net/quic/congestion_control/leaky_bucket.cc

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #include "net/quic/congestion_control/leaky_bucket.h"
   6
   7 #include "base/time/time.h"
   8
   9 namespace net {
  10
  11 LeakyBucket::LeakyBucket(QuicBandwidth draining_rate)
  12     : bytes_(0),
  13       time_last_updated_(QuicTime::Zero()),
  14       draining_rate_(draining_rate) {
  15 }
  16
  17 void LeakyBucket::SetDrainingRate(QuicTime now, QuicBandwidth draining_rate) {
  18   Update(now);
  19   draining_rate_ = draining_rate;
  20 }
  21
  22 void LeakyBucket::Add(QuicTime now, QuicByteCount bytes) {
  23   Update(now);
  24   bytes_ += bytes;
  25 }
  26
  27 QuicTime::Delta LeakyBucket::TimeRemaining(QuicTime now) const {
  28   QuicTime::Delta time_since_last_update = now.Subtract(time_last_updated_);
  29   QuicTime::Delta send_delay = QuicTime::Delta::FromMicroseconds(
  30       (bytes_ * base::Time::kMicrosecondsPerSecond) /
  31       draining_rate_.ToBytesPerSecond());
  32   if (send_delay < time_since_last_update) {
  33     return QuicTime::Delta::Zero();
  34   }
  35   return send_delay.Subtract(time_since_last_update);
  36 }
  37
  38 QuicByteCount LeakyBucket::BytesPending(QuicTime now) {
  39   Update(now);
  40   return bytes_;
  41 }
  42
  43 void LeakyBucket::Update(QuicTime now) {
  44   QuicTime::Delta elapsed_time = now.Subtract(time_last_updated_);
  45   QuicByteCount bytes_cleared = draining_rate_.ToBytesPerPeriod(elapsed_time);
  46   if (bytes_cleared >= bytes_) {
  47     bytes_ = 0;
  48   } else {
  49     bytes_ -= bytes_cleared;
  50   }
  51   time_last_updated_ = now;
  52 }
  53
  54 }  // namespace net