src/chrome/browser/history/url_index_private_data.cc

   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 #include "chrome/browser/history/url_index_private_data.h"
   6
   7 #include <algorithm>
   8 #include <functional>
   9 #include <iterator>
  10 #include <limits>
  11 #include <numeric>
  12 #include <string>
  13 #include <vector>
  14
  15 #include "base/basictypes.h"
  16 #include "base/file_util.h"
  17 #include "base/i18n/case_conversion.h"
  18 #include "base/metrics/histogram.h"
  19 #include "base/strings/string_util.h"
  20 #include "base/strings/utf_string_conversions.h"
  21 #include "base/time/time.h"
  22 #include "chrome/browser/autocomplete/autocomplete_provider.h"
  23 #include "chrome/browser/autocomplete/url_prefix.h"
  24 #include "chrome/browser/bookmarks/bookmark_service.h"
  25 #include "chrome/browser/history/history_database.h"
  26 #include "chrome/browser/history/history_db_task.h"
  27 #include "chrome/browser/history/history_service.h"
  28 #include "chrome/browser/history/in_memory_url_index.h"
  29 #include "content/public/browser/browser_thread.h"
  30 #include "content/public/browser/notification_details.h"
  31 #include "content/public/browser/notification_service.h"
  32 #include "content/public/browser/notification_source.h"
  33 #include "net/base/net_util.h"
  34
  35 #if defined(USE_SYSTEM_PROTOBUF)
  36 #include <google/protobuf/repeated_field.h>
  37 #else
  38 #include "third_party/protobuf/src/google/protobuf/repeated_field.h"
  39 #endif
  40
  41 using google::protobuf::RepeatedField;
  42 using google::protobuf::RepeatedPtrField;
  43 using in_memory_url_index::InMemoryURLIndexCacheItem;
  44
  45 namespace {
  46 static const size_t kMaxVisitsToStoreInCache = 10u;
  47 }  // anonymous namespace
  48
  49 namespace history {
  50
  51 typedef imui::InMemoryURLIndexCacheItem_WordListItem WordListItem;
  52 typedef imui::InMemoryURLIndexCacheItem_WordMapItem_WordMapEntry WordMapEntry;
  53 typedef imui::InMemoryURLIndexCacheItem_WordMapItem WordMapItem;
  54 typedef imui::InMemoryURLIndexCacheItem_CharWordMapItem CharWordMapItem;
  55 typedef imui::InMemoryURLIndexCacheItem_CharWordMapItem_CharWordMapEntry
  56     CharWordMapEntry;
  57 typedef imui::InMemoryURLIndexCacheItem_WordIDHistoryMapItem
  58     WordIDHistoryMapItem;
  59 typedef imui::
  60     InMemoryURLIndexCacheItem_WordIDHistoryMapItem_WordIDHistoryMapEntry
  61     WordIDHistoryMapEntry;
  62 typedef imui::InMemoryURLIndexCacheItem_HistoryInfoMapItem HistoryInfoMapItem;
  63 typedef imui::InMemoryURLIndexCacheItem_HistoryInfoMapItem_HistoryInfoMapEntry
  64     HistoryInfoMapEntry;
  65 typedef imui::
  66     InMemoryURLIndexCacheItem_HistoryInfoMapItem_HistoryInfoMapEntry_VisitInfo
  67     HistoryInfoMapEntry_VisitInfo;
  68 typedef imui::InMemoryURLIndexCacheItem_WordStartsMapItem WordStartsMapItem;
  69 typedef imui::InMemoryURLIndexCacheItem_WordStartsMapItem_WordStartsMapEntry
  70     WordStartsMapEntry;
  71
  72
  73 // Algorithm Functions ---------------------------------------------------------
  74
  75 // Comparison function for sorting search terms by descending length.
  76 bool LengthGreater(const base::string16& string_a,
  77                    const base::string16& string_b) {
  78   return string_a.length() > string_b.length();
  79 }
  80
  81
  82 // UpdateRecentVisitsFromHistoryDBTask -----------------------------------------
  83
  84 // HistoryDBTask used to update the recent visit data for a particular
  85 // row from the history database.
  86 class UpdateRecentVisitsFromHistoryDBTask : public HistoryDBTask {
  87  public:
  88   explicit UpdateRecentVisitsFromHistoryDBTask(
  89       URLIndexPrivateData* private_data,
  90       URLID url_id);
  91
  92   virtual bool RunOnDBThread(HistoryBackend* backend,
  93                              history::HistoryDatabase* db) OVERRIDE;
  94   virtual void DoneRunOnMainThread() OVERRIDE;
  95
  96  private:
  97   virtual ~UpdateRecentVisitsFromHistoryDBTask();
  98
  99   // The URLIndexPrivateData that gets updated after the historyDB
 100   // task returns.
 101   URLIndexPrivateData* private_data_;
 102   // The ID of the URL to get visits for and then update.
 103   URLID url_id_;
 104   // Whether fetching the recent visits for the URL succeeded.
 105   bool succeeded_;
 106   // The awaited data that's shown to private_data_ for it to copy and
 107   // store.
 108   VisitVector recent_visits_;
 109
 110   DISALLOW_COPY_AND_ASSIGN(UpdateRecentVisitsFromHistoryDBTask);
 111 };
 112
 113 UpdateRecentVisitsFromHistoryDBTask::UpdateRecentVisitsFromHistoryDBTask(
 114     URLIndexPrivateData* private_data,
 115     URLID url_id)
 116     : private_data_(private_data),
 117       url_id_(url_id),
 118       succeeded_(false) {
 119 }
 120
 121 bool UpdateRecentVisitsFromHistoryDBTask::RunOnDBThread(
 122     HistoryBackend* backend,
 123     HistoryDatabase* db) {
 124   // Make sure the private data is going to get as many recent visits as
 125   // ScoredHistoryMatch::GetFrecency() hopes to use.
 126   DCHECK_GE(kMaxVisitsToStoreInCache, ScoredHistoryMatch::kMaxVisitsToScore);
 127   succeeded_ = db->GetMostRecentVisitsForURL(url_id_,
 128                                              kMaxVisitsToStoreInCache,
 129                                              &recent_visits_);
 130   if (!succeeded_)
 131     recent_visits_.clear();
 132   return true;  // Always claim to be done; do not retry failures.
 133 }
 134
 135 void UpdateRecentVisitsFromHistoryDBTask::DoneRunOnMainThread() {
 136   if (succeeded_)
 137     private_data_->UpdateRecentVisits(url_id_, recent_visits_);
 138 }
 139
 140 UpdateRecentVisitsFromHistoryDBTask::~UpdateRecentVisitsFromHistoryDBTask() {
 141 }
 142
 143
 144 // URLIndexPrivateData ---------------------------------------------------------
 145
 146 URLIndexPrivateData::URLIndexPrivateData()
 147     : restored_cache_version_(0),
 148       saved_cache_version_(kCurrentCacheFileVersion),
 149       pre_filter_item_count_(0),
 150       post_filter_item_count_(0),
 151       post_scoring_item_count_(0) {
 152 }
 153
 154 ScoredHistoryMatches URLIndexPrivateData::HistoryItemsForTerms(
 155     base::string16 search_string,
 156     size_t cursor_position,
 157     const std::string& languages,
 158     BookmarkService* bookmark_service) {
 159   // If cursor position is set and useful (not at either end of the
 160   // string), allow the search string to be broken at cursor position.
 161   // We do this by pretending there's a space where the cursor is.
 162   if ((cursor_position != base::string16::npos) &&
 163       (cursor_position < search_string.length()) &&
 164       (cursor_position > 0)) {
 165     search_string.insert(cursor_position, base::ASCIIToUTF16(" "));
 166   }
 167   pre_filter_item_count_ = 0;
 168   post_filter_item_count_ = 0;
 169   post_scoring_item_count_ = 0;
 170   // The search string we receive may contain escaped characters. For reducing
 171   // the index we need individual, lower-cased words, ignoring escapings. For
 172   // the final filtering we need whitespace separated substrings possibly
 173   // containing escaped characters.
