autoupdate_cordova.js

var DEBUG_TAG = 'METEOR CORDOVA DEBUG (autoupdate_cordova.js) ';
var log = function (msg) {
  console.log(DEBUG_TAG + msg);
};

// This constant was picked by testing on iOS 7.1
// We limit the number of concurrent downloads because iOS gets angry on the
// application when a certain limit is exceeded and starts timing-out the
// connections in 1-2 minutes which makes the whole HCP really slow.
var MAX_NUM_CONCURRENT_DOWNLOADS = 30;
var MAX_RETRY_COUNT = 5;

var autoupdateVersionCordova = __meteor_runtime_config__.autoupdateVersionCordova || "unknown";

// The collection of acceptable client versions.
ClientVersions = new Mongo.Collection("meteor_autoupdate_clientVersions");

Autoupdate = {};

Autoupdate.newClientAvailable = function () {
  return !! ClientVersions.findOne({
    _id: 'version-cordova',
    version: {$ne: autoupdateVersionCordova}
  });
};

var writeFile = function (directoryPath, fileName, content, cb) {
  var fail = function (err) {
    cb(new Error("Failed to write file: ", err), null);
  };

  window.resolveLocalFileSystemURL(directoryPath, function (dirEntry) {
    var success = function (fileEntry) {
      fileEntry.createWriter(function (writer) {
        writer.onwrite = function (evt) {
          var result = evt.target.result;
          cb(null, result);
        };
        writer.onerror = fail;
        writer.write(content);
      }, fail);
    };

    dirEntry.getFile(fileName, {
      create: true,
      exclusive: false
    }, success, fail);
  }, fail);
};

var restartServer = function (location) {
  log('restartServer with location ' + location);
  var fail = function (err) { log("Unexpected error in restartServer: " + err.message) };
  var httpd = cordova && cordova.plugins && cordova.plugins.CordovaUpdate;

  if (! httpd) {
    fail(new Error('no httpd'));
    return;
  }

  var startServer = function (cordovajsRoot) {
    httpd.startServer({
      'www_root' : location,
      'cordovajs_root': cordovajsRoot
    }, function (url) {
      if (Package.reload) {
        Package.reload.Reload._reload();
      } else {
        window.location.reload();
      }
    }, fail);
  };

  httpd.getCordovajsRoot(function (cordovajsRoot) {
    startServer(cordovajsRoot);
  }, fail);
};

var hasCalledReload = false;
var updating = false;
var localPathPrefix = null;

var onNewVersion = function () {
  var ft = new FileTransfer();
  var urlPrefix = Meteor.absoluteUrl() + '__cordova';
  HTTP.get(urlPrefix + '/manifest.json', function (err, res) {
    if (err || ! res.data) {
      log('Failed to download the manifest ' + (err && err.message) + ' ' + (res && res.content));
      return;
    }

    updating = true;
    ensureLocalPathPrefix(_.bind(downloadNewVersion, null, res.data));
  });
};

var downloadNewVersion = function (program) {
  var urlPrefix = Meteor.absoluteUrl() + '__cordova';
  var manifest = _.clone(program.manifest);
  var version = program.version;
  var ft = new FileTransfer();

  manifest.push({ url: '/index.html?' + Random.id() });

  var versionPrefix = localPathPrefix + version;

  var queue = [];
  _.each(manifest, function (item) {
    if (! item.url) return;

    var url = item.url;
    url = url.replace(/\?.+$/, '');

    queue.push(url);
  });

  var afterAllFilesDownloaded = _.after(queue.length, function () {
    var wroteManifest = function (err) {
      if (err) {
        log("Failed to write manifest.json: " + err);
        // XXX do something smarter?
        return;
      }

      // success! downloaded all sources and saved the manifest
      // save the version string for atomicity
      writeFile(localPathPrefix, 'version', version, function (err) {
        if (err) {
          log("Failed to write version: " + err);
          return;
        }

        // don't call reload twice!
        if (! hasCalledReload) {
          var location = uriToPath(localPathPrefix + version);
          restartServer(location);
        }
      });
    };

    writeFile(versionPrefix, 'manifest.json',
              JSON.stringify(program, undefined, 2), wroteManifest);
  });

  var downloadUrl = function (url) {
    console.log(DEBUG_TAG + "start downloading " + url);
    // Add a cache buster to ensure that we don't cache an old asset.
    var uri = encodeURI(urlPrefix + url + '?' + Random.id());

