Emit session-level WINDOW_UPDATEs less frequently.

net/spdy/spdy_session.h

Index: net/spdy/spdy_session.h
diff --git a/net/spdy/spdy_session.h b/net/spdy/spdy_session.h
index 52ecad76211beefa065a5fca5fd34f0824ff3aaa..74deb5b3fca54b2b8ed0d0ecea1aa5f5fc9035d4 100644
--- a/net/spdy/spdy_session.h
+++ b/net/spdy/spdy_session.h
@@ -245,6 +245,7 @@ class NET_EXPORT SpdySession : public BufferedSpdyFramerVisitorInterface,
               bool enable_compression,
               bool enable_ping_based_connection_checking,
               NextProto default_protocol,
+              size_t session_max_recv_window_size,
               size_t stream_initial_recv_window_size,
               size_t initial_max_concurrent_streams,
               size_t max_concurrent_streams_limit,
@@ -1112,6 +1113,25 @@ class NET_EXPORT SpdySession : public BufferedSpdyFramerVisitorInterface,
   // The (version-dependent) flow control state.
   FlowControlState flow_control_state_;
 
+  // Current send window size.  Zero unless session flow control is turned on.
+  int32 session_send_window_size_;
+
+  // Maximum receive window size.  Each time a WINDOW_UPDATE is sent, it
+  // restores the receive window size to this value.  Zero unless session flow
+  // control is turned on.
+  int32 session_max_recv_window_size_;
+
+  // Sum of |session_unacked_recv_window_bytes_| and current receive window
+  // size.  Zero unless session flow control is turned on.
+  // TODO(bnc): Rename or change semantics so that |window_size_| is actual
+  // window size.
+  int32 session_recv_window_size_;
+
+  // Number of octets that are consumed and thus not stored in a buffer owned by

[Ryan Hamilton, 2015/04/07 14:56:40]

s/octets/bytes/

[Bence, 2015/04/07 20:21:38]

Done.

+  // SpdySession any more, but for which no corresponding WINDOW_UPDATEs have
+  // been sent yet.  Zero unless session flow control is turned on.

[Ryan Hamilton, 2015/04/07 14:56:40]

Can you explain where these bytes are living and how they will eventually be
accounted for? (The SpdyIOBuffer destructor calls back to the SpdySession when
the caller is finished with them. So you can probably paraphrase that)

[Bence, 2015/04/07 20:21:38]

Done.

[Ryan Hamilton, 2015/04/08 03:51:10]

Nice! Looks great.

+  int32 session_unacked_recv_window_bytes_;
+
   // Initial send window size for this session's streams. Can be
   // changed by an arriving SETTINGS frame. Newly created streams use
   // this value for the initial send window size.
@@ -1124,12 +1144,6 @@ class NET_EXPORT SpdySession : public BufferedSpdyFramerVisitorInterface,
   // window size.
   int32 stream_initial_recv_window_size_;
 
-  // Session flow control variables. All zero unless session flow
-  // control is turned on.
-  int32 session_send_window_size_;
-  int32 session_recv_window_size_;
-  int32 session_unacked_recv_window_bytes_;
-
   // A queue of stream IDs that have been send-stalled at some point
   // in the past.
   std::deque<SpdyStreamId> stream_send_unstall_queue_[NUM_PRIORITIES];