 174   base::string16 lower_raw_string(base::i18n::ToLower(search_string));
 175   base::string16 lower_unescaped_string =
 176       net::UnescapeURLComponent(lower_raw_string,
 177           net::UnescapeRule::SPACES | net::UnescapeRule::URL_SPECIAL_CHARS);
 178   // Extract individual 'words' (as opposed to 'terms'; see below) from the
 179   // search string. When the user types "colspec=ID%20Mstone Release" we get
 180   // four 'words': "colspec", "id", "mstone" and "release".
 181   String16Vector lower_words(
 182       history::String16VectorFromString16(lower_unescaped_string, false, NULL));
 183   ScoredHistoryMatches scored_items;
 184
 185   // Do nothing if we have indexed no words (probably because we've not been
 186   // initialized yet) or the search string has no words.
 187   if (word_list_.empty() || lower_words.empty()) {
 188     search_term_cache_.clear();  // Invalidate the term cache.
 189     return scored_items;
 190   }
 191
 192   // Reset used_ flags for search_term_cache_. We use a basic mark-and-sweep
 193   // approach.
 194   ResetSearchTermCache();
 195
 196   HistoryIDSet history_id_set = HistoryIDSetFromWords(lower_words);
 197
 198   // Trim the candidate pool if it is large. Note that we do not filter out
 199   // items that do not contain the search terms as proper substrings -- doing
 200   // so is the performance-costly operation we are trying to avoid in order
 201   // to maintain omnibox responsiveness.
 202   const size_t kItemsToScoreLimit = 500;
 203   pre_filter_item_count_ = history_id_set.size();
 204   // If we trim the results set we do not want to cache the results for next
 205   // time as the user's ultimately desired result could easily be eliminated
 206   // in this early rough filter.
 207   bool was_trimmed = (pre_filter_item_count_ > kItemsToScoreLimit);
 208   if (was_trimmed) {
 209     HistoryIDVector history_ids;
 210     std::copy(history_id_set.begin(), history_id_set.end(),
 211               std::back_inserter(history_ids));
 212     // Trim down the set by sorting by typed-count, visit-count, and last
 213     // visit.
 214     HistoryItemFactorGreater
 215         item_factor_functor(history_info_map_);
 216     std::partial_sort(history_ids.begin(),
 217                       history_ids.begin() + kItemsToScoreLimit,
 218                       history_ids.end(),
 219                       item_factor_functor);
 220     history_id_set.clear();
 221     std::copy(history_ids.begin(), history_ids.begin() + kItemsToScoreLimit,
 222               std::inserter(history_id_set, history_id_set.end()));
 223     post_filter_item_count_ = history_id_set.size();
 224   }
 225
 226   // Pass over all of the candidates filtering out any without a proper
 227   // substring match, inserting those which pass in order by score. Note that
 228   // in this step we are using the raw search string complete with escaped
 229   // URL elements. When the user has specifically typed something akin to
 230   // "sort=pri&colspec=ID%20Mstone%20Release" we want to make sure that that
 231   // specific substring appears in the URL or page title.
 232
 233   // We call these 'terms' (as opposed to 'words'; see above) as in this case
 234   // we only want to break up the search string on 'true' whitespace rather than
 235   // escaped whitespace. When the user types "colspec=ID%20Mstone Release" we
 236   // get two 'terms': "colspec=id%20mstone" and "release".
 237   history::String16Vector lower_raw_terms;
 238   if (Tokenize(lower_raw_string, base::kWhitespaceUTF16,
 239                &lower_raw_terms) == 0) {
 240     // Don't score matches when there are no terms to score against.  (It's
 241     // possible that the word break iterater that extracts words to search
 242     // for in the database allows some whitespace "words" whereas Tokenize
 243     // excludes a long list of whitespace.)  One could write a scoring
 244     // function that gives a reasonable order to matches when there
 245     // are no terms (i.e., all the words are some form of whitespace),
 246     // but this is such a rare edge case that it's not worth the time.
 247     return scored_items;
 248   }
 249   scored_items = std::for_each(history_id_set.begin(), history_id_set.end(),
 250       AddHistoryMatch(*this, languages, bookmark_service, lower_raw_string,
 251                       lower_raw_terms, base::Time::Now())).ScoredMatches();
 252
 253   // Select and sort only the top kMaxMatches results.
 254   if (scored_items.size() > AutocompleteProvider::kMaxMatches) {
 255     std::partial_sort(scored_items.begin(),
 256                       scored_items.begin() +
 257                           AutocompleteProvider::kMaxMatches,
 258                       scored_items.end(),
 259                       ScoredHistoryMatch::MatchScoreGreater);
 260       scored_items.resize(AutocompleteProvider::kMaxMatches);
 261   } else {
 262     std::sort(scored_items.begin(), scored_items.end(),
 263               ScoredHistoryMatch::MatchScoreGreater);
 264   }
 265   post_scoring_item_count_ = scored_items.size();
 266
 267   if (was_trimmed) {
 268     search_term_cache_.clear();  // Invalidate the term cache.
 269   } else {
 270     // Remove any stale SearchTermCacheItems.
 271     for (SearchTermCacheMap::iterator cache_iter = search_term_cache_.begin();
 272          cache_iter != search_term_cache_.end(); ) {
 273       if (!cache_iter->second.used_)
 274         search_term_cache_.erase(cache_iter++);
 275       else
 276         ++cache_iter;
 277     }
 278   }
 279
 280   return scored_items;
 281 }
 282
 283 bool URLIndexPrivateData::UpdateURL(
 284     HistoryService* history_service,
 285     const URLRow& row,
 286     const std::string& languages,
 287     const std::set<std::string>& scheme_whitelist) {
 288   // The row may or may not already be in our index. If it is not already
 289   // indexed and it qualifies then it gets indexed. If it is already
 290   // indexed and still qualifies then it gets updated, otherwise it
 291   // is deleted from the index.
 292   bool row_was_updated = false;
 293   URLID row_id = row.id();
 294   HistoryInfoMap::iterator row_pos = history_info_map_.find(row_id);
 295   if (row_pos == history_info_map_.end()) {
 296     // This new row should be indexed if it qualifies.
 297     URLRow new_row(row);
 298     new_row.set_id(row_id);
 299     row_was_updated = RowQualifiesAsSignificant(new_row, base::Time()) &&
 300         IndexRow(NULL, history_service, new_row, languages, scheme_whitelist);
 301   } else if (RowQualifiesAsSignificant(row, base::Time())) {
 302     // This indexed row still qualifies and will be re-indexed.
 303     // The url won't have changed but the title, visit count, etc.
 304     // might have changed.
 305     URLRow& row_to_update = row_pos->second.url_row;
 306     bool title_updated = row_to_update.title() != row.title();
 307     if (row_to_update.visit_count() != row.visit_count() ||
 308         row_to_update.typed_count() != row.typed_count() ||
 309         row_to_update.last_visit() != row.last_visit() || title_updated) {
 310       row_to_update.set_visit_count(row.visit_count());
 311       row_to_update.set_typed_count(row.typed_count());
 312       row_to_update.set_last_visit(row.last_visit());
 313       // If something appears to have changed, update the recent visits
 314       // information.
 315       ScheduleUpdateRecentVisits(history_service, row_id);
 316       // While the URL is guaranteed to remain stable, the title may have
 317       // changed. If so, then update the index with the changed words.
 318       if (title_updated) {
 319         // Clear all words associated with this row and re-index both the
 320         // URL and title.
 321         RemoveRowWordsFromIndex(row_to_update);
 322         row_to_update.set_title(row.title());
 323         RowWordStarts word_starts;
 324         AddRowWordsToIndex(row_to_update, &word_starts, languages);
 325         word_starts_map_[row_id] = word_starts;
 326       }
 327       row_was_updated = true;
 328     }
 329   } else {
 330     // This indexed row no longer qualifies and will be de-indexed by
 331     // clearing all words associated with this row.
