url_info.h revision c407dc5cd9bdc5668497f21b26b09d988ab439de
1// Copyright (c) 2006-2010 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.h" 23#include "googleurl/src/gurl.h" 24#include "net/base/host_port_pair.h" 25 26namespace chrome_browser_net { 27 28// Use command line switch to enable detailed logging. 29void EnablePredictorDetailedLog(bool enable); 30 31enum DnsBenefit { 32 PREFETCH_NO_BENEFIT, // Prefetch never hit the network. Name was pre-cached. 33 PREFETCH_CACHE_EVICTION, // Prefetch used network, but so did HTTP stack. 34 PREFETCH_NAME_NONEXISTANT, // Valuable prefetch of "name not found" was used. 35 PREFETCH_NAME_FOUND, // Valuable prefetch was used. 36 PREFETCH_OBLIVIOUS // No prefetch attempt was even made. 37}; 38 39class UrlInfo { 40 public: 41 // Reasons for a domain to be resolved. 42 enum ResolutionMotivation { 43 MOUSE_OVER_MOTIVATED, // Mouse-over link induced resolution. 44 PAGE_SCAN_MOTIVATED, // Scan of rendered page induced resolution. 45 UNIT_TEST_MOTIVATED, 46 LINKED_MAX_MOTIVATED, // enum demarkation above motivation from links. 47 OMNIBOX_MOTIVATED, // Omni-box suggested resolving this. 48 STARTUP_LIST_MOTIVATED, // Startup list caused this resolution. 49 50 NO_PREFETCH_MOTIVATION, // Browser navigation info (not prefetch related). 51 52 // The following involve predictive prefetching, triggered by a navigation. 53 // The referrinrg_url_ is also set when these are used. 54 // TODO(jar): Support STATIC_REFERAL_MOTIVATED API and integration. 55 STATIC_REFERAL_MOTIVATED, // External database suggested this resolution. 56 LEARNED_REFERAL_MOTIVATED, // Prior navigation taught us this resolution. 57 }; 58 59 enum DnsProcessingState { 60 // When processed by our prefetching system, the states are: 61 PENDING, // Constructor has completed. 62 QUEUED, // In name queue but not yet being resolved. 63 ASSIGNED, // Being resolved (or being reset to earlier state) 64 ASSIGNED_BUT_MARKED, // Needs to be deleted as soon as it's resolved. 65 FOUND, // DNS resolution completed. 66 NO_SUCH_NAME, // DNS resolution completed. 67 // When processed by the network stack during navigation, the states are: 68 STARTED, // Resolution has begun for a navigation. 69 FINISHED, // Resolution has completed for a navigation. 70 FINISHED_UNRESOLVED}; // No resolution found, so navigation will fail. 71 static const base::TimeDelta kMaxNonNetworkDnsLookupDuration; 72 // The number of OS cache entries we can guarantee(?) before cache eviction 73 // might likely take place. 74 static const int kMaxGuaranteedDnsCacheSize = 50; 75 76 typedef std::vector<UrlInfo> DnsInfoTable; 77 78 static const base::TimeDelta kNullDuration; 79 80 // UrlInfo are usually made by the default constructor during 81 // initializing of the Predictor's map (of info for Hostnames). 82 UrlInfo() 83 : state_(PENDING), 84 old_prequeue_state_(state_), 85 resolve_duration_(kNullDuration), 86 queue_duration_(kNullDuration), 87 benefits_remaining_(), 88 sequence_number_(0), 89 motivation_(NO_PREFETCH_MOTIVATION), 90 was_linked_(false) { 91 } 92 93 ~UrlInfo() {} 94 95 // NeedDnsUpdate decides, based on our internal info, 96 // if it would be valuable to attempt to update (prefectch) 97 // DNS data for hostname. This decision is based 98 // on how recently we've done DNS prefetching for hostname. 99 bool NeedsDnsUpdate(); 100 101 static void set_cache_expiration(base::TimeDelta time); 102 103 // The prefetching lifecycle. 