relnote: Measure HOL blocking in QUIC headers stream. Flag protected by quic_measure_headers_hol_bl…

net/quic/quic_stream_sequencer.h

 // Copyright (c) 2012 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.
 
 #ifndef NET_QUIC_QUIC_STREAM_SEQUENCER_H_
 #define NET_QUIC_QUIC_STREAM_SEQUENCER_H_
 
 #include <map>
 #include <string>
 
 #include "base/basictypes.h"
 #include "net/quic/quic_frame_list.h"
 #include "net/quic/quic_protocol.h"
 
 namespace net {
 
 namespace test {
 class QuicStreamSequencerPeer;
 }  // namespace test
 
+class QuicClock;
 class QuicSession;
 class ReliableQuicStream;
 
 // Buffers frames until we have something which can be passed
 // up to the next layer.
 class NET_EXPORT_PRIVATE QuicStreamSequencer {
  public:
-  explicit QuicStreamSequencer(ReliableQuicStream* quic_stream);
+  QuicStreamSequencer(ReliableQuicStream* quic_stream, const QuicClock* clock);
   virtual ~QuicStreamSequencer();
 
   // If the frame is the next one we need in order to process in-order data,
   // ProcessData will be immediately called on the stream until all buffered
   // data is processed or the stream fails to consume data.  Any unconsumed
   // data will be buffered. If the frame is not the next in line, it will be
   // buffered.
   void OnStreamFrame(const QuicStreamFrame& frame);
 
   // Once data is buffered, it's up to the stream to read it when the stream
   // can handle more data.  The following three functions make that possible.
 
   // Fills in up to iov_len iovecs with the next readable regions.  Returns the
   // number of iovs used.  Non-destructive of the underlying data.
   int GetReadableRegions(iovec* iov, size_t iov_len) const;
 
+  // Fills in one iovec with the next readable region.  |timestamp| is
+  // data arrived at the sequencer, and is used for measuring head of
+  // line blocking (HOL).  Returns false if there is no readable
+  // region available.
+  bool GetReadableRegion(iovec* iov, QuicTime* timestamp) const;
+
   // Copies the data into the iov_len buffers provided.  Returns the number of
   // bytes read.  Any buffered data no longer in use will be released.
   // TODO(rch): remove this method and instead implement it as a helper method
   // based on GetReadableRegions and MarkConsumed.
   int Readv(const struct iovec* iov, size_t iov_len);
 
   // Consumes |num_bytes| data.  Used in conjunction with |GetReadableRegions|
   // to do zero-copy reads.
   void MarkConsumed(size_t num_bytes);
 
@@ skipping 59 matching lines @@
   // Count of the number of frames received.
   int num_frames_received_;
 
   // Count of the number of duplicate frames received.
   int num_duplicate_frames_received_;
 
   // Count of the number of frames received before all previous frames were
   // received.
   int num_early_frames_received_;
 
+  // Not owned.
+  const QuicClock* clock_;
+
   DISALLOW_COPY_AND_ASSIGN(QuicStreamSequencer);
 };
 
 }  // namespace net
 
 #endif  // NET_QUIC_QUIC_STREAM_SEQUENCER_H_