 332     RemoveRowFromIndex(row);
 333     row_was_updated = true;
 334   }
 335   if (row_was_updated)
 336     search_term_cache_.clear();  // This invalidates the cache.
 337   return row_was_updated;
 338 }
 339
 340 void URLIndexPrivateData::UpdateRecentVisits(
 341     URLID url_id,
 342     const VisitVector& recent_visits) {
 343   HistoryInfoMap::iterator row_pos = history_info_map_.find(url_id);
 344   if (row_pos != history_info_map_.end()) {
 345     VisitInfoVector* visits = &row_pos->second.visits;
 346     visits->clear();
 347     const size_t size =
 348         std::min(recent_visits.size(), kMaxVisitsToStoreInCache);
 349     visits->reserve(size);
 350     for (size_t i = 0; i < size; i++) {
 351       // Copy from the VisitVector the only fields visits needs.
 352       visits->push_back(std::make_pair(recent_visits[i].visit_time,
 353                                        recent_visits[i].transition));
 354     }
 355   }
 356   // Else: Oddly, the URL doesn't seem to exist in the private index.
 357   // Ignore this update.  This can happen if, for instance, the user
 358   // removes the URL from URLIndexPrivateData before the historyDB call
 359   // returns.
 360 }
 361
 362 void URLIndexPrivateData::ScheduleUpdateRecentVisits(
 363     HistoryService* history_service,
 364     URLID url_id) {
 365   history_service->ScheduleDBTask(
 366       new UpdateRecentVisitsFromHistoryDBTask(this, url_id),
 367       &recent_visits_consumer_);
 368 }
 369
 370 // Helper functor for DeleteURL.
 371 class HistoryInfoMapItemHasURL {
 372  public:
 373   explicit HistoryInfoMapItemHasURL(const GURL& url): url_(url) {}
 374
 375   bool operator()(const std::pair<const HistoryID, HistoryInfoMapValue>& item) {
 376     return item.second.url_row.url() == url_;
 377   }
 378
 379  private:
 380   const GURL& url_;
 381 };
 382
 383 bool URLIndexPrivateData::DeleteURL(const GURL& url) {
 384   // Find the matching entry in the history_info_map_.
 385   HistoryInfoMap::iterator pos = std::find_if(
 386       history_info_map_.begin(),
 387       history_info_map_.end(),
 388       HistoryInfoMapItemHasURL(url));
 389   if (pos == history_info_map_.end())
 390     return false;
 391   RemoveRowFromIndex(pos->second.url_row);
 392   search_term_cache_.clear();  // This invalidates the cache.
 393   return true;
 394 }
 395
 396 // static
 397 scoped_refptr<URLIndexPrivateData> URLIndexPrivateData::RestoreFromFile(
 398     const base::FilePath& file_path,
 399     const std::string& languages) {
 400   base::TimeTicks beginning_time = base::TimeTicks::Now();
 401   if (!base::PathExists(file_path))
 402     return NULL;
 403   std::string data;
 404   // If there is no cache file then simply give up. This will cause us to
 405   // attempt to rebuild from the history database.
 406   if (!base::ReadFileToString(file_path, &data))
 407     return NULL;
 408
 409   scoped_refptr<URLIndexPrivateData> restored_data(new URLIndexPrivateData);
 410   InMemoryURLIndexCacheItem index_cache;
 411   if (!index_cache.ParseFromArray(data.c_str(), data.size())) {
 412     LOG(WARNING) << "Failed to parse URLIndexPrivateData cache data read from "
 413                  << file_path.value();
 414     return restored_data;
 415   }
 416
 417   if (!restored_data->RestorePrivateData(index_cache, languages))
 418     return NULL;
 419
 420   UMA_HISTOGRAM_TIMES("History.InMemoryURLIndexRestoreCacheTime",
 421                       base::TimeTicks::Now() - beginning_time);
 422   UMA_HISTOGRAM_COUNTS("History.InMemoryURLHistoryItems",
 423                        restored_data->history_id_word_map_.size());
 424   UMA_HISTOGRAM_COUNTS("History.InMemoryURLCacheSize", data.size());
 425   UMA_HISTOGRAM_COUNTS_10000("History.InMemoryURLWords",
 426                              restored_data->word_map_.size());
 427   UMA_HISTOGRAM_COUNTS_10000("History.InMemoryURLChars",
 428                              restored_data->char_word_map_.size());
 429   if (restored_data->Empty())
 430     return NULL;  // 'No data' is the same as a failed reload.
 431   return restored_data;
 432 }
 433
 434 // static
 435 scoped_refptr<URLIndexPrivateData> URLIndexPrivateData::RebuildFromHistory(
 436     HistoryDatabase* history_db,
 437     const std::string& languages,
 438     const std::set<std::string>& scheme_whitelist) {
 439   if (!history_db)
 440     return NULL;
 441
 442   base::TimeTicks beginning_time = base::TimeTicks::Now();
 443
 444   scoped_refptr<URLIndexPrivateData>
 445       rebuilt_data(new URLIndexPrivateData);
 446   URLDatabase::URLEnumerator history_enum;
 447   if (!history_db->InitURLEnumeratorForSignificant(&history_enum))
 448     return NULL;
 449   rebuilt_data->last_time_rebuilt_from_history_ = base::Time::Now();
 450   for (URLRow row; history_enum.GetNextURL(&row); ) {
 451     rebuilt_data->IndexRow(history_db, NULL, row, languages,
 452                            scheme_whitelist);
 453   }
 454
 455   UMA_HISTOGRAM_TIMES("History.InMemoryURLIndexingTime",
 456                       base::TimeTicks::Now() - beginning_time);
 457   UMA_HISTOGRAM_COUNTS("History.InMemoryURLHistoryItems",
 458                        rebuilt_data->history_id_word_map_.size());
 459   UMA_HISTOGRAM_COUNTS_10000("History.InMemoryURLWords",
 460                              rebuilt_data->word_map_.size());
 461   UMA_HISTOGRAM_COUNTS_10000("History.InMemoryURLChars",
 462                              rebuilt_data->char_word_map_.size());
 463   return rebuilt_data;
 464 }
 465
 466 // static
 467 bool URLIndexPrivateData::WritePrivateDataToCacheFileTask(
 468     scoped_refptr<URLIndexPrivateData> private_data,
 469     const base::FilePath& file_path) {
 470   DCHECK(private_data.get());
 471   DCHECK(!file_path.empty());
 472   return private_data->SaveToFile(file_path);
 473 }
 474
 475 void URLIndexPrivateData::CancelPendingUpdates() {
 476   recent_visits_consumer_.CancelAllRequests();
 477 }
 478
 479 scoped_refptr<URLIndexPrivateData> URLIndexPrivateData::Duplicate() const {
 480   scoped_refptr<URLIndexPrivateData> data_copy = new URLIndexPrivateData;
 481   data_copy->last_time_rebuilt_from_history_ = last_time_rebuilt_from_history_;
 482   data_copy->word_list_ = word_list_;
 483   data_copy->available_words_ = available_words_;
 484   data_copy->word_map_ = word_map_;
 485   data_copy->char_word_map_ = char_word_map_;
 486   data_copy->word_id_history_map_ = word_id_history_map_;
 487   data_copy->history_id_word_map_ = history_id_word_map_;
 488   data_copy->history_info_map_ = history_info_map_;
 489   data_copy->word_starts_map_ = word_starts_map_;
 490   return data_copy;
 491   // Not copied:
 492   //    search_term_cache_
 493   //    pre_filter_item_count_
 494   //    post_filter_item_count_
 495   //    post_scoring_item_count_
 496 };
 497
 498 bool URLIndexPrivateData::Empty() const {
 499   return history_info_map_.empty();
 500 }
 501
 502 void URLIndexPrivateData::Clear() {
 503   last_time_rebuilt_from_history_ = base::Time();
 504   word_list_.clear();
 505   available_words_.clear();
 506   word_map_.clear();
 507   char_word_map_.clear();
 508   word_id_history_map_.clear();
 509   history_id_word_map_.clear();
 510   history_info_map_.clear();
 511   word_starts_map_.clear();
 512 }
 513
 514 URLIndexPrivateData::~URLIndexPrivateData() {}
 515
 516 HistoryIDSet URLIndexPrivateData::HistoryIDSetFromWords(
 517     const String16Vector& unsorted_words) {
 518   // Break the terms down into individual terms (words), get the candidate
 519   // set for each term, and intersect each to get a final candidate list.
