Adding upstream version 110.0.1.upstream/110.0.1upstream

Signed-off-by: Daniel Baumann <daniel.baumann@progress-linux.org>

1 files changed, 979 insertions, 0 deletions

diff --git a/toolkit/components/places/PlacesExpiration.sys.mjs b/toolkit/components/places/PlacesExpiration.sys.mjs
new file mode 100644
index 0000000000..e9f8238d80
--- /dev/null
+++ b/toolkit/components/places/PlacesExpiration.sys.mjs
@@ -0,0 +1,979 @@
+/* -*- indent-tabs-mode: nil; js-indent-level: 2 -*-
+ * vim: sw=2 ts=2 sts=2 expandtab
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+/**
+ * This component handles history and orphans expiration.
+ * Expiration runs:
+ * - At idle, but just once, we stop any other kind of expiration during idle
+ *   to preserve batteries in portable devices.
+ * - At shutdown, only if the database is dirty, we should still avoid to
+ *   expire too heavily on shutdown.
+ * - On a repeating timer we expire in small chunks.
+ *
+ * Expiration algorithm will adapt itself based on:
+ * - Memory size of the device.
+ * - Status of the database (clean or dirty).
+ */
+
+import { XPCOMUtils } from "resource://gre/modules/XPCOMUtils.sys.mjs";
+
+const lazy = {};
+
+ChromeUtils.defineESModuleGetters(lazy, {
+  PlacesUtils: "resource://gre/modules/PlacesUtils.sys.mjs",
+});
+
+// Last expiration step should run before the final sync.
+const TOPIC_DEBUG_START_EXPIRATION = "places-debug-start-expiration";
+const TOPIC_IDLE_BEGIN = "idle";
+const TOPIC_IDLE_END = "active";
+const TOPIC_IDLE_DAILY = "idle-daily";
+const TOPIC_TESTING_MODE = "testing-mode";
+const TOPIC_TEST_INTERVAL_CHANGED = "test-interval-changed";
+
+// This value determines which systems we consider to have limited memory.
+// This is used to protect against large database sizes on those systems.
+const DATABASE_MEMORY_CONSTRAINED_THRESHOLD = 2147483648; // 2 GiB
+
+// This value determines which systems we consider to have limited disk space.
+// This is used to protect against large database sizes on those systems.
+const DATABASE_DISK_CONSTRAINED_THRESHOLD = 5368709120; // 5 GiB
+
+// Maximum size of the optimal database.  High-end hardware has plenty of
+// memory and disk space, but performances don't grow linearly.
+const DATABASE_MAX_SIZE = 78643200; // 75 MiB
+// If the physical memory size is bogus, fallback to this.
+const MEMSIZE_FALLBACK_BYTES = 268435456; // 256 MiB
+// If the disk available space is bogus, fallback to this.
+const DISKSIZE_FALLBACK_BYTES = 268435456; // 256 MiB
+
+// Max number of entries to expire at each expiration step.
+// This value is globally used for different kind of data we expire, can be
+// tweaked based on data type.  See below in getQuery.
+const EXPIRE_LIMIT_PER_STEP = 6;
+// When we run a large expiration step, the above limit is multiplied by this.
+const EXPIRE_LIMIT_PER_LARGE_STEP_MULTIPLIER = 10;
+
+// When history is clean or dirty enough we will adapt the expiration algorithm
+// to be more lazy or more aggressive.
+// This is done acting on the interval between expiration steps and the number
+// of expirable items.
+// 1. Clean history:
+//   We expire at (default interval * EXPIRE_AGGRESSIVITY_MULTIPLIER) the
+//   default number of entries.
+// 2. Dirty history:
+//   We expire at the default interval, but a greater number of entries
+//   (default number of entries * EXPIRE_AGGRESSIVITY_MULTIPLIER).
+const EXPIRE_AGGRESSIVITY_MULTIPLIER = 3;
+
+// This is the average size in bytes of an URI entry in the database.
+// Magic numbers are determined through analysis of the distribution of a ratio
+// between number of unique URIs and database size among our users.
+// Used as a fall back value when it's not possible to calculate the real value.
+const URIENTRY_AVG_SIZE = 700;
+
+// Seconds of idle time before starting a larger expiration step.
+// Notice during idle we stop the expiration timer since we don't want to hurt
+// stand-by or mobile devices batteries.
+const IDLE_TIMEOUT_SECONDS = 5 * 60;
+
+// If the number of pages over history limit is greater than this threshold,
+// expiration will be more aggressive, to bring back history to a saner size.
+const OVERLIMIT_PAGES_THRESHOLD = 1000;
+
+// Milliseconds in a day.
+const MSECS_PER_DAY = 86400000;
+
+// When we expire we can use these limits:
+// - SMALL for usual partial expirations, will expire a small chunk.
+// - LARGE for idle or shutdown expirations, will expire a large chunk.
+// - UNLIMITED will expire all the orphans.
+// - DEBUG will use a known limit, passed along with the debug notification.
+const LIMIT = {
+  SMALL: 0,
+  LARGE: 1,
+  UNLIMITED: 2,
+  DEBUG: 3,
+};
+
+// Represents the status of history database.
