history_url_provider.h revision a3f6a49ab37290eeeb8db0f41ec0f1cb74a68be7
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 CHROME_BROWSER_AUTOCOMPLETE_HISTORY_URL_PROVIDER_H_ 6#define CHROME_BROWSER_AUTOCOMPLETE_HISTORY_URL_PROVIDER_H_ 7 8#include <string> 9#include <vector> 10 11#include "base/compiler_specific.h" 12#include "base/synchronization/cancellation_flag.h" 13#include "chrome/browser/autocomplete/autocomplete_input.h" 14#include "chrome/browser/autocomplete/history_provider.h" 15#include "chrome/browser/autocomplete/history_provider_util.h" 16#include "chrome/browser/autocomplete/url_prefix.h" 17#include "chrome/browser/search_engines/search_terms_data.h" 18#include "chrome/browser/search_engines/template_url.h" 19 20class Profile; 21 22namespace base { 23class MessageLoop; 24} 25 26namespace history { 27class HistoryBackend; 28class URLDatabase; 29} 30 31// How history autocomplete works 32// ============================== 33// 34// Read down this diagram for temporal ordering. 35// 36// Main thread History thread 37// ----------- -------------- 38// AutocompleteController::Start 39// -> HistoryURLProvider::Start 40// -> RunAutocompletePasses 41// -> SuggestExactInput 42// [params_ allocated] 43// -> DoAutocomplete (for inline autocomplete) 44// -> URLDatabase::AutocompleteForPrefix (on in-memory DB) 45// -> HistoryService::ScheduleAutocomplete 46// (return to controller) ---- 47// / 48// HistoryBackend::ScheduleAutocomplete 49// -> HistoryURLProvider::ExecuteWithDB 50// -> DoAutocomplete 51// -> URLDatabase::AutocompleteForPrefix 52// / 53// HistoryService::QueryComplete 54// [params_ destroyed] 55// -> AutocompleteProviderListener::OnProviderUpdate 56// 57// The autocomplete controller calls us, and must be called back, on the main 58// thread. When called, we run two autocomplete passes. The first pass runs 59// synchronously on the main thread and queries the in-memory URL database. 60// This pass promotes matches for inline autocomplete if applicable. We do 61// this synchronously so that users get consistent behavior when they type 62// quickly and hit enter, no matter how loaded the main history database is. 63// Doing this synchronously also prevents inline autocomplete from being 64// "flickery" in the AutocompleteEdit. Because the in-memory DB does not have 65// redirect data, results other than the top match might change between the 66// two passes, so we can't just decide to use this pass' matches as the final 67// results. 68// 69// The second autocomplete pass uses the full history database, which must be 70// queried on the history thread. Start() asks the history service schedule to 71// callback on the history thread with a pointer to the main database. When we 72// are done doing queries, we schedule a task on the main thread that notifies 73// the AutocompleteController that we're done. 74// 75// The communication between these threads is done using a 76// HistoryURLProviderParams object. This is allocated in the main thread, and 77// normally deleted in QueryComplete(). So that both autocomplete passes can 78// use the same code, we also use this to hold results during the first 79// autocomplete pass. 80// 81// While the second pass is running, the AutocompleteController may cancel the 82// request. This can happen frequently when the user is typing quickly. In 83// this case, the main thread sets params_->cancel, which the background thread 84// checks periodically. If it finds the flag set, it stops what it's doing 85// immediately and calls back to the main thread. (We don't delete the params 86// on the history thread, because we should only do that when we can safely 87// NULL out params_, and that must be done on the main thread.) 88 89// Used to communicate autocomplete parameters between threads via the history 90// service. 91struct HistoryURLProviderParams { 92 HistoryURLProviderParams(const AutocompleteInput& input, 93 bool trim_http, 94 const std::string& languages, 95 TemplateURL* default_search_provider, 96 const SearchTermsData& search_terms_data); 97 ~HistoryURLProviderParams(); 98 99 base::MessageLoop* message_loop; 100 101 // A copy of the autocomplete input. We need the copy since this object will 102 // live beyond the original query while it runs on the history thread. 103 AutocompleteInput input; 104 105 // Should inline autocompletion be disabled? This is initalized from 106 // |input.prevent_inline_autocomplete()|, but set to false is the input 107 // contains trailing white space. 108 bool prevent_inline_autocomplete; 109 110 // Set when "http://" should be trimmed from the beginning of the URLs. 111 bool trim_http; 112 113 // Set by the main thread to cancel this request. If this flag is set when 114 // the query runs, the query will be abandoned. This allows us to avoid 115 // running queries that are no longer needed. Since we don't care if we run 116 // the extra queries, the lack of signaling is not a problem. 117 base::CancellationFlag cancel_flag; 118 119 // Set by ExecuteWithDB() on the history thread when the query could not be 120 // performed because the history system failed to properly init the database. 