Componentize expire_history_backend.{cc,h}

chrome/browser/history/expire_history_backend.cc

Index: chrome/browser/history/expire_history_backend.cc
diff --git a/chrome/browser/history/expire_history_backend.cc b/chrome/browser/history/expire_history_backend.cc
deleted file mode 100644
index 1e33dd185c035f35008b03b201e10159563ed542..0000000000000000000000000000000000000000
--- a/chrome/browser/history/expire_history_backend.cc
+++ /dev/null
@@ -1,515 +0,0 @@
-// Copyright (c) 2012 The Chromium Authors. All rights reserved.
-// Use of this source code is governed by a BSD-style license that can be
-// found in the LICENSE file.
-
-#include "chrome/browser/history/expire_history_backend.h"
-
-#include <algorithm>
-#include <functional>
-#include <limits>
-
-#include "base/bind.h"
-#include "base/compiler_specific.h"
-#include "base/files/file_enumerator.h"
-#include "base/files/file_util.h"
-#include "base/logging.h"
-#include "base/message_loop/message_loop.h"
-#include "components/history/core/browser/history_backend_notifier.h"
-#include "components/history/core/browser/history_client.h"
-#include "components/history/core/browser/history_database.h"
-#include "components/history/core/browser/thumbnail_database.h"
-
-namespace history {
-
-// Helpers --------------------------------------------------------------------
-
-namespace {
-
-// The number of days by which the expiration threshold is advanced for items
-// that we want to expire early, such as those of AUTO_SUBFRAME transition type.
-//
-// Early expiration stuff is kept around only for edge cases, as subframes
-// don't appear in history and the vast majority of them are ads anyway. The
-// main use case for these is if you're on a site with links to different
-// frames, you'll be able to see those links as visited, and we'll also be
-// able to get redirect information for those URLs.
-//
-// But since these uses are most valuable when you're actually on the site,
-// and because these can take up the bulk of your history, we get a lot of
-// space savings by deleting them quickly.
-const int kEarlyExpirationAdvanceDays = 3;
-
-// Reads all types of visits starting from beginning of time to the given end
-// time. This is the most general reader.
-class AllVisitsReader : public ExpiringVisitsReader {
- public:
-  bool Read(base::Time end_time,
-            HistoryDatabase* db,
-            VisitVector* visits,
-            int max_visits) const override {
-    DCHECK(db) << "must have a database to operate upon";
-    DCHECK(visits) << "visit vector has to exist in order to populate it";
-
-    db->GetAllVisitsInRange(base::Time(), end_time, max_visits, visits);
-    // When we got the maximum number of visits we asked for, we say there could
-    // be additional things to expire now.
-    return static_cast<int>(visits->size()) == max_visits;
-  }
-};
-
-// Reads only AUTO_SUBFRAME visits, within a computed range. The range is
-// computed as follows:
-// * |begin_time| is read from the meta table. This value is updated whenever
-//   there are no more additional visits to expire by this reader.
-// * |end_time| is advanced forward by a constant (kEarlyExpirationAdvanceDay),
-//   but not past the current time.
-class AutoSubframeVisitsReader : public ExpiringVisitsReader {
- public:
-  bool Read(base::Time end_time,
-            HistoryDatabase* db,
-            VisitVector* visits,
-            int max_visits) const override {
-    DCHECK(db) << "must have a database to operate upon";
-    DCHECK(visits) << "visit vector has to exist in order to populate it";
-
-    base::Time begin_time = db->GetEarlyExpirationThreshold();
-    // Advance |end_time| to expire early.
-    base::Time early_end_time = end_time +
-        base::TimeDelta::FromDays(kEarlyExpirationAdvanceDays);
-
-    // We don't want to set the early expiration threshold to a time in the
-    // future.
-    base::Time now = base::Time::Now();
-    if (early_end_time > now)
-      early_end_time = now;
-
-    db->GetVisitsInRangeForTransition(begin_time, early_end_time,
-                                      max_visits,
-                                      ui::PAGE_TRANSITION_AUTO_SUBFRAME,
-                                      visits);
-    bool more = static_cast<int>(visits->size()) == max_visits;
-    if (!more)
-      db->UpdateEarlyExpirationThreshold(early_end_time);
-
-    return more;
-  }
-};
-
-// The number of visits we will expire very time we check for old items. This
-// Prevents us from doing too much work any given time.
