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avoid closures when processing messages

pull/2/head
gorhill 10 years ago
parent
commit
b66683a581
  1. 66
      platform/chromium/vapi-background.js

66
platform/chromium/vapi-background.js

@ -295,17 +295,7 @@ vAPI.messaging.listen = function(listenerName, callback) {
vAPI.messaging.onPortMessage = function(request, port) {
var callback = vAPI.messaging.NOOPFUNC;
if ( request.requestId !== undefined ) {
callback = function(response) {
// https://github.com/gorhill/uBlock/issues/383
if ( vAPI.messaging.ports.hasOwnProperty(port.name) === false ) {
return;
}
port.postMessage({
requestId: request.requestId,
channelName: request.channelName,
msg: response !== undefined ? response : null
});
};
callback = CallbackWrapper.factory(port, request).callback;
}
// Specific handler
@ -382,6 +372,60 @@ vAPI.messaging.broadcast = function(message) {
/******************************************************************************/
// 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"
var CallbackWrapper = function(port, request) {
// No need to bind every single time
this.callback = this.proxy.bind(this);
this.messaging = vAPI.messaging;
this.init(port, request);
};
CallbackWrapper.junkyard = [];
CallbackWrapper.factory = function(port, request) {
var wrapper = CallbackWrapper.junkyard.pop();
if ( wrapper ) {
wrapper.init(port, request);
return wrapper;
}
return new CallbackWrapper(port, request);
};
CallbackWrapper.prototype.init = function(port, request) {
this.port = port;
this.request = request;
};
CallbackWrapper.prototype.proxy = function(response) {
// https://github.com/gorhill/uBlock/issues/383
if ( this.messaging.ports.hasOwnProperty(this.port.name) ) {
this.port.postMessage({
requestId: this.request.requestId,
channelName: this.request.channelName,
msg: response !== undefined ? response : null
});
}
// Mark for reuse
this.port = this.request = null;
CallbackWrapper.junkyard.push(this);
};
/******************************************************************************/
vAPI.net = {};
/******************************************************************************/

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