Probing: Add support for exponential startup probing

webrtc/modules/pacing/paced_sender.h

 /*
  *  Copyright (c) 2012 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_MODULES_PACING_PACED_SENDER_H_
 #define WEBRTC_MODULES_PACING_PACED_SENDER_H_
 
 #include <list>
+#include <map>
 #include <memory>
 #include <set>
 
+#include "webrtc/base/checks.h"
 #include "webrtc/base/thread_annotations.h"
 #include "webrtc/modules/include/module.h"
 #include "webrtc/modules/rtp_rtcp/include/rtp_rtcp_defines.h"
 #include "webrtc/typedefs.h"
 
 namespace webrtc {
 class BitrateProber;
 class Clock;
 class CriticalSectionWrapper;
 
 namespace paced_sender {
 class IntervalBudget;
 struct Packet;
 class PacketQueue;
 }  // namespace paced_sender
 
 class PacedSender : public Module, public RtpPacketSender {
  public:
+  enum class State {
+    kInit,
+    kWaitForProbingResult,
+    kStartupProbing,
+    kNormal,
+  };
+
   class PacketSender {
    public:
     // Note: packets sent as a result of a callback should not pass by this
     // module again.
     // Called when it's time to send a queued packet.
     // Returns false if packet cannot be sent.
     virtual bool TimeToSendPacket(uint32_t ssrc,
                                   uint16_t sequence_number,
                                   int64_t capture_time_ms,
                                   bool retransmission,
@@ skipping 11 matching lines @@
   // encoding them). Bitrate sent may temporarily exceed target set by
   // UpdateBitrate() so that this limit will be upheld.
   static const int64_t kMaxQueueLengthMs;
   // Pacing-rate relative to our target send rate.
   // Multiplicative factor that is applied to the target bitrate to calculate
   // the number of bytes that can be transmitted per interval.
   // Increasing this factor will result in lower delays in cases of bitrate
   // overshoots from the encoder.
   static const float kDefaultPaceMultiplier;
 
-  static const size_t kMinProbePacketSize = 200;
+  // TODO(isheriff): Large enough to allow measurements up-to 7 Mbps.
+  // This requirement will go away when we cluster multiple packets as a single
+  // probe.
+  static const size_t kMinProbePacketSize = 1000;

[stefan-webrtc, 2016/08/16 11:27:04]

I'm not sure about introducing this change. It will break the behavior at low
bitrates, e.g., if the bitrate is set to 300 kbps we may never have 1000 bytes
packets.

[Irfan, 2016/08/16 18:12:47]

I will go ahead and revert this. Since I plan to add support for multiple
packets per probe, this should not be needed.

 
   PacedSender(Clock* clock,
               PacketSender* packet_sender);
 
   virtual ~PacedSender();
 
   // Temporarily pause all sending.
   void Pause();
 
   // Resume sending packets.
   void Resume();
 
   // Enable bitrate probing. Enabled by default, mostly here to simplify
   // testing. Must be called before any packets are being sent to have an
   // effect.
   void SetProbingEnabled(bool enabled);
 
   // Sets the estimated capacity of the network. Must be called once before
   // packets can be sent.
   // |bitrate_bps| is our estimate of what we are allowed to send on average.
   // We will pace out bursts of packets at a bitrate of
   // |bitrate_bps| * kDefaultPaceMultiplier.
-  virtual void SetEstimatedBitrate(uint32_t bitrate_bps);
+  virtual void SetEstimatedBitrate(int bitrate_bps);
 
   // Sets the minimum send bitrate and maximum padding bitrate requested by send
   // streams.
   // |min_send_bitrate_bps| might be higher that the estimated available network
   // bitrate and if so, the pacer will send with |min_send_bitrate_bps|.
   // |max_padding_bitrate_bps| might be higher than the estimate available
   // network bitrate and if so, the pacer will send padding packets to reach
   // the min of the estimated available bitrate and |max_padding_bitrate_bps|.
   void SetSendBitrateLimits(int min_send_bitrate_bps,
                             int max_padding_bitrate_bps);
@@ skipping 20 matching lines @@
   // packets currently in the pacer queue, or 0 if queue is empty.
   virtual int64_t AverageQueueTimeMs();
 
   // Returns the number of milliseconds until the module want a worker thread
   // to call Process.
   int64_t TimeUntilNextProcess() override;
 
   // Process any pending packets in the queue(s).
   void Process() override;
 
+  State PacingState();
+  void OnProbingBitrateMeasured(int bitrate_bps);
+
  private:
   // Updates the number of bytes that can be sent for the next time interval.
   void UpdateBytesPerInterval(int64_t delta_time_in_ms)
       EXCLUSIVE_LOCKS_REQUIRED(critsect_);
 
   bool SendPacket(const paced_sender::Packet& packet, int probe_cluster_id)
       EXCLUSIVE_LOCKS_REQUIRED(critsect_);
   void SendPadding(size_t padding_needed, int probe_cluster_id)
       EXCLUSIVE_LOCKS_REQUIRED(critsect_);
 
   Clock* const clock_;
   PacketSender* const packet_sender_;
 
   std::unique_ptr<CriticalSectionWrapper> critsect_;
   bool paused_ GUARDED_BY(critsect_);
   // This is the media budget, keeping track of how many bits of media
   // we can pace out during the current interval.
   std::unique_ptr<paced_sender::IntervalBudget> media_budget_
       GUARDED_BY(critsect_);
   // This is the padding budget, keeping track of how many bits of padding we're
   // allowed to send out during the current interval. This budget will be
   // utilized when there's no media to send.
   std::unique_ptr<paced_sender::IntervalBudget> padding_budget_
       GUARDED_BY(critsect_);
 
   std::unique_ptr<BitrateProber> prober_ GUARDED_BY(critsect_);
   // Actual configured bitrates (media_budget_ may temporarily be higher in
   // order to meet pace time constraint).
-  uint32_t estimated_bitrate_bps_ GUARDED_BY(critsect_);
-  uint32_t min_send_bitrate_kbps_ GUARDED_BY(critsect_);
-  uint32_t max_padding_bitrate_kbps_ GUARDED_BY(critsect_);
-  uint32_t pacing_bitrate_kbps_ GUARDED_BY(critsect_);
+  int estimated_bitrate_bps_ GUARDED_BY(critsect_);
+  int min_send_bitrate_kbps_ GUARDED_BY(critsect_);
+  int max_padding_bitrate_kbps_ GUARDED_BY(critsect_);
+  int pacing_bitrate_kbps_ GUARDED_BY(critsect_);
 
   int64_t time_last_update_us_ GUARDED_BY(critsect_);
 
   std::unique_ptr<paced_sender::PacketQueue> packets_ GUARDED_BY(critsect_);
   uint64_t packet_counter_;
+  // TODO(isheriff): Adding critsect_ gets clang complaints even with
+  // critsect_ protection turned on!
+  State pacing_state_;
+  int64_t start_time_wait_probe_result_ms_ GUARDED_BY(critsect_);
+  int min_bitrate_to_probe_further_ GUARDED_BY(critsect_);
+  int bitrate_below_expected_count_ GUARDED_BY(critsect_) = 0;

[stefan-webrtc, 2016/08/16 11:27:05]

Initialize in initializer list instead.

[Irfan, 2016/08/16 18:12:47]

Will do, but I seem to recall seeing in style this being encouraged (I cant find
it now though)

 };
 }  // namespace webrtc
 #endif  // WEBRTC_MODULES_PACING_PACED_SENDER_H_