call/receive_time_calculator_unittest.cc - src - Git at Google

 /*
  *  Copyright (c) 2018 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.
  */

 #include "call/receive_time_calculator.h"

 #include <stdlib.h>

 #include <algorithm>
 #include <cmath>
 #include <cstdint>
 #include <vector>

 #include "absl/types/optional.h"
 #include "rtc_base/random.h"
 #include "rtc_base/time_utils.h"
 #include "test/gtest.h"

 namespace webrtc {
 namespace test {
 namespace {

 class EmulatedClock {
  public:
   explicit EmulatedClock(int seed, float drift = 0.0f)
       : random_(seed), clock_us_(random_.Rand<uint32_t>()), drift_(drift) {}
   virtual ~EmulatedClock() = default;
   int64_t GetClockUs() const { return clock_us_; }

  protected:
   int64_t UpdateClock(int64_t time_us) {
     if (!last_query_us_)
       last_query_us_ = time_us;
     int64_t skip_us = time_us - *last_query_us_;
     accumulated_drift_us_ += skip_us * drift_;
     int64_t drift_correction_us = static_cast<int64_t>(accumulated_drift_us_);
     accumulated_drift_us_ -= drift_correction_us;
     clock_us_ += skip_us + drift_correction_us;
     last_query_us_ = time_us;
     return skip_us;
   }
   Random random_;

  private:
   int64_t clock_us_;
   absl::optional<int64_t> last_query_us_;
   float drift_;
   float accumulated_drift_us_ = 0;
 };

 class EmulatedMonotoneousClock : public EmulatedClock {
  public:
   explicit EmulatedMonotoneousClock(int seed) : EmulatedClock(seed) {}
   ~EmulatedMonotoneousClock() = default;

   int64_t Query(int64_t time_us) {
     int64_t skip_us = UpdateClock(time_us);

     // In a stall
     if (stall_recovery_time_us_ > 0) {
       if (GetClockUs() > stall_recovery_time_us_) {
         stall_recovery_time_us_ = 0;
         return GetClockUs();
       } else {
         return stall_recovery_time_us_;
       }
     }

     // Check if we enter a stall
     for (int k = 0; k < skip_us; ++k) {
       if (random_.Rand<double>() < kChanceOfStallPerUs) {
         int64_t stall_duration_us =
             static_cast<int64_t>(random_.Rand<float>() * kMaxStallDurationUs);
         stall_recovery_time_us_ = GetClockUs() + stall_duration_us;
         return stall_recovery_time_us_;
       }
     }
     return GetClockUs();
   }

   void ForceStallUs() {
     int64_t stall_duration_us =
         static_cast<int64_t>(random_.Rand<float>() * kMaxStallDurationUs);
     stall_recovery_time_us_ = GetClockUs() + stall_duration_us;
   }

   bool Stalled() const { return stall_recovery_time_us_ > 0; }

   int64_t GetRemainingStall(int64_t time_us) const {
     return stall_recovery_time_us_ > 0 ? stall_recovery_time_us_ - GetClockUs()
                                        : 0;
   }

   const int64_t kMaxStallDurationUs = rtc::kNumMicrosecsPerSec;

  private:
   const float kChanceOfStallPerUs = 5e-6f;
   int64_t stall_recovery_time_us_ = 0;
 };

 class EmulatedNonMonotoneousClock : public EmulatedClock {
  public:
   EmulatedNonMonotoneousClock(int seed, int64_t duration_us, float drift = 0)
       : EmulatedClock(seed, drift) {
     Pregenerate(duration_us);
   }
   ~EmulatedNonMonotoneousClock() = default;

