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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 "base/basictypes.h"
#include "net/base/net_export.h"
#include "net/quic/quic_protocol.h"
namespace net {
namespace test {
class QuicFlowControllerPeer;
} // namespace test
class QuicConnection;
const QuicStreamId kConnectionLevelId = 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 NET_EXPORT_PRIVATE QuicFlowController {
QuicFlowController(QuicConnection* connection,
QuicStreamId id,
Perspective perspective,
QuicStreamOffset send_window_offset,
QuicStreamOffset receive_window_offset,
bool should_auto_tune_receive_window);
~QuicFlowController() {}
// 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);
// Set a new send window offset.
// Returns true if this increases send_window_offset_ and is now blocked.
bool UpdateSendWindowOffset(QuicStreamOffset new_send_window_offset);
// Returns the current available send window.
QuicByteCount SendWindowSize() const;
// Send a BLOCKED frame if appropriate.
void MaybeSendBlocked();
// 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();
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;
void set_auto_tune_receive_window(bool enable) {
auto_tune_receive_window_ = enable;
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();
// The parent connection, used to send connection close on flow control
// violation, and WINDOW_UPDATE and BLOCKED frames when appropriate.
// Not owned.
QuicConnection* connection_;
// ID of stream this flow controller belongs to. This can be 0 if this is a
// connection level flow controller.
QuicStreamId id_;
// 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_;
// 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 net