WebRtcMediaStreamTrackMap added

content/renderer/media/webrtc/webrtc_media_stream_track_adapter_map.h

+// Copyright (c) 2017 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_RENDERER_MEDIA_WEBRTC_WEBRTC_MEDIA_STREAM_TRACK_COLLECTION_H_
+#define CONTENT_RENDERER_MEDIA_WEBRTC_WEBRTC_MEDIA_STREAM_TRACK_COLLECTION_H_
+
+#include <map>
+#include <string>
+
+#include "base/memory/ref_counted.h"
+#include "base/single_thread_task_runner.h"
+#include "content/common/content_export.h"
+#include "content/renderer/media/webrtc/webrtc_media_stream_track_adapter.h"
+#include "third_party/WebKit/public/platform/WebMediaStreamTrack.h"
+#include "third_party/webrtc/api/mediastreaminterface.h"
+
+namespace content {
+
+class PeerConnectionDependencyFactory;
+
+// A map and owner of |WebRtcMediaStreamTrackAdapter|s. It takes care of
+// creating, initializing and disposing track adapters independently of media
+// streams. Adapters are accessed via |AdapterRef|s, when all references to an
+// adapter are destroyed it is disposed and removed from the map.
+class CONTENT_EXPORT WebRtcMediaStreamTrackAdapterMap
+    : public base::RefCountedThreadSafe<WebRtcMediaStreamTrackAdapterMap> {
+ private:
+  // The map's entries are reference counted in order to |Dispose| the adapter
+  // when all |AdapterRef|s referencing an entry are destroyed.
+  struct AdapterEntry {

[Guido Urdaneta, 2017/06/02 13:19:01]

Can you move the definition of this type to the .cc file?
Also, move this to the private section below. I think it's against the style
guide to define a private section in the beginning of the class.

[hbos_chromium, 2017/06/05 11:55:40]

It has to be *defined* in the header for AdapterEntry to be defined due to
std::map.
It can be moved to the private section, but it still needs to be *declared*
before AdapterEntry is defined or it will say undeclared identifier.

I changed it to:

class WebRtcMediaStreamTrackAdapterMap {
 private:
  struct AdapterEntry;

 public:
  class AdapterRef { ... };
  ...

 private:
  struct AdapterEntry { ... };
  ...
};

The only way to move it out of the header is to change AdapterEntry's std::map
to use std::unique_ptr<AdapterEntry> but I'll probably still have to
forward-declare it before the public section. If you think this is better I can
update before landing.

[hbos_chromium, 2017/06/05 12:25:00]

Above I meant forward-declare and declare, not declare and define.

Seems like on some bots I have to declare it before AdapterEntry for std::map to
work so it's either the old way or the std::unique_ptr way.

[Guido Urdaneta, 2017/06/05 13:05:56]

go for the old way then.

[hbos_chromium, 2017/06/08 09:47:45]

Done.

+    AdapterEntry(const scoped_refptr<WebRtcMediaStreamTrackAdapter>& adapter);
+    AdapterEntry(AdapterEntry&& other);
+    AdapterEntry(const AdapterEntry&) = delete;
+    ~AdapterEntry();
+
+    scoped_refptr<WebRtcMediaStreamTrackAdapter> adapter;
+    size_t ref_count;

[Guido Urdaneta, 2017/06/02 13:19:02]

Can you reuse the reference count in adapter instead of adding a separate one?
If not, can you make WebRtcMediaStreamTrackAdapter not refcounted to avoid the
redundant refcount?

[hbos_chromium, 2017/06/05 11:55:40]

Done, using HasOneRef() to determine if disposing is necessary.

+  };
+
+ public:
+  // Acts as an accessor to adapter members without leaking a reference to the
+  // adapter. When the last |AdapterRef| is destroyed, the corresponding adapter
+  // is |Dispose|d and removed from the map.
+  class CONTENT_EXPORT AdapterRef {
+   public:
+    enum class Type { kLocal, kRemote };

[Guido Urdaneta, 2017/06/02 13:19:02]

Move to private section. It's used only by a private constructor.

[hbos_chromium, 2017/06/05 11:55:40]

Done.

