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lib: improve normalize encoding performance

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This focuses on the common case by making sure they are prioritized.
It also changes some typeof checks to test for undefined since
that is faster and it adds a benchmark.

PR-URL: https://github.com/nodejs/node/pull/18790
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Benjamin Gruenbaum <benjamingr@gmail.com>
Reviewed-By: Matteo Collina <matteo.collina@gmail.com>
This commit is contained in:
Ruben Bridgewater 2018-02-14 23:48:35 +01:00
parent 876836b135
commit 341770fedf
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GPG Key ID: F07496B3EB3C1762
4 changed files with 101 additions and 33 deletions
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43
benchmark/buffers/buffer-normalize-encoding.js Normal file
View File

@ -0,0 +1,43 @@
'use strict';
const common = require('../common.js');
const bench = common.createBenchmark(main, {
encoding: [
'ascii',
'ASCII',
'base64',
'BASE64',
'binary',
'BINARY',
'hex',
'HEX',
'latin1',
'LATIN1',
'ucs-2',
'UCS-2',
'ucs2',
'UCS2',
'utf-16le',
'UTF-16LE',
'utf-8',
'UTF-8',
'utf16le',
'UTF16LE',
'utf8',
'UTF8'
],
n: [1e6]
}, {
flags: ['--expose-internals']
});
function main({ encoding, n }) {
const { normalizeEncoding } = require('internal/util');
bench.start();
for (var i = 0; i < n; i++) {
normalizeEncoding(encoding);
}
bench.end(n);
}

4
lib/buffer.js
View File

@ -242,7 +242,7 @@ function assertSize(size) {
err = new errors.RangeError('ERR_INVALID_OPT_VALUE', 'size', size);
}
if (err) {
if (err !== null) {
Error.captureStackTrace(err, assertSize);
throw err;
}
@ -428,7 +428,7 @@ Buffer.compare = function compare(a, b) {
Buffer.isEncoding = function isEncoding(encoding) {
return typeof encoding === 'string' &&
typeof normalizeEncoding(encoding) === 'string';
normalizeEncoding(encoding) !== undefined;
};
Buffer[kIsEncodingSymbol] = Buffer.isEncoding;

77
lib/internal/util.js
View File

@ -96,36 +96,59 @@ function assertCrypto() {
throw new errors.Error('ERR_NO_CRYPTO');
}
// The loop should only run at most twice, retrying with lowercased enc
// if there is no match in the first pass.
// We use a loop instead of branching to retry with a helper
// function in order to avoid the performance hit.
// Return undefined if there is no match.
// Move the "slow cases" to a separate function to make sure this function gets
// inlined properly. That prioritizes the common case.
function normalizeEncoding(enc) {
if (enc == null || enc === '') return 'utf8';
let retried;
while (true) {
switch (enc) {
case 'utf8':
case 'utf-8':
return 'utf8';
case 'ucs2':
case 'ucs-2':
case 'utf16le':
case 'utf-16le':
if (enc == null || enc === 'utf8' || enc === 'utf-8') return 'utf8';
return slowCases(enc);
}
function slowCases(enc) {
switch (enc.length) {
case 4:
if (enc === 'UTF8') return 'utf8';
if (enc === 'ucs2' || enc === 'UCS2') return 'utf16le';
enc = `${enc}`.toLowerCase();
if (enc === 'utf8') return 'utf8';
if (enc === 'ucs2' || enc === 'UCS2') return 'utf16le';
break;
case 3:
if (enc === 'hex' || enc === 'HEX' || `${enc}`.toLowerCase() === 'hex')
return 'hex';
break;
case 5:
if (enc === 'ascii') return 'ascii';
if (enc === 'ucs-2') return 'utf16le';
if (enc === 'UTF-8') return 'utf8';
if (enc === 'ASCII') return 'ascii';
if (enc === 'UCS-2') return 'utf16le';
enc = `${enc}`.toLowerCase();
if (enc === 'utf-8') return 'utf8';
if (enc === 'ascii') return 'ascii';
if (enc === 'usc-2') return 'utf16le';
break;
case 6:
if (enc === 'base64') return 'base64';
if (enc === 'latin1' || enc === 'binary') return 'latin1';
if (enc === 'BASE64') return 'base64';
if (enc === 'LATIN1' || enc === 'BINARY') return 'latin1';
enc = `${enc}`.toLowerCase();
if (enc === 'base64') return 'base64';
if (enc === 'latin1' || enc === 'binary') return 'latin1';
break;
case 7:
if (enc === 'utf16le' || enc === 'UTF16LE' ||
`${enc}`.toLowerCase() === 'utf16le')
return 'utf16le';
case 'latin1':
case 'binary':
return 'latin1';
case 'base64':
case 'ascii':
case 'hex':
return enc;
default:
if (retried) return; // undefined
enc = ('' + enc).toLowerCase();
retried = true;
}
break;
case 8:
if (enc === 'utf-16le' || enc === 'UTF-16LE' ||
`${enc}`.toLowerCase() === 'utf-16le')
return 'utf16le';
break;
default:
if (enc === '') return 'utf8';
}
}

10
lib/string_decoder.js
View File

@ -43,10 +43,12 @@ const kNativeDecoder = Symbol('kNativeDecoder');
// modules monkey-patch it to support additional encodings
function normalizeEncoding(enc) {
const nenc = internalUtil.normalizeEncoding(enc);
if (typeof nenc !== 'string' &&
(Buffer.isEncoding === isEncoding || !Buffer.isEncoding(enc)))
throw new errors.TypeError('ERR_UNKNOWN_ENCODING', enc);
return nenc || enc;
if (nenc === undefined) {
if (Buffer.isEncoding === isEncoding || !Buffer.isEncoding(enc))
throw new errors.TypeError('ERR_UNKNOWN_ENCODING', enc);
return enc;
}
return nenc;
}
const encodingsMap = {};