-const int kNumExpirePerIteration = 32;
-
-// The number of seconds between checking for items that should be expired when
-// we think there might be more items to expire. This timeout is used when the
-// last expiration found at least kNumExpirePerIteration and we want to check
-// again "soon."
-const int kExpirationDelaySec = 30;
-
-// The number of minutes between checking, as with kExpirationDelaySec, but
-// when we didn't find enough things to expire last time. If there was no
-// history to expire last iteration, it's likely there is nothing next
-// iteration, so we want to wait longer before checking to avoid wasting CPU.
-const int kExpirationEmptyDelayMin = 5;
-
-}  // namespace
-
-
-// ExpireHistoryBackend::DeleteEffects ----------------------------------------
-
-ExpireHistoryBackend::DeleteEffects::DeleteEffects() {
-}
-
-ExpireHistoryBackend::DeleteEffects::~DeleteEffects() {
-}
-
-
-// ExpireHistoryBackend -------------------------------------------------------
-
-ExpireHistoryBackend::ExpireHistoryBackend(
-    HistoryBackendNotifier* notifier,
-    HistoryClient* history_client)
-    : notifier_(notifier),
-      main_db_(NULL),
-      thumb_db_(NULL),
-      history_client_(history_client),
-      weak_factory_(this) {
-  DCHECK(notifier_);
-}
-
-ExpireHistoryBackend::~ExpireHistoryBackend() {
-}
-
-void ExpireHistoryBackend::SetDatabases(HistoryDatabase* main_db,
-                                        ThumbnailDatabase* thumb_db) {
-  main_db_ = main_db;
-  thumb_db_ = thumb_db;
-}
-
-void ExpireHistoryBackend::DeleteURL(const GURL& url) {
-  DeleteURLs(std::vector<GURL>(1, url));
-}
-
-void ExpireHistoryBackend::DeleteURLs(const std::vector<GURL>& urls) {
-  if (!main_db_)
-    return;
-
-  DeleteEffects effects;
-  HistoryClient* history_client = GetHistoryClient();
-  for (std::vector<GURL>::const_iterator url = urls.begin(); url != urls.end();
-       ++url) {
-    URLRow url_row;
-    if (!main_db_->GetRowForURL(*url, &url_row))
-      continue;  // Nothing to delete.
-
-    // Collect all the visits and delete them. Note that we don't give up if
-    // there are no visits, since the URL could still have an entry that we
-    // should delete.
-    VisitVector visits;
-    main_db_->GetVisitsForURL(url_row.id(), &visits);
-
-    DeleteVisitRelatedInfo(visits, &effects);
-
-    // We skip ExpireURLsForVisits (since we are deleting from the
-    // URL, and not starting with visits in a given time range). We
-    // therefore need to call the deletion and favicon update
-    // functions manually.
-    DeleteOneURL(url_row,
-                 history_client && history_client->IsBookmarked(*url),
-                 &effects);
-  }
-
-  DeleteFaviconsIfPossible(&effects);
-
-  BroadcastNotifications(&effects, DELETION_USER_INITIATED);
-}
-
-void ExpireHistoryBackend::ExpireHistoryBetween(
-    const std::set<GURL>& restrict_urls,
-    base::Time begin_time,
-    base::Time end_time) {
-  if (!main_db_)
-    return;
-
-  // Find the affected visits and delete them.
-  VisitVector visits;
-  main_db_->GetAllVisitsInRange(begin_time, end_time, 0, &visits);
-  if (!restrict_urls.empty()) {
-    std::set<URLID> url_ids;
-    for (std::set<GURL>::const_iterator url = restrict_urls.begin();
-        url != restrict_urls.end(); ++url)
-      url_ids.insert(main_db_->GetRowForURL(*url, NULL));
-    VisitVector all_visits;
-    all_visits.swap(visits);
-    for (VisitVector::iterator visit = all_visits.begin();
-         visit != all_visits.end(); ++visit) {
-      if (url_ids.find(visit->url_id) != url_ids.end())
-        visits.push_back(*visit);
-    }
-  }
-  ExpireVisits(visits);
-}
-
-void ExpireHistoryBackend::ExpireHistoryForTimes(
-    const std::vector<base::Time>& times) {
-  // |times| must be in reverse chronological order and have no
-  // duplicates, i.e. each member must be earlier than the one before
-  // it.
