Adding the logic for releasing decoder resources in WebMediaPlayerManagerAndroid

webkit/media/android/webmediaplayer_manager_android.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 "webkit/media/android/webmediaplayer_manager_android.h"
 
 #include "webkit/media/android/webmediaplayer_android.h"
 
+// The number of maximum active player allowed in a renderer.
+static const int kMaxMediaPlayerLimit = 2;
+
 namespace webkit_media {
 
 WebMediaPlayerManagerAndroid::WebMediaPlayerManagerAndroid()
-    : next_media_player_id_(0) {
+    : next_media_player_id_(0),
+      num_active_players_(0) {
 }
 
 WebMediaPlayerManagerAndroid::~WebMediaPlayerManagerAndroid() {}

[scherkus (not reviewing), 2012/06/07 21:44:34]

based on our discussion doesn't this rely on the shutdown behaviour of RVImpl to
call ReleaseMediaResource() as a result of RVImpl::OnWasHidden() being called
prior to ~RVImpl()?

Should we consider calling ReleaseMediaResources() here?

[qinmin, 2012/06/08 17:09:06]

Done.

 
 int WebMediaPlayerManagerAndroid::RegisterMediaPlayer(
     WebMediaPlayerAndroid* player) {
-  MediaPlayerInfo info;
-  info.player = player;
-  media_players_[next_media_player_id_] = info;
+  media_players_[next_media_player_id_] = player;
   return next_media_player_id_++;
 }
 
 void WebMediaPlayerManagerAndroid::UnregisterMediaPlayer(int player_id) {
-  std::map<int32, MediaPlayerInfo>::iterator iter =
+  std::map<int32, WebMediaPlayerAndroid*>::iterator iter =
       media_players_.find(player_id);
   DCHECK(iter != media_players_.end());
 
+  if ((iter->second)->IsInitialized())
+    num_active_players_--;
   media_players_.erase(player_id);
 }
 
+void WebMediaPlayerManagerAndroid::RequestMediaResources(int player_id) {
+  std::map<int32, WebMediaPlayerAndroid*>::iterator iter =
+      media_players_.find(player_id);
+  DCHECK(iter != media_players_.end());
+
+  if ((iter->second)->IsInitialized())
+    return;
+
+  // Release active players that are paused. Because we only release paused
+  // players, the number of running players could go beyond the limit.
+  // TODO(qinmin): we should use LRU to release the oldest player if we are
+  // reaching hardware limit.
+  if (num_active_players_ >= kMaxMediaPlayerLimit) {
+    std::map<int32, WebMediaPlayerAndroid*>::iterator player_it;
+    for (player_it = media_players_.begin();
+        player_it != media_players_.end(); ++player_it) {
+      WebMediaPlayerAndroid* player = player_it->second;
+      if (player->IsInitialized() && player->paused()) {
+        player->ReleaseMediaResources();
+        num_active_players_--;
+      }
+    }
+  }
+
+  num_active_players_++;
+}
+
 void WebMediaPlayerManagerAndroid::ReleaseMediaResources() {
-  std::map<int32, MediaPlayerInfo>::iterator player_it;
+  std::map<int32, WebMediaPlayerAndroid*>::iterator player_it;
   for (player_it = media_players_.begin();
       player_it != media_players_.end(); ++player_it) {
-    (player_it->second).player->ReleaseMediaResources();
+    (player_it->second)->ReleaseMediaResources();
   }
+  num_active_players_ = 0;

[scherkus (not reviewing), 2012/06/07 21:44:34]

this is a scary/bug-prone design as you're manually tracking a ref-count for
objects that live (and can be destroyed) in WMPA without this class being aware

considering that requesting + releasing media resources shouldn't happen too
often could we replace this count (which could get out of sync!) with a helper
method that iterates over active WMPA objects and counts IsInitialized()?

[qinmin, 2012/06/08 17:09:06]

Done.

 }
 
 WebMediaPlayerAndroid* WebMediaPlayerManagerAndroid::GetMediaPlayer(
     int player_id) {
-  std::map<int32, MediaPlayerInfo>::iterator iter =
+  std::map<int32, WebMediaPlayerAndroid*>::iterator iter =
       media_players_.find(player_id);
   if (iter != media_players_.end())
-    return (iter->second).player;
+    return iter->second;
   return NULL;
 }
 
 }  // namespace webkit_media