syncing.js

/*
    This file is part of web3.js.

    web3.js is free software: you can redistribute it and/or modify
    it under the terms of the GNU Lesser General Public License as published by
    the Free Software Foundation, either version 3 of the License, or
    (at your option) any later version.

    web3.js 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 Lesser General Public License for more details.

    You should have received a copy of the GNU Lesser General Public License
    along with web3.js.  If not, see <http://www.gnu.org/licenses/>.
*/
/** @file syncing.js
 * @authors:
 *   Fabian Vogelsteller <fabian@ethdev.com>
 * @date 2015
 */

var formatters = require('./formatters');
var utils = require('../utils/utils');

var count = 1;

/**
Adds the callback and sets up the methods, to iterate over the results.

@method pollSyncing
@param {Object} self
*/
var pollSyncing = function(self) {

    var onMessage = function (error, sync) {
        if (error) {
            return self.callbacks.forEach(function (callback) {
                callback(error);
            });
        }

        if(utils.isObject(sync) && sync.startingBlock)
            sync = formatters.outputSyncingFormatter(sync);

        self.callbacks.forEach(function (callback) {
            if (self.lastSyncState !== sync) {
                
                // call the callback with true first so the app can stop anything, before receiving the sync data
                if(!self.lastSyncState && utils.isObject(sync))
                    callback(null, true);
                
                // call on the next CPU cycle, so the actions of the sync stop can be processes first
                setTimeout(function() {
                    callback(null, sync);
                }, 0);
                
                self.lastSyncState = sync;
            }
        });
    };

    self.requestManager.startPolling({
        method: 'eth_syncing',
        params: [],
    }, self.pollId, onMessage, self.stopWatching.bind(self));

};

var IsSyncing = function (requestManager, callback) {
    this.requestManager = requestManager;
    this.pollId = 'syncPoll_'+ count++;
    this.callbacks = [];
    this.addCallback(callback);
    this.lastSyncState = false;
    pollSyncing(this);

    return this;
};

IsSyncing.prototype.addCallback = function (callback) {
    if(callback)
        this.callbacks.push(callback);
    return this;
};

IsSyncing.prototype.stopWatching = function () {
    this.requestManager.stopPolling(this.pollId);
    this.callbacks = [];
};

module.exports = IsSyncing;