 520   // Note that a single 'term' from the user's perspective might be
 521   // a string like "http://www.somewebsite.com" which, from our perspective,
 522   // is four words: 'http', 'www', 'somewebsite', and 'com'.
 523   HistoryIDSet history_id_set;
 524   String16Vector words(unsorted_words);
 525   // Sort the words into the longest first as such are likely to narrow down
 526   // the results quicker. Also, single character words are the most expensive
 527   // to process so save them for last.
 528   std::sort(words.begin(), words.end(), LengthGreater);
 529   for (String16Vector::iterator iter = words.begin(); iter != words.end();
 530        ++iter) {
 531     base::string16 uni_word = *iter;
 532     HistoryIDSet term_history_set = HistoryIDsForTerm(uni_word);
 533     if (term_history_set.empty()) {
 534       history_id_set.clear();
 535       break;
 536     }
 537     if (iter == words.begin()) {
 538       history_id_set.swap(term_history_set);
 539     } else {
 540       HistoryIDSet new_history_id_set;
 541       std::set_intersection(history_id_set.begin(), history_id_set.end(),
 542                             term_history_set.begin(), term_history_set.end(),
 543                             std::inserter(new_history_id_set,
 544                                           new_history_id_set.begin()));
 545       history_id_set.swap(new_history_id_set);
 546     }
 547   }
 548   return history_id_set;
 549 }
 550
 551 HistoryIDSet URLIndexPrivateData::HistoryIDsForTerm(
 552     const base::string16& term) {
 553   if (term.empty())
 554     return HistoryIDSet();
 555
 556   // TODO(mrossetti): Consider optimizing for very common terms such as
 557   // 'http[s]', 'www', 'com', etc. Or collect the top 100 more frequently
 558   // occuring words in the user's searches.
 559
 560   size_t term_length = term.length();
 561   WordIDSet word_id_set;
 562   if (term_length > 1) {
 563     // See if this term or a prefix thereof is present in the cache.
 564     SearchTermCacheMap::iterator best_prefix(search_term_cache_.end());
 565     for (SearchTermCacheMap::iterator cache_iter = search_term_cache_.begin();
 566          cache_iter != search_term_cache_.end(); ++cache_iter) {
 567       if (StartsWith(term, cache_iter->first, false) &&
 568           (best_prefix == search_term_cache_.end() ||
 569            cache_iter->first.length() > best_prefix->first.length()))
 570         best_prefix = cache_iter;
 571     }
 572
 573     // If a prefix was found then determine the leftover characters to be used
 574     // for further refining the results from that prefix.
 575     Char16Set prefix_chars;
 576     base::string16 leftovers(term);
 577     if (best_prefix != search_term_cache_.end()) {
 578       // If the prefix is an exact match for the term then grab the cached
 579       // results and we're done.
 580       size_t prefix_length = best_prefix->first.length();
 581       if (prefix_length == term_length) {
 582         best_prefix->second.used_ = true;
 583         return best_prefix->second.history_id_set_;
 584       }
 585
 586       // Otherwise we have a handy starting point.
 587       // If there are no history results for this prefix then we can bail early
 588       // as there will be no history results for the full term.
 589       if (best_prefix->second.history_id_set_.empty()) {
 590         search_term_cache_[term] = SearchTermCacheItem();
 591         return HistoryIDSet();
 592       }
 593       word_id_set = best_prefix->second.word_id_set_;
 594       prefix_chars = Char16SetFromString16(best_prefix->first);
 595       leftovers = term.substr(prefix_length);
 596     }
 597
 598     // Filter for each remaining, unique character in the term.
 599     Char16Set leftover_chars = Char16SetFromString16(leftovers);
 600     Char16Set unique_chars =
 601         base::STLSetDifference<Char16Set>(leftover_chars, prefix_chars);
 602
 603     // Reduce the word set with any leftover, unprocessed characters.
 604     if (!unique_chars.empty()) {
 605       WordIDSet leftover_set(WordIDSetForTermChars(unique_chars));
 606       // We might come up empty on the leftovers.
 607       if (leftover_set.empty()) {
 608         search_term_cache_[term] = SearchTermCacheItem();
 609         return HistoryIDSet();
 610       }
 611       // Or there may not have been a prefix from which to start.
 612       if (prefix_chars.empty()) {
 613         word_id_set.swap(leftover_set);
 614       } else {
 615         WordIDSet new_word_id_set;
 616         std::set_intersection(word_id_set.begin(), word_id_set.end(),
 617                               leftover_set.begin(), leftover_set.end(),
 618                               std::inserter(new_word_id_set,
 619                                             new_word_id_set.begin()));
 620         word_id_set.swap(new_word_id_set);
 621       }
 622     }
 623
 624     // We must filter the word list because the resulting word set surely
 625     // contains words which do not have the search term as a proper subset.
 626     for (WordIDSet::iterator word_set_iter = word_id_set.begin();
 627          word_set_iter != word_id_set.end(); ) {
 628       if (word_list_[*word_set_iter].find(term) == base::string16::npos)
 629         word_id_set.erase(word_set_iter++);
 630       else
 631         ++word_set_iter;
 632     }
 633   } else {
 634     word_id_set = WordIDSetForTermChars(Char16SetFromString16(term));
 635   }
 636
 637   // If any words resulted then we can compose a set of history IDs by unioning
 638   // the sets from each word.
 639   HistoryIDSet history_id_set;
 640   if (!word_id_set.empty()) {
 641     for (WordIDSet::iterator word_id_iter = word_id_set.begin();
 642          word_id_iter != word_id_set.end(); ++word_id_iter) {
 643       WordID word_id = *word_id_iter;
 644       WordIDHistoryMap::iterator word_iter = word_id_history_map_.find(word_id);
 645       if (word_iter != word_id_history_map_.end()) {
 646         HistoryIDSet& word_history_id_set(word_iter->second);
 647         history_id_set.insert(word_history_id_set.begin(),
 648                               word_history_id_set.end());
 649       }
 650     }
 651   }
 652
 653   // Record a new cache entry for this word if the term is longer than
 654   // a single character.
 655   if (term_length > 1)
 656     search_term_cache_[term] = SearchTermCacheItem(word_id_set, history_id_set);
 657
 658   return history_id_set;
 659 }
 660
 661 WordIDSet URLIndexPrivateData::WordIDSetForTermChars(
 662     const Char16Set& term_chars) {
 663   WordIDSet word_id_set;
 664   for (Char16Set::const_iterator c_iter = term_chars.begin();
 665        c_iter != term_chars.end(); ++c_iter) {
 666     CharWordIDMap::iterator char_iter = char_word_map_.find(*c_iter);
 667     if (char_iter == char_word_map_.end()) {
 668       // A character was not found so there are no matching results: bail.
 669       word_id_set.clear();
 670       break;
 671     }
 672     WordIDSet& char_word_id_set(char_iter->second);
 673     // It is possible for there to no longer be any words associated with
 674     // a particular character. Give up in that case.
 675     if (char_word_id_set.empty()) {
 676       word_id_set.clear();
 677       break;
 678     }
 679
 680     if (c_iter == term_chars.begin()) {
 681       // First character results becomes base set of results.
 682       word_id_set = char_word_id_set;
 683     } else {
 684       // Subsequent character results get intersected in.