-  DCHECK(
-      std::adjacent_find(
-          times.begin(), times.end(), std::less_equal<base::Time>()) ==
-      times.end());
-
-  if (!main_db_)
-    return;
-
-  // Find the affected visits and delete them.
-  VisitVector visits;
-  main_db_->GetVisitsForTimes(times, &visits);
-  ExpireVisits(visits);
-}
-
-void ExpireHistoryBackend::ExpireVisits(const VisitVector& visits) {
-  if (visits.empty())
-    return;
-
-  DeleteEffects effects;
-  DeleteVisitRelatedInfo(visits, &effects);
-
-  // Delete or update the URLs affected. We want to update the visit counts
-  // since this is called by the user who wants to delete their recent history,
-  // and we don't want to leave any evidence.
-  ExpireURLsForVisits(visits, &effects);
-  DeleteFaviconsIfPossible(&effects);
-  BroadcastNotifications(&effects, DELETION_USER_INITIATED);
-
-  // Pick up any bits possibly left over.
-  ParanoidExpireHistory();
-}
-
-void ExpireHistoryBackend::ExpireHistoryBefore(base::Time end_time) {
-  if (!main_db_)
-    return;
-
-  // Expire as much history as possible before the given date.
-  ExpireSomeOldHistory(end_time, GetAllVisitsReader(),
-                       std::numeric_limits<int>::max());
-  ParanoidExpireHistory();
-}
-
-void ExpireHistoryBackend::InitWorkQueue() {
-  DCHECK(work_queue_.empty()) << "queue has to be empty prior to init";
-
-  for (size_t i = 0; i < readers_.size(); i++)
-    work_queue_.push(readers_[i]);
-}
-
-const ExpiringVisitsReader* ExpireHistoryBackend::GetAllVisitsReader() {
-  if (!all_visits_reader_)
-    all_visits_reader_.reset(new AllVisitsReader());
-  return all_visits_reader_.get();
-}
-
-const ExpiringVisitsReader*
-    ExpireHistoryBackend::GetAutoSubframeVisitsReader() {
-  if (!auto_subframe_visits_reader_)
-    auto_subframe_visits_reader_.reset(new AutoSubframeVisitsReader());
-  return auto_subframe_visits_reader_.get();
-}
-
-void ExpireHistoryBackend::StartExpiringOldStuff(
-    base::TimeDelta expiration_threshold) {
-  expiration_threshold_ = expiration_threshold;
-
-  // Remove all readers, just in case this was method was called before.
-  readers_.clear();
-  // For now, we explicitly add all known readers. If we come up with more
-  // reader types (in case we want to expire different types of visits in
-  // different ways), we can make it be populated by creator/owner of
-  // ExpireHistoryBackend.
-  readers_.push_back(GetAllVisitsReader());
-  readers_.push_back(GetAutoSubframeVisitsReader());
-
-  // Initialize the queue with all tasks for the first set of iterations.
