1 /*
2  *  Copyright (c) 2014 The WebRTC project authors. All Rights Reserved.
3  *
4  *  Use of this source code is governed by a BSD-style license
5  *  that can be found in the LICENSE file in the root of the source
6  *  tree. An additional intellectual property rights grant can be found
7  *  in the file PATENTS.  All contributing project authors may
8  *  be found in the AUTHORS file in the root of the source tree.
9  */
10 
11 #ifndef WEBRTC_MODULES_PACING_BITRATE_PROBER_H_
12 #define WEBRTC_MODULES_PACING_BITRATE_PROBER_H_
13 
14 #include <cstddef>
15 #include <list>
16 
17 #include "webrtc/typedefs.h"
18 
19 namespace webrtc {
20 
21 // Note that this class isn't thread-safe by itself and therefore relies
22 // on being protected by the caller.
23 class BitrateProber {
24  public:
25   BitrateProber();
26 
27   void SetEnabled(bool enable);
28 
29   // Returns true if the prober is in a probing session, i.e., it currently
30   // wants packets to be sent out according to the time returned by
31   // TimeUntilNextProbe().
32   bool IsProbing() const;
33 
34   // Initializes a new probing session if the prober is allowed to probe.
35   void MaybeInitializeProbe(int bitrate_bps);
36 
37   // Returns the number of milliseconds until the next packet should be sent to
38   // get accurate probing.
39   int TimeUntilNextProbe(int64_t now_ms);
40 
41   // Returns the number of bytes that the prober recommends for the next probe
42   // packet.
43   size_t RecommendedPacketSize() const;
44 
45   // Called to report to the prober that a packet has been sent, which helps the
46   // prober know when to move to the next packet in a probe.
47   void PacketSent(int64_t now_ms, size_t packet_size);
48 
49  private:
50   enum ProbingState { kDisabled, kAllowedToProbe, kProbing, kWait };
51 
52   ProbingState probing_state_;
53   // Probe bitrate per packet. These are used to compute the delta relative to
54   // the previous probe packet based on the size and time when that packet was
55   // sent.
56   std::list<int> probe_bitrates_;
57   size_t packet_size_last_send_;
58   int64_t time_last_send_ms_;
59 };
60 }  // namespace webrtc
61 #endif  // WEBRTC_MODULES_PACING_BITRATE_PROBER_H_
62