net/quic/quic_connection_helper.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/quic_connection_helper.h"
   6
   7 #include "base/location.h"
   8 #include "base/logging.h"
   9 #include "base/metrics/sparse_histogram.h"
  10 #include "base/task_runner.h"
  11 #include "base/time/time.h"
  12 #include "net/base/io_buffer.h"
  13 #include "net/base/net_errors.h"
  14 #include "net/quic/quic_utils.h"
  15
  16 namespace net {
  17
  18 namespace {
  19
  20 class QuicChromeAlarm : public QuicAlarm {
  21  public:
  22   QuicChromeAlarm(const QuicClock* clock,
  23                   base::TaskRunner* task_runner,
  24                   QuicAlarm::Delegate* delegate)
  25       : QuicAlarm(delegate),
  26         clock_(clock),
  27         task_runner_(task_runner),
  28         task_deadline_(QuicTime::Zero()),
  29         weak_factory_(this) {}
  30
  31  protected:
  32   void SetImpl() override {
  33     DCHECK(deadline().IsInitialized());
  34     if (task_deadline_.IsInitialized()) {
  35       if (task_deadline_ <= deadline()) {
  36         // Since tasks can not be un-posted, OnAlarm will be invoked which
  37         // will notice that deadline has not yet been reached, and will set
  38         // the alarm for the new deadline.
  39         return;
  40       }
  41       // The scheduled task is after new deadline.  Invalidate the weak ptrs
  42       // so that task does not execute when we're not expecting it.
  43       weak_factory_.InvalidateWeakPtrs();
  44     }
  45
  46     int64 delay_us = deadline().Subtract(clock_->Now()).ToMicroseconds();
  47     if (delay_us < 0) {
  48       delay_us = 0;
  49     }
  50     task_runner_->PostDelayedTask(
  51         FROM_HERE,
  52         base::Bind(&QuicChromeAlarm::OnAlarm, weak_factory_.GetWeakPtr()),
  53         base::TimeDelta::FromMicroseconds(delay_us));
  54     task_deadline_ = deadline();
  55   }
  56
  57   void CancelImpl() override {
  58     DCHECK(!deadline().IsInitialized());
  59     // Since tasks can not be un-posted, OnAlarm will be invoked which
  60     // will notice that deadline is not Initialized and will do nothing.
  61   }
  62
  63  private:
  64   void OnAlarm() {
  65     DCHECK(task_deadline_.IsInitialized());
  66     task_deadline_ = QuicTime::Zero();
  67     // The alarm may have been cancelled.
  68     if (!deadline().IsInitialized()) {
  69       return;
  70     }
  71
  72     // The alarm may have been re-set to a later time.
  73     if (clock_->Now() < deadline()) {
  74       SetImpl();
  75       return;
  76     }
  77
  78     Fire();
  79   }
  80
  81   const QuicClock* clock_;
  82   base::TaskRunner* task_runner_;
  83   // If a task has been posted to the message loop, this is the time it
  84   // was scheduled to fire.  Tracking this allows us to avoid posting a
  85   // new tast if the new deadline is in the future, but permits us to
  86   // post a new task when the new deadline now earlier than when
  87   // previously posted.
  88   QuicTime task_deadline_;
  89   base::WeakPtrFactory<QuicChromeAlarm> weak_factory_;
  90 };
  91
  92 }  // namespace
  93
  94 QuicConnectionHelper::QuicConnectionHelper(base::TaskRunner* task_runner,
  95                                            const QuicClock* clock,
  96                                            QuicRandom* random_generator)
  97     : task_runner_(task_runner),
  98       clock_(clock),
  99       random_generator_(random_generator),
 100       weak_factory_(this) {
 101 }
 102
 103 QuicConnectionHelper::~QuicConnectionHelper() {
 104 }
 105
 106 const QuicClock* QuicConnectionHelper::GetClock() const {
 107   return clock_;
 108 }
 109
 110 QuicRandom* QuicConnectionHelper::GetRandomGenerator() {
 111   return random_generator_;
 112 }
 113
 114 QuicAlarm* QuicConnectionHelper::CreateAlarm(QuicAlarm::Delegate* delegate) {
 115   return new QuicChromeAlarm(clock_, task_runner_, delegate);
 116 }
 117
 118 }  // namespace net