Project import generated by Copybara.
PiperOrigin-RevId: 237361882
Change-Id: I109a68f44db867b20f8c6a7732b0ce657133e52a
diff --git a/quic/core/congestion_control/cubic_bytes.h b/quic/core/congestion_control/cubic_bytes.h
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+// 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 QUICHE_QUIC_CORE_CONGESTION_CONTROL_CUBIC_BYTES_H_
+#define QUICHE_QUIC_CORE_CONGESTION_CONTROL_CUBIC_BYTES_H_
+
+#include <cstdint>
+
+#include "base/macros.h"
+#include "net/third_party/quiche/src/quic/core/quic_bandwidth.h"
+#include "net/third_party/quiche/src/quic/core/quic_connection_stats.h"
+#include "net/third_party/quiche/src/quic/core/quic_time.h"
+#include "net/third_party/quiche/src/quic/platform/api/quic_clock.h"
+#include "net/third_party/quiche/src/quic/platform/api/quic_export.h"
+
+namespace quic {
+
+namespace test {
+class CubicBytesTest;
+} // namespace test
+
+class QUIC_EXPORT_PRIVATE CubicBytes {
+ public:
+ explicit CubicBytes(const QuicClock* clock);
+ CubicBytes(const CubicBytes&) = delete;
+ CubicBytes& operator=(const CubicBytes&) = delete;
+
+ 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();
+
+ 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_;
+
+ // 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_;
+};
+
+} // namespace quic
+
+#endif // QUICHE_QUIC_CORE_CONGESTION_CONTROL_CUBIC_BYTES_H_
