Issue 4878 - Start using ESLint for adblockpluscore

lib/downloader.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
  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
  * GNU General Public License for more details.
  *
  * You should have received a copy of the GNU General Public License
  * along with Adblock Plus.  If not, see <http://www.gnu.org/licenses/>.
  */
 
+"use strict";
+
+/* globals XMLHttpRequest */

[Sebastian Noack, 2017/02/20 13:14:51]

I would rather put this in the .eslintrc.json. Generally, I'd like to avoid
inline boilerplate as much as possible. And if XMLHttpRequest is available here,
it is also available in most (for Chrome and WebExtensions even all) scripts.

[kzar, 2017/02/21 06:13:58]

Done.

+
 /**
  * @fileOverview Downloads a set of URLs in regular time intervals.
  */
 
 let {Utils} = require("utils");
 
 let MILLIS_IN_SECOND = exports.MILLIS_IN_SECOND = 1000;
 let MILLIS_IN_MINUTE = exports.MILLIS_IN_MINUTE = 60 * MILLIS_IN_SECOND;
 let MILLIS_IN_HOUR = exports.MILLIS_IN_HOUR = 60 * MILLIS_IN_MINUTE;
 let MILLIS_IN_DAY = exports.MILLIS_IN_DAY = 24 * MILLIS_IN_HOUR;
 
+let Downloader =
 /**
  * Creates a new downloader instance.
- * @param {Function} dataSource  Function that will yield downloadable objects on each check
- * @param {Integer} initialDelay  Number of milliseconds to wait before the first check
+ * @param {Function} dataSource  Function that will yield downloadable objects
+ *                               on each check
+ * @param {Integer} initialDelay  Number of milliseconds to wait before the
+ *                                 first check
  * @param {Integer} checkInterval  Interval between the checks
  * @constructor
  */
-let Downloader = exports.Downloader = function Downloader(dataSource, initialDelay, checkInterval)
+exports.Downloader = function(dataSource, initialDelay, checkInterval)
 {
   this.dataSource = dataSource;
   this._timer = Cc["@mozilla.org/timer;1"].createInstance(Ci.nsITimer);
-  this._timer.initWithCallback(function()
+  this._timer.initWithCallback(() =>
   {
     this._timer.delay = checkInterval;
     this._doCheck();
-  }.bind(this), initialDelay, Ci.nsITimer.TYPE_REPEATING_SLACK);
+  }, initialDelay, Ci.nsITimer.TYPE_REPEATING_SLACK);
   this._downloading = Object.create(null);
-}
+};
 Downloader.prototype =
 {
   /**
    * Timer triggering the downloads.
-   * @type nsITimer
+   * @type {nsITimer}
    */
   _timer: null,
 
   /**
    * Map containing the URLs of objects currently being downloaded as its keys.
    */
   _downloading: null,
 
   /**
    * Function that will yield downloadable objects on each check.
-   * @type Function
+   * @type {Function}
    */
   dataSource: null,
 
   /**
    * Maximal time interval that the checks can be left out until the soft
    * expiration interval increases.
-   * @type Integer
+   * @type {Integer}

[Sebastian Noack, 2017/02/20 13:14:51]

There is no type or class called "Integer". This should rather be "number".

[kzar, 2017/02/21 06:13:58]

Done.

    */
   maxAbsenceInterval: 1 * MILLIS_IN_DAY,
 
   /**
    * Minimal time interval before retrying a download after an error.
-   * @type Integer
+   * @type {Integer}
    */
   minRetryInterval: 1 * MILLIS_IN_DAY,
 
   /**
    * Maximal allowed expiration interval, larger expiration intervals will be
    * corrected.
-   * @type Integer
+   * @type {Integer}
    */
   maxExpirationInterval: 14 * MILLIS_IN_DAY,
 
   /**
    * Maximal number of redirects before the download is considered as failed.
-   * @type Integer
+   * @type {Integer}
    */
   maxRedirects: 5,
 
   /**
    * Called whenever expiration intervals for an object need to be adapted.
-   * @type Function
+   * @type {Function}
    */
   onExpirationChange: null,
 
   /**
    * Callback to be triggered whenever a download starts.
-   * @type Function
+   * @type {Function}
    */
   onDownloadStarted: null,
 
   /**
    * Callback to be triggered whenever a download finishes successfully. The
    * callback can return an error code to indicate that the data is wrong.
-   * @type Function
+   * @type {Function}
    */
   onDownloadSuccess: null,
 
   /**
    * Callback to be triggered whenever a download fails.
-   * @type Function
+   * @type {Function}
    */
   onDownloadError: null,
 