121 // If this is set when the main thread is called back, it avoids changing 122 // |matches_| at all, so it won't delete the default match 123 // RunAutocompletePasses() creates. 124 bool failed; 125 126 // List of matches written by the history thread. We keep this separate list 127 // to avoid having the main thread read the provider's matches while the 128 // history thread is manipulating them. The provider copies this list back 129 // to matches_ on the main thread in QueryComplete(). 130 ACMatches matches; 131 132 // Languages we should pass to gfx::GetCleanStringFromUrl. 133 std::string languages; 134 135 // When true, we should avoid calling SuggestExactInput(). 136 bool dont_suggest_exact_input; 137 138 // The default search provider and search terms data necessary to cull results 139 // that correspond to searches (on the default engine). These can only be 140 // obtained on the UI thread, so we have to copy them into here to pass them 141 // to the history thread. We use a scoped_ptr<TemplateURL> for the DSP since 142 // TemplateURLs can't be copied by value. We use a scoped_ptr<SearchTermsData> 143 // so that we can store a snapshot of the SearchTermsData accessible from the 144 // history thread. 145 scoped_ptr<TemplateURL> default_search_provider; 146 scoped_ptr<SearchTermsData> search_terms_data; 147 148 private: 149 DISALLOW_COPY_AND_ASSIGN(HistoryURLProviderParams); 150}; 151 152// This class is an autocomplete provider and is also a pseudo-internal 153// component of the history system. See comments above. 154class HistoryURLProvider : public HistoryProvider { 155 public: 156 // Various values used in scoring, made public so other providers 157 // can insert results in appropriate ranges relative to these. 158 static const int kScoreForBestInlineableResult; 159 static const int kScoreForUnvisitedIntranetResult; 160 static const int kScoreForWhatYouTypedResult; 161 static const int kBaseScoreForNonInlineableResult; 162 163 HistoryURLProvider(AutocompleteProviderListener* listener, Profile* profile); 164 165 // HistoryProvider: 166 virtual void Start(const AutocompleteInput& input, 167 bool minimal_changes) OVERRIDE; 168 virtual void Stop(bool clear_cached_results) OVERRIDE; 169 170 // Returns a match representing a navigation to |destination_url| given user 171 // input of |text|. |trim_http| controls whether the match's |fill_into_edit| 172 // and |contents| should have any HTTP scheme stripped off, and should not be 173 // set to true if |text| contains an http prefix. 174 // NOTE: This does not set the relevance of the returned match, as different 175 // callers want different behavior. Callers must set this manually. 176 AutocompleteMatch SuggestExactInput(const base::string16& text, 177 const GURL& destination_url, 178 bool trim_http); 179 180 // Runs the history query on the history thread, called by the history 181 // system. The history database MAY BE NULL in which case it is not 182 // available and we should return no data. Also schedules returning the 183 // results to the main thread 184 void ExecuteWithDB(history::HistoryBackend* backend, 185 history::URLDatabase* db, 186 HistoryURLProviderParams* params); 187 188 // Actually runs the autocomplete job on the given database, which is 189 // guaranteed not to be NULL. 190 void DoAutocomplete(history::HistoryBackend* backend, 191 history::URLDatabase* db, 192 HistoryURLProviderParams* params); 193 194 // Dispatches the results to the autocomplete controller. Called on the 195 // main thread by ExecuteWithDB when the results are available. 196 // Frees params_gets_deleted on exit. 197 void QueryComplete(HistoryURLProviderParams* params_gets_deleted); 198 199 private: 200 enum MatchType { 201 NORMAL, 202 WHAT_YOU_TYPED, 203 INLINE_AUTOCOMPLETE, 204 UNVISITED_INTRANET, // An intranet site that has never been visited. 205 }; 206 class VisitClassifier; 207 208 ~HistoryURLProvider(); 209 210 // Determines the relevance for a match, given its type. If 211 // |match_type| is NORMAL, |match_number| is a number [0, 212 // kMaxSuggestions) indicating the relevance of the match (higher == 213 // more relevant). For other values of |match_type|, |match_number| 214 // is ignored. Only called some of the time; for some matches, 215 // relevancy scores are assigned consecutively decreasing (1416, 216 // 1415, 1414, ...). 217 int CalculateRelevance(MatchType match_type, size_t match_number) const; 218 219 // Helper function that actually launches the two autocomplete passes. 220 void RunAutocompletePasses(const AutocompleteInput& input, 221 bool fixup_input_and_run_pass_1); 222 223 // Given a |match| containing the "what you typed" suggestion created by 224 // SuggestExactInput(), looks up its info in the DB. If found, fills in the 225 // title from the DB, promotes the match's priority to that of an inline 226 // autocomplete match (maybe it should be slightly better?), and places it on 227 // the front of |matches| (so we pick the right matches to throw away 228 // when culling redirects to/from it). Returns whether a match was promoted. 