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October 20, 2014 09:36
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/** | |
* @module vow-queue | |
* @author Filatov Dmitry <dfilatov@yandex-team.ru> | |
* @version 0.3.1 | |
* @license | |
* Dual licensed under the MIT and GPL licenses: | |
* * http://www.opensource.org/licenses/mit-license.php | |
* * http://www.gnu.org/licenses/gpl.html | |
*/ | |
(function() { | |
function getModule(vow, nextTick) { | |
var extend = function() { | |
var res = {}; | |
for(var i = 0, len = arguments.length; i < len; i++) { | |
var obj = arguments[i]; | |
if(obj) { | |
for(var key in obj) { | |
obj.hasOwnProperty(key) && (res[key] = obj[key]); | |
} | |
} | |
} | |
return res; | |
}, | |
DEFAULT_QUEUE_PARAMS = { | |
weightLimit : 100 | |
}, | |
DEFAULT_TASK_PARAMS = { | |
weight : 1, | |
priority : 1 | |
}; | |
/** | |
* @class Queue | |
* @exports vow-queue | |
*/ | |
/** | |
* @constructor | |
* @param {Object} [params] | |
* @param {Number} [params.weightLimit=100] | |
*/ | |
function Queue(params) { | |
this._pendingTasks = []; | |
this._params = extend(DEFAULT_QUEUE_PARAMS, params); | |
this._curWeight = 0; | |
this._isRunScheduled = false; | |
this._isStopped = true; | |
this._processedBuffer = []; | |
this._stats = { | |
pendingTasksCount : 0, | |
processingTasksCount : 0, | |
processedTasksCount : 0 | |
}; | |
} | |
Queue.prototype = /** @lends Queue.prototype */ { | |
/** | |
* Adds task to queue | |
* | |
* @param {Function} taskFn | |
* @param {Object} [taskParams] | |
* @param {Number} [taskParams.weight=1] | |
* @param {Number} [taskParams.priority=1] | |
* @returns {vow:promise} | |
*/ | |
enqueue : function(taskFn, taskParams) { | |
var task = this._buildTask(taskFn, taskParams); | |
if(task.params.weight > this._params.weightLimit) { | |
throw Error('task with weight of ' + | |
task.params.weight + | |
' can\'t be performed in queue with limit of ' + | |
this._params.weightLimit); | |
} | |
this._enqueueTask(task); | |
this._isStopped || this._scheduleRun(); | |
task.defer.promise().always( | |
function() { | |
this._stats.processingTasksCount--; | |
this._stats.processedTasksCount++; | |
}, | |
this); | |
return task.defer.promise(); | |
}, | |
/** | |
* Starts processing of queue | |
*/ | |
start : function() { | |
if(!this._isStopped) { | |
return; | |
} | |
this._isStopped = false; | |
var processedBuffer = this._processedBuffer; | |
if(processedBuffer.length) { | |
this._processedBuffer = []; | |
nextTick(function() { | |
while(processedBuffer.length) { | |
processedBuffer.shift()(); | |
} | |
}); | |
} | |
this._hasPendingTasks() && this._scheduleRun(); | |
}, | |
/** | |
* Stops processing of queue | |
*/ | |
stop : function() { | |
this._isStopped = true; | |
}, | |
/** | |
* Checks whether the queue is started | |
* @returns {Boolean} | |
*/ | |
isStarted : function() { | |
return !this._isStopped; | |
}, | |
/** | |
* Sets params of queue | |
* | |
* @param {Object} params | |
* @param {Number} [params.weightLimit] | |
*/ | |
params : function(params) { | |
if(typeof params.weightLimit !== 'undefined') { | |
this._params.weightLimit = params.weightLimit; | |
this._scheduleRun(); | |
} | |
}, | |
getStats : function() { | |
return this._stats; | |
}, | |
_buildTask : function(taskFn, taskParams) { | |
return { | |
fn : taskFn, | |
params : extend(DEFAULT_TASK_PARAMS, taskParams), | |
defer : vow.defer() | |
}; | |
}, | |
_enqueueTask : function(task) { | |
var pendingTasks = this._pendingTasks, | |
i = pendingTasks.length; | |
this._stats.pendingTasksCount++; | |
while(i) { | |
if(pendingTasks[i - 1].params.priority >= task.params.priority) { | |
i === pendingTasks.length? | |
pendingTasks.push(task) : | |
pendingTasks.splice(i, 0, task); | |
return; | |
} | |
i--; | |
} | |
pendingTasks.push(task); | |
}, | |
_scheduleRun : function() { | |
if(!this._isRunScheduled) { | |
this._isRunScheduled = true; | |
nextTick(this._run.bind(this)); | |
} | |
}, | |
_run : function() { | |
this._isRunScheduled = false; | |
while(this._hasPendingTasks() && this._allowRunTask(this._pendingTasks[0])) { | |
this._runTask(this._pendingTasks.shift()); | |
} | |
}, | |
_hasPendingTasks : function() { | |
return !!this._pendingTasks.length; | |
}, | |
_allowRunTask : function(task) { | |
return this._curWeight + task.params.weight <= this._params.weightLimit; | |
}, | |
_runTask : function(task) { | |
this._curWeight += task.params.weight; | |
this._stats.pendingTasksCount--; | |
this._stats.processingTasksCount++; | |
var taskRes = vow.invoke(task.fn); | |
taskRes | |
.progress( | |
task.defer.notify, | |
task.defer) | |
.always( | |
function() { | |
this._curWeight -= task.params.weight; | |
if(this._isStopped) { | |
this._processedBuffer.push(function() { | |
task.defer.resolve(taskRes); | |
}); | |
} | |
else { | |
task.defer.resolve(taskRes); | |
this._scheduleRun(); | |
} | |
}, | |
this); | |
} | |
}; | |
return Queue; | |
} | |
var nextTick = typeof setImmediate !== 'undefined'? | |
setImmediate : | |
typeof process === 'object' && process.nextTick? | |
process.nextTick : | |
function(fn) { | |
setTimeout(fn, 0); | |
}; | |
if(typeof modules !== 'undefined') { | |
/* global modules */ | |
modules.define('vow-queue', ['vow'], function(provide, vow) { | |
provide(getModule(vow, nextTick)); | |
}); | |
} | |
else if(typeof exports === 'object') { | |
module.exports = getModule(require('vow'), nextTick); | |
} | |
})(); |
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