 685       WordIDSet new_word_id_set;
 686       std::set_intersection(word_id_set.begin(), word_id_set.end(),
 687                             char_word_id_set.begin(), char_word_id_set.end(),
 688                             std::inserter(new_word_id_set,
 689                                           new_word_id_set.begin()));
 690       word_id_set.swap(new_word_id_set);
 691     }
 692   }
 693   return word_id_set;
 694 }
 695
 696 bool URLIndexPrivateData::IndexRow(
 697     HistoryDatabase* history_db,
 698     HistoryService* history_service,
 699     const URLRow& row,
 700     const std::string& languages,
 701     const std::set<std::string>& scheme_whitelist) {
 702   const GURL& gurl(row.url());
 703
 704   // Index only URLs with a whitelisted scheme.
 705   if (!URLSchemeIsWhitelisted(gurl, scheme_whitelist))
 706     return false;
 707
 708   URLID row_id = row.id();
 709   // Strip out username and password before saving and indexing.
 710   base::string16 url(net::FormatUrl(gurl, languages,
 711       net::kFormatUrlOmitUsernamePassword,
 712       net::UnescapeRule::NONE,
 713       NULL, NULL, NULL));
 714
 715   HistoryID history_id = static_cast<HistoryID>(row_id);
 716   DCHECK_LT(history_id, std::numeric_limits<HistoryID>::max());
 717
 718   // Add the row for quick lookup in the history info store.
 719   URLRow new_row(GURL(url), row_id);
 720   new_row.set_visit_count(row.visit_count());
 721   new_row.set_typed_count(row.typed_count());
 722   new_row.set_last_visit(row.last_visit());
 723   new_row.set_title(row.title());
 724   history_info_map_[history_id].url_row = new_row;
 725
 726   // Index the words contained in the URL and title of the row.
 727   RowWordStarts word_starts;
 728   AddRowWordsToIndex(new_row, &word_starts, languages);
 729   word_starts_map_[history_id] = word_starts;
 730
 731   // Update the recent visits information or schedule the update
 732   // as appropriate.
 733   if (history_db) {
 734     // We'd like to check that we're on the history DB thread.
 735     // However, unittest code actually calls this on the UI thread.
 736     // So we don't do any thread checks.
 737     VisitVector recent_visits;
 738     // Make sure the private data is going to get as many recent visits as
 739     // ScoredHistoryMatch::GetFrecency() hopes to use.
 740     DCHECK_GE(kMaxVisitsToStoreInCache, ScoredHistoryMatch::kMaxVisitsToScore);
 741     if (history_db->GetMostRecentVisitsForURL(row_id,
 742                                               kMaxVisitsToStoreInCache,
 743                                               &recent_visits))
 744       UpdateRecentVisits(row_id, recent_visits);
 745   } else {
 746     DCHECK(history_service);
 747     ScheduleUpdateRecentVisits(history_service, row_id);
 748   }
 749
 750   return true;
 751 }
 752
 753 void URLIndexPrivateData::AddRowWordsToIndex(const URLRow& row,
 754                                              RowWordStarts* word_starts,
 755                                              const std::string& languages) {
 756   HistoryID history_id = static_cast<HistoryID>(row.id());
 757   // Split URL into individual, unique words then add in the title words.
 758   const GURL& gurl(row.url());
 759   const base::string16& url = CleanUpUrlForMatching(gurl, languages);
 760   String16Set url_words = String16SetFromString16(url,
 761       word_starts ? &word_starts->url_word_starts_ : NULL);
 762   const base::string16& title = CleanUpTitleForMatching(row.title());
 763   String16Set title_words = String16SetFromString16(title,
 764       word_starts ? &word_starts->title_word_starts_ : NULL);
 765   String16Set words;
 766   std::set_union(url_words.begin(), url_words.end(),
 767                  title_words.begin(), title_words.end(),
 768                  std::insert_iterator<String16Set>(words, words.begin()));
 769   for (String16Set::iterator word_iter = words.begin();
 770        word_iter != words.end(); ++word_iter)
 771     AddWordToIndex(*word_iter, history_id);
 772
 773   search_term_cache_.clear();  // Invalidate the term cache.
 774 }
 775
 776 void URLIndexPrivateData::AddWordToIndex(const base::string16& term,
 777                                          HistoryID history_id) {
 778   WordMap::iterator word_pos = word_map_.find(term);
 779   if (word_pos != word_map_.end())
 780     UpdateWordHistory(word_pos->second, history_id);
 781   else
 782     AddWordHistory(term, history_id);
 783 }
 784
 785 void URLIndexPrivateData::AddWordHistory(const base::string16& term,
 786                                          HistoryID history_id) {
 787   WordID word_id = word_list_.size();
 788   if (available_words_.empty()) {
 789     word_list_.push_back(term);
 790   } else {
 791     word_id = *(available_words_.begin());
 792     word_list_[word_id] = term;
 793     available_words_.erase(word_id);
 794   }
 795   word_map_[term] = word_id;
 796
 797   HistoryIDSet history_id_set;
 798   history_id_set.insert(history_id);
 799   word_id_history_map_[word_id] = history_id_set;
 800   AddToHistoryIDWordMap(history_id, word_id);
 801
 802   // For each character in the newly added word (i.e. a word that is not
 803   // already in the word index), add the word to the character index.
 804   Char16Set characters = Char16SetFromString16(term);
 805   for (Char16Set::iterator uni_char_iter = characters.begin();
 806        uni_char_iter != characters.end(); ++uni_char_iter) {
 807     base::char16 uni_char = *uni_char_iter;
 808     CharWordIDMap::iterator char_iter = char_word_map_.find(uni_char);
 809     if (char_iter != char_word_map_.end()) {
 810       // Update existing entry in the char/word index.
 811       WordIDSet& word_id_set(char_iter->second);
 812       word_id_set.insert(word_id);
 813     } else {
 814       // Create a new entry in the char/word index.
 815       WordIDSet word_id_set;
 816       word_id_set.insert(word_id);
 817       char_word_map_[uni_char] = word_id_set;
 818     }
 819   }
 820 }
 821
 822 void URLIndexPrivateData::UpdateWordHistory(WordID word_id,
 823                                             HistoryID history_id) {
 824   WordIDHistoryMap::iterator history_pos = word_id_history_map_.find(word_id);
 825   DCHECK(history_pos != word_id_history_map_.end());
 826   HistoryIDSet& history_id_set(history_pos->second);
 827   history_id_set.insert(history_id);
 828   AddToHistoryIDWordMap(history_id, word_id);
 829 }
 830
 831 void URLIndexPrivateData::AddToHistoryIDWordMap(HistoryID history_id,
 832                                                 WordID word_id) {
 833   HistoryIDWordMap::iterator iter = history_id_word_map_.find(history_id);
 834   if (iter != history_id_word_map_.end()) {
 835     WordIDSet& word_id_set(iter->second);
 836     word_id_set.insert(word_id);
 837   } else {
 838     WordIDSet word_id_set;
 839     word_id_set.insert(word_id);
 840     history_id_word_map_[history_id] = word_id_set;
 841   }
 842 }
 843
 844 void URLIndexPrivateData::RemoveRowFromIndex(const URLRow& row) {
 845   RemoveRowWordsFromIndex(row);
 846   HistoryID history_id = static_cast<HistoryID>(row.id());
 847   history_info_map_.erase(history_id);
 848   word_starts_map_.erase(history_id);
 849 }
 850
 851 void URLIndexPrivateData::RemoveRowWordsFromIndex(const URLRow& row) {
 852   // Remove the entries in history_id_word_map_ and word_id_history_map_ for
 853   // this row.
 854   HistoryID history_id = static_cast<HistoryID>(row.id());
 855   WordIDSet word_id_set = history_id_word_map_[history_id];
 856   history_id_word_map_.erase(history_id);
 857
 858   // Reconcile any changes to word usage.
