp,
                  linked_ptr<media::cast::proto::AggregatedFrameEvent> >
     FrameEventMap;
 typedef std::map<RtpTimestamp,
                  linked_ptr<media::cast::proto::AggregatedPacketEvent> >
     PacketEventMap;
-typedef std::map<CastLoggingEvent,
-                 linked_ptr<media::cast::proto::AggregatedGenericEvent> >
-    GenericEventMap;
 
 // A RawEventSubscriber implementation that subscribes to events,
 // encodes them in protocol buffer format, and aggregates them into a more
 // compact structure.
-// TODO(imcheng): Implement event filtering and windowing based on size.
 class EncodingEventSubscriber : public RawEventSubscriber {
  public:
-  EncodingEventSubscriber();
+  // |event_media_type|: The subscriber will only process events that
+  // corresponds to this type.
+  // |max_frames|: How many events to keep in the frame / packet map.
+  // This helps keep memory usage bounded.
+  // Every time one of |OnReceive[Frame,Packet]Event()| is
+  // called, it will check if the respective map size has exceeded |max_frames|.
+  // If so, it will remove the oldest aggregated entry (ordered by RTP
+  // timestamp).
+  EncodingEventSubscriber(EventMediaType event_media_type, size_t max_frames);
 
   virtual ~EncodingEventSubscriber();
 
   // RawReventSubscriber implementations.
   virtual void OnReceiveFrameEvent(const FrameEvent& frame_event) OVERRIDE;
   virtual void OnReceivePacketEvent(const PacketEvent& packet_event) OVERRIDE;
   virtual void OnReceiveGenericEvent(const GenericEvent& generic_event)
       OVERRIDE;
 
   // Assigns frame events received so far to |frame_events| and clears them
   // from this object.
   void GetFrameEventsAndReset(FrameEventMap* frame_events);
 
   // Assigns packet events received so far to |packet_events| and clears them
   // from this object.
   void GetPacketEventsAndReset(PacketEventMap* packet_events);
 
-  // Assigns generic events received so far to |generic_events| and clears them
-  // from this object.
-  void GetGenericEventsAndReset(GenericEventMap* generic_events);
+ private:
+  bool ShouldProcessEvent(CastLoggingEvent event);
 
- private:
+  // Removes oldest entry from |frame_event_map_| (ordered by RTP timestamp).
+  void TruncateFrameEventMapIfNeeded();
+
+  // Removes oldest entry from |packet_event_map_| (ordered by RTP timestamp).
+  void TruncatePacketEventMapIfNeeded();
+
+  const EventMediaType event_media_type_;
+  const size_t max_frames_;
+
   FrameEventMap frame_event_map_;
   PacketEventMap packet_event_map_;
-  GenericEventMap generic_event_map_;
 
   // All functions must be called on the main thread.
   base::ThreadChecker thread_checker_;
 
   DISALLOW_COPY_AND_ASSIGN(EncodingEventSubscriber);
 };
 
 }  // namespace cast
 }  // namespace media
 
 #endif  // MEDIA_CAST_LOGGING_ENCODING_EVENT_SUBSCRIBER_H_