load_timing_info.h revision 2a99a7e74a7f215066514fe81d2bfa6639d9eddd 
1// Copyright (c) 2012 The Chromium Authors. All rights reserved.
2// Use of this source code is governed by a BSD-style license that can be
3// found in the LICENSE file.
4
5#ifndef NET_BASE_LOAD_TIMING_INFO_H_
6#define NET_BASE_LOAD_TIMING_INFO_H_
7
8#include "base/basictypes.h"
9#include "base/time.h"
10#include "net/base/net_export.h"
11
12namespace net {
13
14// Structure containing timing information for a request.
15// It addresses the needs of
16// http://groups.google.com/group/http-archive-specification/web/har-1-1-spec,
17// http://dev.w3.org/2006/webapi/WebTiming/, and
18// http://www.w3.org/TR/resource-timing/.
19//
20// All events that do not apply to a request have null times.  For non-HTTP
21// requests, all times other than the request_start times are null.
22//
23// Requests with connection errors generally only have request start times as
24// well, since they never received an established socket.
25//
26// The general order for events is:
27// request_start
28// proxy_start
29// proxy_end
30// *dns_start
31// *dns_end
32// *connect_start
33// *ssl_start
34// *ssl_end
35// *connect_end
36// send_start
37// send_end
38// receive_headers_end
39//
40// Those times without an asterisk are computed by the URLRequest, or by objects
41// it directly creates and always owns.  Those with an asterisk are computed
42// by the connection attempt itself.  Since the connection attempt may be
43// started before a URLRequest, the starred times may occur before, during, or
44// after the request_start and proxy events.
45//
46// DNS and SSL times are both times for the host, not the proxy, so DNS times
47// when using proxies are null, and only requests to HTTPS hosts (Not proxies)
48// have SSL times.  One exception to this is when a proxy server itself returns
49// a redirect response.  In this case, the connect times treat the proxy as the
50// host.  The send and receive times will all be null, however.
51// See HttpNetworkTransaction::OnHttpsProxyTunnelResponse.
52// TODO(mmenke):  Is this worth fixing?
53struct NET_EXPORT LoadTimingInfo {
54  // Contains the LoadTimingInfo events related to establishing a connection.
55  // These are all set by ConnectJobs.
56  struct NET_EXPORT_PRIVATE ConnectTiming {
57    ConnectTiming();
58    ~ConnectTiming();
59
60    // The time spent looking up the host's DNS address.  Null for requests that
61    // used proxies to look up the DNS address.  Also null for SOCKS4 proxies,
62    // since the DNS address is only looked up after the connection is
63    // established, which results in unexpected event ordering.
64    // TODO(mmenke):  The SOCKS4 event ordering could be refactored to allow
65    //                these times to be non-null.
66    base::TimeTicks dns_start;
67    base::TimeTicks dns_end;
68
69    // The time spent establishing the connection. Connect time includes proxy
70    // connect times (Though not proxy_resolve times), DNS lookup times, time
71    // spent waiting in certain queues, TCP, and SSL time.
72    // TODO(mmenke):  For proxies, this includes time spent blocking on higher
73    //                level socket pools.  Fix this.
74    // TODO(mmenke):  Retried connections to the same server should apparently
75    //                be included in this time.  Consider supporting that.
76    //                Since the network stack has multiple notions of a "retry",
77    //                handled at different levels, this may not be worth
78    //                worrying about - backup jobs, reused socket failure,
79    //                multiple round authentication.
80    base::TimeTicks connect_start;
81    base::TimeTicks connect_end;
82
83    // The time when the SSL handshake started / completed. For non-HTTPS
84    // requests these are null.  These times are only for the SSL connection to
85    // the final destination server, not an SSL/SPDY proxy.
86    base::TimeTicks ssl_start;
87    base::TimeTicks ssl_end;
88  };
89
90  LoadTimingInfo();
91  ~LoadTimingInfo();
92
93  // True if the socket was reused.  When true, DNS, connect, and SSL times
94  // will all be null.  When false, those times may be null, too, for non-HTTP
95  // requests, or when they don't apply to a request.
96  //
97  // For requests that are sent again after an AUTH challenge, this will be true
98  // if the original socket is reused, and false if a new socket is used.
99  // Responding to a proxy AUTH challenge is never considered to be reusing a
100  // socket, since a connection to the host wasn't established when the
101  // challenge was received.
102  bool socket_reused;
103
104  // Unique socket ID, can be used to identify requests served by the same
105  // socket.  For connections tunnelled over SPDY proxies, this is the ID of
106  // the virtual connection (The SpdyProxyClientSocket), not the ID of the
107  // actual socket.  HTTP requests handled by the SPDY proxy itself all use the
108  // actual socket's ID.
109  //
110  // 0 when there is no socket associated with the request, or it's not an HTTP
111  // request.
112  uint32 socket_log_id;
113
114  // Start time as a base::Time, so times can be coverted into actual times.
115  // Other times are recorded as TimeTicks so they are not affected by clock
116  // changes.
117  base::Time request_start_time;
118
119  base::TimeTicks request_start;
120
121  // The time spent determing which proxy to use.  Null when there is no PAC.
122  base::TimeTicks proxy_resolve_start;
123  base::TimeTicks proxy_resolve_end;
124
125  ConnectTiming connect_timing;
126
127  // The time that sending HTTP request started / ended.
128  base::TimeTicks send_start;
129  base::TimeTicks send_end;
130
131  // The time at which the end of the HTTP headers were received.
132  base::TimeTicks receive_headers_end;
133};
134
135}  // namespace net
136
137#endif  // NET_BASE_LOAD_TIMING_INFO_H_
138