-  InitWorkQueue();
-  ScheduleExpire();
-}
-
-void ExpireHistoryBackend::DeleteFaviconsIfPossible(DeleteEffects* effects) {
-  if (!thumb_db_)
-    return;
-
-  for (std::set<favicon_base::FaviconID>::const_iterator i =
-           effects->affected_favicons.begin();
-       i != effects->affected_favicons.end(); ++i) {
-    if (!thumb_db_->HasMappingFor(*i)) {
-      GURL icon_url;
-      favicon_base::IconType icon_type;
-      if (thumb_db_->GetFaviconHeader(*i,
-                                      &icon_url,
-                                      &icon_type) &&
-          thumb_db_->DeleteFavicon(*i)) {
-        effects->deleted_favicons.insert(icon_url);
-      }
-    }
-  }
-}
-
-void ExpireHistoryBackend::BroadcastNotifications(DeleteEffects* effects,
-                                                  DeletionType type) {
-  if (!effects->modified_urls.empty()) {
-    notifier_->NotifyURLsModified(effects->modified_urls);
-  }
-  if (!effects->deleted_urls.empty()) {
-    notifier_->NotifyURLsDeleted(false,
-                                 type == DELETION_EXPIRED,
-                                 effects->deleted_urls,
-                                 effects->deleted_favicons);
-  }
-}
-
-void ExpireHistoryBackend::DeleteVisitRelatedInfo(const VisitVector& visits,
-                                                  DeleteEffects* effects) {
-  for (size_t i = 0; i < visits.size(); i++) {
-    // Delete the visit itself.
-    main_db_->DeleteVisit(visits[i]);
-
-    // Add the URL row to the affected URL list.
-    if (!effects->affected_urls.count(visits[i].url_id)) {
-      URLRow row;
-      if (main_db_->GetURLRow(visits[i].url_id, &row))
-        effects->affected_urls[visits[i].url_id] = row;
-    }
-  }
-}
-
-void ExpireHistoryBackend::DeleteOneURL(const URLRow& url_row,
-                                        bool is_bookmarked,
-                                        DeleteEffects* effects) {
-  main_db_->DeleteSegmentForURL(url_row.id());
-
-  if (!is_bookmarked) {
-    effects->deleted_urls.push_back(url_row);
-
-    // Delete stuff that references this URL.
-    if (thumb_db_) {
-      // Collect shared information.
-      std::vector<IconMapping> icon_mappings;
-      if (thumb_db_->GetIconMappingsForPageURL(url_row.url(), &icon_mappings)) {
-        for (std::vector<IconMapping>::iterator m = icon_mappings.begin();
-             m != icon_mappings.end(); ++m) {
-          effects->affected_favicons.insert(m->icon_id);
-        }
-        // Delete the mapping entries for the url.
-        thumb_db_->DeleteIconMappings(url_row.url());
-      }
-    }
-    // Last, delete the URL entry.
-    main_db_->DeleteURLRow(url_row.id());
-  }
-}
-
-namespace {
-
-struct ChangedURL {
-  ChangedURL() : visit_count(0), typed_count(0) {}
-  int visit_count;
-  int typed_count;
-};
-
-}  // namespace
-
-void ExpireHistoryBackend::ExpireURLsForVisits(const VisitVector& visits,
-                                               DeleteEffects* effects) {
-  // First find all unique URLs and the number of visits we're deleting for
-  // each one.
-  std::map<URLID, ChangedURL> changed_urls;
-  for (size_t i = 0; i < visits.size(); i++) {
-    ChangedURL& cur = changed_urls[visits[i].url_id];
-    // NOTE: This code must stay in sync with HistoryBackend::AddPageVisit().
-    // TODO(pkasting): http://b/1148304 We shouldn't be marking so many URLs as
-    // typed, which would help eliminate the need for this code (we still would
-    // need to handle RELOAD transitions specially, though).
-    ui::PageTransition transition =
-        ui::PageTransitionStripQualifier(visits[i].transition);
-    if (transition != ui::PAGE_TRANSITION_RELOAD)
-      cur.visit_count++;
-    if ((transition == ui::PAGE_TRANSITION_TYPED &&
-        !ui::PageTransitionIsRedirect(visits[i].transition)) ||
-        transition == ui::PAGE_TRANSITION_KEYWORD_GENERATED)
-      cur.typed_count++;
-  }
-
-  // Check each unique URL with deleted visits.
-  HistoryClient* history_client = GetHistoryClient();
-  for (std::map<URLID, ChangedURL>::const_iterator i = changed_urls.begin();
-       i != changed_urls.end(); ++i) {
-    // The unique URL rows should already be filled in.
-    URLRow& url_row = effects->affected_urls[i->first];
-    if (!url_row.id())
-      continue;  // URL row doesn't exist in the database.
-
-    // Check if there are any other visits for this URL and update the time
-    // (the time change may not actually be synced to disk below when we're
-    // archiving).
