199 lines
No EOL
4.3 KiB
JavaScript
199 lines
No EOL
4.3 KiB
JavaScript
var EventEmitter = require('events').EventEmitter;
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var util = require('util');
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var DEFAULT_TIMEOUT = 3000;
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var INIT_ID = 0;
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var EVENT_CLOSED = 'closed';
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var EVENT_DRAINED = 'drained';
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/**
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* Instance a new queue
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*
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* @param {Number} timeout a global timeout for new queue
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* @class
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* @constructor
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*/
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var SeqQueue = function(timeout) {
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EventEmitter.call(this);
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if(timeout && timeout > 0) {
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this.timeout = timeout;
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} else {
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this.timeout = DEFAULT_TIMEOUT;
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}
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this.status = SeqQueueManager.STATUS_IDLE;
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this.curId = INIT_ID;
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this.queue = [];
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};
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util.inherits(SeqQueue, EventEmitter);
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/**
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* Add a task into queue.
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*
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* @param fn new request
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* @param ontimeout callback when task timeout
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* @param timeout timeout for current request. take the global timeout if this is invalid
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* @returns true or false
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*/
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SeqQueue.prototype.push = function(fn, ontimeout, timeout) {
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if(this.status !== SeqQueueManager.STATUS_IDLE && this.status !== SeqQueueManager.STATUS_BUSY) {
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//ignore invalid status
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return false;
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}
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if(typeof fn !== 'function') {
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throw new Error('fn should be a function.');
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}
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this.queue.push({fn: fn, ontimeout: ontimeout, timeout: timeout});
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if(this.status === SeqQueueManager.STATUS_IDLE) {
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this.status = SeqQueueManager.STATUS_BUSY;
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var self = this;
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process.nextTick(function() {
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self._next(self.curId);
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});
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}
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return true;
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};
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/**
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* Close queue
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*
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* @param {Boolean} force if true will close the queue immediately else will execute the rest task in queue
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*/
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SeqQueue.prototype.close = function(force) {
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if(this.status !== SeqQueueManager.STATUS_IDLE && this.status !== SeqQueueManager.STATUS_BUSY) {
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//ignore invalid status
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return;
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}
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if(force) {
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this.status = SeqQueueManager.STATUS_DRAINED;
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if(this.timerId) {
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clearTimeout(this.timerId);
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this.timerId = undefined;
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}
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this.emit(EVENT_DRAINED);
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} else {
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this.status = SeqQueueManager.STATUS_CLOSED;
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this.emit(EVENT_CLOSED);
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}
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};
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/**
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* Invoke next task
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*
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* @param {String|Number} tid last executed task id
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* @api private
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*/
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SeqQueue.prototype._next = function(tid) {
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if(tid !== this.curId || this.status !== SeqQueueManager.STATUS_BUSY && this.status !== SeqQueueManager.STATUS_CLOSED) {
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//ignore invalid next call
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return;
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}
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if(this.timerId) {
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clearTimeout(this.timerId);
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this.timerId = undefined;
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}
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var task = this.queue.shift();
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if(!task) {
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if(this.status === SeqQueueManager.STATUS_BUSY) {
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this.status = SeqQueueManager.STATUS_IDLE;
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this.curId++; //modify curId to invalidate timeout task
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} else {
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this.status = SeqQueueManager.STATUS_DRAINED;
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this.emit(EVENT_DRAINED);
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}
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return;
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}
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var self = this;
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task.id = ++this.curId;
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var timeout = task.timeout > 0 ? task.timeout : this.timeout;
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timeout = timeout > 0 ? timeout : DEFAULT_TIMEOUT;
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this.timerId = setTimeout(function() {
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process.nextTick(function() {
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self._next(task.id);
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});
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self.emit('timeout', task);
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if(task.ontimeout) {
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task.ontimeout();
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}
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}, timeout);
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try {
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task.fn({
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done: function() {
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var res = task.id === self.curId;
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process.nextTick(function() {
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self._next(task.id);
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});
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return res;
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}
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});
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} catch(err) {
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self.emit('error', err, task);
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process.nextTick(function() {
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self._next(task.id);
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});
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}
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};
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/**
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* Queue manager.
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*
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* @module
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*/
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var SeqQueueManager = module.exports;
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/**
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* Queue status: idle, welcome new tasks
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*
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* @const
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* @type {Number}
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* @memberOf SeqQueueManager
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*/
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SeqQueueManager.STATUS_IDLE = 0;
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/**
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* Queue status: busy, queue is working for some tasks now
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*
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* @const
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* @type {Number}
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* @memberOf SeqQueueManager
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*/
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SeqQueueManager.STATUS_BUSY = 1;
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/**
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* Queue status: closed, queue has closed and would not receive task any more
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* and is processing the remaining tasks now.
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*
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* @const
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* @type {Number}
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* @memberOf SeqQueueManager
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*/
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SeqQueueManager.STATUS_CLOSED = 2;
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/**
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* Queue status: drained, queue is ready to be destroy
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*
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* @const
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* @type {Number}
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* @memberOf SeqQueueManager
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*/
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SeqQueueManager.STATUS_DRAINED = 3;
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/**
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* Create Sequence queue
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*
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* @param {Number} timeout a global timeout for the new queue instance
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* @return {Object} new queue instance
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* @memberOf SeqQueueManager
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*/
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SeqQueueManager.createQueue = function(timeout) {
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return new SeqQueue(timeout);
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}; |