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buffer: improve copy() performance

PR-URL: #29066
Reviewed-By: James M Snell <jasnell@gmail.com>
Reviewed-By: Rich Trott <rtrott@gmail.com>
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mscdex authored and targos committed Aug 9, 2019
1 parent 9ead4ec commit 90578142061865aac852aafd7578400d69695228
Showing with 105 additions and 10 deletions.
  1. +19 −0 benchmark/buffers/buffer-copy.js
  2. +69 −1 lib/buffer.js
  3. +2 −1 test/parallel/test-buffer-alloc.js
  4. +15 −8 test/parallel/test-buffer-copy.js
@@ -0,0 +1,19 @@
'use strict';
const common = require('../common.js');

const bench = common.createBenchmark(main, {
bytes: [0, 8, 128, 32 * 1024],
partial: ['true', 'false'],
n: [6e6]
});

function main({ n, bytes, partial }) {
const source = Buffer.allocUnsafe(bytes);
const target = Buffer.allocUnsafe(bytes);
const sourceStart = (partial === 'true' ? Math.floor(bytes / 2) : 0);
bench.start();
for (let i = 0; i < n; i++) {
source.copy(target, 0, sourceStart);
}
bench.end(n);
}
@@ -25,7 +25,6 @@ const { Math, Object } = primordials;

const {
byteLengthUtf8,
copy: _copy,
compare: _compare,
compareOffset,
createFromString,
@@ -69,6 +68,7 @@ const {
ERR_INVALID_ARG_VALUE,
ERR_INVALID_BUFFER_SIZE,
ERR_INVALID_OPT_VALUE,
ERR_OUT_OF_RANGE,
ERR_UNKNOWN_ENCODING
},
hideStackFrames
@@ -157,6 +157,74 @@ function showFlaggedDeprecation() {
bufferWarningAlreadyEmitted = true;
}

function toInteger(n, defaultVal) {
n = +n;
if (!Number.isNaN(n) &&
n >= Number.MIN_SAFE_INTEGER &&
n <= Number.MAX_SAFE_INTEGER) {
return ((n % 1) === 0 ? n : Math.floor(n));
}
return defaultVal;
}

function _copy(source, target, targetStart, sourceStart, sourceEnd) {
if (!isUint8Array(source))
throw new ERR_INVALID_ARG_TYPE('source', ['Buffer', 'Uint8Array'], source);
if (!isUint8Array(target))
throw new ERR_INVALID_ARG_TYPE('target', ['Buffer', 'Uint8Array'], target);

if (targetStart === undefined) {
targetStart = 0;
} else {
targetStart = toInteger(targetStart, 0);
if (targetStart < 0)
throw new ERR_OUT_OF_RANGE('targetStart', '>= 0', targetStart);
}

if (sourceStart === undefined) {
sourceStart = 0;
} else {
sourceStart = toInteger(sourceStart, 0);
if (sourceStart < 0)
throw new ERR_OUT_OF_RANGE('sourceStart', '>= 0', sourceStart);
}

if (sourceEnd === undefined) {
sourceEnd = source.length;
} else {
sourceEnd = toInteger(sourceEnd, 0);
if (sourceEnd < 0)
throw new ERR_OUT_OF_RANGE('sourceEnd', '>= 0', sourceEnd);
}

if (targetStart >= target.length || sourceStart >= sourceEnd)
return 0;

if (sourceStart > source.length) {
throw new ERR_OUT_OF_RANGE('sourceStart',
`<= ${source.length}`,
sourceStart);
}

if (sourceEnd - sourceStart > target.length - targetStart)
sourceEnd = sourceStart + target.length - targetStart;

let nb = sourceEnd - sourceStart;
const targetLen = target.length - targetStart;
const sourceLen = source.length - sourceStart;
if (nb > targetLen)
nb = targetLen;
if (nb > sourceLen)
nb = sourceLen;

if (sourceStart !== 0 || sourceEnd !== source.length)
source = new Uint8Array(source.buffer, source.byteOffset + sourceStart, nb);

target.set(source, targetStart);

return nb;
}

/**
* The Buffer() constructor is deprecated in documentation and should not be
* used moving forward. Rather, developers should use one of the three new
@@ -967,7 +967,8 @@ common.expectsError(
{
code: 'ERR_INVALID_ARG_TYPE',
type: TypeError,
message: 'argument must be a buffer'
message: 'The "target" argument must be one of type Buffer or Uint8Array.' +
' Received type undefined'
});

assert.throws(() => Buffer.from(), {
@@ -6,12 +6,6 @@ const assert = require('assert');
const b = Buffer.allocUnsafe(1024);
const c = Buffer.allocUnsafe(512);

const errorProperty = {
code: 'ERR_OUT_OF_RANGE',
type: RangeError,
message: 'Index out of range'
};

let cntr = 0;

{
@@ -116,7 +110,13 @@ b.copy(c, 0, 100, 10);
// Copy throws at negative sourceStart
common.expectsError(
() => Buffer.allocUnsafe(5).copy(Buffer.allocUnsafe(5), 0, -1),
errorProperty);
{
code: 'ERR_OUT_OF_RANGE',
type: RangeError,
message: 'The value of "sourceStart" is out of range. ' +
'It must be >= 0. Received -1'
}
);

{
// Check sourceEnd resets to targetEnd if former is greater than the latter
@@ -130,7 +130,14 @@ common.expectsError(

// Throw with negative sourceEnd
common.expectsError(
() => b.copy(c, 0, -1), errorProperty);
() => b.copy(c, 0, 0, -1),
{
code: 'ERR_OUT_OF_RANGE',
type: RangeError,
message: 'The value of "sourceEnd" is out of range. ' +
'It must be >= 0. Received -1'
}
);

// When sourceStart is greater than sourceEnd, zero copied
assert.strictEqual(b.copy(c, 0, 100, 10), 0);

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