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// Copyright 2014 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.
#include "net/third_party/quiche/src/quic/core/quic_packets.h"
#include "net/third_party/quiche/src/quic/platform/api/quic_export.h"
namespace quic {
namespace test {
class QuicFlowControllerPeer;
} // namespace test
class QuicConnection;
class QuicSession;
// How much larger the session flow control window needs to be relative to any
// stream's flow control window.
const float kSessionFlowControlMultiplier = 1.5;
class QUIC_EXPORT_PRIVATE QuicFlowControllerInterface {
virtual ~QuicFlowControllerInterface() {}
// Ensures the flow control window is at least |window_size| and send out an
// update frame if it is increased.
virtual void EnsureWindowAtLeast(QuicByteCount window_size) = 0;
// QuicFlowController allows a QUIC stream or connection to perform flow
// control. The stream/connection owns a QuicFlowController which keeps track of
// bytes sent/received, can tell the owner if it is flow control blocked, and
// can send WINDOW_UPDATE or BLOCKED frames when needed.
class QUIC_EXPORT_PRIVATE QuicFlowController
: public QuicFlowControllerInterface {
QuicFlowController(QuicSession* session,
QuicStreamId id,
bool is_connection_flow_controller,
QuicStreamOffset send_window_offset,
QuicStreamOffset receive_window_offset,
QuicByteCount receive_window_size_limit,
bool should_auto_tune_receive_window,
QuicFlowControllerInterface* session_flow_controller);
QuicFlowController(const QuicFlowController&) = delete;
QuicFlowController(QuicFlowController&&) = default;
QuicFlowController& operator=(const QuicFlowController&) = delete;
~QuicFlowController() override {}
// Called when we see a new highest received byte offset from the peer, either
// via a data frame or a RST.
// Returns true if this call changes highest_received_byte_offset_, and false
// in the case where |new_offset| is <= highest_received_byte_offset_.
bool UpdateHighestReceivedOffset(QuicStreamOffset new_offset);
// Called when bytes received from the peer are consumed locally. This may
// trigger the sending of a WINDOW_UPDATE frame using |connection|.
void AddBytesConsumed(QuicByteCount bytes_consumed);
// Called when bytes are sent to the peer.
void AddBytesSent(QuicByteCount bytes_sent);
// Increases |send_window_offset_| if |new_send_window_offset| is
// greater than the current value. Returns true if this increase
// also causes us to change from a blocked state to unblocked. In
// all other cases, returns false.
bool UpdateSendWindowOffset(QuicStreamOffset new_send_window_offset);
// QuicFlowControllerInterface.
void EnsureWindowAtLeast(QuicByteCount window_size) override;
// Returns the current available send window.
QuicByteCount SendWindowSize() const;
// Returns whether a BLOCKED frame should be sent.
bool ShouldSendBlocked();
// Returns true if flow control send limits have been reached.
bool IsBlocked() const;
// Returns true if flow control receive limits have been violated by the peer.
bool FlowControlViolation();
// Inform the peer of new receive window.
void SendWindowUpdate();
QuicByteCount bytes_consumed() const { return bytes_consumed_; }
QuicStreamOffset highest_received_byte_offset() const {
return highest_received_byte_offset_;
void set_receive_window_size_limit(QuicByteCount receive_window_size_limit) {
DCHECK_GE(receive_window_size_limit, receive_window_size_limit_);
receive_window_size_limit_ = receive_window_size_limit;
// Should only be called before any data is received.
void UpdateReceiveWindowSize(QuicStreamOffset size);
bool auto_tune_receive_window() { return auto_tune_receive_window_; }
friend class test::QuicFlowControllerPeer;
// Send a WINDOW_UPDATE frame if appropriate.
void MaybeSendWindowUpdate();
// Auto-tune the max receive window size.
void MaybeIncreaseMaxWindowSize();
// Updates the current offset and sends a window update frame.
void UpdateReceiveWindowOffsetAndSendWindowUpdate(
QuicStreamOffset available_window);
// Double the window size as long as we haven't hit the max window size.
void IncreaseWindowSize();
// The parent session/connection, used to send connection close on flow
// control violation, and WINDOW_UPDATE and BLOCKED frames when appropriate.
// Not owned.
QuicSession* session_;
QuicConnection* connection_;
// ID of stream this flow controller belongs to. If
// |is_connection_flow_controller_| is false, this must be a valid stream ID.
QuicStreamId id_;
// Whether this flow controller is the connection level flow controller
// instead of the flow controller for a stream. If true, |id_| is ignored.
bool is_connection_flow_controller_;
// Tracks if this is owned by a server or a client.
Perspective perspective_;
// Tracks number of bytes sent to the peer.
QuicByteCount bytes_sent_;
// The absolute offset in the outgoing byte stream. If this offset is reached
// then we become flow control blocked until we receive a WINDOW_UPDATE.
QuicStreamOffset send_window_offset_;
// Overview of receive flow controller.
// 0=...===1=======2-------3 ...... FIN
// |<--- <= 4 --->|
// 1) bytes_consumed_ - moves forward when data is read out of the
// stream.
// 2) highest_received_byte_offset_ - moves when data is received
// from the peer.
// 3) receive_window_offset_ - moves when WINDOW_UPDATE is sent.
// 4) receive_window_size_ - maximum allowed unread data (3 - 1).
// This value may be increased by auto-tuning.
// 5) receive_window_size_limit_ - limit on receive_window_size_;
// auto-tuning will not increase window size beyond this limit.
// Track number of bytes received from the peer, which have been consumed
// locally.
QuicByteCount bytes_consumed_;
// The highest byte offset we have seen from the peer. This could be the
// highest offset in a data frame, or a final value in a RST.
QuicStreamOffset highest_received_byte_offset_;
// The absolute offset in the incoming byte stream. The peer should never send
// us bytes which are beyond this offset.
QuicStreamOffset receive_window_offset_;
// Largest size the receive window can grow to.
QuicByteCount receive_window_size_;
// Upper limit on receive_window_size_;
QuicByteCount receive_window_size_limit_;
// Used to dynamically enable receive window auto-tuning.
bool auto_tune_receive_window_;
// The session's flow controller. null if this is stream id 0.
// Not owned.
QuicFlowControllerInterface* session_flow_controller_;
// Send window update when receive window size drops below this.
QuicByteCount WindowUpdateThreshold();
// Keep track of the last time we sent a BLOCKED frame. We should only send
// another when the number of bytes we have sent has changed.
QuicStreamOffset last_blocked_send_window_offset_;
// Keep time of the last time a window update was sent. We use this
// as part of the receive window auto tuning.
QuicTime prev_window_update_time_;
} // namespace quic