   void Pregenerate(int64_t duration_us) {
     int64_t time_since_reset_us = kMinTimeBetweenResetsUs;
     int64_t clock_offset_us = 0;
     for (int64_t time_us = 0; time_us < duration_us; time_us += kResolutionUs) {
       int64_t skip_us = UpdateClock(time_us);
       time_since_reset_us += skip_us;
       int64_t reset_us = 0;
       if (time_since_reset_us >= kMinTimeBetweenResetsUs) {
         for (int k = 0; k < skip_us; ++k) {
           if (random_.Rand<double>() < kChanceOfResetPerUs) {
             reset_us = static_cast<int64_t>(2 * random_.Rand<float>() *
                                             kMaxAbsResetUs) -
                        kMaxAbsResetUs;
             clock_offset_us += reset_us;
             time_since_reset_us = 0;
             break;
           }
         }
       }
       pregenerated_clock_.emplace_back(GetClockUs() + clock_offset_us);
       resets_us_.emplace_back(reset_us);
     }
   }

   int64_t Query(int64_t time_us) {
     size_t ixStart =
         (last_reset_query_time_us_ + (kResolutionUs >> 1)) / kResolutionUs + 1;
     size_t ixEnd = (time_us + (kResolutionUs >> 1)) / kResolutionUs;
     if (ixEnd >= pregenerated_clock_.size())
       return -1;
     last_reset_size_us_ = 0;
     for (size_t ix = ixStart; ix <= ixEnd; ++ix) {
       if (resets_us_[ix] != 0) {
         last_reset_size_us_ = resets_us_[ix];
       }
     }
     last_reset_query_time_us_ = time_us;
     return pregenerated_clock_[ixEnd];
   }

   bool WasReset() const { return last_reset_size_us_ != 0; }
   bool WasNegativeReset() const { return last_reset_size_us_ < 0; }
   int64_t GetLastResetUs() const { return last_reset_size_us_; }

  private:
   const float kChanceOfResetPerUs = 1e-6f;
   const int64_t kMaxAbsResetUs = rtc::kNumMicrosecsPerSec;
   const int64_t kMinTimeBetweenResetsUs = 3 * rtc::kNumMicrosecsPerSec;
   const int64_t kResolutionUs = rtc::kNumMicrosecsPerMillisec;
   int64_t last_reset_query_time_us_ = 0;
   int64_t last_reset_size_us_ = 0;
   std::vector<int64_t> pregenerated_clock_;
   std::vector<int64_t> resets_us_;
 };

 TEST(ClockRepair, NoClockDrift) {
   const int kSeeds = 10;
   const int kFirstSeed = 1;
   const int64_t kRuntimeUs = 10 * rtc::kNumMicrosecsPerSec;
   const float kDrift = 0.0f;
   const int64_t kMaxPacketInterarrivalUs = 50 * rtc::kNumMicrosecsPerMillisec;
   for (int seed = kFirstSeed; seed < kSeeds + kFirstSeed; ++seed) {
     EmulatedMonotoneousClock monotone_clock(seed);
     EmulatedNonMonotoneousClock non_monotone_clock(
         seed + 1, kRuntimeUs + rtc::kNumMicrosecsPerSec, kDrift);
     ReceiveTimeCalculator reception_time_tracker;
     int64_t corrected_clock_0 = 0;
     int64_t reset_during_stall_tol_us = 0;
     bool initial_clock_stall = true;
     int64_t accumulated_upper_bound_tolerance_us = 0;
     int64_t accumulated_lower_bound_tolerance_us = 0;
     Random random(1);
     monotone_clock.ForceStallUs();
     int64_t last_time_us = 0;
     bool add_tolerance_on_next_packet = false;
     int64_t monotone_noise_us = 1000;

     for (int64_t time_us = 0; time_us < kRuntimeUs;
          time_us += static_cast<int64_t>(random.Rand<float>() *
                                          kMaxPacketInterarrivalUs)) {
       int64_t socket_time_us = non_monotone_clock.Query(time_us);
       int64_t monotone_us = monotone_clock.Query(time_us) +
                             2 * random.Rand<float>() * monotone_noise_us -
                             monotone_noise_us;
       int64_t system_time_us = non_monotone_clock.Query(
           time_us + monotone_clock.GetRemainingStall(time_us));

       int64_t corrected_clock_us = reception_time_tracker.ReconcileReceiveTimes(
           socket_time_us, system_time_us, monotone_us);
       if (time_us == 0)
         corrected_clock_0 = corrected_clock_us;

       if (add_tolerance_on_next_packet)
         accumulated_lower_bound_tolerance_us -= (time_us - last_time_us);

