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buffer,util: refactor for performance

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internal/util.js definied toInteger() and toLength() but they were only
used by buffer.js. Inlining these small functions results in a small but
statistically-significant performance gain.

PR-URL: https://github.com/nodejs/node/pull/12153
Reviewed-By: Joyee Cheung <joyeec9h3@gmail.com>
Reviewed-By: Michaël Zasso <targos@protonmail.com>
Reviewed-By: James M Snell <jasnell@gmail.com>
This commit is contained in:
Rich Trott 2017-03-31 22:48:35 -07:00 committed by James M Snell
parent dc7d9eb0a9
commit 1e6186e902
4 changed files with 8 additions and 87 deletions
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10
lib/buffer.js
View File

@ -254,7 +254,9 @@ function fromArrayLike(obj) {
}
function fromArrayBuffer(obj, byteOffset, length) {
byteOffset = internalUtil.toInteger(byteOffset);
// convert byteOffset to integer
byteOffset = +byteOffset;
byteOffset = byteOffset ? Math.trunc(byteOffset) : 0;
const maxLength = obj.byteLength - byteOffset;
@ -264,7 +266,11 @@ function fromArrayBuffer(obj, byteOffset, length) {
if (length === undefined) {
length = maxLength;
} else {
length = internalUtil.toLength(length);
// convert length to non-negative integer
length = +length;
length = length ? Math.trunc(length) : 0;
length = length <= 0 ? 0 : Math.min(length, Number.MAX_SAFE_INTEGER);
if (length > maxLength)
throw new RangeError("'length' is out of bounds");
}

18
lib/internal/util.js
View File

@ -143,24 +143,6 @@ exports.cachedResult = function cachedResult(fn) {
};
};
/*
* Implementation of ToInteger as per ECMAScript Specification
* Refer: http://www.ecma-international.org/ecma-262/6.0/#sec-tointeger
*/
const toInteger = exports.toInteger = function toInteger(argument) {
const number = +argument;
return Number.isNaN(number) ? 0 : Math.trunc(number);
};
/*
* Implementation of ToLength as per ECMAScript Specification
* Refer: http://www.ecma-international.org/ecma-262/6.0/#sec-tolength
*/
exports.toLength = function toLength(argument) {
const len = toInteger(argument);
return len <= 0 ? 0 : Math.min(len, Number.MAX_SAFE_INTEGER);
};
// Useful for Wrapping an ES6 Class with a constructor Function that
// does not require the new keyword. For instance:
// class A { constructor(x) {this.x = x;}}

32
test/parallel/test-internal-util-toInteger.js
View File

@ -1,32 +0,0 @@
// Flags: --expose-internals
'use strict';
require('../common');
const assert = require('assert');
const {toInteger} = require('internal/util');
const expectZero = [
'0', '-0', NaN, {}, [], {'a': 'b'}, [1, 2], '0x', '0o', '0b', false,
'', ' ', undefined, null
];
expectZero.forEach(function(value) {
assert.strictEqual(toInteger(value), 0);
});
assert.strictEqual(toInteger(Infinity), Infinity);
assert.strictEqual(toInteger(-Infinity), -Infinity);
const expectSame = [
'0x100', '0o100', '0b100', 0x100, -0x100, 0o100, -0o100, 0b100, -0b100, true
];
expectSame.forEach(function(value) {
assert.strictEqual(toInteger(value), +value, `${value} is not an Integer`);
});
const expectIntegers = new Map([
[[1], 1], [[-1], -1], [['1'], 1], [['-1'], -1],
[3.14, 3], [-3.14, -3], ['3.14', 3], ['-3.14', -3],
]);
expectIntegers.forEach(function(expected, value) {
assert.strictEqual(toInteger(value), expected);
});

35
test/parallel/test-internal-util-toLength.js
View File

@ -1,35 +0,0 @@
// Flags: --expose-internals
'use strict';
require('../common');
const assert = require('assert');
const {toLength} = require('internal/util');
const maxValue = Number.MAX_SAFE_INTEGER;
const expectZero = [
'0', '-0', NaN, {}, [], {'a': 'b'}, [1, 2], '0x', '0o', '0b', false,
'', ' ', undefined, null, -1, -1.25, -1.1, -1.9, -Infinity
];
expectZero.forEach(function(value) {
assert.strictEqual(toLength(value), 0);
});
assert.strictEqual(toLength(maxValue - 1), maxValue - 1);
assert.strictEqual(maxValue, maxValue);
assert.strictEqual(toLength(Infinity), maxValue);
assert.strictEqual(toLength(maxValue + 1), maxValue);
[
'0x100', '0o100', '0b100', 0x100, -0x100, 0o100, -0o100, 0b100, -0b100, true
].forEach(function(value) {
assert.strictEqual(toLength(value), +value > 0 ? +value : 0);
});
const expectIntegers = new Map([
[[1], 1], [[-1], 0], [['1'], 1], [['-1'], 0],
[3.14, 3], [-3.14, 0], ['3.14', 3], ['-3.14', 0],
]);
expectIntegers.forEach(function(expected, value) {
assert.strictEqual(toLength(value), expected);
});