-    VisitRow last_visit;
-    if (main_db_->GetMostRecentVisitForURL(url_row.id(), &last_visit))
-      url_row.set_last_visit(last_visit.visit_time);
-    else
-      url_row.set_last_visit(base::Time());
-
-    // Don't delete URLs with visits still in the DB, or bookmarked.
-    bool is_bookmarked =
-        (history_client && history_client->IsBookmarked(url_row.url()));
-    if (!is_bookmarked && url_row.last_visit().is_null()) {
-      // Not bookmarked and no more visits. Nuke the url.
-      DeleteOneURL(url_row, is_bookmarked, effects);
-    } else {
-      // NOTE: The calls to std::max() below are a backstop, but they should
-      // never actually be needed unless the database is corrupt (I think).
-      url_row.set_visit_count(
-          std::max(0, url_row.visit_count() - i->second.visit_count));
-      url_row.set_typed_count(
-          std::max(0, url_row.typed_count() - i->second.typed_count));
-
-      // Update the db with the new details.
-      main_db_->UpdateURLRow(url_row.id(), url_row);
-
-      effects->modified_urls.push_back(url_row);
-    }
-  }
-}
-
-void ExpireHistoryBackend::ScheduleExpire() {
-  base::TimeDelta delay;
-  if (work_queue_.empty()) {
-    // If work queue is empty, reset the work queue to contain all tasks and
-    // schedule next iteration after a longer delay.
-    InitWorkQueue();
-    delay = base::TimeDelta::FromMinutes(kExpirationEmptyDelayMin);
-  } else {
-    delay = base::TimeDelta::FromSeconds(kExpirationDelaySec);
-  }
-
-  base::MessageLoop::current()->PostDelayedTask(
-      FROM_HERE,
-      base::Bind(&ExpireHistoryBackend::DoExpireIteration,
-                 weak_factory_.GetWeakPtr()),
-      delay);
-}
-
-void ExpireHistoryBackend::DoExpireIteration() {
-  DCHECK(!work_queue_.empty()) << "queue has to be non-empty";
-
-  const ExpiringVisitsReader* reader = work_queue_.front();
-  bool more_to_expire = ExpireSomeOldHistory(
-      GetCurrentExpirationTime(), reader, kNumExpirePerIteration);
-
-  work_queue_.pop();
-  // If there are more items to expire, add the reader back to the queue, thus
-  // creating a new task for future iterations.
-  if (more_to_expire)
-    work_queue_.push(reader);
-
-  ScheduleExpire();
-}
-
-bool ExpireHistoryBackend::ExpireSomeOldHistory(
-    base::Time end_time,
-    const ExpiringVisitsReader* reader,
-    int max_visits) {
-  if (!main_db_)
-    return false;
-
-  // Add an extra time unit to given end time, because
-  // GetAllVisitsInRange, et al. queries' end value is non-inclusive.
-  base::Time effective_end_time =
-      base::Time::FromInternalValue(end_time.ToInternalValue() + 1);
-
-  VisitVector deleted_visits;
-  bool more_to_expire = reader->Read(effective_end_time, main_db_,
-                                     &deleted_visits, max_visits);
-
-  DeleteEffects deleted_effects;
-  DeleteVisitRelatedInfo(deleted_visits, &deleted_effects);
-  ExpireURLsForVisits(deleted_visits, &deleted_effects);
-  DeleteFaviconsIfPossible(&deleted_effects);
-
-  BroadcastNotifications(&deleted_effects, DELETION_EXPIRED);
-
-  return more_to_expire;
-}
-
-void ExpireHistoryBackend::ParanoidExpireHistory() {
-  // TODO(brettw): Bug 1067331: write this to clean up any errors.
-}
-
-HistoryClient* ExpireHistoryBackend::GetHistoryClient() {
-  // We use the history client to determine if a URL is bookmarked. The data is
-  // loaded on a separate thread and may not be done by the time we get here.
-  // We therefore block until the bookmarks have finished loading.
-  if (history_client_)
-    history_client_->BlockUntilBookmarksLoaded();
-  return history_client_;
-}
-
-}  // namespace history