       // Perfect repair cannot be achiveved if non-monotone clock resets during
       // a monotone clock stall.
       add_tolerance_on_next_packet = false;
       if (monotone_clock.Stalled() && non_monotone_clock.WasReset()) {
         reset_during_stall_tol_us =
             std::max(reset_during_stall_tol_us, time_us - last_time_us);
         if (non_monotone_clock.WasNegativeReset()) {
           add_tolerance_on_next_packet = true;
         }
         if (initial_clock_stall && !non_monotone_clock.WasNegativeReset()) {
           // Positive resets during an initial clock stall cannot be repaired
           // and error will propagate through rest of trace.
           accumulated_upper_bound_tolerance_us +=
               std::abs(non_monotone_clock.GetLastResetUs());
         }
       } else {
         reset_during_stall_tol_us = 0;
         initial_clock_stall = false;
       }
       int64_t err = corrected_clock_us - corrected_clock_0 - time_us;

       // Resets during stalls may lead to small errors temporarily.
       int64_t lower_tol_us = accumulated_lower_bound_tolerance_us -
                              reset_during_stall_tol_us - monotone_noise_us -
                              2 * rtc::kNumMicrosecsPerMillisec;
       EXPECT_GE(err, lower_tol_us);
       int64_t upper_tol_us = accumulated_upper_bound_tolerance_us +
                              monotone_noise_us +
                              2 * rtc::kNumMicrosecsPerMillisec;
       EXPECT_LE(err, upper_tol_us);

       last_time_us = time_us;
     }
   }
 }
 }  // namespace
 }  // namespace test
 }  // namespace webrtc
	/*
	* Copyright (c) 2018 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.
	*/

	#include "call/receive_time_calculator.h"

	#include <stdlib.h>

	#include <algorithm>
	#include <cmath>
	#include <cstdint>
	#include <vector>

	#include "absl/types/optional.h"
	#include "rtc_base/random.h"
	#include "rtc_base/time_utils.h"
	#include "test/gtest.h"

	namespace webrtc {
	namespace test {
	namespace {

	class EmulatedClock {
	public:
	explicit EmulatedClock(int seed, float drift = 0.0f)
	: random_(seed), clock_us_(random_.Rand<uint32_t>()), drift_(drift) {}
	virtual ~EmulatedClock() = default;
	int64_t GetClockUs() const { return clock_us_; }

	protected:
	int64_t UpdateClock(int64_t time_us) {
	if (!last_query_us_)
	last_query_us_ = time_us;
	int64_t skip_us = time_us - *last_query_us_;
	accumulated_drift_us_ += skip_us * drift_;
	int64_t drift_correction_us = static_cast<int64_t>(accumulated_drift_us_);
	accumulated_drift_us_ -= drift_correction_us;
	clock_us_ += skip_us + drift_correction_us;
	last_query_us_ = time_us;
	return skip_us;
	}
	Random random_;

	private:
	int64_t clock_us_;
	absl::optional<int64_t> last_query_us_;
	float drift_;
	float accumulated_drift_us_ = 0;
	};

	class EmulatedMonotoneousClock : public EmulatedClock {
	public:
	explicit EmulatedMonotoneousClock(int seed) : EmulatedClock(seed) {}
	~EmulatedMonotoneousClock() = default;

	int64_t Query(int64_t time_us) {
	int64_t skip_us = UpdateClock(time_us);

	// In a stall
	if (stall_recovery_time_us_ > 0) {
	if (GetClockUs() > stall_recovery_time_us_) {
	stall_recovery_time_us_ = 0;
	return GetClockUs();
	} else {
	return stall_recovery_time_us_;
	}
	}

