SPDY - flow control optimizations. Send WINDOW_UPDATE

message only when window update size is greater than
50% of the session's send window size.

BUG=107472
R=willchan
TEST=network unittests

Review URL: http://codereview.chromium.org/9443022

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@124153 0039d316-1c4b-4281-b951-d872f2087c98

4 files changed, 30 insertions, 1 deletions

diff --git a/net/spdy/spdy_network_transaction_unittest.cc b/net/spdy/spdy_network_transaction_unittest.cc
index 10b0ceb..6f770cb 100644
--- a/net/spdy/spdy_network_transaction_unittest.cc
+++ b/net/spdy/spdy_network_transaction_unittest.cc
@@ -2020,6 +2020,10 @@ TEST_P(SpdyNetworkTransactionTest, WindowUpdateSent) {
   EXPECT_EQ("HTTP/1.1 200 OK", response->headers->GetStatusLine());
   EXPECT_TRUE(response->was_fetched_via_spdy);
 
+  // Force sending of WINDOW_UPDATE by setting initial_recv_window_size to a
+  // small value.
+  stream->stream()->set_initial_recv_window_size(kUploadDataSize / 2);
+
   // Issue a read which will cause a WINDOW_UPDATE to be sent and window
   // size increased to default.
   scoped_refptr<net::IOBuffer> buf(new net::IOBuffer(kUploadDataSize));
diff --git a/net/spdy/spdy_session.h b/net/spdy/spdy_session.h
index 1e49559..743cced 100644
--- a/net/spdy/spdy_session.h
+++ b/net/spdy/spdy_session.h
@@ -264,6 +264,14 @@ class NET_EXPORT SpdySession : public base::RefCounted<SpdySession>,
     return flow_control_;
   }
 
+  // Returns the current |initial_recv_window_size_|.
+  int32 initial_recv_window_size() const { return initial_recv_window_size_; }
+
+  // Sets |initial_recv_window_size_| used by unittests.
+  void set_initial_recv_window_size(int32 window_size) {
+    initial_recv_window_size_ = window_size;
+  }
+
   const BoundNetLog& net_log() const { return net_log_; }
 
   int GetPeerAddress(AddressList* address) const;
diff --git a/net/spdy/spdy_stream.cc b/net/spdy/spdy_stream.cc
index ab2cbfa..3280d00 100644
--- a/net/spdy/spdy_stream.cc
+++ b/net/spdy/spdy_stream.cc
@@ -76,6 +76,7 @@ SpdyStream::SpdyStream(SpdySession* session,
       stalled_by_flow_control_(false),
       send_window_size_(spdy::kSpdyStreamInitialWindowSize),
       recv_window_size_(spdy::kSpdyStreamInitialWindowSize),
+      unacked_recv_window_bytes_(0),
       pushed_(pushed),
       response_received_(false),
       session_(session),
@@ -159,12 +160,18 @@ void SpdyStream::set_spdy_headers(
   request_ = headers;
 }
 
+void SpdyStream::set_initial_recv_window_size(int32 window_size) {
+  session_->set_initial_recv_window_size(window_size);
+}
+
 void SpdyStream::AdjustSendWindowSize(int32 delta_window_size) {
   send_window_size_ += delta_window_size;
 }
 
 void SpdyStream::IncreaseSendWindowSize(int32 delta_window_size) {
+  DCHECK(session_->is_flow_control_enabled());
   DCHECK_GE(delta_window_size, 1);
+
   int32 new_window_size = send_window_size_ + delta_window_size;
 
   // We should ignore WINDOW_UPDATEs received before or after this state,
@@ -202,6 +209,7 @@ void SpdyStream::IncreaseSendWindowSize(int32 delta_window_size) {
 void SpdyStream::DecreaseSendWindowSize(int32 delta_window_size) {
   // we only call this method when sending a frame, therefore
   // |delta_window_size| should be within the valid frame size range.
+  DCHECK(session_->is_flow_control_enabled());
   DCHECK_GE(delta_window_size, 1);
   DCHECK_LE(delta_window_size, kMaxSpdyFrameChunkSize);
 
@@ -235,7 +243,12 @@ void SpdyStream::IncreaseRecvWindowSize(int32 delta_window_size) {
       NetLog::TYPE_SPDY_STREAM_UPDATE_RECV_WINDOW,
       make_scoped_refptr(new NetLogSpdyStreamWindowUpdateParameter(
           stream_id_, delta_window_size, recv_window_size_)));
-  session_->SendWindowUpdate(stream_id_, delta_window_size);
+
+  unacked_recv_window_bytes_ += delta_window_size;
+  if (unacked_recv_window_bytes_ > session_->initial_recv_window_size() / 2) {
+    session_->SendWindowUpdate(stream_id_, unacked_recv_window_bytes_);
+    unacked_recv_window_bytes_ = 0;
+  }
 }
 
 void SpdyStream::DecreaseRecvWindowSize(int32 delta_window_size) {
diff --git a/net/spdy/spdy_stream.h b/net/spdy/spdy_stream.h
index a40c744..a7342a7 100644
--- a/net/spdy/spdy_stream.h
+++ b/net/spdy/spdy_stream.h
@@ -135,6 +135,9 @@ class NET_EXPORT_PRIVATE SpdyStream
     recv_window_size_ = window_size;
   }
 
+  // Set session_'s initial_recv_window_size. Used by unittests.
+  void set_initial_recv_window_size(int32 window_size);
+
   void set_stalled_by_flow_control(bool stalled) {
     stalled_by_flow_control_ = stalled;
   }
@@ -308,6 +311,7 @@ class NET_EXPORT_PRIVATE SpdyStream
   bool stalled_by_flow_control_;
   int32 send_window_size_;
   int32 recv_window_size_;
+  int32 unacked_recv_window_bytes_;
 
   const bool pushed_;
   ScopedBandwidthMetrics metrics_;