RTCStatsCollector and RTCPeerConnectionStats added

webrtc/stats/rtcstatscollector.h

+/*
+ *  Copyright 2016 The WebRTC Project Authors. All rights reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#ifndef WEBRTC_STATS_RTCSTATSCOLLECTOR_H_
+#define WEBRTC_STATS_RTCSTATSCOLLECTOR_H_
+
+#include <memory>
+
+#include "webrtc/api/peerconnection.h"

[magjed_webrtc, 2016/08/25 09:07:52]

If this is only used for PeerConnection*, forward declare it instead of
including it.

[hbos, 2016/08/29 13:10:58]

Done.

+#include "webrtc/api/rtcstats_objects.h"
+#include "webrtc/api/rtcstatsreport.h"
+#include "webrtc/base/refcount.h"

[magjed_webrtc, 2016/08/25 09:07:52]

refcount is not needed?

[hbos, 2016/08/29 13:10:59]

Done.

+#include "webrtc/base/scoped_ref_ptr.h"
+#include "webrtc/base/timing.h"
+
+namespace webrtc {
+
+// All calls to the collector and gathering of stats is performed on the
+// signaling thread. A stats report is cached for |cache_lifetime_| ms.
+class RTCStatsCollector {
+ public:
+  RTCStatsCollector(

[magjed_webrtc, 2016/08/25 09:07:52]

You have only one mandatory argument, so I think you need to use explicit here
to disallow implicit conversions from PeerConnection*.

[hbos, 2016/08/29 13:10:58]

Done.

+      PeerConnection* pc,
+      double cache_lifetime = 0.05,
+      std::unique_ptr<rtc::Timing> timing = std::unique_ptr<rtc::Timing>(
+          new rtc::Timing()));
+
+  // Gets a recent stats report. If there is a report cached that is still fresh
+  // it is returned, otherwise new stats are gathered and returned. A report is
+  // considered fresh for |cache_lifetime_| ms. const RTCStatsReports are safe
+  // to use across multiple threads and may be destructed on any thread.
+  rtc::scoped_refptr<const RTCStatsReport> GetStatsReport();
+  // Clears the cache's reference to the most recent stats report. Subsequently
+  // calling |GetStatsReport| guarantees fresh stats.
+  void ClearCachedStatsReport();
+
+ private:
+  bool IsSignalingThread() const;

[hta-webrtc, 2016/08/26 09:28:57]

Naming nit: This isn't a thread, so "IsSignalingThread" is a misleading name.
"IsOnSignalingThread" is better.
(Unless there's other code that you want to be consistent with)

[hbos, 2016/08/29 13:10:58]

Done.

+
+  std::unique_ptr<RTCPeerConnectionStats> ProducePeerConnectionStats() const;
+
+  PeerConnection* const pc_;
+  mutable std::unique_ptr<rtc::Timing> timing_;
+  // Time relative to the UNIX epoch (Jan 1, 1970, UTC), in seconds.
+  double cache_timestamp_;
+  double cache_lifetime_;  // In seconds.
+  rtc::scoped_refptr<const RTCStatsReport> cached_report_;
+};
+
+}  // namespace webrtc
+
+#endif  // WEBRTC_STATS_RTCSTATSCOLLECTOR_H_