Implemented the GetSources() in native code.

webrtc/modules/rtp_rtcp/source/rtp_receiver_impl.h

Index: webrtc/modules/rtp_rtcp/source/rtp_receiver_impl.h
diff --git a/webrtc/modules/rtp_rtcp/source/rtp_receiver_impl.h b/webrtc/modules/rtp_rtcp/source/rtp_receiver_impl.h
index 4b5524877c77206c58eb8db145ba0f88202b75c9..2ff7efa75e179b83978b8c3aaf1ac1a85d24bf96 100644
--- a/webrtc/modules/rtp_rtcp/source/rtp_receiver_impl.h
+++ b/webrtc/modules/rtp_rtcp/source/rtp_receiver_impl.h
@@ -11,7 +11,10 @@
 #ifndef WEBRTC_MODULES_RTP_RTCP_SOURCE_RTP_RECEIVER_IMPL_H_
 #define WEBRTC_MODULES_RTP_RTCP_SOURCE_RTP_RECEIVER_IMPL_H_
 
+#include <list>
 #include <memory>
+#include <unordered_map>
+#include <vector>
 
 #include "webrtc/base/criticalsection.h"
 #include "webrtc/modules/rtp_rtcp/include/rtp_receiver.h"
@@ -56,6 +59,12 @@ class RtpReceiverImpl : public RtpReceiver {
 
   TelephoneEventHandler* GetTelephoneEventHandler() override;
 
+  std::vector<RtpSource> GetSources() const override;
+
+  const std::vector<RtpSource>& ssrc_sources() { return ssrc_sources_; }

[the sun, 2017/04/06 06:55:38]

Is this for testing? Mark that with a comment, or changing the names to e.g.
..._for_testing().

And the methods should be const.

[hbos, 2017/04/06 08:17:16]

+1. These should be for_testing because they expose a reference to a variable
that requires use of locks unless you know what you're doing.

[Zhi Huang, 2017/04/06 22:30:25]

Done.

+
+  const std::list<RtpSource>& csrc_sources() { return csrc_sources_; }
+
  private:
   bool HaveReceivedFrame() const;
 
@@ -66,6 +75,9 @@ class RtpReceiverImpl : public RtpReceiver {
                               bool* is_red,
                               PayloadUnion* payload);
 
+  void UpdateSources();
+  void RemoveOutdatedSources(int64_t now);
+
   Clock* clock_;
   RTPPayloadRegistry* rtp_payload_registry_;
   std::unique_ptr<RTPReceiverStrategy> rtp_media_receiver_;
@@ -84,6 +96,12 @@ class RtpReceiverImpl : public RtpReceiver {
   uint32_t last_received_timestamp_;
   int64_t last_received_frame_time_ms_;
   uint16_t last_received_sequence_number_;
+
+  std::unordered_map<uint32_t, std::list<RtpSource>::iterator>
+      iterator_by_csrc_;
+  // The RtpSource objects are sorted chronologically.
+  std::list<RtpSource> csrc_sources_;

[philipel, 2017/04/06 14:33:34]

I think an std::deque might be better in this case since we only insert/remove
at begining/end of the container.

[Zhi Huang, 2017/04/06 22:30:25]

For csrc_sources, we need to use the std::list::splice operation to maintain the
order.
For ssrc_sources, yes, we can use a deque. But this collection is not expected
to be large, not sure if it will make a big difference.

[philipel, 2017/04/07 08:44:07]

I was thinking instead of splicing, just push_front(back()), update the
timestamp and then pop_back(), but as you said, I don't think it matters much in
this case.

+  std::vector<RtpSource> ssrc_sources_;
 };
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_RTP_RTCP_SOURCE_RTP_RECEIVER_IMPL_H_