async.js

/*******************************************************************************

    httpswitchboard - a Chromium browser extension to black/white list requests.
    Copyright (C) 2013  Raymond Hill

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

    This program 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 this program.  If not, see {http://www.gnu.org/licenses/}.

    Home: https://github.com/gorhill/httpswitchboard
*/

/* global chrome, HTTPSB */

/******************************************************************************/

// Async job queue module

HTTPSB.asyncJobs = (function() {

var processJobs = function() {
    asyncJobManager.process();
};

var AsyncJobEntry = function(name) {
    this.name = name;
    this.data = null;
    this.callback = null;
    this.when = 0;
    this.period = 0;
};

AsyncJobEntry.prototype.destroy = function() {
    this.name = '';
    this.data = null;
    this.callback = null;
};

var AsyncJobManager = function() {
    this.timeResolution = 200;
    this.jobs = {};
    this.jobCount = 0;
    this.jobJunkyard = [];
    this.timerId = null;
    this.timerWhen = Number.MAX_VALUE;
};

AsyncJobManager.prototype.restartTimer = function() {
    var when = Number.MAX_VALUE;
    var jobs = this.jobs, job;
    for ( var jobName in jobs ) {
        job = jobs[jobName];
        if ( job instanceof AsyncJobEntry ) {
            if ( job.when < when ) {
                when = job.when;
            }
        }
    }
    // Quantize time value
    when = Math.floor((when + this.timeResolution - 1) / this.timeResolution) * this.timeResolution;

    if ( when < this.timerWhen ) {
        clearTimeout(this.timerId);
        this.timerWhen = when;
        this.timerId = setTimeout(processJobs, Math.max(when - Date.now(), 10));
    }
};

AsyncJobManager.prototype.add = function(name, data, callback, delay, recurrent) {
    var job = this.jobs[name];
    if ( !job ) {
        job = this.jobJunkyard.pop();
        if ( !job ) {
            job = new AsyncJobEntry(name);
        } else {
            job.name = name;
        }
        this.jobs[name] = job;
        this.jobCount++;
    }
    job.data = data;
    job.callback = callback;
    job.when = Date.now() + delay;
    job.period = recurrent ? delay : 0;
    this.restartTimer();
};

AsyncJobManager.prototype.process = function() {
    this.timerId = null;
    this.timerWhen = Number.MAX_VALUE;
    var now = Date.now();
    var job;
    for ( var jobName in this.jobs ) {
        if ( this.jobs.hasOwnProperty(jobName) === false ) {
            continue;
        }
        job = this.jobs[jobName];
        if ( job.when > now ) {
            continue;
        }
        job.callback(job.data);
        if ( job.period ) {
            job.when = now + job.period;
        } else {
            delete this.jobs[jobName];
            job.destroy();
            this.jobCount--;
            this.jobJunkyard.push(job);
        }
    }
    this.restartTimer();
};

// Only one instance
var asyncJobManager = new AsyncJobManager();

// Publish
return asyncJobManager;

})();

/******************************************************************************/

// Update visual of extension icon.
// A time out is used to coalesce adjacent requests to update badge.

HTTPSB.updateBadge = function(pageUrl) {
    var updateBadgeCallback = function(pageUrl) {
        var httpsb = HTTPSB;
        if ( pageUrl === httpsb.behindTheSceneURL ) {
            return;
        }
        var tabId = httpsb.tabIdFromPageUrl(pageUrl);
        if ( !tabId ) {
            return;
        }
        var pageStats = httpsb.pageStatsFromTabId(tabId);
        if ( pageStats ) {
            pageStats.updateBadge(tabId);
        } else {
            chrome.browserAction.setIcon({ tabId: tabId, path: 'img/browsericons/icon19.png' });
            chrome.browserAction.setBadgeText({ tabId: tabId, text: '?' });
        }
    };

    this.asyncJobs.add('updateBadge ' + pageUrl, pageUrl, updateBadgeCallback, 250);
};

/******************************************************************************/

// Notify whoever care that url stats have changed (they need to
// rebuild their matrix).

HTTPSB.urlStatsChanged = function(pageUrl) {
    // rhill 2013-11-17: No point in sending this message if the popup menu
    // does not exist. I suspect this could be related to
    // https://github.com/gorhill/httpswitchboard/issues/58
    var urlStatsChangedCallback = function(pageUrl) {
        HTTPSB.messaging.tell('popup.js', {
            what: 'urlStatsChanged',
            pageURL: pageUrl
        });
    };

    this.asyncJobs.add('urlStatsChanged-' + pageUrl, pageUrl, urlStatsChangedCallback, 1000);
};