   /**
    * Checks whether anything needs downloading.
    */
-  _doCheck: function()
+  _doCheck()
   {
     let now = Date.now();
     for (let downloadable of this.dataSource())
     {
-      if (downloadable.lastCheck && now - downloadable.lastCheck > this.maxAbsenceInterval)
+      if (downloadable.lastCheck &&
+          now - downloadable.lastCheck > this.maxAbsenceInterval)
       {
-        // No checks for a long time interval - user must have been offline, e.g.
-        // during a weekend. Increase soft expiration to prevent load peaks on the
-        // server.
+        // No checks for a long time interval - user must have been
+        // offline, e.g.  during a weekend. Increase soft expiration
+        // to prevent load peaks on the server.
         downloadable.softExpiration += now - downloadable.lastCheck;
       }
       downloadable.lastCheck = now;
 
       // Sanity check: do expiration times make sense? Make sure people changing
       // system clock don't get stuck with outdated subscriptions.
       if (downloadable.hardExpiration - now > this.maxExpirationInterval)
         downloadable.hardExpiration = now + this.maxExpirationInterval;
       if (downloadable.softExpiration - now > this.maxExpirationInterval)
         downloadable.softExpiration = now + this.maxExpirationInterval;
 
       // Notify the caller about changes to expiration parameters
       if (this.onExpirationChange)
         this.onExpirationChange(downloadable);
 
       // Does that object need downloading?
-      if (downloadable.softExpiration > now && downloadable.hardExpiration > now)
+      if (downloadable.softExpiration > now &&
+          downloadable.hardExpiration > now)
         continue;
 
       // Do not retry downloads too often
-      if (downloadable.lastError && now - downloadable.lastError < this.minRetryInterval)
+      if (downloadable.lastError &&
+          now - downloadable.lastError < this.minRetryInterval)
         continue;
 
       this._download(downloadable, 0);
     }
   },
 
   /**
    * Stops the periodic checks.
    */
-  cancel: function()
+  cancel()
   {
     this._timer.cancel();
   },
 
   /**
    * Checks whether an address is currently being downloaded.
+   * @param {String} url
+   * @return {Boolean}
    */
-  isDownloading: function(/**String*/ url) /**Boolean*/
+  isDownloading(url)
   {
     return url in this._downloading;
   },
 
   /**
    * Starts downloading for an object.
+   * @param {Downloadable} downloadable
    */
-  download: function(/**Downloadable*/ downloadable)
+  download(downloadable)
   {
     // Make sure to detach download from the current execution context
     Utils.runAsync(this._download.bind(this, downloadable, 0));
   },
 
   /**
    * Generates the real download URL for an object by appending various
    * parameters.
+   * @param {Downloadable} downloadable
+   * @return {String}
    */
-  getDownloadUrl: function(/**Downloadable*/ downloadable)  /** String*/
+  getDownloadUrl(downloadable)
   {
-    let {addonName, addonVersion, application, applicationVersion, platform, platformVersion} = require("info");
+    let {addonName, addonVersion, application, applicationVersion,
+         platform, platformVersion} = require("info");
     let url = downloadable.redirectURL || downloadable.url;
     if (url.indexOf("?") >= 0)
       url += "&";
     else
       url += "?";
     // We limit the download count to 4+ to keep the request anonymized
-    let downloadCount = downloadable.downloadCount;
+    let {downloadCount} = downloadable;
     if (downloadCount > 4)
       downloadCount = "4+";
     url += "addonName=" + encodeURIComponent(addonName) +
         "&addonVersion=" + encodeURIComponent(addonVersion) +
         "&application=" + encodeURIComponent(application) +
         "&applicationVersion=" + encodeURIComponent(applicationVersion) +
         "&platform=" + encodeURIComponent(platform) +
         "&platformVersion=" + encodeURIComponent(platformVersion) +
         "&lastVersion=" + encodeURIComponent(downloadable.lastVersion) +
         "&downloadCount=" + encodeURIComponent(downloadCount);
     return url;
   },
 
-  _download: function(downloadable, redirects)
+  _download(downloadable, redirects)
   {
     if (this.isDownloading(downloadable.url))
       return;
 
     let downloadUrl = this.getDownloadUrl(downloadable);
     let request = null;
 
     let errorCallback = function errorCallback(error)
     {
       let channelStatus = -1;
       try
       {
         channelStatus = request.channel.status;
-      } catch (e) {}
+      }
+      catch (e) {}
 
       let responseStatus = request.status;
 
-      Cu.reportError("Adblock Plus: Downloading URL " + downloadable.url + " failed (" + error + ")\n" +
+      Cu.reportError("Adblock Plus: Downloading URL " + downloadable.url +
+                     " failed (" + error + ")\n" +
                      "Download address: " + downloadUrl + "\n" +
                      "Channel status: " + channelStatus + "\n" +
                      "Server response: " + responseStatus);
 
       if (this.onDownloadError)
       {
         // Allow one extra redirect if the error handler gives us a redirect URL
         let redirectCallback = null;
         if (redirects <= this.maxRedirects)
         {
-          redirectCallback = function redirectCallback(url)
+          redirectCallback = (url) =>
           {
             downloadable.redirectURL = url;
             this._download(downloadable, redirects + 1);
-          }.bind(this);
+          };
         }
 
