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   virtual ~QuicStreamSequencer();
  33
  34   // If the frame is the next one we need in order to process in-order data,
  35   // ProcessData will be immediately called on the stream until all buffered
  36   // data is processed or the stream fails to consume data.  Any unconsumed
  37   // data will be buffered. If the frame is not the next in line, it will be
  38   // buffered.
  39   bool OnStreamFrame(const QuicStreamFrame& frame);
  40
  41   // Once data is buffered, it's up to the stream to read it when the stream
  42   // can handle more data.  The following three functions make that possible.
  43
  44   // Fills in up to iov_len iovecs with the next readable regions.  Returns the
  45   // number of iovs used.  Non-destructive of the underlying data.
  46   int GetReadableRegions(iovec* iov, size_t iov_len);
  47
  48   // Copies the data into the iov_len buffers provided.  Returns the number of
  49   // bytes read.  Any buffered data no longer in use will be released.
  50   int Readv(const struct iovec* iov, size_t iov_len);
  51
  52   // Returns true if the sequncer has bytes available for reading.
  53   bool HasBytesToRead() const;
  54
  55   // Returns true if the sequencer has delivered the fin.
  56   bool IsClosed() const;
  57
  58   // Returns true if the sequencer has received this frame before.
  59   bool IsDuplicate(const QuicStreamFrame& frame) const;
  60
  61   // Returns true if |frame| contains data which overlaps buffered data
  62   // (indicating an invalid stream frame has been received).
  63   bool FrameOverlapsBufferedData(const QuicStreamFrame& frame) const;
  64
  65   // Calls |ProcessRawData| on |stream_| for each buffered frame that may
  66   // be processed.
  67   void FlushBufferedFrames();
  68
  69   // Blocks processing of frames until |FlushBufferedFrames| is called.
  70   void SetBlockedUntilFlush();
  71
  72   size_t num_bytes_buffered() const { return num_bytes_buffered_; }
  73   QuicStreamOffset num_bytes_consumed() const { return num_bytes_consumed_; }
  74
  75   int num_frames_received() const { return num_frames_received_; }
  76
  77   int num_duplicate_frames_received() const {
  78     return num_duplicate_frames_received_;
  79   }
  80
  81  private:
  82   friend class test::QuicStreamSequencerPeer;
  83
  84   // Wait until we've seen 'offset' bytes, and then terminate the stream.
  85   void CloseStreamAtOffset(QuicStreamOffset offset);
  86
  87   // If we've received a FIN and have processed all remaining data, then inform
  88   // the stream of FIN, and clear buffers.
  89   bool MaybeCloseStream();
  90
  91   // Called whenever bytes are consumed by the stream. Updates
  92   // num_bytes_consumed_ and num_bytes_buffered_.
  93   void RecordBytesConsumed(size_t bytes_consumed);
  94
  95   // The stream which owns this sequencer.
  96   ReliableQuicStream* stream_;
  97
  98   // The last data consumed by the stream.
  99   QuicStreamOffset num_bytes_consumed_;
 100
 101   // TODO(alyssar) use something better than strings.
 102   // TODO(rjshade): In future we may support retransmission of partial stream
 103   // frames, in which case we will have to allow receipt of overlapping frames.
 104   // Maybe write new frames into a ring buffer, and keep track of consumed
 105   // bytes, and gaps.
 106   typedef map<QuicStreamOffset, string> FrameMap;
 107
 108   // Stores buffered frames (maps from sequence number -> frame data as string).
 109   FrameMap buffered_frames_;
 110
 111   // The offset, if any, we got a stream termination for.  When this many bytes
 112   // have been processed, the sequencer will be closed.
 113   QuicStreamOffset close_offset_;
 114
 115   // If true, the sequencer is blocked from passing data to the stream and will
 116   // buffer all new incoming data until FlushBufferedFrames is called.
 117   bool blocked_;
 118
 119   // Tracks how many bytes the sequencer has buffered.
 120   size_t num_bytes_buffered_;
 121
 122   // Count of the number of frames received.
 123   int num_frames_received_;
 124
 125   // Count of the number of duplicate frames received.
 126   int num_duplicate_frames_received_;
 127
 128   DISALLOW_COPY_AND_ASSIGN(QuicStreamSequencer);
 129 };
 130
 131 }  // namespace net
 132
 133 #endif  // NET_QUIC_QUIC_STREAM_SEQUENCER_H_