 859   for (WordIDSet::iterator word_id_iter = word_id_set.begin();
 860        word_id_iter != word_id_set.end(); ++word_id_iter) {
 861     WordID word_id = *word_id_iter;
 862     word_id_history_map_[word_id].erase(history_id);
 863     if (!word_id_history_map_[word_id].empty())
 864       continue;  // The word is still in use.
 865
 866     // The word is no longer in use. Reconcile any changes to character usage.
 867     base::string16 word = word_list_[word_id];
 868     Char16Set characters = Char16SetFromString16(word);
 869     for (Char16Set::iterator uni_char_iter = characters.begin();
 870          uni_char_iter != characters.end(); ++uni_char_iter) {
 871       base::char16 uni_char = *uni_char_iter;
 872       char_word_map_[uni_char].erase(word_id);
 873       if (char_word_map_[uni_char].empty())
 874         char_word_map_.erase(uni_char);  // No longer in use.
 875     }
 876
 877     // Complete the removal of references to the word.
 878     word_id_history_map_.erase(word_id);
 879     word_map_.erase(word);
 880     word_list_[word_id] = base::string16();
 881     available_words_.insert(word_id);
 882   }
 883 }
 884
 885 void URLIndexPrivateData::ResetSearchTermCache() {
 886   for (SearchTermCacheMap::iterator iter = search_term_cache_.begin();
 887        iter != search_term_cache_.end(); ++iter)
 888     iter->second.used_ = false;
 889 }
 890
 891 bool URLIndexPrivateData::SaveToFile(const base::FilePath& file_path) {
 892   base::TimeTicks beginning_time = base::TimeTicks::Now();
 893   InMemoryURLIndexCacheItem index_cache;
 894   SavePrivateData(&index_cache);
 895   std::string data;
 896   if (!index_cache.SerializeToString(&data)) {
 897     LOG(WARNING) << "Failed to serialize the InMemoryURLIndex cache.";
 898     return false;
 899   }
 900
 901   int size = data.size();
 902   if (file_util::WriteFile(file_path, data.c_str(), size) != size) {
 903     LOG(WARNING) << "Failed to write " << file_path.value();
 904     return false;
 905   }
 906   UMA_HISTOGRAM_TIMES("History.InMemoryURLIndexSaveCacheTime",
 907                       base::TimeTicks::Now() - beginning_time);
 908   return true;
 909 }
 910
 911 void URLIndexPrivateData::SavePrivateData(
 912     InMemoryURLIndexCacheItem* cache) const {
 913   DCHECK(cache);
 914   cache->set_last_rebuild_timestamp(
 915       last_time_rebuilt_from_history_.ToInternalValue());
 916   cache->set_version(saved_cache_version_);
 917   // history_item_count_ is no longer used but rather than change the protobuf
 918   // definition use a placeholder. This will go away with the switch to SQLite.
 919   cache->set_history_item_count(0);
 920   SaveWordList(cache);
 921   SaveWordMap(cache);
 922   SaveCharWordMap(cache);
 923   SaveWordIDHistoryMap(cache);
 924   SaveHistoryInfoMap(cache);
 925   SaveWordStartsMap(cache);
 926 }
 927
 928 void URLIndexPrivateData::SaveWordList(InMemoryURLIndexCacheItem* cache) const {
 929   if (word_list_.empty())
 930     return;
 931   WordListItem* list_item = cache->mutable_word_list();
 932   list_item->set_word_count(word_list_.size());
 933   for (String16Vector::const_iterator iter = word_list_.begin();
 934        iter != word_list_.end(); ++iter)
 935     list_item->add_word(base::UTF16ToUTF8(*iter));
 936 }
 937
 938 void URLIndexPrivateData::SaveWordMap(InMemoryURLIndexCacheItem* cache) const {
 939   if (word_map_.empty())
 940     return;
 941   WordMapItem* map_item = cache->mutable_word_map();
 942   map_item->set_item_count(word_map_.size());
 943   for (WordMap::const_iterator iter = word_map_.begin();
 944        iter != word_map_.end(); ++iter) {
 945     WordMapEntry* map_entry = map_item->add_word_map_entry();
 946     map_entry->set_word(base::UTF16ToUTF8(iter->first));
 947     map_entry->set_word_id(iter->second);
 948   }
 949 }
 950
 951 void URLIndexPrivateData::SaveCharWordMap(
 952     InMemoryURLIndexCacheItem* cache) const {
 953   if (char_word_map_.empty())
 954     return;
 955   CharWordMapItem* map_item = cache->mutable_char_word_map();
 956   map_item->set_item_count(char_word_map_.size());
 957   for (CharWordIDMap::const_iterator iter = char_word_map_.begin();
 958        iter != char_word_map_.end(); ++iter) {
 959     CharWordMapEntry* map_entry = map_item->add_char_word_map_entry();
 960     map_entry->set_char_16(iter->first);
 961     const WordIDSet& word_id_set(iter->second);
 962     map_entry->set_item_count(word_id_set.size());
 963     for (WordIDSet::const_iterator set_iter = word_id_set.begin();
 964          set_iter != word_id_set.end(); ++set_iter)
 965       map_entry->add_word_id(*set_iter);
 966   }
 967 }
 968
 969 void URLIndexPrivateData::SaveWordIDHistoryMap(
 970     InMemoryURLIndexCacheItem* cache) const {
 971   if (word_id_history_map_.empty())
 972     return;
 973   WordIDHistoryMapItem* map_item = cache->mutable_word_id_history_map();
 974   map_item->set_item_count(word_id_history_map_.size());
 975   for (WordIDHistoryMap::const_iterator iter = word_id_history_map_.begin();
 976        iter != word_id_history_map_.end(); ++iter) {
 977     WordIDHistoryMapEntry* map_entry =
 978         map_item->add_word_id_history_map_entry();
 979     map_entry->set_word_id(iter->first);
 980     const HistoryIDSet& history_id_set(iter->second);
 981     map_entry->set_item_count(history_id_set.size());
 982     for (HistoryIDSet::const_iterator set_iter = history_id_set.begin();
 983          set_iter != history_id_set.end(); ++set_iter)
 984       map_entry->add_history_id(*set_iter);
 985   }
 986 }
 987
 988 void URLIndexPrivateData::SaveHistoryInfoMap(
 989     InMemoryURLIndexCacheItem* cache) const {
 990   if (history_info_map_.empty())
 991     return;
 992   HistoryInfoMapItem* map_item = cache->mutable_history_info_map();
 993   map_item->set_item_count(history_info_map_.size());
 994   for (HistoryInfoMap::const_iterator iter = history_info_map_.begin();
 995        iter != history_info_map_.end(); ++iter) {
 996     HistoryInfoMapEntry* map_entry = map_item->add_history_info_map_entry();
 997     map_entry->set_history_id(iter->first);
 998     const URLRow& url_row(iter->second.url_row);
 999     // Note: We only save information that contributes to the index so there
1000     // is no need to save search_term_cache_ (not persistent).
1001     map_entry->set_visit_count(url_row.visit_count());
1002     map_entry->set_typed_count(url_row.typed_count());
1003     map_entry->set_last_visit(url_row.last_visit().ToInternalValue());
1004     map_entry->set_url(url_row.url().spec());
1005     map_entry->set_title(base::UTF16ToUTF8(url_row.title()));
1006     const VisitInfoVector& visits(iter->second.visits);
1007     for (VisitInfoVector::const_iterator visit_iter = visits.begin();
1008          visit_iter != visits.end(); ++visit_iter) {
1009       HistoryInfoMapEntry_VisitInfo* visit_info = map_entry->add_visits();
1010       visit_info->set_visit_time(visit_iter->first.ToInternalValue());
1011       visit_info->set_transition_type(visit_iter->second);
1012     }
1013   }
1014 }
1015
1016 void URLIndexPrivateData::SaveWordStartsMap(
1017     InMemoryURLIndexCacheItem* cache) const {
1018   if (word_starts_map_.empty())
1019     return;
1020   // For unit testing: Enable saving of the cache as an earlier version to
1021   // allow testing of cache file upgrading in ReadFromFile().
