Let alr dectector use a budged to detect underuse.

webrtc/modules/pacing/alr_detector.h

 /*
  *  Copyright (c) 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_MODULES_PACING_ALR_DETECTOR_H_
 #define WEBRTC_MODULES_PACING_ALR_DETECTOR_H_
 
 #include "webrtc/common_types.h"
+#include "webrtc/modules/pacing/interval_budget.h"
 #include "webrtc/modules/pacing/paced_sender.h"
 #include "webrtc/rtc_base/optional.h"
 #include "webrtc/rtc_base/rate_statistics.h"
 #include "webrtc/typedefs.h"
 
 namespace webrtc {
 
 // Application limited region detector is a class that utilizes signals of
 // elapsed time and bytes sent to estimate whether network traffic is
 // currently limited by the application's ability to generate traffic.
 //
 // AlrDetector provides a signal that can be utilized to adjust
 // estimate bandwidth.
 // Note: This class is not thread-safe.
 
 class AlrDetector {
  public:
   AlrDetector();
   ~AlrDetector();
 
-  void OnBytesSent(size_t bytes_sent, int64_t now_ms);
+  void OnBytesSent(size_t bytes_sent, int64_t delta_time_ms);
 
   // Set current estimated bandwidth.
   void SetEstimatedBitrate(int bitrate_bps);
 
   // Returns time in milliseconds when the current application-limited region
   // started or empty result if the sender is currently not application-limited.
   rtc::Optional<int64_t> GetApplicationLimitedRegionStartTime() const;
 
   struct AlrExperimentSettings {
     float pacing_factor = PacedSender::kDefaultPaceMultiplier;
     int64_t max_paced_queue_time = PacedSender::kMaxQueueLengthMs;
-    int alr_start_usage_percent = kDefaultAlrStartUsagePercent;
-    int alr_end_usage_percent = kDefaultAlrEndUsagePercent;
+    int alr_bandwidth_usage_percent = kDefaultAlrBandwidthUsagePercent;
+    int alr_start_budget_level_percent = kDefaultAlrStartBudgetLevelPercent;
+    int alr_stop_budget_level_percent = kDefaultAlrStopBudgetLevelPercent;
   };
   static rtc::Optional<AlrExperimentSettings> ParseAlrSettingsFromFieldTrial();
 
   // Sent traffic percentage as a function of network capacity used to determine
   // application-limited region. ALR region start when bandwidth usage drops
   // below kAlrStartUsagePercent and ends when it raises above
   // kAlrEndUsagePercent. NOTE: This is intentionally conservative at the moment
   // until BW adjustments of application limited region is fine tuned.
-  static constexpr int kDefaultAlrStartUsagePercent = 60;
-  static constexpr int kDefaultAlrEndUsagePercent = 70;
+  static constexpr int kDefaultAlrBandwidthUsagePercent = 65;
+  static constexpr int kDefaultAlrStartBudgetLevelPercent = 20;
+  static constexpr int kDefaultAlrStopBudgetLevelPercent = -20;
   static const char* kScreenshareProbingBweExperimentName;
 
+  void UpdateBudgetWithElapsedTime(int64_t delta_time_ms);
+  void UpdateBudgetWithBytesSent(size_t bytes_sent);
+
  private:
-  int alr_start_usage_percent_;
-  int alr_end_usage_percent_;
-  RateStatistics rate_;
-  int estimated_bitrate_bps_;
+  int bandwidth_usage_percent_;
+  int alr_start_budget_level_percent_;
+  int alr_stop_budget_level_percent_;
 
-  // Non-empty in ALR state.
+  IntervalBudget alr_budget_;
   rtc::Optional<int64_t> alr_started_time_ms_;
 };
 
 }  // namespace webrtc
 
 #endif  // WEBRTC_MODULES_PACING_ALR_DETECTOR_H_