LoadTiming implementation in net, part 1.

net/base/load_timing_info.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 LOAD_TIMING_INFO_H_
+#define LOAD_TIMING_INFO_H_
+
+#include "base/basictypes.h"
+#include "base/time.h"
+#include "net/base/net_export.h"
+
+namespace net {
+
+// All events that do not apply to a request are NULL.  For non-HTTP requests,
+// all times other than the request_start times are NULL.
+//
+// The general order for events is:
+// request_start
+// proxy_start
+// proxy_end
+// *dns_start
+// *dns_end
+// *connect_start
+// *ssl_start
+// *connect_end
+// send_start
+// send_end
+// receive_headers_end
+//
+// Due to preconnect, late-binding, and cancelled requests, a request may use a
+// fresh connection that was started before the request was issued.  In this
+// case, while the events without a * will always appear in the same order
+// relative to each other, and those with a * will as well, starred events may
+// occur before, during, or after request_start and proxy events.  socket_reused
+// will be false in this case.
+struct NET_EXPORT LoadTimingInfo {
+  LoadTimingInfo();
+  ~LoadTimingInfo();
+
+  // True if the socket was reused.  When true, DNS, connect, and SSL times
+  // will all be NULL.  When false, those times may be NULL, too, if the socket
+  // was preconnected.
+  bool socket_reused;
+
+  // Unique socket ID, can be used to identify requests served by the same
+  // socket.
+  // TODO(mmenke):  Do something reasonable for SPDY proxies.
+  uint32 socket_log_id;
+
+  base::Time request_start_time;

[mmenke, 2012/12/14 01:15:18]

This could be taken care of by the caller, but we record the time at the same
place at request_start, anyways, so seemed reasonable to include it.

+  base::TimeTicks request_start;
+
+  // The time spent determing which proxy to use.
+  base::TimeTicks proxy_start;
+  base::TimeTicks proxy_end;
+
+  // The time spent looking up the host's DNS address.  NULL for requests that
+  // used proxies to look up the DNS address.  Also NULL for SOCKS4 proxies,
+  // since the DNS address is only looked up after the connection is
+  // established, which results in unexpected event ordering.
+  base::TimeTicks dns_start;
+  base::TimeTicks dns_end;
+
+  // The time spent establishing the connection started. Connect time includes
+  // proxy DNS lookup times, blocking, TCP, TCP retries and SSL time.
+  base::TimeTicks connect_start;
+  base::TimeTicks connect_end;
+
+  // The time when the SSL handshake started / completed. For non-HTTPS requests
+  // these are NULL.  These times are only for the SSL connection to the final
+  // destination server, not an SSL/SPDY proxy.
+  base::TimeTicks ssl_start;
+  base::TimeTicks ssl_end;
+
+  // The time that sending HTTP request started / ended.
+  base::TimeTicks send_start;
+  base::TimeTicks send_end;
+
+  // The time at which the end of the HTTP headers were received.
+  base::TimeTicks receive_headers_end;
+};
+
+}  // namespace net
+
+#endif  // LOAD_TIMING_INFO_H_