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lib: micro-optimize url.resolve()

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Replace the call to Array#splice() with a faster open-coded version
that creates less garbage.

Add a new benchmark to prove it.  With the change applied, it scores
about 5% higher and that is nothing to sneeze at.

PR-URL: https://github.com/iojs/io.js/pull/184
Reviewed-By: Chris Dickinson <christopher.s.dickinson@gmail.com>
This commit is contained in:
Ben Noordhuis 2014-12-19 23:46:37 +01:00
parent 6b2af5f0c7
commit aff56cd2b4
2 changed files with 41 additions and 3 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

31
benchmark/url/url-resolve.js Normal file
View File

@ -0,0 +1,31 @@
var common = require('../common.js');
var url = require('url');
var v8 = require('v8');
var bench = common.createBenchmark(main, {
type: ['one'],
n: [1e5],
});
function main(conf) {
var type = conf.type;
var n = conf.n | 0;
var inputs = {
one: ['http://example.com/', '../../../../../etc/passwd'],
};
var input = inputs[type] || [];
// Force-optimize url.resolve() so that the benchmark doesn't get
// disrupted by the optimizer kicking in halfway through.
for (var name in inputs)
url.resolve(inputs[name][0], inputs[name][1]);
v8.setFlagsFromString('--allow_natives_syntax');
eval('%OptimizeFunctionOnNextCall(url.resolve)');
bench.start();
for (var i = 0; i < n; i += 1)
url.resolve(input[0], input[1]);
bench.end(n);
}

13
lib/url.js
View File

@ -670,12 +670,12 @@ Url.prototype.resolveObject = function(relative) {
for (var i = srcPath.length; i >= 0; i--) {
last = srcPath[i];
if (last === '.') {
srcPath.splice(i, 1);
spliceOne(srcPath, i);
} else if (last === '..') {
srcPath.splice(i, 1);
spliceOne(srcPath, i);
up++;
} else if (up) {
srcPath.splice(i, 1);
spliceOne(srcPath, i);
up--;
}
}
@ -750,3 +750,10 @@ Url.prototype.parseHost = function() {
}
if (host) this.hostname = host;
};
// About 1.5x faster than the two-arg version of Array#splice().
function spliceOne(list, index) {
for (var i = index, k = i + 1, n = list.length; k < n; i += 1, k += 1)
list[i] = list[k];
list.pop();
}