+const STATUS = {
+  CLEAN: 0,
+  DIRTY: 1,
+  UNKNOWN: 2,
+};
+
+// Represents actions on which a query will run.
+const ACTION = {
+  TIMED: 1 << 0, // happens every this.intervalSeconds
+  TIMED_OVERLIMIT: 1 << 1, // like TIMED but only when history is over limits
+  SHUTDOWN_DIRTY: 1 << 2, // happens at shutdown for DIRTY state
+  IDLE_DIRTY: 1 << 3, // happens on idle for DIRTY state
+  IDLE_DAILY: 1 << 4, // happens once a day on idle
+  DEBUG: 1 << 5, // happens on TOPIC_DEBUG_START_EXPIRATION
+};
+
+// The queries we use to expire.
+const EXPIRATION_QUERIES = {
+  // Some visits can be expired more often than others, cause they are less
+  // useful to the user and can pollute awesomebar results:
+  // 1. visits to urls over 255 chars
+  // 2. downloads
+  // We never expire redirect targets, because they are currently necessary to
+  // recognize redirect sources (see Bug 468710 for better options).
+  // Note: due to the REPLACE option, this should be executed before
+  // QUERY_FIND_VISITS_TO_EXPIRE, that has a more complete result.
+  QUERY_FIND_EXOTIC_VISITS_TO_EXPIRE: {
+    sql: `INSERT INTO expiration_notify (v_id, url, guid, visit_date, reason)
+          SELECT v.id, h.url, h.guid, v.visit_date, "exotic"
+          FROM moz_historyvisits v
+          JOIN moz_places h ON h.id = v.place_id
+          WHERE visit_date < strftime('%s','now','localtime','start of day','-60 days','utc') * 1000000
+          AND visit_type NOT IN (5,6)
+          AND ( LENGTH(h.url) > 255 OR v.visit_type = 7 )
+          ORDER BY v.visit_date ASC
+          LIMIT :limit_visits`,
+    actions:
+      ACTION.TIMED_OVERLIMIT |
+      ACTION.IDLE_DIRTY |
+      ACTION.IDLE_DAILY |
+      ACTION.DEBUG,
+  },
+
+  // Finds visits to be expired when history is over the unique pages limit,
+  // otherwise will return nothing.
+  // This explicitly excludes any visits added in the last 7 days, to protect
+  // users with thousands of bookmarks from constantly losing history.
+  QUERY_FIND_VISITS_TO_EXPIRE: {
+    sql: `INSERT INTO expiration_notify
+            (v_id, url, guid, visit_date, expected_results)
+          SELECT v.id, h.url, h.guid, v.visit_date, :limit_visits
+          FROM moz_historyvisits v
+          JOIN moz_places h ON h.id = v.place_id
+          WHERE (SELECT COUNT(*) FROM moz_places) > :max_uris
+          AND visit_date < strftime('%s','now','localtime','start of day','-7 days','utc') * 1000000
+          ORDER BY v.visit_date ASC
+          LIMIT :limit_visits`,
+    actions:
+      ACTION.TIMED_OVERLIMIT |
+      ACTION.IDLE_DIRTY |
+      ACTION.IDLE_DAILY |
+      ACTION.DEBUG,
+  },
+
+  // Removes the previously found visits.
+  QUERY_EXPIRE_VISITS: {
+    sql: `DELETE FROM moz_historyvisits WHERE id IN (
+            SELECT v_id FROM expiration_notify WHERE v_id NOTNULL
+          )`,
+    actions:
+      ACTION.TIMED_OVERLIMIT |
+      ACTION.IDLE_DIRTY |
+      ACTION.IDLE_DAILY |
+      ACTION.DEBUG,
+  },
+
+  // Finds orphan URIs in the database.
+  // Notice we won't notify single removed URIs on History.clear(), so we don't
+  // run this query in such a case, but just delete URIs.
+  // This could run in the middle of adding a visit or bookmark to a new page.
+  // In such a case since it is async, could end up expiring the orphan page
+  // before it actually gets the new visit or bookmark.
+  // Thus, since new pages get frecency -1, we filter on that.
+  QUERY_FIND_URIS_TO_EXPIRE: {
+    sql: `INSERT INTO expiration_notify (p_id, url, guid, visit_date)
+          SELECT h.id, h.url, h.guid, h.last_visit_date
+          FROM moz_places h
+          LEFT JOIN moz_historyvisits v ON h.id = v.place_id
+          WHERE h.last_visit_date IS NULL
+            AND h.foreign_count = 0
+            AND v.id IS NULL
+            AND frecency <> -1
+          LIMIT :limit_uris`,
+    actions:
+      ACTION.TIMED |
+      ACTION.TIMED_OVERLIMIT |
+      ACTION.SHUTDOWN_DIRTY |
+      ACTION.IDLE_DIRTY |
+      ACTION.IDLE_DAILY |
+      ACTION.DEBUG,
+  },
+
+  // Expire found URIs from the database.
