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timer: Improve performance of callbacks
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setImmediate, setTimeout, and setInterval were called in an inefficient
way, especially in the presence of arguments.  This optimization
improves their performance, with special cases for up to 4 arguments.
Performance of setImmediate increases with 35%, setInterval with 60%,
setTimeout with 70%.

PR-URL: #406
Reviewed-by: Trevor Norris <[email protected]>
Reviewed-by: Christian Tellnes <[email protected]>
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RubenVerborgh authored and trevnorris committed Mar 4, 2015
1 parent 6190a22 commit bd1bd7e
Showing 1 changed file with 97 additions and 33 deletions.
130 changes: 97 additions & 33 deletions lib/timers.js
Original file line number Diff line number Diff line change
Expand Up @@ -173,8 +173,9 @@ exports.active = function(item) {
*/


exports.setTimeout = function(callback, after) {
var timer;
exports.setTimeout = function(callback, after, arg1, arg2, arg3) {
var timer, i, args;
var len = arguments.length;

after *= 1; // coalesce to number or NaN

Expand All @@ -184,22 +185,38 @@ exports.setTimeout = function(callback, after) {

timer = new Timeout(after);

if (arguments.length <= 2) {
timer._onTimeout = callback;
} else {
/*
* Sometimes setTimeout is called with arguments, EG
*
* setTimeout(callback, 2000, "hello", "world")
*
* If that's the case we need to call the callback with
* those args. The overhead of an extra closure is not
* desired in the normal case.
*/
var args = Array.prototype.slice.call(arguments, 2);
timer._onTimeout = function() {
callback.apply(timer, args);
};
switch (len) {
// fast cases
case 0:
case 1:
case 2:
timer._onTimeout = callback;
break;
case 3:
timer._onTimeout = function() {
callback.call(timer, arg1);
};
break;
case 4:
timer._onTimeout = function() {
callback.call(timer, arg1, arg2);
};
break;
case 5:
timer._onTimeout = function() {
callback.call(timer, arg1, arg2, arg3);
};
break;
// slow case
default:
args = new Array(len - 2);
for (i = 2; i < len; i++)
args[i - 2] = arguments[i];

timer._onTimeout = function() {
callback.apply(timer, args);
};
break;
}

if (process.domain) timer.domain = process.domain;
Expand All @@ -222,25 +239,50 @@ exports.clearTimeout = function(timer) {
};


exports.setInterval = function(callback, repeat) {
exports.setInterval = function(callback, repeat, arg1, arg2, arg3) {
repeat *= 1; // coalesce to number or NaN

if (!(repeat >= 1 && repeat <= TIMEOUT_MAX)) {
repeat = 1; // schedule on next tick, follows browser behaviour
}

var args, i;
var timer = new Timeout(repeat);
var args = Array.prototype.slice.call(arguments, 2);
var len = arguments.length - 2;
timer._onTimeout = wrapper;
timer._repeat = true;
// Initialize args once for repeated invocation of slow case below
if (len > 3) {
args = new Array(len);
for (i = 0; i < len; i++)
args[i] = arguments[i + 2];
}

if (process.domain) timer.domain = process.domain;
exports.active(timer);

return timer;

function wrapper() {
callback.apply(this, args);
switch (len) {
// fast cases
case 0:
callback.call(this);
break;
case 1:
callback.call(this, arg1);
break;
case 2:
callback.call(this, arg1, arg2);
break;
case 3:
callback.call(this, arg1, arg2, arg3);
break;
// slow case
default:
callback.apply(this, args);
break;
}
// If callback called clearInterval().
if (timer._repeat === false) return;
// If timer is unref'd (or was - it's permanently removed from the list.)
Expand Down Expand Up @@ -361,22 +403,44 @@ Immediate.prototype._idleNext = undefined;
Immediate.prototype._idlePrev = undefined;


exports.setImmediate = function(callback) {
exports.setImmediate = function(callback, arg1, arg2, arg3) {
var i, args;
var len = arguments.length;
var immediate = new Immediate();
var args, index;

L.init(immediate);

immediate._onImmediate = callback;

if (arguments.length > 1) {
args = [];
for (index = 1; index < arguments.length; index++)
args.push(arguments[index]);

immediate._onImmediate = function() {
callback.apply(immediate, args);
};
switch (len) {
// fast cases
case 0:
case 1:
immediate._onImmediate = callback;
break;
case 2:
immediate._onImmediate = function() {
callback.call(immediate, arg1);
};
break;
case 3:
immediate._onImmediate = function() {
callback.call(immediate, arg1, arg2);
};
break;
case 4:
immediate._onImmediate = function() {
callback.call(immediate, arg1, arg2, arg3);
};
break;
// slow case
default:
args = new Array(len - 1);
for (i = 1; i < len; i++)
args[i - 1] = arguments[i];

immediate._onImmediate = function() {
callback.apply(immediate, args);
};
break;
}

if (!process._needImmediateCallback) {
Expand Down

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