	// Check if we enter a stall
	for (int k = 0; k < skip_us; ++k) {
	if (random_.Rand<double>() < kChanceOfStallPerUs) {
	int64_t stall_duration_us =
	static_cast<int64_t>(random_.Rand<float>() * kMaxStallDurationUs);
	stall_recovery_time_us_ = GetClockUs() + stall_duration_us;
	return stall_recovery_time_us_;
	}
	}
	return GetClockUs();
	}

	void ForceStallUs() {
	int64_t stall_duration_us =
	static_cast<int64_t>(random_.Rand<float>() * kMaxStallDurationUs);
	stall_recovery_time_us_ = GetClockUs() + stall_duration_us;
	}

	bool Stalled() const { return stall_recovery_time_us_ > 0; }

	int64_t GetRemainingStall(int64_t time_us) const {
	return stall_recovery_time_us_ > 0 ? stall_recovery_time_us_ - GetClockUs()
	: 0;
	}

	const int64_t kMaxStallDurationUs = rtc::kNumMicrosecsPerSec;

	private:
	const float kChanceOfStallPerUs = 5e-6f;
	int64_t stall_recovery_time_us_ = 0;
	};

	class EmulatedNonMonotoneousClock : public EmulatedClock {
	public:
	EmulatedNonMonotoneousClock(int seed, int64_t duration_us, float drift = 0)
	: EmulatedClock(seed, drift) {
	Pregenerate(duration_us);
	}
	~EmulatedNonMonotoneousClock() = default;

	void Pregenerate(int64_t duration_us) {
	int64_t time_since_reset_us = kMinTimeBetweenResetsUs;
	int64_t clock_offset_us = 0;
	for (int64_t time_us = 0; time_us < duration_us; time_us += kResolutionUs) {
	int64_t skip_us = UpdateClock(time_us);
	time_since_reset_us += skip_us;
	int64_t reset_us = 0;
	if (time_since_reset_us >= kMinTimeBetweenResetsUs) {
	for (int k = 0; k < skip_us; ++k) {
	if (random_.Rand<double>() < kChanceOfResetPerUs) {
	reset_us = static_cast<int64_t>(2 * random_.Rand<float>() *
	kMaxAbsResetUs) -
	kMaxAbsResetUs;
	clock_offset_us += reset_us;
	time_since_reset_us = 0;
	break;
	}
	}
	}
	pregenerated_clock_.emplace_back(GetClockUs() + clock_offset_us);
	resets_us_.emplace_back(reset_us);
	}
	}

	int64_t Query(int64_t time_us) {
	size_t ixStart =
	(last_reset_query_time_us_ + (kResolutionUs >> 1)) / kResolutionUs + 1;
	size_t ixEnd = (time_us + (kResolutionUs >> 1)) / kResolutionUs;
	if (ixEnd >= pregenerated_clock_.size())
	return -1;
	last_reset_size_us_ = 0;
	for (size_t ix = ixStart; ix <= ixEnd; ++ix) {
	if (resets_us_[ix] != 0) {
	last_reset_size_us_ = resets_us_[ix];
	}
	}
	last_reset_query_time_us_ = time_us;
	return pregenerated_clock_[ixEnd];
	}

	bool WasReset() const { return last_reset_size_us_ != 0; }
	bool WasNegativeReset() const { return last_reset_size_us_ < 0; }
	int64_t GetLastResetUs() const { return last_reset_size_us_; }

	private:
	const float kChanceOfResetPerUs = 1e-6f;
	const int64_t kMaxAbsResetUs = rtc::kNumMicrosecsPerSec;
	const int64_t kMinTimeBetweenResetsUs = 3 * rtc::kNumMicrosecsPerSec;
	const int64_t kResolutionUs = rtc::kNumMicrosecsPerMillisec;
	int64_t last_reset_query_time_us_ = 0;
	int64_t last_reset_size_us_ = 0;
	std::vector<int64_t> pregenerated_clock_;
	std::vector<int64_t> resets_us_;
	};