+  QUERY_EXPIRE_URIS: {
+    sql: `DELETE FROM moz_places WHERE id IN (
+            SELECT p_id FROM expiration_notify WHERE p_id NOTNULL
+          ) AND foreign_count = 0 AND last_visit_date ISNULL`,
+    actions:
+      ACTION.TIMED |
+      ACTION.TIMED_OVERLIMIT |
+      ACTION.SHUTDOWN_DIRTY |
+      ACTION.IDLE_DIRTY |
+      ACTION.IDLE_DAILY |
+      ACTION.DEBUG,
+  },
+
+  // Hosts accumulated during the places delete are updated through a trigger
+  // (see nsPlacesTriggers.h).
+  QUERY_UPDATE_HOSTS: {
+    sql: `DELETE FROM moz_updateoriginsdelete_temp`,
+    actions:
+      ACTION.TIMED |
+      ACTION.TIMED_OVERLIMIT |
+      ACTION.SHUTDOWN_DIRTY |
+      ACTION.IDLE_DIRTY |
+      ACTION.IDLE_DAILY |
+      ACTION.DEBUG,
+  },
+
+  // Expire old favicons for:
+  //  - urls that permanently redirect.
+  //  - urls with ref, when the origin has a root favicon that can be used as
+  //    a fallback.
+  // This deletes pages instead of icons, because icons may be referenced by
+  // multiple pages. The moz_pages_to_icons entries are removed by the table's
+  // FOREIGN KEY, while orphan icons are removed by one of the next queries.
+  QUERY_EXPIRE_OLD_FAVICONS: {
+    sql: `DELETE FROM moz_pages_w_icons WHERE id IN (
+            SELECT DISTINCT page_id FROM moz_icons i
+            JOIN moz_icons_to_pages ON icon_id = i.id
+            JOIN moz_pages_w_icons p ON page_id = p.id
+            JOIN moz_places h ON h.url_hash = page_url_hash
+            JOIN moz_origins o ON o.id = h.origin_id
+            WHERE root = 0
+              AND h.foreign_count = 0
+              AND i.expire_ms BETWEEN 1 AND strftime('%s','now','localtime','start of day','-180 days','utc') * 1000
+              AND (
+              h.id IN (
+                SELECT v.place_id
+                FROM moz_historyvisits v
+                JOIN moz_historyvisits v_dest on v_dest.from_visit = v.id
+                WHERE v_dest.visit_type = 5
+              )
+              OR (
+                INSTR(page_url, '#') >= 0
+                AND EXISTS(SELECT id FROM moz_icons WHERE root = 1 AND fixed_icon_url_hash = hash(fixup_url(o.host) || '/favicon.ico'))
+              )
+            )
+            LIMIT 100
+          )`,
+    actions:
+      ACTION.SHUTDOWN_DIRTY |
+      ACTION.IDLE_DIRTY |
+      ACTION.IDLE_DAILY |
+      ACTION.DEBUG,
+  },
+
+  // Expire orphan pages from the icons database.
+  QUERY_EXPIRE_FAVICONS_PAGES: {
+    sql: `DELETE FROM moz_pages_w_icons
+          WHERE page_url_hash NOT IN (
+            SELECT url_hash FROM moz_places
+          ) OR NOT EXISTS (
+            SELECT 1 FROM moz_icons_to_pages WHERE page_id = moz_pages_w_icons.id
+          )`,
+    actions:
+      ACTION.TIMED_OVERLIMIT |
+      ACTION.SHUTDOWN_DIRTY |
+      ACTION.IDLE_DIRTY |
+      ACTION.IDLE_DAILY |
+      ACTION.DEBUG,
+  },
+
+  // Expire orphan icons from the database.
+  QUERY_EXPIRE_FAVICONS: {
+    sql: `DELETE FROM moz_icons WHERE id IN (
+            SELECT id FROM moz_icons WHERE root = 0
+            EXCEPT
+            SELECT icon_id FROM moz_icons_to_pages
+          )`,
+    actions:
+      ACTION.TIMED_OVERLIMIT |
+      ACTION.SHUTDOWN_DIRTY |
+      ACTION.IDLE_DIRTY |
+      ACTION.IDLE_DAILY |
+      ACTION.DEBUG,
+  },
+
+  // Expire orphan page annotations from the database.
+  QUERY_EXPIRE_ANNOS: {
+    sql: `DELETE FROM moz_annos WHERE id in (
+            SELECT a.id FROM moz_annos a
+            LEFT JOIN moz_places h ON a.place_id = h.id
+            WHERE h.id IS NULL
+            LIMIT :limit_annos
+          )`,
+    actions:
+      ACTION.TIMED |
+      ACTION.TIMED_OVERLIMIT |
+      ACTION.SHUTDOWN_DIRTY |
+      ACTION.IDLE_DIRTY |
+      ACTION.IDLE_DAILY |
+      ACTION.DEBUG,
+  },
+
+  // Expire item annos without a corresponding item id.