229 bool FixupExactSuggestion(history::URLDatabase* db, 230 const AutocompleteInput& input, 231 const VisitClassifier& classifier, 232 AutocompleteMatch* match, 233 history::HistoryMatches* matches) const; 234 235 // Helper function for FixupExactSuggestion, this returns true if the input 236 // corresponds to some intranet URL where the user has previously visited the 237 // host in question. In this case the input should be treated as a URL. 238 bool CanFindIntranetURL(history::URLDatabase* db, 239 const AutocompleteInput& input) const; 240 241 // Determines if |match| is suitable for inline autocomplete. If so, and if 242 // |params| is non-NULL, promotes the match. Returns whether |match| is 243 // suitable for inline autocomplete. 244 bool PromoteMatchForInlineAutocomplete(const history::HistoryMatch& match, 245 HistoryURLProviderParams* params); 246 247 // Sees if a shorter version of the best match should be created, and if so 248 // places it at the front of |matches|. This can suggest history URLs that 249 // are prefixes of the best match (if they've been visited enough, compared to 250 // the best match), or create host-only suggestions even when they haven't 251 // been visited before: if the user visited http://example.com/asdf once, 252 // we'll suggest http://example.com/ even if they've never been to it. 253 void PromoteOrCreateShorterSuggestion( 254 history::URLDatabase* db, 255 const HistoryURLProviderParams& params, 256 bool have_what_you_typed_match, 257 const AutocompleteMatch& what_you_typed_match, 258 history::HistoryMatches* matches); 259 260 // Removes results that have been rarely typed or visited, and not any time 261 // recently. The exact parameters for this heuristic can be found in the 262 // function body. Also culls results corresponding to queries from the default 263 // search engine. These are low-quality, difficult-to-understand matches for 264 // users, and the SearchProvider should surface past queries in a better way 265 // anyway. 266 void CullPoorMatches(const HistoryURLProviderParams& params, 267 history::HistoryMatches* matches) const; 268 269 // Removes results that redirect to each other, leaving at most |max_results| 270 // results. 271 void CullRedirects(history::HistoryBackend* backend, 272 history::HistoryMatches* matches, 273 size_t max_results) const; 274 275 // Helper function for CullRedirects, this removes all but the first 276 // occurance of [any of the set of strings in |remove|] from the |matches| 277 // list. 278 // 279 // The return value is the index of the item that is after the item in the 280 // input identified by |source_index|. If |source_index| or an item before 281 // is removed, the next item will be shifted, and this allows the caller to 282 // pick up on the next one when this happens. 283 size_t RemoveSubsequentMatchesOf(history::HistoryMatches* matches, 284 size_t source_index, 285 const std::vector<GURL>& remove) const; 286 287 // Converts a line from the database into an autocomplete match for display. 288 AutocompleteMatch HistoryMatchToACMatch( 289 const HistoryURLProviderParams& params, 290 const history::HistoryMatch& history_match, 291 MatchType match_type, 292 int relevance); 293 294 // Returns a set of classifications that highlight all the occurrences 295 // of |input_text| at word breaks in |description|. 296 static ACMatchClassifications ClassifyDescription( 297 const base::string16& input_text, 298 const base::string16& description); 299 300 // Params for the current query. The provider should not free this directly; 301 // instead, it is passed as a parameter through the history backend, and the 302 // parameter itself is freed once it's no longer needed. The only reason we 303 // keep this member is so we can set the cancel bit on it. 304 HistoryURLProviderParams* params_; 305 306 // If true, HistoryURL provider should lookup and cull redirects. If 307 // false, it returns matches that may be redirects to each other and 308 // simply hopes the default AutoCompleteController behavior to remove 309 // URLs that are likely duplicates (http://google.com <-> 310 // https://www.google.com/, etc.) will do a good enough job. 311 bool cull_redirects_; 312 313 // Used in PromoteOrCreateShorterSuggestion(). If true, we may create 314 // shorter suggestions even when they haven't been visited before: 315 // if the user visited http://example.com/asdf once, we'll suggest 316 // http://example.com/ even if they've never been to it. 317 bool create_shorter_match_; 318 319 // Whether to query the history URL database to match. Even if 320 // false, we still use the URL database to decide if the 321 // URL-what-you-typed was visited before or not. If false, the only 322 // possible result that HistoryURL provider can return is 323 // URL-what-you-typed. This variable is not part of params_ because 324 // it never changes after the HistoryURLProvider is initialized. 325 // It's used to aid the transition to get all URLs from history to 326 // be scored in the HistoryQuick provider only. 327 bool search_url_database_; 328}; 329 330#endif // CHROME_BROWSER_AUTOCOMPLETE_HISTORY_URL_PROVIDER_H_ 331