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 #include <string>
  10
  11 #include "base/basictypes.h"
  12 #include "net/base/iovec.h"
  13 #include "net/quic/quic_protocol.h"
  14
  15 namespace net {
  16
  17 namespace test {
  18 class QuicStreamSequencerPeer;
  19 }  // namespace test
  20
  21 class QuicSession;
  22 class ReliableQuicStream;
  23
  24 // Buffers frames until we have something which can be passed
  25 // up to the next layer.
  26 class NET_EXPORT_PRIVATE QuicStreamSequencer {
  27  public:
  28   explicit QuicStreamSequencer(ReliableQuicStream* quic_stream);
  29   virtual ~QuicStreamSequencer();
  30
  31   // If the frame is the next one we need in order to process in-order data,
  32   // ProcessData will be immediately called on the stream until all buffered
  33   // data is processed or the stream fails to consume data.  Any unconsumed
  34   // data will be buffered. If the frame is not the next in line, it will be
  35   // buffered.
  36   void OnStreamFrame(const QuicStreamFrame& frame);
  37
  38   // Once data is buffered, it's up to the stream to read it when the stream
  39   // can handle more data.  The following three functions make that possible.
  40
  41   // Fills in up to iov_len iovecs with the next readable regions.  Returns the
  42   // number of iovs used.  Non-destructive of the underlying data.
  43   int GetReadableRegions(iovec* iov, size_t iov_len);
  44
  45   // Copies the data into the iov_len buffers provided.  Returns the number of
  46   // bytes read.  Any buffered data no longer in use will be released.
  47   int Readv(const struct iovec* iov, size_t iov_len);
  48
  49   // Returns true if the sequncer has bytes available for reading.
  50   bool HasBytesToRead() const;
  51
  52   // Returns true if the sequencer has delivered the fin.
  53   bool IsClosed() const;
  54
  55   // Returns true if the sequencer has received this frame before.
  56   bool IsDuplicate(const QuicStreamFrame& frame) const;
  57
  58   // Returns true if |frame| contains data which overlaps buffered data
  59   // (indicating an invalid stream frame has been received).
  60   bool FrameOverlapsBufferedData(const QuicStreamFrame& frame) const;
  61
  62   // Calls |ProcessRawData| on |stream_| for each buffered frame that may
  63   // be processed.
  64   void FlushBufferedFrames();
  65
  66   // Blocks processing of frames until |FlushBufferedFrames| is called.
  67   void SetBlockedUntilFlush();
  68
  69   size_t num_bytes_buffered() const { return num_bytes_buffered_; }
  70   QuicStreamOffset num_bytes_consumed() const { return num_bytes_consumed_; }
  71
  72   int num_frames_received() const { return num_frames_received_; }
  73
  74   int num_duplicate_frames_received() const {
  75     return num_duplicate_frames_received_;
  76   }
  77
  78   int num_early_frames_received() const { return num_early_frames_received_; }
  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   // TODO(rjshade): In future we may support retransmission of partial stream
 102   // frames, in which case we will have to allow receipt of overlapping frames.
 103   // Maybe write new frames into a ring buffer, and keep track of consumed
 104   // bytes, and gaps.
 105   typedef std::map<QuicStreamOffset, std::string> FrameMap;
 106
 107   // Stores buffered frames (maps from sequence number -> frame data as string).
 108   FrameMap buffered_frames_;
 109
 110   // The offset, if any, we got a stream termination for.  When this many bytes
 111   // have been processed, the sequencer will be closed.
 112   QuicStreamOffset close_offset_;
 113
 114   // If true, the sequencer is blocked from passing data to the stream and will
 115   // buffer all new incoming data until FlushBufferedFrames is called.
 116   bool blocked_;
 117
 118   // Tracks how many bytes the sequencer has buffered.
 119   size_t num_bytes_buffered_;
 120
 121   // Count of the number of frames received.
 122   int num_frames_received_;
 123
 124   // Count of the number of duplicate frames received.
 125   int num_duplicate_frames_received_;
 126
 127   // Count of the number of frames received before all previous frames were
 128   // received.
 129   int num_early_frames_received_;
 130
 131   DISALLOW_COPY_AND_ASSIGN(QuicStreamSequencer);
 132 };
 133
 134 }  // namespace net
 135
 136 #endif  // NET_QUIC_QUIC_STREAM_SEQUENCER_H_