+  QUERY_EXPIRE_ITEMS_ANNOS: {
+    sql: `DELETE FROM moz_items_annos WHERE id IN (
+            SELECT a.id FROM moz_items_annos a
+            LEFT JOIN moz_bookmarks b ON a.item_id = b.id
+            WHERE b.id IS NULL
+            LIMIT :limit_annos
+          )`,
+    actions: ACTION.IDLE_DAILY | ACTION.DEBUG,
+  },
+
+  // Expire all annotation names without a corresponding annotation.
+  QUERY_EXPIRE_ANNO_ATTRIBUTES: {
+    sql: `DELETE FROM moz_anno_attributes WHERE id IN (
+            SELECT n.id FROM moz_anno_attributes n
+            LEFT JOIN moz_annos a ON n.id = a.anno_attribute_id
+            LEFT JOIN moz_items_annos t ON n.id = t.anno_attribute_id
+            WHERE a.anno_attribute_id IS NULL
+              AND t.anno_attribute_id IS NULL
+            LIMIT :limit_annos
+          )`,
+    actions:
+      ACTION.SHUTDOWN_DIRTY |
+      ACTION.IDLE_DIRTY |
+      ACTION.IDLE_DAILY |
+      ACTION.DEBUG,
+  },
+
+  // Expire orphan inputhistory.
+  QUERY_EXPIRE_INPUTHISTORY: {
+    sql: `DELETE FROM moz_inputhistory
+          WHERE place_id IN (SELECT p_id FROM expiration_notify)
+          AND place_id IN (
+            SELECT i.place_id FROM moz_inputhistory i
+            LEFT JOIN moz_places h ON h.id = i.place_id
+            WHERE h.id IS NULL
+            LIMIT :limit_inputhistory
+          )`,
+    actions:
+      ACTION.TIMED |
+      ACTION.TIMED_OVERLIMIT |
+      ACTION.SHUTDOWN_DIRTY |
+      ACTION.IDLE_DIRTY |
+      ACTION.IDLE_DAILY |
+      ACTION.DEBUG,
+  },
+
+  // Select entries for notifications.
+  // If p_id is set whole_entry = 1, then we have expired the full page.
+  // Either p_id or v_id are always set.
+  QUERY_SELECT_NOTIFICATIONS: {
+    sql: `/* do not warn (bug no): temp table has no index */
+          SELECT url, guid, MAX(visit_date) AS visit_date,
+                 MAX(IFNULL(MIN(p_id, 1), MIN(v_id, 0))) AS whole_entry,
+                 MAX(expected_results) AS expected_results,
+                 (SELECT MAX(visit_date) FROM expiration_notify
+                  WHERE reason = "expired" AND url = n.url AND p_id ISNULL
+                 ) AS most_recent_expired_visit
+          FROM expiration_notify n
+          GROUP BY url`,
+    actions:
+      ACTION.TIMED |
+      ACTION.TIMED_OVERLIMIT |
+      ACTION.SHUTDOWN_DIRTY |
+      ACTION.IDLE_DIRTY |
+      ACTION.IDLE_DAILY |
+      ACTION.DEBUG,
+  },
+
+  // Empty the notifications table.
+  QUERY_DELETE_NOTIFICATIONS: {
+    sql: "DELETE FROM expiration_notify",
+    actions:
+      ACTION.TIMED |
+      ACTION.TIMED_OVERLIMIT |
+      ACTION.SHUTDOWN_DIRTY |
+      ACTION.IDLE_DIRTY |
+      ACTION.IDLE_DAILY |
+      ACTION.DEBUG,
+  },
+
+  // Expire interactions older than N days.
+  QUERY_EXPIRE_INTERACTIONS: {
+    sql: `DELETE FROM moz_places_metadata
+          WHERE id IN (
+            SELECT id FROM moz_places_metadata
+            WHERE updated_at < strftime('%s','now','localtime','-' || :days_interactions || ' day','start of day','utc') * 1000
+            ORDER BY updated_at ASC
+            LIMIT :limit_interactions
+          )`,
+    get disabled() {
+      return !Services.prefs.getBoolPref(
+        "browser.places.interactions.enabled",
+        false
+      );
+    },
+    actions:
+      ACTION.SHUTDOWN_DIRTY |
+      ACTION.IDLE_DIRTY |
+      ACTION.IDLE_DAILY |
+      ACTION.DEBUG,
+  },
+};
+
+export function nsPlacesExpiration() {
+  // Allows other components to easily access getPagesLimit.
+  this.wrappedJSObject = this;
+
+  XPCOMUtils.defineLazyServiceGetter(
+    this,
+    "_idle",
+    "@mozilla.org/widget/useridleservice;1",
+    "nsIUserIdleService"
+  );
+
+  // Max number of unique URIs to retain in history.
+  // Notice this is a lazy limit.  This means we will start to expire if we will
+  // go over it, but we won't ensure that we will stop exactly when we reach it,
+  // instead we will stop after the next expiration step that will bring us
+  // below it.
+  // If this preference does not exist or has a negative value, we will
+  // calculate a limit based on current hardware.
+  XPCOMUtils.defineLazyPreferenceGetter(
+    this,
+    "maxPages",
+    "places.history.expiration.max_pages",
+    -1,
+    () => {
+      // Clear the cache.