104 void SetQueuedState(ResolutionMotivation motivation); 105 void SetAssignedState(); 106 void RemoveFromQueue(); 107 void SetPendingDeleteState(); 108 void SetFoundState(); 109 void SetNoSuchNameState(); 110 // The actual browsing resolution lifecycle. 111 void SetStartedState(); 112 void SetFinishedState(bool was_resolved); 113 114 // Finish initialization. Must only be called once. 115 void SetUrl(const GURL& url); 116 117 bool was_linked() const { return was_linked_; } 118 119 GURL referring_url() const { return referring_url_; } 120 void SetReferringHostname(const GURL& url) { 121 referring_url_ = url; 122 } 123 124 bool was_found() const { return FOUND == state_; } 125 bool was_nonexistant() const { return NO_SUCH_NAME == state_; } 126 bool is_assigned() const { 127 return ASSIGNED == state_ || ASSIGNED_BUT_MARKED == state_; 128 } 129 bool is_marked_to_delete() const { return ASSIGNED_BUT_MARKED == state_; } 130 const GURL url() const { return url_; } 131 132 bool HasUrl(const GURL& url) const { 133 return url_ == url; 134 } 135 136 base::TimeDelta resolve_duration() const { return resolve_duration_;} 137 base::TimeDelta queue_duration() const { return queue_duration_;} 138 base::TimeDelta benefits_remaining() const { return benefits_remaining_; } 139 140 DnsBenefit AccruePrefetchBenefits(UrlInfo* navigation_info); 141 142 void DLogResultsStats(const char* message) const; 143 144 static void GetHtmlTable(const DnsInfoTable host_infos, 145 const char* description, 146 const bool brief, 147 std::string* output); 148 149 private: 150 base::TimeDelta GetDuration() { 151 base::TimeTicks old_time = time_; 152 time_ = base::TimeTicks::Now(); 153 return time_ - old_time; 154 } 155 156 // IsStillCached() guesses if the DNS cache still has IP data. 157 bool IsStillCached() const; 158 159 // Record why we created, or have updated (reqested pre-resolution) of this 160 // instance. 161 void SetMotivation(ResolutionMotivation motivation); 162 163 // Helper function for about:dns printing. 164 std::string GetAsciiMotivation() const; 165 166 // The next declaration is non-const to facilitate testing. 167 static base::TimeDelta kCacheExpirationDuration; 168 169 // The current state of this instance. 170 DnsProcessingState state_; 171 172 // Record the state prior to going to a queued state, in case we have to back 173 // out of the queue. 174 DnsProcessingState old_prequeue_state_; 175 176 GURL url_; // Host, port and scheme for this info. 177 178 // When was last state changed (usually lookup completed). 179 base::TimeTicks time_; 180 // Time needed for DNS to resolve. 181 base::TimeDelta resolve_duration_; 182 // Time spent in queue. 183 base::TimeDelta queue_duration_; 184 // Unused potential benefits of a prefetch. 185 base::TimeDelta benefits_remaining_; 186 187 int sequence_number_; // Used to calculate potential of cache eviction. 188 static int sequence_counter; // Used to allocate sequence_number_'s. 189 190 // Motivation for creation of this instance. 191 ResolutionMotivation motivation_; 192 193 // Record if the motivation for prefetching was ever a page-link-scan. 194 bool was_linked_; 195 196 // If this instance holds data about a navigation, we store the referrer. 197 // If this instance hold data about a prefetch, and the prefetch was 198 // instigated by a referrer, we store it here (for use in about:dns). 199 GURL referring_url_; 200 201 // We put these objects into a std::map, and hence we 202 // need some "evil" constructors. 203 // DISALLOW_COPY_AND_ASSIGN(UrlInfo); 204}; 205 206} // namespace chrome_browser_net 207 208#endif // CHROME_BROWSER_NET_URL_INFO_H_ 209