1022   // TODO(mrossetti): Instead of intruding on production code with this kind of
1023   // test harness, save a copy of an older version cache with known results.
1024   // Implement this when switching the caching over to SQLite.
1025   if (saved_cache_version_ < 1)
1026     return;
1027
1028   WordStartsMapItem* map_item = cache->mutable_word_starts_map();
1029   map_item->set_item_count(word_starts_map_.size());
1030   for (WordStartsMap::const_iterator iter = word_starts_map_.begin();
1031        iter != word_starts_map_.end(); ++iter) {
1032     WordStartsMapEntry* map_entry = map_item->add_word_starts_map_entry();
1033     map_entry->set_history_id(iter->first);
1034     const RowWordStarts& word_starts(iter->second);
1035     for (WordStarts::const_iterator i = word_starts.url_word_starts_.begin();
1036          i != word_starts.url_word_starts_.end(); ++i)
1037       map_entry->add_url_word_starts(*i);
1038     for (WordStarts::const_iterator i = word_starts.title_word_starts_.begin();
1039          i != word_starts.title_word_starts_.end(); ++i)
1040       map_entry->add_title_word_starts(*i);
1041   }
1042 }
1043
1044 bool URLIndexPrivateData::RestorePrivateData(
1045     const InMemoryURLIndexCacheItem& cache,
1046     const std::string& languages) {
1047   last_time_rebuilt_from_history_ =
1048       base::Time::FromInternalValue(cache.last_rebuild_timestamp());
1049   const base::TimeDelta rebuilt_ago =
1050       base::Time::Now() - last_time_rebuilt_from_history_;
1051   if ((rebuilt_ago > base::TimeDelta::FromDays(7)) ||
1052       (rebuilt_ago < base::TimeDelta::FromDays(-1))) {
1053     // Cache is more than a week old or, somehow, from some time in the future.
1054     // It's probably a good time to rebuild the index from history to
1055     // allow synced entries to now appear, expired entries to disappear, etc.
1056     // Allow one day in the future to make the cache not rebuild on simple
1057     // system clock changes such as time zone changes.
1058     return false;
1059   }
1060   if (cache.has_version()) {
1061     if (cache.version() < kCurrentCacheFileVersion) {
1062       // Don't try to restore an old format cache file.  (This will cause
1063       // the InMemoryURLIndex to schedule rebuilding the URLIndexPrivateData
1064       // from history.)
1065       return false;
1066     }
1067     restored_cache_version_ = cache.version();
1068   }
1069   return RestoreWordList(cache) && RestoreWordMap(cache) &&
1070       RestoreCharWordMap(cache) && RestoreWordIDHistoryMap(cache) &&
1071       RestoreHistoryInfoMap(cache) && RestoreWordStartsMap(cache, languages);
1072 }
1073
1074 bool URLIndexPrivateData::RestoreWordList(
1075     const InMemoryURLIndexCacheItem& cache) {
1076   if (!cache.has_word_list())
1077     return false;
1078   const WordListItem& list_item(cache.word_list());
1079   uint32 expected_item_count = list_item.word_count();
1080   uint32 actual_item_count = list_item.word_size();
1081   if (actual_item_count == 0 || actual_item_count != expected_item_count)
1082     return false;
1083   const RepeatedPtrField<std::string>& words(list_item.word());
1084   for (RepeatedPtrField<std::string>::const_iterator iter = words.begin();
1085        iter != words.end(); ++iter)
1086     word_list_.push_back(base::UTF8ToUTF16(*iter));
1087   return true;
1088 }
1089
1090 bool URLIndexPrivateData::RestoreWordMap(
1091     const InMemoryURLIndexCacheItem& cache) {
1092   if (!cache.has_word_map())
1093     return false;
1094   const WordMapItem& list_item(cache.word_map());
1095   uint32 expected_item_count = list_item.item_count();
1096   uint32 actual_item_count = list_item.word_map_entry_size();
1097   if (actual_item_count == 0 || actual_item_count != expected_item_count)
1098     return false;
1099   const RepeatedPtrField<WordMapEntry>& entries(list_item.word_map_entry());
1100   for (RepeatedPtrField<WordMapEntry>::const_iterator iter = entries.begin();
1101        iter != entries.end(); ++iter)
1102     word_map_[base::UTF8ToUTF16(iter->word())] = iter->word_id();
1103   return true;
1104 }
1105
1106 bool URLIndexPrivateData::RestoreCharWordMap(
1107     const InMemoryURLIndexCacheItem& cache) {
1108   if (!cache.has_char_word_map())
1109     return false;
1110   const CharWordMapItem& list_item(cache.char_word_map());
1111   uint32 expected_item_count = list_item.item_count();
1112   uint32 actual_item_count = list_item.char_word_map_entry_size();
1113   if (actual_item_count == 0 || actual_item_count != expected_item_count)
1114     return false;
1115   const RepeatedPtrField<CharWordMapEntry>&
1116       entries(list_item.char_word_map_entry());
1117   for (RepeatedPtrField<CharWordMapEntry>::const_iterator iter =
1118        entries.begin(); iter != entries.end(); ++iter) {
1119     expected_item_count = iter->item_count();
1120     actual_item_count = iter->word_id_size();
1121     if (actual_item_count == 0 || actual_item_count != expected_item_count)
1122       return false;
1123     base::char16 uni_char = static_cast<base::char16>(iter->char_16());
1124     WordIDSet word_id_set;
1125     const RepeatedField<int32>& word_ids(iter->word_id());
1126     for (RepeatedField<int32>::const_iterator jiter = word_ids.begin();
1127          jiter != word_ids.end(); ++jiter)
1128       word_id_set.insert(*jiter);
1129     char_word_map_[uni_char] = word_id_set;
1130   }
1131   return true;
1132 }
1133
1134 bool URLIndexPrivateData::RestoreWordIDHistoryMap(
1135     const InMemoryURLIndexCacheItem& cache) {
1136   if (!cache.has_word_id_history_map())
1137     return false;
1138   const WordIDHistoryMapItem& list_item(cache.word_id_history_map());
1139   uint32 expected_item_count = list_item.item_count();
1140   uint32 actual_item_count = list_item.word_id_history_map_entry_size();
1141   if (actual_item_count == 0 || actual_item_count != expected_item_count)
1142     return false;
1143   const RepeatedPtrField<WordIDHistoryMapEntry>&
1144       entries(list_item.word_id_history_map_entry());
1145   for (RepeatedPtrField<WordIDHistoryMapEntry>::const_iterator iter =
1146        entries.begin(); iter != entries.end(); ++iter) {
1147     expected_item_count = iter->item_count();
1148     actual_item_count = iter->history_id_size();
1149     if (actual_item_count == 0 || actual_item_count != expected_item_count)
1150       return false;
1151     WordID word_id = iter->word_id();
1152     HistoryIDSet history_id_set;
1153     const RepeatedField<int64>& history_ids(iter->history_id());
1154     for (RepeatedField<int64>::const_iterator jiter = history_ids.begin();
1155          jiter != history_ids.end(); ++jiter) {
1156       history_id_set.insert(*jiter);
1157       AddToHistoryIDWordMap(*jiter, word_id);
1158     }
1159     word_id_history_map_[word_id] = history_id_set;
1160   }
1161   return true;
1162 }
1163
1164 bool URLIndexPrivateData::RestoreHistoryInfoMap(
1165     const InMemoryURLIndexCacheItem& cache) {
1166   if (!cache.has_history_info_map())
1167     return false;
1168   const HistoryInfoMapItem& list_item(cache.history_info_map());
1169   uint32 expected_item_count = list_item.item_count();
1170   uint32 actual_item_count = list_item.history_info_map_entry_size();
1171   if (actual_item_count == 0 || actual_item_count != expected_item_count)
1172     return false;
1173   const RepeatedPtrField<HistoryInfoMapEntry>&
1174       entries(list_item.history_info_map_entry());
1175   for (RepeatedPtrField<HistoryInfoMapEntry>::const_iterator iter =
1176        entries.begin(); iter != entries.end(); ++iter) {
1177     HistoryID history_id = iter->history_id();
1178     GURL url(iter->url());
1179     URLRow url_row(url, history_id);
1180     url_row.set_visit_count(iter->visit_count());
1181     url_row.set_typed_count(iter->typed_count());
1182     url_row.set_last_visit(base::Time::FromInternalValue(iter->last_visit()));
1183     if (iter->has_title()) {
1184       base::string16 title(base::UTF8ToUTF16(iter->title()));
1185       url_row.set_title(title);
1186     }
1187     history_info_map_[history_id].url_row = url_row;
1188
1189     // Restore visits list.