    // Try to download the file a few times.
    var tries = 0;
    var tryDownload = function () {
      ft.download(uri, versionPrefix + encodeURI(url), function (entry) {
        if (entry) {
          console.log(DEBUG_TAG + "done downloading " + url);
          // start downloading next queued url
          if (queue.length)
            downloadUrl(queue.shift());
          afterAllFilesDownloaded();
        }
      }, function (err) {
        // It failed, try again if we have tried less than 5 times.
        if (tries++ < MAX_RETRY_COUNT) {
          log("Download error, will retry (#" + tries + "): " + uri);
          tryDownload();
        } else {
          log('Download failed: ' + JSON.stringify(err) + ", source=" + err.source + ", target=" + err.target);
        }
      });
    };

    tryDownload();
  };

  _.times(Math.min(MAX_NUM_CONCURRENT_DOWNLOADS, queue.length), function () {
    var nextUrl = queue.shift();
    // XXX defer the next download so iOS doesn't rate limit us on concurrent
    // downloads
    Meteor.setTimeout(downloadUrl.bind(null, nextUrl), 50);
  });
};

var retry = new Retry({
  minCount: 0, // don't do any immediate retries
  baseTimeout: 30*1000 // start with 30s
});
var failures = 0;

Autoupdate._retrySubscription = function () {
  var appId = __meteor_runtime_config__.appId;
  Meteor.subscribe("meteor_autoupdate_clientVersions", appId, {
    onError: function (err) {
      Meteor._debug("autoupdate subscription failed:", err);
      failures++;
      retry.retryLater(failures, function () {
        // Just retry making the subscription, don't reload the whole
        // page. While reloading would catch more cases (for example,
        // the server went back a version and is now doing old-style hot
        // code push), it would also be more prone to reload loops,
        // which look really bad to the user. Just retrying the
        // subscription over DDP means it is at least possible to fix by
        // updating the server.
        Autoupdate._retrySubscription();
      });
    }
  });
  if (Package.reload) {
    var checkNewVersionDocument = function (doc) {
      var self = this;
      if (doc.version !== autoupdateVersionCordova) {
        onNewVersion();
      }
    };

    var handle = ClientVersions.find({
      _id: 'version-cordova'
    }).observe({
      added: checkNewVersionDocument,
      changed: checkNewVersionDocument
    });
  }
};

Meteor.startup(function () {
  clearAutoupdateCache(autoupdateVersionCordova);
});
Meteor.startup(Autoupdate._retrySubscription);


// A helper that removes old directories left from previous autoupdates
var clearAutoupdateCache = function (currentVersion) {
  ensureLocalPathPrefix(function () {
    // Try to clean up our cache directory, make sure to scan the directory
    // *before* loading the actual app. This ordering will prevent race
    // conditions when the app code tries to download a new version before
    // the old-cache removal has scanned the cache folder.
    listDirectory(localPathPrefix, {dirsOnly: true}, function (err, names) {
      // Couldn't get the list of dirs or risking to get into a race with an
      // on-going update to disk.
      if (err || updating) {
        return;
      }

      _.each(names, function (name) {
        // Skip the folder with the latest version
        if (name === currentVersion)
          return;

        // remove everything else, as we don't want to keep too much cache
        // around on disk
        removeDirectory(localPathPrefix + name + '/', function (err) {
          if (err) {
            log('Failed to remove an old cache folder '
                + name + ':' + err.message);
          } else {
            log('Successfully removed an old cache folder ' + name);
          }
        });
      });
    });
  })
};

// Cordova File plugin helpers
var listDirectory = function (url, options, cb) {
  if (typeof options === 'function')
    cb = options, options = {};

  var fail = function (err) { cb(err); };
  window.resolveLocalFileSystemURL(url, function (entry) {
    var reader = entry.createReader();
    reader.readEntries(function (entries) {
      var names = [];
      _.each(entries, function (entry) {
        if (! options.dirsOnly || entry.isDirectory)
          names.push(entry.name);
      });
      cb(null, names);
    }, fail);
  }, fail);
};

var removeDirectory = function (url, cb) {
  var fail = function (err) {
    cb(err);
  };
  window.resolveLocalFileSystemURL(url, function (entry) {
    entry.removeRecursively(function () { cb(); }, fail);
  }, fail);
};

var uriToPath = function (uri) {
  return decodeURI(uri).replace(/^file:\/\//g, '');
};

var ensureLocalPathPrefix = function (cb) {
  if (! localPathPrefix) {
    if (! cordova.file.dataDirectory) {
      // Since ensureLocalPathPrefix function is always called on
      // Meteor.startup, all Cordova plugins should be ready.
      // XXX Experiments have shown that it is not always the case, even when
      // the cordova.file symbol is attached, properties like dataDirectory
      // still can be null. Poll until we are sure the property is attached.
      console.log(DEBUG_TAG + 'cordova.file.dataDirectory is null, retrying in 20ms');
      Meteor.setTimeout(_.bind(ensureLocalPathPrefix, null, cb), 20);
    } else {
      localPathPrefix = cordova.file.dataDirectory + 'meteor/';
      cb();
    }
  } else {
    cb();
  }
};