commit 7b3e0a9f90645e4c6f386fc44f925b81663d2e8d
author bnc <bnc@google.com> Mon Jun 24 16:06:45 2019 -0700
committer Copybara-Service <copybara-worker@google.com> Mon Jun 24 16:14:43 2019 -0700
tree f563cbfdc49e1b6604eb55bfb9fd01af5812776b
parent 62c32b414ba0d661881048358fae59e25c3c8a36

Implement QuicStreamSequencerBuffer::PeekRegion().

gfe-relnote: n/a, no functional change.
PiperOrigin-RevId: 254856738
Change-Id: I34f1fd30429f8d5d403fa17fc1f4a127c074f952

quic/core/quic_stream_sequencer_buffer.cc

diff --git a/quic/core/quic_stream_sequencer_buffer.cc b/quic/core/quic_stream_sequencer_buffer.cc
index 47211cc..f4ff276 100644
--- a/quic/core/quic_stream_sequencer_buffer.cc
+++ b/quic/core/quic_stream_sequencer_buffer.cc
@@ -335,18 +335,23 @@
   return GetReadableRegions(iov, 1) == 1;
 }
 
-bool QuicStreamSequencerBuffer::PrefetchNextRegion(iovec* iov) {
-  DCHECK(iov != nullptr);
-  DCHECK_LE(total_bytes_read_, total_bytes_prefetched_);
-  DCHECK_LE(total_bytes_prefetched_, FirstMissingByte());
+bool QuicStreamSequencerBuffer::PeekRegion(QuicStreamOffset offset,
+                                           iovec* iov) const {
+  DCHECK(iov);
 
-  if (total_bytes_prefetched_ == FirstMissingByte()) {
+  if (offset < total_bytes_read_) {
+    // Data at |offset| has already been consumed.
+    return false;
+  }
+
+  if (offset >= FirstMissingByte()) {
+    // Data at |offset| has not been received yet.
     return false;
   }
 
   // Beginning of region.
-  size_t block_idx = GetBlockIndex(total_bytes_prefetched_);
-  size_t block_offset = GetInBlockOffset(total_bytes_prefetched_);
+  size_t block_idx = GetBlockIndex(offset);
+  size_t block_offset = GetInBlockOffset(offset);
   iov->iov_base = blocks_[block_idx]->buffer + block_offset;
 
   // Determine if entire block has been received.
@@ -359,6 +364,18 @@
     iov->iov_len = GetBlockCapacity(block_idx) - block_offset;
   }
 
+  return true;
+}
+
+bool QuicStreamSequencerBuffer::PrefetchNextRegion(iovec* iov) {
+  DCHECK(iov);
+  DCHECK_LE(total_bytes_read_, total_bytes_prefetched_);
+  DCHECK_LE(total_bytes_prefetched_, FirstMissingByte());
+
+  if (!PeekRegion(total_bytes_prefetched_, iov)) {
+    return false;
+  }
+
   total_bytes_prefetched_ += iov->iov_len;
   return true;
 }