chrome/browser/net/url_info.h

   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_