+      dump("max_pages changing\n");
+      this._pagesLimit = null;
+    }
+  );
+
+  // Seconds between each expiration step.
+  XPCOMUtils.defineLazyPreferenceGetter(
+    this,
+    "intervalSeconds",
+    "places.history.expiration.interval_seconds",
+    3 * 60, // 3 minutes
+    () => {
+      // Renew the timer with the new interval value.
+      this._newTimer();
+    },
+    v => (v > 0 ? v : 3 * 60) // Accept only positive values.
+  );
+
+  this._dbInitializedPromise = lazy.PlacesUtils.withConnectionWrapper(
+    "PlacesExpiration.jsm: setup",
+    async db => {
+      await db.execute(
+        `CREATE TEMP TABLE expiration_notify (
+          id INTEGER PRIMARY KEY,
+          v_id INTEGER,
+          p_id INTEGER,
+          url TEXT NOT NULL,
+          guid TEXT NOT NULL,
+          visit_date INTEGER,
+          expected_results INTEGER NOT NULL DEFAULT 0,
+          reason TEXT NOT NULL DEFAULT "expired"
+        )`
+      );
+    }
+  )
+    .then(() => {
+      // Start the expiration timer.
+      this._newTimer();
+      // Expire daily on idle.
+      Services.obs.addObserver(this, TOPIC_IDLE_DAILY, true);
+    })
+    .catch(Cu.reportError);
+
+  // Block shutdown.
+  let shutdownClient =
+    lazy.PlacesUtils.history.connectionShutdownClient.jsclient;
+  shutdownClient.addBlocker("Places Expiration: shutdown", () => {
+    if (this._shuttingDown) {
+      return;
+    }
+    this._shuttingDown = true;
+    this.expireOnIdle = false;
+    if (this._timer) {
+      this._timer.cancel();
+      this._timer = null;
+    }
+    // If the database is dirty, we want to expire some entries, to speed up
+    // the expiration process.
+    if (this.status == STATUS.DIRTY) {
+      this._expire(ACTION.SHUTDOWN_DIRTY, LIMIT.LARGE).catch(Cu.reportError);
+    }
+  });
+}
+
+nsPlacesExpiration.prototype = {
+  observe(aSubject, aTopic, aData) {
+    if (this._shuttingDown) {
+      return;
+    }
+
+    if (aTopic == TOPIC_DEBUG_START_EXPIRATION) {
+      // The passed-in limit is the maximum number of visits to expire when
+      // history is over capacity.  Mind to correctly handle the NaN value.
+      let limit = parseInt(aData);
+      if (limit == -1) {
+        // Everything should be expired without any limit.  If history is over
+        // capacity then all existing visits will be expired.
+        // Should only be used in tests, since may cause dataloss.
+        this._expire(ACTION.DEBUG, LIMIT.UNLIMITED).catch(Cu.reportError);
+      } else if (limit > 0) {
+        // The number of expired visits is limited by this amount.  It may be
+        // used for testing purposes, like checking that limited queries work.
+        this._debugLimit = limit;
+        this._expire(ACTION.DEBUG, LIMIT.DEBUG).catch(Cu.reportError);
+      } else {
+        // Any other value is intended as a 0 limit, that means no visits
+        // will be expired.  Even if this doesn't touch visits, it will remove
+        // any orphan pages, icons, annotations and similar from the database,
+        // so it may be used for cleanup purposes.
+        this._debugLimit = -1;
+        this._expire(ACTION.DEBUG, LIMIT.DEBUG).catch(Cu.reportError);
+      }
+    } else if (aTopic == TOPIC_IDLE_BEGIN) {
+      // Stop the expiration timer.  We don't want to keep up expiring on idle
+      // to preserve batteries on mobile devices and avoid killing stand-by.
+      if (this._timer) {
+        this._timer.cancel();
+        this._timer = null;
+      }
+      if (this.expireOnIdle) {
+        this._expire(ACTION.IDLE_DIRTY, LIMIT.LARGE).catch(Cu.reportError);
+      }
+    } else if (aTopic == TOPIC_IDLE_END) {
+      // Restart the expiration timer.
+      if (!this._timer) {
+        this._newTimer();
+      }
+    } else if (aTopic == TOPIC_IDLE_DAILY) {
+      this._expire(ACTION.IDLE_DAILY, LIMIT.LARGE).catch(Cu.reportError);
+    } else if (aTopic == TOPIC_TESTING_MODE) {
+      this._testingMode = true;
+    } else if (aTopic == lazy.PlacesUtils.TOPIC_INIT_COMPLETE) {
+      const placesObserver = new PlacesWeakCallbackWrapper(
+        // History status is clean after a clear history.
+        () => {
+          this.status = STATUS.CLEAN;
+        }
+      );
+      PlacesObservers.addListener(["history-cleared"], placesObserver);
+    }
+  },
+
+  // nsITimerCallback
+
+  notify() {
+    // Run at the first idle, or after 5 minutes, whatever comes first.
