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// Copyright (c) 2013 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.
// Ramp up bitrate from a start point normally our "current_rate" as long as we
// have no packet loss or delay events.
// The first half of the ramp up curve follows a cubic function with its orgin
// at the estimated available bandwidth, onece the bitrate pass the halfway
// point between the estimated available bandwidth and the estimated max
// bandwidth it will follw a new cubic function with its orgin at the estimated
// max bandwidth.
#ifndef NET_QUIC_CONGESTION_CONTROL_INTER_ARRIVAL_BITRATE_RAMP_UP_H_
#define NET_QUIC_CONGESTION_CONTROL_INTER_ARRIVAL_BITRATE_RAMP_UP_H_
#include "base/basictypes.h"
#include "net/base/net_export.h"
#include "net/quic/quic_bandwidth.h"
#include "net/quic/quic_clock.h"
#include "net/quic/quic_time.h"
namespace net {
class NET_EXPORT_PRIVATE InterArrivalBitrateRampUp {
public:
explicit InterArrivalBitrateRampUp(const QuicClock* clock);
// Call after a decision to lower the bitrate and after a probe.
void Reset(QuicBandwidth current_rate,
QuicBandwidth available_channel_estimate,
QuicBandwidth channel_estimate);
// Call everytime we get a new channel estimate.
void UpdateChannelEstimate(QuicBandwidth channel_estimate);
// Compute a new send pace to use.
QuicBandwidth GetNewBitrate(QuicBandwidth sent_bitrate);
private:
uint32 CalcuateTimeToOriginPoint(QuicBandwidth rate_difference) const;
static const QuicTime::Delta MaxCubicTimeInterval() {
return QuicTime::Delta::FromMilliseconds(30);
}
const QuicClock* clock_;
QuicBandwidth current_rate_;
QuicBandwidth channel_estimate_;
QuicBandwidth available_channel_estimate_;
QuicBandwidth halfway_point_;
// Time when this cycle started, after a Reset.
QuicTime epoch_;
// Time when we updated current_rate_.
QuicTime last_update_time_;
// Time to origin point of cubic function in 2^10 fractions of a second.
uint32 time_to_origin_point_;
DISALLOW_COPY_AND_ASSIGN(InterArrivalBitrateRampUp);
};
} // namespace net
#endif // NET_QUIC_CONGESTION_CONTROL_INTER_ARRIVAL_BITRATE_RAMP_UP_H_
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