| // Copyright (c) 2015 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. |
| |
| // Cubic algorithm, helper class to TCP cubic. |
| // For details see http://netsrv.csc.ncsu.edu/export/cubic_a_new_tcp_2008.pdf. |
| |
| #ifndef NET_QUIC_CORE_CONGESTION_CONTROL_CUBIC_BYTES_H_ |
| #define NET_QUIC_CORE_CONGESTION_CONTROL_CUBIC_BYTES_H_ |
| |
| #include <cstdint> |
| |
| #include "base/macros.h" |
| #include "net/quic/core/quic_bandwidth.h" |
| #include "net/quic/core/quic_connection_stats.h" |
| #include "net/quic/core/quic_time.h" |
| #include "net/quic/platform/api/quic_clock.h" |
| #include "net/quic/platform/api/quic_export.h" |
| |
| namespace net { |
| |
| namespace test { |
| class CubicBytesTest; |
| } // namespace test |
| |
| class QUIC_EXPORT_PRIVATE CubicBytes { |
| public: |
| explicit CubicBytes(const QuicClock* clock); |
| |
| void SetNumConnections(int num_connections); |
| |
| // Call after a timeout to reset the cubic state. |
| void ResetCubicState(); |
| |
| // Compute a new congestion window to use after a loss event. |
| // Returns the new congestion window in packets. The new congestion window is |
| // a multiplicative decrease of our current window. |
| QuicByteCount CongestionWindowAfterPacketLoss(QuicPacketCount current); |
| |
| // Compute a new congestion window to use after a received ACK. |
| // Returns the new congestion window in bytes. The new congestion window |
| // follows a cubic function that depends on the time passed since last packet |
| // loss. |
| QuicByteCount CongestionWindowAfterAck(QuicByteCount acked_bytes, |
| QuicByteCount current, |
| QuicTime::Delta delay_min, |
| QuicTime event_time); |
| |
| // Call on ack arrival when sender is unable to use the available congestion |
| // window. Resets Cubic state during quiescence. |
| void OnApplicationLimited(); |
| |
| // If true, enable the fix for the convex-mode signing bug. See |
| // b/32170105 for more information about the bug. |
| // TODO(jokulik): Remove once the fix is enabled by default. |
| void SetFixConvexMode(bool fix_convex_mode); |
| // If true, fix CubicBytes quantization bug. See b/33273459 for |
| // more information about the bug. |
| // TODO(jokulik): Remove once the fix is enabled by default. |
| void SetFixCubicQuantization(bool fix_cubic_quantization); |
| // If true, enable the fix for scaling BetaLastMax for n-nonnection |
| // emulation. See b/33272010 for more information about the bug. |
| // TODO(jokulik): Remove once the fix is enabled by default. |
| void SetFixBetaLastMax(bool fix_beta_last_max); |
| // If true, unconditionally enable each ack to update the congestion |
| // window. See b/33410956 for further information about this bug. |
| // TODO(jokulik): Remove once the fix is enabled by default. |
| void SetAllowPerAckUpdates(bool allow_per_ack_updates); |
| |
| private: |
| friend class test::CubicBytesTest; |
| |
| static const QuicTime::Delta MaxCubicTimeInterval() { |
| return QuicTime::Delta::FromMilliseconds(30); |
| } |
| |
| // Compute the TCP Cubic alpha, beta, and beta-last-max based on the |
| // current number of connections. |
| float Alpha() const; |
| float Beta() const; |
| float BetaLastMax() const; |
| |
| QuicByteCount last_max_congestion_window() const { |
| return last_max_congestion_window_; |
| } |
| |
| const QuicClock* clock_; |
| |
| // Number of connections to simulate. |
| int num_connections_; |
| |
| // Time when this cycle started, after last loss event. |
| QuicTime epoch_; |
| |
| // Time when we updated last_congestion_window. |
| QuicTime last_update_time_; |
| |
| // Last congestion window used. |
| QuicByteCount last_congestion_window_; |
| |
| // Max congestion window used just before last loss event. |
| // Note: to improve fairness to other streams an additional back off is |
| // applied to this value if the new value is below our latest value. |
| QuicByteCount last_max_congestion_window_; |
| |
| // Number of acked bytes since the cycle started (epoch). |
| QuicByteCount acked_bytes_count_; |
| |
| // TCP Reno equivalent congestion window in packets. |
| QuicByteCount estimated_tcp_congestion_window_; |
| |
| // Origin point of cubic function. |
| QuicByteCount origin_point_congestion_window_; |
| |
| // Time to origin point of cubic function in 2^10 fractions of a second. |
| uint32_t time_to_origin_point_; |
| |
| // Last congestion window in packets computed by cubic function. |
| QuicByteCount last_target_congestion_window_; |
| |
| // Fix convex mode for cubic. |
| // TODO(jokulik): Remove once the cubic convex experiment is done. |
| bool fix_convex_mode_; |
| |
| // Fix for quantization in cubic mode. |
| // TODO(jokulik): Remove once the experiment is done. |
| bool fix_cubic_quantization_; |
| |
| // Fix beta last max for n-connection-emulation. |
| // TODO(jokulik): Remove once the corresponding experiment is done. |
| bool fix_beta_last_max_; |
| |
| // Allow per ack updates, rather than limiting the frequency of |
| // updates when in cubic-mode. |
| // TODO(jokulik): Remove once the experiment is done. |
| bool allow_per_ack_updates_; |
| |
| DISALLOW_COPY_AND_ASSIGN(CubicBytes); |
| }; |
| |
| } // namespace net |
| |
| #endif // NET_QUIC_CORE_CONGESTION_CONTROL_CUBIC_BYTES_H_ |