+    Services.tm.idleDispatchToMainThread(async () => {
+      let db = await lazy.PlacesUtils.promiseDBConnection();
+      let pagesCount = (
+        await db.executeCached("SELECT count(*) AS count FROM moz_places")
+      )[0].getResultByName("count");
+      let pagesLimit = await this.getPagesLimit();
+      // Check if we are over history capacity, if so visits must be expired.
+      let overLimitPages = pagesCount - pagesLimit;
+      let action = overLimitPages > 0 ? ACTION.TIMED_OVERLIMIT : ACTION.TIMED;
+      // Adapt expiration aggressivity to the number of pages over the limit.
+      let limit =
+        overLimitPages > OVERLIMIT_PAGES_THRESHOLD ? LIMIT.LARGE : LIMIT.SMALL;
+      this._expire(action, limit).catch(Cu.reportError);
+    }, 300000);
+  },
+
+  _onQueryResult(row) {
+    // We don't want to notify after shutdown.
+    if (this._shuttingDown) {
+      return;
+    }
+
+    // expected_results is set to the number of expected visits by
+    // QUERY_FIND_VISITS_TO_EXPIRE.  We decrease that counter for each found
+    // visit and if it reaches zero we mark the database as dirty, since all
+    // the expected visits were expired, so it's likely the next run will
+    // find more.
+    let expectedResults = row.getResultByName("expected_results");
+    if (expectedResults > 0) {
+      if (!("_expectedResultsCount" in this)) {
+        this._expectedResultsCount = expectedResults;
+      }
+      if (this._expectedResultsCount > 0) {
+        this._expectedResultsCount--;
+      }
+    }
+
+    let uri = Services.io.newURI(row.getResultByName("url"));
+    let guid = row.getResultByName("guid");
+    let visitDate = row.getResultByName("visit_date");
+    let wholeEntry = row.getResultByName("whole_entry");
+    let mostRecentExpiredVisit = row.getResultByName(
+      "most_recent_expired_visit"
+    );
+
+    if (mostRecentExpiredVisit) {
+      let days = parseInt(
+        (Date.now() - mostRecentExpiredVisit / 1000) / MSECS_PER_DAY
+      );
+      if (!this._mostRecentExpiredVisitDays) {
+        this._mostRecentExpiredVisitDays = days;
+      } else if (days < this._mostRecentExpiredVisitDays) {
+        this._mostRecentExpiredVisitDays = days;
+      }
+    }
+
+    // Dispatch expiration notifications to history.
+    const isRemovedFromStore = !!wholeEntry;
+    PlacesObservers.notifyListeners([
+      new PlacesVisitRemoved({
+        url: uri.spec,
+        pageGuid: guid,
+        reason: PlacesVisitRemoved.REASON_EXPIRED,
+        isRemovedFromStore,
+        isPartialVisistsRemoval: !isRemovedFromStore && visitDate > 0,
+      }),
+    ]);
+  },
+
+  _shuttingDown: false,
+
+  _status: STATUS.UNKNOWN,
+  set status(aNewStatus) {
+    if (aNewStatus != this._status) {
+      // If status changes we should restart the timer.
+      this._status = aNewStatus;
+      this._newTimer();
+      // If needed add/remove the cleanup step on idle.  We want to expire on
+      // idle only if history is dirty, to preserve mobile devices batteries.
+      this.expireOnIdle = aNewStatus == STATUS.DIRTY;
+    }
+  },
+  get status() {
+    return this._status;
+  },
+
+  async getPagesLimit() {
+    if (this._pagesLimit != null) {
+      return this._pagesLimit;
+    }
+    if (this.maxPages >= 0) {
+      return (this._pagesLimit = this.maxPages);
+    }
+
+    // The user didn't specify a custom limit, so we calculate the number of
+    // unique places that may fit an optimal database size on this hardware.
+    // Oldest pages over this threshold will be expired.
+    let memSizeBytes = MEMSIZE_FALLBACK_BYTES;
+    try {
+      // Limit the size on systems with small memory.
+      memSizeBytes = Services.sysinfo.getProperty("memsize");
+    } catch (ex) {}
+    if (memSizeBytes <= 0) {
+      memSizeBytes = MEMSIZE_FALLBACK_BYTES;
+    }
+
+    let diskAvailableBytes = DISKSIZE_FALLBACK_BYTES;
+    try {
+      // Protect against a full disk or tiny quota.
+      diskAvailableBytes = lazy.PlacesUtils.history.DBConnection.databaseFile.QueryInterface(
+        Ci.nsIFile
+      ).diskSpaceAvailable;
+    } catch (ex) {}
+    if (diskAvailableBytes <= 0) {
+      diskAvailableBytes = DISKSIZE_FALLBACK_BYTES;
+    }
+
+    const isMemoryConstrained =
+      memSizeBytes < DATABASE_MEMORY_CONSTRAINED_THRESHOLD;
+    const isDiskConstrained =
+      diskAvailableBytes < DATABASE_DISK_CONSTRAINED_THRESHOLD;
+
+    let optimalDatabaseSize = DATABASE_MAX_SIZE;
+    if (isMemoryConstrained || isDiskConstrained) {
+      // This size is used to protect against a large database size
+      // on disks with limited space or on systems with small memory
+      optimalDatabaseSize /= 2;
+    }
+
+    // Calculate avg size of a URI in the database.
