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 339 matching lines @@
 require.scopes["io"] = (function()
 {
   var exports = {};
   var keyPrefix = "file:";
 
   function fileToKey(file)
   {
     return keyPrefix + (file instanceof FakeFile ? file.path : file.spec);
   }
 
-  function loadFile(file)
-  {
-    return new Promise(function(resolve, reject)
-    {
-      var key = fileToKey(file);
-      ext.storage.get([key], function(items)
-      {
-        var entry = items[key];
-        if (entry)
-        {
-          resolve(entry);
-        }
-        else
-        {
-          try
-          {
-            entry = localforage.getItem(key, function(err, value) 

[kzar, 2016/10/05 12:14:17]

Since apparently `localforage.getItem` returns a promise if called without the
callback parameter couldn't we simplify this code? We could return the Promise
it gave us (after checking the `err` and `value`, resolving with only `value`)
instead of creating a new one from scratch.

[Oleksandr, 2016/10/05 13:32:40]

I am not 100% sure I follow your suggestion, but we still need to check the
ext.storage first to be able to migrate the current users to IndexedDB. So we
still need to create a promise from scratch at least for that.  

[kzar, 2016/10/05 13:46:53]

I mean for you do to something like this (untested):

function loadFile(file)
{
  var key = fileToKey(file);
  return localforage.getItem(key).then(value => value || Promise.reject(new
Error("File doesn't exist")));
}

[Oleksandr, 2016/10/05 21:07:40]

That won't work because like I said above we also need to call ext.storage.get
first. Isn't that right?

[Sebastian Noack, 2016/10/05 21:27:31]

Why do we have to call ext.storage.get() first? I don't think we have to.

[Oleksandr, 2016/10/05 21:49:12]

Current ABP for Edge users have their subscriptions stored using ext.storage. It
wouldn't be great to just reset their settings. We want to gently migrate those
to IndexedDB, no?

[Sebastian Noack, 2016/10/05 21:53:30]

Do they? Don't we use localStorage here in the version that is out for a while?

But you are right, we have to migrate those data from localStorage.

[Oleksandr, 2016/10/05 22:57:35]

Ah, you're right. Version 0.9.6, which is the current public build in Windows
Store does use localStorage. Switched to checking localStorage first and made
loadFile async again.

-            {
-              if (err || !value)
-              {

[kzar, 2016/10/05 12:14:17]

Nit: No need for braces around if... else... clauses here.

-                reject(new Error("File doesn't exist"));                
-              }
-              else
-              {
-                resolve(value);
-              }
-            });
-          }
-          catch (err)
-          {}
-        }
-      });
-    }.bind(this));
-  }
+  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 (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 entry = {};
     var key = fileToKey(file);
-    entry[key] = {

[kzar, 2016/10/05 12:14:17]

Since this review is for changes to adblockplusedgems can't we remove `entry`
and simplify some of this logic?

+    var entry = {
       lastModified: Date.now(),
       content: data
     };
 
-    if (typeof browser == "undefined")
-    {
-      ext.storage.set(entry, callback);
-      callback();

[kzar, 2016/10/05 12:14:17]

Could you explain this change? How come ext.storage.set isn't calling the
callback? Also it looks kind of weird here since couldn't the callback be called
both here and by ext.storage.set?

[Oleksandr, 2016/10/05 13:32:40]

Yeah, that was a bug.

-    }
-    else
-    {
-      // Use IndexedDB to store data

[kzar, 2016/10/05 12:14:17]

This comment seems kind of pointless.

-      ext.storage.remove(key);
-      localforage.setItem(key, entry[key], callback);
-    }
+    localStorage.removeItem(key);
+    localforage.setItem(key, entry, callback);
   }
   exports.IO = {
     resolveFilePath: function(path)
     {
       return new FakeFile(path);
     },
     readFromFile: function(file, listener, callback)
     {
       function onLoaded(entry)
       {
         if ("content" in entry)
         {
           for (var _loopIndex15 = 0; _loopIndex15 < entry.content.length; ++_loopIndex15)
           {
             var line = entry.content[_loopIndex15];
             listener.process(line);
           }
         }
         callback(null);
       }
-      loadFile(file).then(onLoaded, callback);
+      loadFile(file, onLoaded, callback);
     },
     writeToFile: function(file, data, callback)
     {
       saveFile(file, data, callback);
     },
     copyFile: function(fromFile, toFile, callback)
     {
       function onLoaded(entry)
       {
         saveFile(toFile, entry.content, callback);
       }
-      loadFile(file).then(onLoaded, callback);
+      loadFile(file, onLoaded, callback);
     },
     renameFile: function(fromFile, newName, callback)
     {
       function onLoaded()
       {
         ext.storage.remove(fileToKey(fromFile), function()
         {
           ext.storage.set(keyPrefix + newName, entry, callback);
         });
       }
-      loadFile(file).then(onLoaded, callback);
+      loadFile(file, onLoaded, callback);
     },
     removeFile: function(file, callback)
     {
       ext.storage.remove(fileToKey(file), callback);
     },
     statFile: function(file, callback)
     {
       function onLoaded(entry)
       {
         callback(null,
         {
           exists: true,
           lastModified: entry.lastModified
         });
       }
-      loadFile(file).then(onLoaded, callback);
+      loadFile(file, onLoaded, callback);
     }
   };
   return exports;
 })();
 require.scopes["downloader"] = (function()
 {
   var exports = {};
   var Utils = require("utils").Utils;
   var MILLIS_IN_SECOND = exports.MILLIS_IN_SECOND = 1000;
   var MILLIS_IN_MINUTE = exports.MILLIS_IN_MINUTE = 60 * MILLIS_IN_SECOND;
@@ skipping 6088 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;
 })();