	TEST(ClockRepair, NoClockDrift) {
	const int kSeeds = 10;
	const int kFirstSeed = 1;
	const int64_t kRuntimeUs = 10 * rtc::kNumMicrosecsPerSec;
	const float kDrift = 0.0f;
	const int64_t kMaxPacketInterarrivalUs = 50 * rtc::kNumMicrosecsPerMillisec;
	for (int seed = kFirstSeed; seed < kSeeds + kFirstSeed; ++seed) {
	EmulatedMonotoneousClock monotone_clock(seed);
	EmulatedNonMonotoneousClock non_monotone_clock(
	seed + 1, kRuntimeUs + rtc::kNumMicrosecsPerSec, kDrift);
	ReceiveTimeCalculator reception_time_tracker;
	int64_t corrected_clock_0 = 0;
	int64_t reset_during_stall_tol_us = 0;
	bool initial_clock_stall = true;
	int64_t accumulated_upper_bound_tolerance_us = 0;
	int64_t accumulated_lower_bound_tolerance_us = 0;
	Random random(1);
	monotone_clock.ForceStallUs();
	int64_t last_time_us = 0;
	bool add_tolerance_on_next_packet = false;
	int64_t monotone_noise_us = 1000;

	for (int64_t time_us = 0; time_us < kRuntimeUs;
	time_us += static_cast<int64_t>(random.Rand<float>() *
	kMaxPacketInterarrivalUs)) {
	int64_t socket_time_us = non_monotone_clock.Query(time_us);
	int64_t monotone_us = monotone_clock.Query(time_us) +
	2 * random.Rand<float>() * monotone_noise_us -
	monotone_noise_us;
	int64_t system_time_us = non_monotone_clock.Query(
	time_us + monotone_clock.GetRemainingStall(time_us));

	int64_t corrected_clock_us = reception_time_tracker.ReconcileReceiveTimes(
	socket_time_us, system_time_us, monotone_us);
	if (time_us == 0)
	corrected_clock_0 = corrected_clock_us;

	if (add_tolerance_on_next_packet)
	accumulated_lower_bound_tolerance_us -= (time_us - last_time_us);

	// Perfect repair cannot be achiveved if non-monotone clock resets during
	// a monotone clock stall.
	add_tolerance_on_next_packet = false;
	if (monotone_clock.Stalled() && non_monotone_clock.WasReset()) {
	reset_during_stall_tol_us =
	std::max(reset_during_stall_tol_us, time_us - last_time_us);
	if (non_monotone_clock.WasNegativeReset()) {
	add_tolerance_on_next_packet = true;
	}
	if (initial_clock_stall && !non_monotone_clock.WasNegativeReset()) {
	// Positive resets during an initial clock stall cannot be repaired
	// and error will propagate through rest of trace.
	accumulated_upper_bound_tolerance_us +=
	std::abs(non_monotone_clock.GetLastResetUs());
	}
	} else {
	reset_during_stall_tol_us = 0;
	initial_clock_stall = false;
	}
	int64_t err = corrected_clock_us - corrected_clock_0 - time_us;

	// Resets during stalls may lead to small errors temporarily.
	int64_t lower_tol_us = accumulated_lower_bound_tolerance_us -
	reset_during_stall_tol_us - monotone_noise_us -
	2 * rtc::kNumMicrosecsPerMillisec;
	EXPECT_GE(err, lower_tol_us);
	int64_t upper_tol_us = accumulated_upper_bound_tolerance_us +
	monotone_noise_us +
	2 * rtc::kNumMicrosecsPerMillisec;
	EXPECT_LE(err, upper_tol_us);

	last_time_us = time_us;
	}
	}
	}
	} // namespace
	} // namespace test
	} // namespace webrtc