+    let db;
+    try {
+      db = await lazy.PlacesUtils.promiseDBConnection();
+      if (db) {
+        let row = (
+          await db.execute(`SELECT * FROM pragma_page_size(),
+                                              pragma_page_count(),
+                                              pragma_freelist_count(),
+                                              (SELECT count(*) FROM moz_places)`)
+        )[0];
+        let pageSize = row.getResultByIndex(0);
+        let pageCount = row.getResultByIndex(1);
+        let freelistCount = row.getResultByIndex(2);
+        let uriCount = row.getResultByIndex(3);
+        let dbSize = (pageCount - freelistCount) * pageSize;
+        let avgURISize = Math.ceil(dbSize / uriCount);
+        // For new profiles this value may be too large, due to the Sqlite header,
+        // or Infinity when there are no pages.  Thus we must limit it.
+        if (avgURISize > URIENTRY_AVG_SIZE * 3) {
+          avgURISize = URIENTRY_AVG_SIZE;
+        }
+        return (this._pagesLimit = Math.ceil(optimalDatabaseSize / avgURISize));
+      }
+    } catch (ex) {
+      // We may have been initialized late in the shutdown process, maybe
+      // by a call to clear history on shutdown.
+      // If we're unable to get a connection clone, we'll just proceed with a
+      // large default value, it should not be critical at this point in the
+      // application life-cycle.
+    }
+    return (this._pagesLimit = 100000);
+  },
+
+  _isIdleObserver: false,
+  _expireOnIdle: false,
+  set expireOnIdle(aExpireOnIdle) {
+    // Observe idle regardless aExpireOnIdle, since we always want to stop
+    // timed expiration on idle, to preserve mobile battery life.
+    if (!this._isIdleObserver && !this._shuttingDown) {
+      this._idle.addIdleObserver(this, IDLE_TIMEOUT_SECONDS);
+      this._isIdleObserver = true;
+    } else if (this._isIdleObserver && this._shuttingDown) {
+      this._idle.removeIdleObserver(this, IDLE_TIMEOUT_SECONDS);
+      this._isIdleObserver = false;
+    }
+
+    // If running a debug expiration we need full control of what happens
+    // but idle cleanup could activate in the middle, since tinderboxes are
+    // permanently idle.  That would cause unexpected oranges, so disable it.
+    if (this._debugLimit !== undefined) {
+      this._expireOnIdle = false;
+    } else {
+      this._expireOnIdle = aExpireOnIdle;
+    }
+  },
+  get expireOnIdle() {
+    return this._expireOnIdle;
+  },
+
+  // Number of expiration steps needed to reach a CLEAN status.
+  _telemetrySteps: 1,
+
+  /**
+   * Expires visits and orphans.
+   *
+   * @param aAction
+   *        The ACTION we are expiring for.  See the ACTION const for values.
+   * @param aLimit
+   *        Whether to use small, large or no limits when expiring.  See the
+   *        LIMIT const for values.
+   */
+  async _expire(aAction, aLimit) {
+    // Don't try to further expire after shutdown.
+    if (this._shuttingDown && aAction != ACTION.SHUTDOWN_DIRTY) {
+      return;
+    }
+    await this._dbInitializedPromise;
+
+    try {
+      await lazy.PlacesUtils.withConnectionWrapper(
+        "PlacesExpiration.jsm: expire",
+        async db => {
+          await db.executeTransaction(async () => {
+            for (let queryType in EXPIRATION_QUERIES) {
+              let query = EXPIRATION_QUERIES[queryType];
+              if (query.actions & aAction && !query.disabled) {
+                let params = await this._getQueryParams(
+                  queryType,
+                  aLimit,
+                  aAction
+                );
+                await db.executeCached(
+                  query.sql,
+                  params,
+                  this._onQueryResult.bind(this)
+                );
+              }
+            }
+          });
+        }
+      );
+    } catch (ex) {
+      console.error(ex);
+      return;
+    }
+
+    if (this._mostRecentExpiredVisitDays) {
+      try {
+        Services.telemetry
+          .getHistogramById("PLACES_MOST_RECENT_EXPIRED_VISIT_DAYS")
+          .add(this._mostRecentExpiredVisitDays);
+      } catch (ex) {
+        console.error("Unable to report telemetry.");
+      } finally {
+        delete this._mostRecentExpiredVisitDays;
+      }
+    }
+
+    if ("_expectedResultsCount" in this) {
+      // Adapt the aggressivity of steps based on the status of history.
+      // A dirty history will return all the entries we are expecting bringing
+      // our countdown to zero, while a clean one will not.
+      let oldStatus = this.status;
+      this.status =
+        this._expectedResultsCount == 0 ? STATUS.DIRTY : STATUS.CLEAN;
+
+      // Collect or send telemetry data.
+      if (this.status == STATUS.DIRTY) {
+        this._telemetrySteps++;
+      } else {
+        // Avoid reporting the common cases where the database is clean, or
+        // a single step is needed.
