Issue 6050 - Use localStorage for blocked_total preference on Gecko

lib/prefs.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-present eyeo GmbH
  *
  * Adblock Plus is free software: you can redistribute it and/or modify
  * it under the terms of the GNU General Public License version 3 as
  * published by the Free Software Foundation.
  *
  * Adblock Plus is distributed in the hope that it will be useful,
  * but WITHOUT ANY WARRANTY; without even the implied warranty of
@@ skipping 241 matching lines @@
 }
 
 function savePref(pref)
 {
   ext.storage.set(prefToKey(pref), overrides[pref]);
 }
 
 let customSave = new Map();
 if (require("info").platform == "gecko")
 {
-  // Saving one storage value causes all others to be saved as well on Gecko.
-  // Make sure that updating ad counter doesn't cause the filters data to be
-  // saved frequently as a side-effect.
-  const MIN_UPDATE_INTERVAL = 60 * 1000;
-  let lastUpdate = -MIN_UPDATE_INTERVAL;
-  let updateScheduled = false;
+  // Saving one browser.storage value causes all others to be saved as well on
+  // Gecko. Until that is rectified[1] we need to avoid saving the ad counter
+  // using browser.storage too often, since the filters data is saved as a
+  // side-effect. We do this by using localStorage instead, only updating the
+  // value saved in browser.storage when the extension first initializes.
+  // Note: This workaround is sub-optimal since if the user clears browser data
+  // localStorage is cleared.
+  // [1] - https://bugzilla.mozilla.org/show_bug.cgi?id=1277612
   customSave.set("blocked_total", pref =>
   {
-    if (updateScheduled)
-      return;
-
-    let callback = () =>
-    {
-      lastUpdate = performance.now();
-      updateScheduled = false;
-      savePref(pref);
-    };
-
-    let timeElapsed = performance.now() - lastUpdate;
-    if (timeElapsed < MIN_UPDATE_INTERVAL)
-    {
-      setTimeout(callback, MIN_UPDATE_INTERVAL - timeElapsed);
-      updateScheduled = true;
-    }
-    else
-      callback();
+    window.localStorage.setItem("blocked_total", overrides.blocked_total);
   });
 }
 
 function addPreference(pref)
 {
   Object.defineProperty(Prefs, pref, {
     get() { return (pref in overrides ? overrides : defaults)[pref]; },
     set(value)
     {
       let defaultValue = defaults[pref];
@@ skipping 21 matching lines @@
   let prefs = Object.keys(defaults);
   prefs.forEach(addPreference);
 
   let localLoaded = new Promise(resolve =>
   {
     ext.storage.get(prefs.map(prefToKey), items =>
     {
       for (let key in items)
         overrides[keyToPref(key)] = items[key];
 
+      if (require("info").platform == "gecko")
+      {
+        let blockedTotal = window.localStorage.getItem("blocked_total");
+        if (typeof blockedTotal == "string")
+        {
+          blockedTotal = JSON.parse(blockedTotal);
+          if (blockedTotal > overrides.blocked_total)
+          {
+            overrides.blocked_total = blockedTotal;
+            savePref("blocked_total");
+          }
+        }
+      }
+
       resolve();
     });
   });
 
   let managedLoaded = new Promise(resolve =>
   {
     if (require("info").platform == "chromium" && "managed" in browser.storage)
     {
       browser.storage.managed.get(null, items =>
       {
@@ skipping 33 matching lines @@
           eventEmitter.emit(pref);
         }
       }
     });
   }
 
   Prefs.untilLoaded = Promise.all([localLoaded, managedLoaded]).then(onLoaded);
 }
 
 init();