+
+    // Must be invoked on the main thread. If this was the last reference to the
+    // adapter it will be disposed and removed from the map.
+    ~AdapterRef();
+
+    bool is_initialized() const { return adapter()->is_initialized(); }
+    const blink::WebMediaStreamTrack& web_track() const {
+      return adapter()->web_track();
+    }
+    webrtc::MediaStreamTrackInterface* webrtc_track() const {
+      return adapter()->webrtc_track();
+    }
+
+    const scoped_refptr<WebRtcMediaStreamTrackAdapter>& GetAdapterForTesting()
+        const {
+      return adapter();
+    }
+
+   private:
+    friend class WebRtcMediaStreamTrackAdapterMap;
+
+    // Increments the |AdapterEntry::ref_count|. Assumes map's |lock_| is held.
+    AdapterRef(const scoped_refptr<WebRtcMediaStreamTrackAdapterMap>& map,
+               Type type,
+               const std::map<std::string, AdapterEntry>::iterator& it);
+
+    AdapterEntry* entry() { return &it_->second; }
+    const scoped_refptr<WebRtcMediaStreamTrackAdapter>& adapter() const {
+      return it_->second.adapter;
+    }
+
+    scoped_refptr<WebRtcMediaStreamTrackAdapterMap> map_;
+    Type type_;
+    std::map<std::string, AdapterEntry>::iterator it_;

[Guido Urdaneta, 2017/06/02 13:19:02]

A private type alias (e.g., MapEntry = std::map<std::string,
AdapterEntry>::iterator) would make it easier to see that this field points to
an entry in the map.

[hbos_chromium, 2017/06/05 11:55:40]

Done.

+  };
+
+  WebRtcMediaStreamTrackAdapterMap(
+      PeerConnectionDependencyFactory* const factory,
+      const scoped_refptr<base::SingleThreadTaskRunner>& main_thread);
+
+  // Gets a new reference to the local track adapter by ID, or null if no such

[Guido Urdaneta, 2017/06/02 13:19:01]

nit: the -> a

[hbos_chromium, 2017/06/05 11:55:40]

Done.

+  // adapter was found. When all references are destroyed the adapter is
+  // disposed and removed from the map. This method can be called from any
+  // thread, but references must be destroyed on the main thread.
+  std::unique_ptr<AdapterRef> GetLocalTrackAdapter(const std::string& id);
+  // Invoke on the main thread. Gets a new reference to the local track adapter
+  // by web track. If no adapter exists for the track one is created and

[Guido Urdaneta, 2017/06/02 13:19:01]

nit: by -> for

[hbos_chromium, 2017/06/05 11:55:40]

Done.

+  // initialized. When all references are destroyed the adapter is disposed and
+  // removed from the map. References must be destroyed on the main thread.
+  std::unique_ptr<AdapterRef> GetOrCreateLocalTrackAdapter(
+      const blink::WebMediaStreamTrack& web_track);
+  size_t GetLocalTrackCount() const;
+
+  // Gets a new reference to the remote track adapter by ID, or null if no such
+  // adapter was found. When all references are destroyed the adapter is
+  // disposed and removed from the map. This method can be called from any
+  // thread, but references must be destroyed on the main thread.
+  std::unique_ptr<AdapterRef> GetRemoteTrackAdapter(const std::string& id);
+  // Invoke on the webrtc signaling thread. Gets a new reference to the remote
+  // track adapter by webrtc track. If no adapter exists for the track one is
+  // created and initialization completes on the main thread in a post. When all
+  // references are destroyed the adapter is disposed and removed from the map.
+  // References must be destroyed on the main thread.
+  std::unique_ptr<AdapterRef> GetOrCreateRemoteTrackAdapter(
+      webrtc::MediaStreamTrackInterface* webrtc_track);
+  size_t GetRemoteTrackCount() const;
+
+ protected:
+  friend class base::RefCountedThreadSafe<WebRtcMediaStreamTrackAdapterMap>;
+
+  // Invoke on the main thread.
+  virtual ~WebRtcMediaStreamTrackAdapterMap();
+
+ private:
+  // Pointer to a |PeerConnectionDependencyFactory| owned by the |RenderThread|.
+  // It's valid for the lifetime of |RenderThread|.
+  PeerConnectionDependencyFactory* const factory_;
+  scoped_refptr<base::SingleThreadTaskRunner> main_thread_;
+
+  mutable base::Lock lock_;
+  std::map<std::string, AdapterEntry> local_track_adapters_;
+  std::map<std::string, AdapterEntry> remote_track_adapters_;
+};
+
+}  // namespace content
+
+#endif  // CONTENT_RENDERER_MEDIA_WEBRTC_WEBRTC_MEDIA_STREAM_TRACK_COLLECTION_H_