buffer: optimize Buffer#toString()
Break up Buffer#toString() into a fast and slow path. The fast path optimizes for zero-length buffers and no-arg method invocation. The speedup for zero-length buffers is a satisfying 700%. The no-arg toString() operation gets faster by about 13% for a one-byte buffer. This change exploits the fact that most Buffer#toString() calls are plain no-arg method calls. Rewriting the method to take no arguments means a call doesn't go through an ArgumentsAdaptorTrampoline stack frame in the common case. PR-URL: https://github.com/nodejs/io.js/pull/2027 Reviewed-By: Brian White <mscdex@mscdex.net> Reviewed-By: Christian Tellnes <christian@tellnes.no> Reviewed-By: Daniel Cousens <email@dcousens.com> Reviewed-By: Jeremiah Senkpiel <fishrock123@rocketmail.com> Reviewed-By: Trevor Norris <trev.norris@gmail.com>
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benchmark/buffers/buffer-tostring.js
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26
benchmark/buffers/buffer-tostring.js
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@ -0,0 +1,26 @@
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'use strict';
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const common = require('../common.js');
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const bench = common.createBenchmark(main, {
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arg: [true, false],
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len: [0, 1, 64, 1024],
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n: [1e7]
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});
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function main(conf) {
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const arg = conf.arg;
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const len = conf.len | 0;
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const n = conf.n | 0;
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const buf = Buffer(len).fill(42);
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bench.start();
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if (arg) {
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for (var i = 0; i < n; i += 1)
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buf.toString('utf8');
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} else {
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for (var i = 0; i < n; i += 1)
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buf.toString();
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}
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bench.end(n);
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}
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@ -333,8 +333,7 @@ function byteLength(string, encoding) {
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Buffer.byteLength = byteLength;
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// toString(encoding, start=0, end=buffer.length)
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Buffer.prototype.toString = function(encoding, start, end) {
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function slowToString(encoding, start, end) {
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var loweredCase = false;
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start = start >>> 0;
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@ -376,6 +375,16 @@ Buffer.prototype.toString = function(encoding, start, end) {
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loweredCase = true;
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}
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}
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}
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Buffer.prototype.toString = function() {
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const length = this.length | 0;
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if (length === 0)
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return '';
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if (arguments.length === 0)
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return this.utf8Slice(0, length);
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return slowToString.apply(this, arguments);
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};
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