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 // A UrlInfo object is used to store prediction related information about a host 6 // port and scheme triplet. When performing DNS pre-resolution of the host/port 7 // pair, its state is monitored as it is resolved. 8 // It includes progress, from placement in the Predictor's queue, to resolution 9 // by the DNS service as either FOUND or NO_SUCH_NAME. Each instance may also 10 // hold records of previous resolution times, which might later be shown to be 11 // savings relative to resolution time during a navigation. 12 // UrlInfo objects are also used to describe frames, and additional instances 13 // may describe associated subresources, for future speculative connections to 14 // those expected subresources. 15 16 #ifndef CHROME_BROWSER_NET_URL_INFO_H_ 17 #define CHROME_BROWSER_NET_URL_INFO_H_ 18 19 #include <string> 20 #include <vector> 21 22 #include "base/time/time.h" 23 #include "net/base/host_port_pair.h" 24 #include "url/gurl.h" 25 26 namespace chrome_browser_net { 27 28 // Use command line switch to enable detailed logging. 29 void EnablePredictorDetailedLog(bool enable); 30 31 class UrlInfo { 32 public: 33 // Reasons for a domain to be resolved. 34 enum ResolutionMotivation { 35 MOUSE_OVER_MOTIVATED, // Mouse-over link induced resolution. 36 PAGE_SCAN_MOTIVATED, // Scan of rendered page induced resolution. 37 UNIT_TEST_MOTIVATED, 38 LINKED_MAX_MOTIVATED, // enum demarkation above motivation from links. 39 OMNIBOX_MOTIVATED, // Omni-box suggested resolving this. 40 STARTUP_LIST_MOTIVATED, // Startup list caused this resolution. 41 EARLY_LOAD_MOTIVATED, // In some cases we use the prefetcher to warm up 42 // the connection in advance of issuing the real 43 // request. 44 45 NO_PREFETCH_MOTIVATION, // Browser navigation info (not prefetch related). 46 47 // The following involve predictive prefetching, triggered by a navigation. 48 // The referrinrg_url_ is also set when these are used. 49 // TODO(jar): Support STATIC_REFERAL_MOTIVATED API and integration. 50 STATIC_REFERAL_MOTIVATED, // External database suggested this resolution. 51 LEARNED_REFERAL_MOTIVATED, // Prior navigation taught us this resolution. 52 SELF_REFERAL_MOTIVATED, // Guess about need for a second connection. 53 54 MAX_MOTIVATED // Beyond all enums, for use in histogram bounding. 55 }; 56 57 enum DnsProcessingState { 58 // When processed by our prefetching system, the states are: 59 PENDING, // Constructor has completed. 60 QUEUED, // In name queue but not yet being resolved. 61 ASSIGNED, // Being resolved (or being reset to earlier state) 62 ASSIGNED_BUT_MARKED, // Needs to be deleted as soon as it's resolved. 63 FOUND, // DNS resolution completed. 64 NO_SUCH_NAME, // DNS resolution completed. 65 }; 66 67 typedef std::vector<UrlInfo> UrlInfoTable; 68 69 static base::TimeDelta NullDuration() { 70 return base::TimeDelta::FromMilliseconds(-1); 71 } 72 73 // UrlInfo are usually made by the default constructor during 74 // initializing of the Predictor's map (of info for Hostnames). 75 UrlInfo(); 76 77 ~UrlInfo(); 78 79 // NeedDnsUpdate decides, based on our internal info, 80 // if it would be valuable to attempt to update (prefectch) 81 // DNS data for hostname. This decision is based 82 // on how recently we've done DNS prefetching for hostname. 83 bool NeedsDnsUpdate(); 84 85 // FOR TEST ONLY: The following access the otherwise constant values. 86 static void set_cache_expiration(base::TimeDelta time); 87 static base::TimeDelta get_cache_expiration(); 88 89 // The prefetching lifecycle. 90 void SetQueuedState(ResolutionMotivation motivation); 91 void SetAssignedState(); 92 void RemoveFromQueue(); 93 void SetPendingDeleteState(); 94 void SetFoundState(); 95 void SetNoSuchNameState(); 96 97 // Finish initialization. Must only be called once. 98 void SetUrl(const GURL& url); 99 100 bool was_linked() const { return was_linked_; } 101 102 GURL referring_url() const { return referring_url_; } 103 void SetReferringHostname(const GURL& url) { 104 referring_url_ = url; 105 } 106 107 bool was_found() const { return FOUND == state_; } 108 bool was_nonexistent() const { return NO_SUCH_NAME == state_; } 109 bool is_assigned() const { 110 return ASSIGNED == state_ || ASSIGNED_BUT_MARKED == state_; 111 } 112 bool is_marked_to_delete() const { return ASSIGNED_BUT_MARKED == state_; } 113 114 bool HasUrl(const GURL& url) const { 115 return url_ == url; 116 } 117 118 base::TimeDelta resolve_duration() const { return resolve_duration_;} 119 base::TimeDelta queue_duration() const { return queue_duration_;} 120 121 void DLogResultsStats(const char* message) const; 122 123 static void GetHtmlTable(const UrlInfoTable& host_infos, 124 const char* description, 125 bool brief, 126 std::string* output); 127 128 // For testing, and use in printing tables of info, we sometimes need to 129 // adjust the time manually. Usually, this value is maintained by state 130 // transition, and this call is not made. 131 void set_time(const base::TimeTicks& time) { time_ = time; } 132 133 private: 134 base::TimeDelta GetDuration() { 135 base::TimeTicks old_time = time_; 136 time_ = base::TimeTicks::Now(); 137 return time_ - old_time; 138 } 139 140 // IsStillCached() guesses if the DNS cache still has IP data. 141 bool IsStillCached() const; 142 143 // Record why we created, or have updated (reqested pre-resolution) of this 144 // instance. 145 void SetMotivation(ResolutionMotivation motivation); 146 147 // Helper function for about:dns printing. 148 std::string GetAsciiMotivation() const; 149 150 // The current state of this instance. 151 DnsProcessingState state_; 152 153 // Record the state prior to going to a queued state, in case we have to back 154 // out of the queue. 155 DnsProcessingState old_prequeue_state_; 156 157 GURL url_; // Host, port and scheme for this info. 158 159 // When was last state changed (usually lookup completed). 160 base::TimeTicks time_; 161 // Time needed for DNS to resolve. 162 base::TimeDelta resolve_duration_; 163 // Time spent in queue. 164 base::TimeDelta queue_duration_; 165 166 int sequence_number_; // Used to calculate potential of cache eviction. 167 static int sequence_counter; // Used to allocate sequence_number_'s. 168 169 // Motivation for creation of this instance. 170 ResolutionMotivation motivation_; 171 172 // Record if the motivation for prefetching was ever a page-link-scan. 173 bool was_linked_; 174 175 // If this instance holds data about a navigation, we store the referrer. 176 // If this instance hold data about a prefetch, and the prefetch was 177 // instigated by a referrer, we store it here (for use in about:dns). 178 GURL referring_url_; 179 180 // We put these objects into a std::map, and hence we 181 // need some "evil" constructors. 182 // DISALLOW_COPY_AND_ASSIGN(UrlInfo); 183 }; 184 185 } // namespace chrome_browser_net 186 187 #endif // CHROME_BROWSER_NET_URL_INFO_H_ 188