1190     VisitInfoVector visits;
1191     visits.reserve(iter->visits_size());
1192     for (int i = 0; i < iter->visits_size(); ++i) {
1193       visits.push_back(std::make_pair(
1194           base::Time::FromInternalValue(iter->visits(i).visit_time()),
1195           static_cast<content::PageTransition>(iter->visits(i).
1196                                                transition_type())));
1197     }
1198     history_info_map_[history_id].visits = visits;
1199   }
1200   return true;
1201 }
1202
1203 bool URLIndexPrivateData::RestoreWordStartsMap(
1204     const InMemoryURLIndexCacheItem& cache,
1205     const std::string& languages) {
1206   // Note that this function must be called after RestoreHistoryInfoMap() has
1207   // been run as the word starts may have to be recalculated from the urls and
1208   // page titles.
1209   if (cache.has_word_starts_map()) {
1210     const WordStartsMapItem& list_item(cache.word_starts_map());
1211     uint32 expected_item_count = list_item.item_count();
1212     uint32 actual_item_count = list_item.word_starts_map_entry_size();
1213     if (actual_item_count == 0 || actual_item_count != expected_item_count)
1214       return false;
1215     const RepeatedPtrField<WordStartsMapEntry>&
1216         entries(list_item.word_starts_map_entry());
1217     for (RepeatedPtrField<WordStartsMapEntry>::const_iterator iter =
1218          entries.begin(); iter != entries.end(); ++iter) {
1219       HistoryID history_id = iter->history_id();
1220       RowWordStarts word_starts;
1221       // Restore the URL word starts.
1222       const RepeatedField<int32>& url_starts(iter->url_word_starts());
1223       for (RepeatedField<int32>::const_iterator jiter = url_starts.begin();
1224            jiter != url_starts.end(); ++jiter)
1225         word_starts.url_word_starts_.push_back(*jiter);
1226       // Restore the page title word starts.
1227       const RepeatedField<int32>& title_starts(iter->title_word_starts());
1228       for (RepeatedField<int32>::const_iterator jiter = title_starts.begin();
1229            jiter != title_starts.end(); ++jiter)
1230         word_starts.title_word_starts_.push_back(*jiter);
1231       word_starts_map_[history_id] = word_starts;
1232     }
1233   } else {
1234     // Since the cache did not contain any word starts we must rebuild then from
1235     // the URL and page titles.
1236     for (HistoryInfoMap::const_iterator iter = history_info_map_.begin();
1237          iter != history_info_map_.end(); ++iter) {
1238       RowWordStarts word_starts;
1239       const URLRow& row(iter->second.url_row);
1240       const base::string16& url = CleanUpUrlForMatching(row.url(), languages);
1241       String16VectorFromString16(url, false, &word_starts.url_word_starts_);
1242       const base::string16& title = CleanUpTitleForMatching(row.title());
1243       String16VectorFromString16(title, false, &word_starts.title_word_starts_);
1244       word_starts_map_[iter->first] = word_starts;
1245     }
1246   }
1247   return true;
1248 }
1249
1250 // static
1251 bool URLIndexPrivateData::URLSchemeIsWhitelisted(
1252     const GURL& gurl,
1253     const std::set<std::string>& whitelist) {
1254   return whitelist.find(gurl.scheme()) != whitelist.end();
1255 }
1256
1257
1258 // SearchTermCacheItem ---------------------------------------------------------
1259
1260 URLIndexPrivateData::SearchTermCacheItem::SearchTermCacheItem(
1261     const WordIDSet& word_id_set,
1262     const HistoryIDSet& history_id_set)
1263     : word_id_set_(word_id_set),
1264       history_id_set_(history_id_set),
1265       used_(true) {}
1266
1267 URLIndexPrivateData::SearchTermCacheItem::SearchTermCacheItem()
1268     : used_(true) {}
1269
1270 URLIndexPrivateData::SearchTermCacheItem::~SearchTermCacheItem() {}
1271
1272
1273 // URLIndexPrivateData::AddHistoryMatch ----------------------------------------
1274
1275 URLIndexPrivateData::AddHistoryMatch::AddHistoryMatch(
1276     const URLIndexPrivateData& private_data,
1277     const std::string& languages,
1278     BookmarkService* bookmark_service,
1279     const base::string16& lower_string,
1280     const String16Vector& lower_terms,
1281     const base::Time now)
1282   : private_data_(private_data),
1283     languages_(languages),
1284     bookmark_service_(bookmark_service),
1285     lower_string_(lower_string),
1286     lower_terms_(lower_terms),
1287     now_(now) {}
1288
1289 URLIndexPrivateData::AddHistoryMatch::~AddHistoryMatch() {}
1290
1291 void URLIndexPrivateData::AddHistoryMatch::operator()(
1292     const HistoryID history_id) {
1293   HistoryInfoMap::const_iterator hist_pos =
1294       private_data_.history_info_map_.find(history_id);
1295   if (hist_pos != private_data_.history_info_map_.end()) {
1296     const URLRow& hist_item = hist_pos->second.url_row;
1297     const VisitInfoVector& visits = hist_pos->second.visits;
1298     WordStartsMap::const_iterator starts_pos =
1299         private_data_.word_starts_map_.find(history_id);
1300     DCHECK(starts_pos != private_data_.word_starts_map_.end());
1301     ScoredHistoryMatch match(hist_item, visits, languages_, lower_string_,
1302                              lower_terms_, starts_pos->second, now_,
1303                              bookmark_service_);
1304     if (match.raw_score() > 0)
1305       scored_matches_.push_back(match);
1306   }
1307 }
1308
1309
1310 // URLIndexPrivateData::HistoryItemFactorGreater -------------------------------
1311
1312 URLIndexPrivateData::HistoryItemFactorGreater::HistoryItemFactorGreater(
1313     const HistoryInfoMap& history_info_map)
1314     : history_info_map_(history_info_map) {
1315 }
1316
1317 URLIndexPrivateData::HistoryItemFactorGreater::~HistoryItemFactorGreater() {}
1318
1319 bool URLIndexPrivateData::HistoryItemFactorGreater::operator()(
1320     const HistoryID h1,
1321     const HistoryID h2) {
1322   HistoryInfoMap::const_iterator entry1(history_info_map_.find(h1));
1323   if (entry1 == history_info_map_.end())
1324     return false;
1325   HistoryInfoMap::const_iterator entry2(history_info_map_.find(h2));
1326   if (entry2 == history_info_map_.end())
1327     return true;
1328   const URLRow& r1(entry1->second.url_row);
1329   const URLRow& r2(entry2->second.url_row);
1330   // First cut: typed count, visit count, recency.
1331   // TODO(mrossetti): This is too simplistic. Consider an approach which ranks
1332   // recently visited (within the last 12/24 hours) as highly important. Get
1333   // input from mpearson.
1334   if (r1.typed_count() != r2.typed_count())
1335     return (r1.typed_count() > r2.typed_count());
1336   if (r1.visit_count() != r2.visit_count())
1337     return (r1.visit_count() > r2.visit_count());
1338   return (r1.last_visit() > r2.last_visit());
1339 }
1340
1341 }  // namespace history