+        if (oldStatus == STATUS.DIRTY) {
+          try {
+            Services.telemetry
+              .getHistogramById("PLACES_EXPIRATION_STEPS_TO_CLEAN2")
+              .add(this._telemetrySteps);
+          } catch (ex) {
+            console.error("Unable to report telemetry.");
+          }
+        }
+        this._telemetrySteps = 1;
+      }
+
+      delete this._expectedResultsCount;
+    }
+
+    // Dispatch a notification that expiration has finished.
+    Services.obs.notifyObservers(
+      null,
+      lazy.PlacesUtils.TOPIC_EXPIRATION_FINISHED
+    );
+  },
+
+  /**
+   * Generate a query used for expiration.
+   *
+   * @param aQueryType
+   *        Type of the query.
+   * @param aLimit
+   *        Whether to use small, large or no limits when expiring.  See the
+   *        LIMIT const for values.
+   * @param aAction
+   *        Current action causing the expiration.  See the ACTION const.
+   */
+  async _getQueryParams(aQueryType, aLimit, aAction) {
+    let baseLimit;
+    switch (aLimit) {
+      case LIMIT.UNLIMITED:
+        baseLimit = -1;
+        break;
+      case LIMIT.SMALL:
+        baseLimit = EXPIRE_LIMIT_PER_STEP;
+        break;
+      case LIMIT.LARGE:
+        baseLimit =
+          EXPIRE_LIMIT_PER_STEP * EXPIRE_LIMIT_PER_LARGE_STEP_MULTIPLIER;
+        break;
+      case LIMIT.DEBUG:
+        baseLimit = this._debugLimit;
+        break;
+    }
+    if (
+      this.status == STATUS.DIRTY &&
+      aAction != ACTION.DEBUG &&
+      baseLimit > 0
+    ) {
+      baseLimit *= EXPIRE_AGGRESSIVITY_MULTIPLIER;
+    }
+
+    switch (aQueryType) {
+      case "QUERY_FIND_EXOTIC_VISITS_TO_EXPIRE":
+        return {
+          // Avoid expiring all visits in case of an unlimited debug expiration,
+          // just remove orphans instead.
+          limit_visits:
+            aLimit == LIMIT.DEBUG && baseLimit == -1 ? 0 : baseLimit,
+        };
+      case "QUERY_FIND_VISITS_TO_EXPIRE":
+        return {
+          max_uris: await this.getPagesLimit(),
+          // Avoid expiring all visits in case of an unlimited debug expiration,
+          // just remove orphans instead.
+          limit_visits:
+            aLimit == LIMIT.DEBUG && baseLimit == -1 ? 0 : baseLimit,
+        };
+      case "QUERY_FIND_URIS_TO_EXPIRE":
+        return {
+          limit_uris: baseLimit,
+        };
+      case "QUERY_EXPIRE_ANNOS":
+        return {
+          // Each page may have multiple annos.
+          limit_annos: baseLimit * EXPIRE_AGGRESSIVITY_MULTIPLIER,
+        };
+      case "QUERY_EXPIRE_ITEMS_ANNOS":
+        return {
+          limit_annos: baseLimit,
+        };
+      case "QUERY_EXPIRE_ANNO_ATTRIBUTES":
+        return {
+          limit_annos: baseLimit,
+        };
+      case "QUERY_EXPIRE_INPUTHISTORY":
+        return {
+          limit_inputhistory: baseLimit,
+        };
+      case "QUERY_EXPIRE_INTERACTIONS":
+        return {
+          days_interactions: Services.prefs.getIntPref(
+            "browser.places.interactions.expireDays",
+            60
+          ),
+          limit_interactions:
+            aLimit == LIMIT.DEBUG && baseLimit == -1 ? 0 : baseLimit,
+        };
+    }
+    return undefined;
+  },
+
+  /**
+   * Creates a new timer based on this.intervalSeconds.
+   *
+   * @return a REPEATING_SLACK nsITimer that runs every this.intervalSeconds.
+   */
+  _newTimer() {
+    if (this._timer) {
+      this._timer.cancel();
+    }
+    if (this._shuttingDown) {
+      return undefined;
+    }
+    let interval =
+      this.status != STATUS.DIRTY
+        ? this.intervalSeconds * EXPIRE_AGGRESSIVITY_MULTIPLIER
+        : this.intervalSeconds;
+
+    let timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
+    timer.initWithCallback(
+      this,
+      interval * 1000,
+      Ci.nsITimer.TYPE_REPEATING_SLACK_LOW_PRIORITY
+    );
+    if (this._testingMode) {
+      Services.obs.notifyObservers(null, TOPIC_TEST_INTERVAL_CHANGED, interval);
+    }
+    return (this._timer = timer);
+  },
+
+  classID: Components.ID("705a423f-2f69-42f3-b9fe-1517e0dee56f"),
+
+  QueryInterface: ChromeUtils.generateQI([
+    "nsIObserver",
+    "nsITimerCallback",
+    "nsISupportsWeakReference",
+  ]),
+};