Warmth of a connection (cwnd) is estimated by the amount of data written to the socket.

Choosing the warmest connection would mean faster resource load times. 

idle time is the time a socket has remained idle (no http requests being served on it). 
Probability of server resetting a connection increases with idle time duration. 

Using a cost function that takes into account bytes transferred and idle time to pick best connection to schedule http requests on.

CODEREVIEW done in http://codereview.chromium.org/6990036/

Contributed by gagansingh@google.com

Committed: http://src.chromium.org/viewvc/chrome?view=rev&revision=90373

Reverted: http://codereview.chromium.org/7255002 :(

Have fixed 2 things since:
1. Removed LOG(ERROR) from http_basic_stream.cc that was causing layout tests to fail.
2. Initialized class variables in http_basic_stream.cc that was causing uninitialized memory bugs in valgrind: http://code.google.com/p/chromium/issues/detail?id=87423

Review URL: http://codereview.chromium.org/7251004

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@90601 0039d316-1c4b-4281-b951-d872f2087c98

1 files changed, 14 insertions, 1 deletions

diff --git a/net/socket/tcp_client_socket_libevent.cc b/net/socket/tcp_client_socket_libevent.cc
index 3c5ec13..bc6270d 100644
--- a/net/socket/tcp_client_socket_libevent.cc
+++ b/net/socket/tcp_client_socket_libevent.cc
@@ -137,7 +137,8 @@ TCPClientSocketLibevent::TCPClientSocketLibevent(
       net_log_(BoundNetLog::Make(net_log, NetLog::SOURCE_SOCKET)),
       previously_disconnected_(false),
       use_tcp_fastopen_(false),
-      tcp_fastopen_connected_(false) {
+      tcp_fastopen_connected_(false),
+      num_bytes_read_(0) {
   scoped_refptr<NetLog::EventParameters> params;
   if (source.is_valid())
     params = new NetLogSourceParameter("source_dependency", source);
@@ -298,6 +299,7 @@ int TCPClientSocketLibevent::DoConnect() {
 
   // Connect the socket.
   if (!use_tcp_fastopen_) {
+    connect_start_time_ = base::TimeTicks::Now();
     if (!HANDLE_EINTR(connect(socket_, current_ai_->ai_addr,
                               static_cast<int>(current_ai_->ai_addrlen)))) {
       // Connected without waiting!
@@ -337,6 +339,7 @@ int TCPClientSocketLibevent::DoConnectComplete(int result) {
   net_log_.EndEvent(NetLog::TYPE_TCP_CONNECT_ATTEMPT, params);
 
   if (result == OK) {
+    connect_time_micros_ = base::TimeTicks::Now() - connect_start_time_;
     write_socket_watcher_.StopWatchingFileDescriptor();
     use_history_.set_was_ever_connected();
     return OK;  // Done!
@@ -439,6 +442,7 @@ int TCPClientSocketLibevent::Read(IOBuffer* buf,
   if (nread >= 0) {
     base::StatsCounter read_bytes("tcp.read_bytes");
     read_bytes.Add(nread);
+    num_bytes_read_ += static_cast<int64>(nread);
     if (nread > 0)
       use_history_.set_was_used_to_convey_data();
     net_log_.AddByteTransferEvent(NetLog::TYPE_SOCKET_BYTES_RECEIVED, nread,
@@ -633,6 +637,7 @@ void TCPClientSocketLibevent::DidCompleteRead() {
     result = bytes_transferred;
     base::StatsCounter read_bytes("tcp.read_bytes");
     read_bytes.Add(bytes_transferred);
+    num_bytes_read_ += static_cast<int64>(bytes_transferred);
     if (bytes_transferred > 0)
       use_history_.set_was_used_to_convey_data();
     net_log_.AddByteTransferEvent(NetLog::TYPE_SOCKET_BYTES_RECEIVED, result,
@@ -722,4 +727,12 @@ bool TCPClientSocketLibevent::UsingTCPFastOpen() const {
   return use_tcp_fastopen_;
 }
 
+int64 TCPClientSocketLibevent::NumBytesRead() const {
+  return num_bytes_read_;
+}
+
+base::TimeDelta TCPClientSocketLibevent::GetConnectTimeMicros() const {
+  return connect_time_micros_;
+}
+
 }  // namespace net