Issue 6599 - Detect data corruption of storage.local

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 279 matching lines @@
 }
 
 let customSave = new Map();
 if (require("../buildtools/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;
+  let promise = null;
   customSave.set("blocked_total", pref =>
   {
-    if (!updateScheduled)
-    {
-      let callback = () =>
+    if (!promise)
+    {
+      promise = new Promise((resolve, reject) =>
       {
-        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();
+        setTimeout(
+          () =>
+          {
+            lastUpdate = performance.now();
+            promise = null;
+            savePref(pref).then(resolve, reject);
+          },
+          lastUpdate + MIN_UPDATE_INTERVAL - performance.now()
+        );
+      });
     }
-    return Promise.resolve();
+    return promise;
   });
 }
 
 function addPreference(pref)
 {
   Object.defineProperty(Prefs, pref, {
     get() { return (pref in overrides ? overrides : defaults)[pref]; },
     set(value)
     {
       Prefs.set(pref, value);
@@ skipping 53 matching lines @@
           eventEmitter.emit(pref);
         }
       }
     });
   }
 
   Prefs.untilLoaded = Promise.all([localLoaded, managedLoaded]).then(onLoaded);
 }
 
 init();