Issue 4023 - Use localforage (IndexedDB) instead of localStorage

lib/adblockplus.js

 /*
  * This file is part of Adblock Plus <https://adblockplus.org/>,
  * Copyright (C) 2006-2016 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 342 matching lines @@
   var keyPrefix = "file:";
 
   function fileToKey(file)
   {
     return keyPrefix + (file instanceof FakeFile ? file.path : file.spec);
   }
 
   function loadFile(file, successCallback, errorCallback)
   {
     var key = fileToKey(file);
+    // Make sure we do not have subscriptions in localStorage from older versions first
     var entry = localStorage.getItem(key);
-    if (entry)
-    {
-      successCallback(JSON.parse(entry));

[Sebastian Noack, 2016/10/06 12:07:36]

Don't we have to respond asynchronously here (i.e. wrap it by setTimeout)?

[Oleksandr, 2016/10/06 23:28:13]

Indeed, we should. Great catch! For reference, this is discussed here:
https://codereview.adblockplus.org/29348698/diff/29348738/lib/adblockplus.js#....
I wasn't able to test the full upgrade, but a synthetic test did show that this
has to return asynchronously.

[Sebastian Noack, 2016/10/06 23:38:35]

Yes, that is what I remember, and why I brought it up here.

-    }
-    else
-    {
-      entry = localforage.getItem(key, function(err, value) 

[Sebastian Noack, 2016/10/06 12:07:36]

It seems unnecessary to assign to "entry" here. It seems unused.

[Oleksandr, 2016/10/06 23:28:13]

Done.

-      {
-        if (err || !value)
-          errorCallback(new Error("File doesn't exist"));                
-        else
-          successCallback(value);
-      });
-    }
+    if (typeof entry == "string")
+    {
+      try
+      {
+        entry = JSON.parse(entry);
+      }
+      catch(err) 
+      {
+        setTimeout(errorCallback(new Error("File is corrupted")));
+        return;
+      }
+      setTimeout(successCallback(entry));
+      return;
+    }
+    // Now try to read from IndexedDB
+    localforage.getItem(key, function(err, value) 
+    {
+      if (err || !value)
+        errorCallback(new Error("File doesn't exist"));                
+      else
+        successCallback(value);
+    });
   }
 
   function saveFile(file, data, callback)
   {
     var key = fileToKey(file);
     var entry = {
       lastModified: Date.now(),
       content: data
     };
 
@@ skipping 6160 matching lines @@
     search.push("notificationDownloadCount=" + encodeURIComponent(downlCount));
     chrome.runtime.setUninstallURL(Utils.getDocLink("uninstalled") + "&" + search.join("&"));
   }
   if ("setUninstallURL" in chrome.runtime)
   {
     Prefs.untilLoaded.then(setUninstallURL);
     Prefs.on("notificationdata", setUninstallURL);
   }
   return exports;
 })();