-        this.onDownloadError(downloadable, downloadUrl, error, channelStatus, responseStatus, redirectCallback);
+        this.onDownloadError(downloadable, downloadUrl, error, channelStatus,
+                             responseStatus, redirectCallback);
       }
     }.bind(this);
 
     try
     {
       request = new XMLHttpRequest();
       request.mozBackgroundRequest = true;
       request.open("GET", downloadUrl);
     }
     catch (e)
     {
       errorCallback("synchronize_invalid_url");
       return;
     }
 
-    try {
+    try
+    {
       request.overrideMimeType("text/plain");
       request.channel.loadFlags = request.channel.loadFlags |
                                   request.channel.INHIBIT_CACHING |
                                   request.channel.VALIDATE_ALWAYS;
 
       // Override redirect limit from preferences, user might have set it to 1
       if (request.channel instanceof Ci.nsIHttpChannel)
         request.channel.redirectionLimit = this.maxRedirects;
     }
     catch (e)
     {
-      Cu.reportError(e)
+      Cu.reportError(e);
     }
 
-    request.addEventListener("error", function(event)
+    request.addEventListener("error", event =>
     {
       if (onShutdown.done)
         return;
 
       delete this._downloading[downloadable.url];
       errorCallback("synchronize_connection_error");
-    }.bind(this), false);
+    }, false);
 
-    request.addEventListener("load", function(event)
+    request.addEventListener("load", event =>
     {
       if (onShutdown.done)
         return;
 
       delete this._downloading[downloadable.url];
 
       // Status will be 0 for non-HTTP requests
       if (request.status && request.status != 200)
       {
         errorCallback("synchronize_connection_error");
         return;
       }
 
       downloadable.downloadCount++;
 
-      this.onDownloadSuccess(downloadable, request.responseText, errorCallback, function redirectCallback(url)
-      {
-        if (redirects >= this.maxRedirects)
-          errorCallback("synchronize_connection_error");
-        else
+      this.onDownloadSuccess(
+        downloadable, request.responseText, errorCallback,
+        url =>
         {
-          downloadable.redirectURL = url;
-          this._download(downloadable, redirects + 1);
+          if (redirects >= this.maxRedirects)
+            errorCallback("synchronize_connection_error");
+          else
+          {
+            downloadable.redirectURL = url;
+            this._download(downloadable, redirects + 1);
+          }
         }
-      }.bind(this));
-    }.bind(this), false);
+      );
+    });
 
     request.send(null);
 
     this._downloading[downloadable.url] = true;
     if (this.onDownloadStarted)
       this.onDownloadStarted(downloadable);
   },
 
   /**
    * Produces a soft and a hard expiration interval for a given supplied
    * expiration interval.
+   * @param {Integer} interval
    * @return {Array} soft and hard expiration interval
    */
-  processExpirationInterval: function(/**Integer*/ interval)
+  processExpirationInterval(interval)
   {
     interval = Math.min(Math.max(interval, 0), this.maxExpirationInterval);
     let soft = Math.round(interval * (Math.random() * 0.4 + 0.8));
     let hard = interval * 2;
     let now = Date.now();
     return [now + soft, now + hard];
   }
 };
 
 /**
  * An object that can be downloaded by the downloadable
  * @param {String} url  URL that has to be requested for the object
  * @constructor
  */
 let Downloadable = exports.Downloadable = function Downloadable(url)
 {
   this.url = url;
-}
+};
 Downloadable.prototype =
 {
   /**
    * URL that has to be requested for the object.
-   * @type String
+   * @type {String}
    */
   url: null,
 
   /**
    * URL that the download was redirected to if any.
-   * @type String
+   * @type {String}
    */
   redirectURL: null,
 
   /**
    * Time of last download error or 0 if the last download was successful.
-   * @type Integer
+   * @type {Integer}
    */
   lastError: 0,
 
   /**
    * Time of last check whether the object needs downloading.
-   * @type Integer
+   * @type {Integer}
    */
   lastCheck: 0,
 
   /**
    * Object version corresponding to the last successful download.
-   * @type Integer
+   * @type {Integer}
    */
   lastVersion: 0,
 
   /**
    * Soft expiration interval, will increase if no checks are performed for a
    * while.
-   * @type Integer
+   * @type {Integer}
    */
   softExpiration: 0,
 
   /**
    * Hard expiration interval, this is fixed.
-   * @type Integer
+   * @type {Integer}
    */
   hardExpiration: 0,
-  
+
   /**
    * Number indicating how often the object was downloaded.
-   * @type Integer
+   * @type {Integer}
    */
-  downloadCount: 0,
+  downloadCount: 0
 };