net/quic/quic_stream_sequencer.h

   1 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
   2 // Use of this source code is governed by a BSD-style license that can be
   3 // found in the LICENSE file.
   4
   5 #ifndef NET_QUIC_QUIC_STREAM_SEQUENCER_H_
   6 #define NET_QUIC_QUIC_STREAM_SEQUENCER_H_
   7
   8 #include <map>
   9
  10 #include "base/basictypes.h"
  11 #include "net/base/iovec.h"
  12 #include "net/quic/quic_protocol.h"
  13
  14 using std::map;
  15 using std::string;
  16
  17 namespace net {
  18
  19 namespace test {
  20 class QuicStreamSequencerPeer;
  21 }  // namespace test
  22
  23 class QuicSession;
  24 class ReliableQuicStream;
  25
  26 // Buffers frames until we have something which can be passed
  27 // up to the next layer.
  28 // TOOD(alyssar) add some checks for overflow attempts [1, 256,] [2, 256]
  29 class NET_EXPORT_PRIVATE QuicStreamSequencer {
  30  public:
  31   explicit QuicStreamSequencer(ReliableQuicStream* quic_stream);
  32   QuicStreamSequencer(size_t max_frame_memory,
  33                       ReliableQuicStream* quic_stream);
  34
  35   virtual ~QuicStreamSequencer();
  36
  37   // Returns the expected value of OnStreamFrame for this frame.
  38   bool WillAcceptStreamFrame(const QuicStreamFrame& frame) const;
  39
  40   // If the frame is the next one we need in order to process in-order data,
  41   // ProcessData will be immediately called on the stream until all buffered
  42   // data is processed or the stream fails to consume data.  Any unconsumed
  43   // data will be buffered.
  44   //
  45   // If the frame is not the next in line, it will either be buffered, and
  46   // this will return true, or it will be rejected and this will return false.
  47   bool OnStreamFrame(const QuicStreamFrame& frame);
  48
  49   // Once data is buffered, it's up to the stream to read it when the stream
  50   // can handle more data.  The following three functions make that possible.
  51
  52   // Fills in up to iov_len iovecs with the next readable regions.  Returns the
  53   // number of iovs used.  Non-destructive of the underlying data.
  54   int GetReadableRegions(iovec* iov, size_t iov_len);
  55
  56   // Copies the data into the iov_len buffers provided.  Returns the number of
  57   // bytes read.  Any buffered data no longer in use will be released.
  58   int Readv(const struct iovec* iov, size_t iov_len);
  59
  60   // Returns true if the sequncer has bytes available for reading.
  61   bool HasBytesToRead() const;
  62
  63   // Returns true if the sequencer has delivered the fin.
  64   bool IsClosed() const;
  65
  66   // Returns true if the sequencer has received this frame before.
  67   bool IsDuplicate(const QuicStreamFrame& frame) const;
  68
  69   // Calls |ProcessRawData| on |stream_| for each buffered frame that may
  70   // be processed.
  71   void FlushBufferedFrames();
  72
  73   // Blocks processing of frames until |FlushBufferedFrames| is called.
  74   void SetBlockedUntilFlush();
  75
  76   size_t num_bytes_buffered() const {
  77     return num_bytes_buffered_;
  78   }
  79
  80  private:
  81   friend class test::QuicStreamSequencerPeer;
  82
  83   // Wait until we've seen 'offset' bytes, and then terminate the stream.
  84   void CloseStreamAtOffset(QuicStreamOffset offset);
  85
  86   // If we've received a FIN and have processed all remaining data, then inform
  87   // the stream of FIN, and clear buffers.
  88   bool MaybeCloseStream();
  89
  90   // Called whenever bytes are consumed by the stream. Updates
  91   // num_bytes_consumed_ and num_bytes_buffered_.
  92   void RecordBytesConsumed(size_t bytes_consumed);
  93
  94   // The stream which owns this sequencer.
  95   ReliableQuicStream* stream_;
  96
  97   // The last data consumed by the stream.
  98   QuicStreamOffset num_bytes_consumed_;
  99
 100   // TODO(alyssar) use something better than strings.
 101   typedef map<QuicStreamOffset, string> FrameMap;
 102
 103   // Stores buffered frames (maps from sequence number -> frame data as string).
 104   FrameMap frames_;
 105
 106   // The maximum memory the sequencer can buffer.
 107   size_t max_frame_memory_;
 108
 109   // The offset, if any, we got a stream termination for.  When this many bytes
 110   // have been processed, the sequencer will be closed.
 111   QuicStreamOffset close_offset_;
 112
 113   // If true, the sequencer is blocked from passing data to the stream and will
 114   // buffer all new incoming data until FlushBufferedFrames is called.
 115   bool blocked_;
 116
 117   // Tracks how many bytes the sequencer has buffered.
 118   size_t num_bytes_buffered_;
 119 };
 120
 121 }  // namespace net
 122
 123 #endif  // NET_QUIC_QUIC_STREAM_SEQUENCER_H_