/**
* Extends the IO base class to include basic queue interfaces for transaction
* queuing.
* @module io
* @submodule io-queue
*/
/**
* @description Array of transactions queued for processing
*
* @property _q
* @private
* @static
* @type array
*/
var _q = [],
/**
* @description Property to determine whether the queue is set to
* 1 (active) or 0 (inactive). When inactive, transactions
* will be stored in the queue until the queue is set to active.
*
* @property _qState
* @private
* @static
* @type int
*/
_qState = 1,
/**
* @description Queue property to set a maximum queue storage size. When
* this property is set, the queue will not store any more transactions
* until the queue size os reduced below this threshold. There is no
* maximum queue size until it is explicitly set.
*
* @property _qMaxSize
* @private
* @static
* @type int
*/
_qMaxSize = false;
/**
* @description Method for requesting a transaction, and queueing the
* request before it is sent to the resource.
*
* @method _queue
* @private
* @static
* @return int
*/
function _queue(uri, c) {
if (_qMaxSize === false || _q.length < _qMaxSize) {
var id = Y.io._id();
_q.push({ uri: uri, id: id, cfg:c });
}
else {
Y.log('Unable to queue transaction object. Maximum queue size reached.', 'warn', 'io');
return false;
}
if (_qState === 1) {
_shift();
}
Y.log('Object queued. Transaction id is' + id, 'info', 'io');
return id;
};
/**
* @description Method for promoting a transaction to the top of the queue.
*
* @method _unshift
* @private
* @static
* @return void
*/
function _unshift(id) {
var r;
for (var i = 0; i < _q.length; i++) {
if (_q[i].id === id) {
r = _q.splice(i, 1);
var p = _q.unshift(r[0]);
Y.log('Object promoted to top of queue. Transaction id is' + id, 'info', 'io');
break;
}
}
};
/**
* @description Method for removing a transaction from the top of the
* queue, and sending the transaction to _io().
*
* @method _shift
* @private
* @static
* @return void
*/
function _shift() {
var c = _q.shift();
Y.io(c.uri, c.cfg, c.id);
};
/**
* @description Method to query the current size of the queue, or to
* set a maximum queue size.
*
* @method _size
* @private
* @static
* @return int
*/
function _size(i) {
if (i) {
_qMaxSize = i;
Y.log('Queue size set to ' + i, 'info', 'io');
return i;
}
else {
return _q.length;
}
};
/**
* @description Method for setting the queue to active. If there are
* transactions pending in the queue, they will be processed from the
* queue in FIFO order.
*
* @method _start
* @private
* @static
* @return void
*/
function _start() {
var len = (_q.length > _qMaxSize > 0) ? _qMaxSize : _q.length;
if (len > 1) {
for (var i=0; i < len; i++) {
_shift();
}
}
else {
_shift();
}
Y.log('Queue started.', 'info', 'io');
};
/**
* @description Method for setting queue processing to inactive.
* Transaction requests to YUI.io.queue() will be stored in the queue, but
* not processed until the queue is reset to "active".
*
* @method _stop
* @private
* @static
* @return void
*/
function _stop() {
_qState = 0;
Y.log('Queue stopped.', 'info', 'io');
};
/**
* @description Method for removing a specific, pending transaction from
* the queue.
*
* @method _purge
* @private
* @static
* @return void
*/
function _purge(id) {
if (Y.Lang.isNumber(id)) {
for (var i = 0; i < _q.length; i++) {
if (_q[i].id === id) {
_q.splice(i, 1);
Y.log('Object purged from queue. Transaction id is' + id, 'info', 'io');
break;
}
}
}
};
/**
* @description Method to query the current size of the queue, or to
* set a maximum queue size. This is the interface for _size().
*
* @method size
* @public
* @static
* @param {number} i - Specified maximum size of queue.
* @return number
*/
_queue.size = _size;
/**
* @description Method for setting the queue to "active". If there are
* transactions pending in the queue, they will be processed from the
* queue in FIFO order. This is the interface for _start().
*
* @method start
* @public
* @static
* @return void
*/
_queue.start = _start;
/**
* @description Method for setting queue processing to inactive.
* Transaction requests to YUI.io.queue() will be stored in the queue, but
* not processed until the queue is set to "active". This is the
* interface for _stop().
*
* @method stop
* @public
* @static
* @return void
*/
_queue.stop = _stop;
/**
* @description Method for promoting a transaction to the top of the queue.
* This is the interface for _unshift().
*
* @method promote
* @public
* @static
* @param {number} i - ID of queued transaction.
* @return void
*/
_queue.promote = _unshift;
/**
* @description Method for removing a specific, pending transaction from
* the queue. This is the interface for _purge().
*
* @method purge
* @public
* @static
* @param {number} i - ID of queued transaction.
* @return void
*/
_queue.purge = _purge;
Y.mix(Y.io, {
queue: _queue,
}, true);