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/*******************************************************************************
ηMatrix - a browser extension to black/white list requests.
Copyright (C) 2014-2019 The uMatrix/uBlock Origin authors
Copyright (C) 2019-2020 Alessio Vanni
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://libregit.org/heckyel/ematrix
uMatrix Home: https://github.com/gorhill/uMatrix
*/
'use strict';
var EXPORTED_SYMBOLS = ['CallbackWrapper'];
var junkyard = [];
var CallbackWrapper = function (messageManager, channelName,
listenerId, requestId) {
// This allows to avoid creating a closure for every single
// message which expects an answer. Having a closure created
// each time a message is processed has been always bothering
// me. Another benefit of the implementation here is to reuse
// the callback proxy object, so less memory churning.
//
// https://developers.google.com/speed/articles/optimizing-javascript
// "Creating a closure is significantly slower then creating
// an inner function without a closure, and much slower than
// reusing a static function"
//
// http://hacksoflife.blogspot.ca/2015/01/the-four-horsemen-of-performance.html
// "the dreaded 'uniformly slow code' case where every
// function takes 1% of CPU and you have to make one hundred
// separate performance optimizations to improve performance
// at all"
//
// http://jsperf.com/closure-no-closure/2
this.callback = this.proxy.bind(this); // bind once
this.init(messageManager, channelName, listenerId, requestId);
};
CallbackWrapper.factory = function (messageManager, channelName,
listenerId, requestId) {
let wrapper = junkyard.pop();
if (wrapper) {
wrapper.init(messageManager, channelName, listenerId, requestId);
return wrapper;
}
return new CallbackWrapper(messageManager, channelName,
listenerId, requestId);
};
CallbackWrapper.prototype.init = function (messageManager, channelName,
listenerId, requestId) {
this.messageManager = messageManager;
this.channelName = channelName;
this.listenerId = listenerId;
this.requestId = requestId;
};
CallbackWrapper.prototype.proxy = function (response) {
let message = JSON.stringify({
requestId: this.requestId,
channelName: this.channelName,
msg: response !== undefined ? response : null
});
if (this.messageManager.sendAsyncMessage) {
this.messageManager.sendAsyncMessage(this.listenerId, message);
} else {
this.messageManager.broadcastAsyncMessage(this.listenerId, message);
}
// Mark for reuse
this.messageManager = this.channelName =
this.requestId = this.listenerId = null;
junkyard.push(this);
};
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