Remove //net (except for Android test stuff) and sdch

net/quic/congestion_control/rtt_stats.cc

-// Copyright 2014 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "net/quic/congestion_control/rtt_stats.h"
-
-#include <complex>  // std::abs
-
-using std::max;
-
-namespace net {
-
-namespace {
-
-// Default initial rtt used before any samples are received.
-const int kInitialRttMs = 100;
-const float kAlpha = 0.125f;
-const float kOneMinusAlpha = (1 - kAlpha);
-const float kBeta = 0.25f;
-const float kOneMinusBeta = (1 - kBeta);
-const float kHalfWindow = 0.5f;
-const float kQuarterWindow = 0.25f;
-
-}  // namespace
-
-RttStats::RttStats()
-    : latest_rtt_(QuicTime::Delta::Zero()),
-      min_rtt_(QuicTime::Delta::Zero()),
-      smoothed_rtt_(QuicTime::Delta::Zero()),
-      mean_deviation_(QuicTime::Delta::Zero()),
-      initial_rtt_us_(kInitialRttMs * kNumMicrosPerMilli),
-      num_min_rtt_samples_remaining_(0),
-      recent_min_rtt_window_(QuicTime::Delta::Infinite()) {}
-
-void RttStats::SampleNewRecentMinRtt(uint32 num_samples) {
-  num_min_rtt_samples_remaining_ = num_samples;
-  new_min_rtt_ = RttSample();
-}
-
-void RttStats::ExpireSmoothedMetrics() {
-  mean_deviation_ =
-      max(mean_deviation_,
-          QuicTime::Delta::FromMicroseconds(
-              std::abs(smoothed_rtt_.Subtract(latest_rtt_).ToMicroseconds())));
-  smoothed_rtt_ = max(smoothed_rtt_, latest_rtt_);
-}
-
-// Updates the RTT based on a new sample.
-void RttStats::UpdateRtt(QuicTime::Delta send_delta,
-                         QuicTime::Delta ack_delay,
-                         QuicTime now) {
-  if (send_delta.IsInfinite() || send_delta <= QuicTime::Delta::Zero()) {
-    LOG(WARNING) << "Ignoring measured send_delta, because it's is "
-                 << "either infinite, zero, or negative.  send_delta = "
-                 << send_delta.ToMicroseconds();
-    return;
-  }
-
-  // Update min_rtt_ first. min_rtt_ does not use an rtt_sample corrected for
-  // ack_delay but the raw observed send_delta, since poor clock granularity at
-  // the client may cause a high ack_delay to result in underestimation of the
-  // min_rtt_.
-  if (min_rtt_.IsZero() || min_rtt_ > send_delta) {
-    min_rtt_ = send_delta;
-  }
-  UpdateRecentMinRtt(send_delta, now);
-
-  // Correct for ack_delay if information received from the peer results in a
-  // positive RTT sample. Otherwise, we use the send_delta as a reasonable
-  // measure for smoothed_rtt.
-  QuicTime::Delta rtt_sample(send_delta);
-  if (rtt_sample > ack_delay) {
-    rtt_sample = rtt_sample.Subtract(ack_delay);
-  }
-  latest_rtt_ = rtt_sample;
-  // First time call.
-  if (smoothed_rtt_.IsZero()) {
-    smoothed_rtt_ = rtt_sample;
-    mean_deviation_ = QuicTime::Delta::FromMicroseconds(
-        rtt_sample.ToMicroseconds() / 2);
-  } else {
-    mean_deviation_ = QuicTime::Delta::FromMicroseconds(static_cast<int64>(
-        kOneMinusBeta * mean_deviation_.ToMicroseconds() +
-        kBeta * std::abs(smoothed_rtt_.Subtract(rtt_sample).ToMicroseconds())));
-    smoothed_rtt_ = smoothed_rtt_.Multiply(kOneMinusAlpha).Add(
-        rtt_sample.Multiply(kAlpha));
-    DVLOG(1) << " smoothed_rtt(us):" << smoothed_rtt_.ToMicroseconds()
-             << " mean_deviation(us):" << mean_deviation_.ToMicroseconds();
-  }
-}
-
-void RttStats::UpdateRecentMinRtt(QuicTime::Delta rtt_sample, QuicTime now) {
-  // Recent min_rtt update.
-  if (num_min_rtt_samples_remaining_ > 0) {
-    --num_min_rtt_samples_remaining_;
-    if (new_min_rtt_.rtt.IsZero() || rtt_sample <= new_min_rtt_.rtt) {
-      new_min_rtt_ = RttSample(rtt_sample, now);
-    }
-    if (num_min_rtt_samples_remaining_ == 0) {
-      quarter_window_rtt_ = half_window_rtt_ = recent_min_rtt_ = new_min_rtt_;
-    }
-  }
-
-  // Update the three recent rtt samples.
-  if (recent_min_rtt_.rtt.IsZero() || rtt_sample <= recent_min_rtt_.rtt) {
-    recent_min_rtt_ = RttSample(rtt_sample, now);
-    quarter_window_rtt_ = half_window_rtt_ = recent_min_rtt_;
-  } else if (rtt_sample <= half_window_rtt_.rtt) {
-    half_window_rtt_ = RttSample(rtt_sample, now);
-    quarter_window_rtt_ = half_window_rtt_;
-  } else if (rtt_sample <= quarter_window_rtt_.rtt) {
-    quarter_window_rtt_ = RttSample(rtt_sample, now);
-  }
-
-  // Expire old min rtt samples.
-  if (recent_min_rtt_.time < now.Subtract(recent_min_rtt_window_)) {
-    recent_min_rtt_ = half_window_rtt_;
-    half_window_rtt_ = quarter_window_rtt_;
-    quarter_window_rtt_ = RttSample(rtt_sample, now);
-  } else if (half_window_rtt_.time <
-      now.Subtract(recent_min_rtt_window_.Multiply(kHalfWindow))) {
-    half_window_rtt_ = quarter_window_rtt_;
-    quarter_window_rtt_ = RttSample(rtt_sample, now);
-  } else if (quarter_window_rtt_.time <
-      now.Subtract(recent_min_rtt_window_.Multiply(kQuarterWindow))) {
-    quarter_window_rtt_ = RttSample(rtt_sample, now);
-  }
-}
-
-}  // namespace net