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Backport 6893 for v6.x (buffer: improve creation performance) #7349

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Backport 6893 for v6.x (buffer: improve creation performance) #7349

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87 changes: 58 additions & 29 deletions lib/buffer.js
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Original file line number Diff line number Diff line change
Expand Up @@ -2,8 +2,14 @@
'use strict';

const binding = process.binding('buffer');
const { isArrayBuffer } = process.binding('util');
const bindingObj = {};

class FastBuffer extends Uint8Array {}

FastBuffer.prototype.constructor = Buffer;
Buffer.prototype = FastBuffer.prototype;

exports.Buffer = Buffer;
exports.SlowBuffer = SlowBuffer;
exports.INSPECT_MAX_BYTES = 50;
Expand Down Expand Up @@ -62,20 +68,18 @@ Buffer.prototype.swap32 = function swap32() {
const flags = bindingObj.flags;
const kNoZeroFill = 0;

function createBuffer(size, noZeroFill) {
flags[kNoZeroFill] = noZeroFill ? 1 : 0;
function createUnsafeBuffer(size) {
flags[kNoZeroFill] = 1;
try {
const ui8 = new Uint8Array(size);
Object.setPrototypeOf(ui8, Buffer.prototype);
return ui8;
return new FastBuffer(size);
} finally {
flags[kNoZeroFill] = 0;
}
}

function createPool() {
poolSize = Buffer.poolSize;
allocPool = createBuffer(poolSize, true);
allocPool = createUnsafeBuffer(poolSize);
poolOffset = 0;
}
createPool();
Expand Down Expand Up @@ -133,7 +137,6 @@ Buffer.from = function(value, encodingOrOffset, length) {
return fromObject(value);
};

Object.setPrototypeOf(Buffer.prototype, Uint8Array.prototype);
Object.setPrototypeOf(Buffer, Uint8Array);

function assertSize(size) {
Expand All @@ -153,18 +156,16 @@ function assertSize(size) {
**/
Buffer.alloc = function(size, fill, encoding) {
assertSize(size);
if (size <= 0)
return createBuffer(size);
if (fill !== undefined) {
if (size > 0 && fill !== undefined) {
// Since we are filling anyway, don't zero fill initially.
// Only pay attention to encoding if it's a string. This
// prevents accidentally sending in a number that would
// be interpretted as a start offset.
return typeof encoding === 'string' ?
createBuffer(size, true).fill(fill, encoding) :
createBuffer(size, true).fill(fill);
if (typeof encoding !== 'string')
encoding = undefined;
return createUnsafeBuffer(size).fill(fill, encoding);
}
return createBuffer(size);
return new FastBuffer(size);
};

/**
Expand All @@ -183,15 +184,15 @@ Buffer.allocUnsafe = function(size) {
**/
Buffer.allocUnsafeSlow = function(size) {
assertSize(size);
return createBuffer(size, true);
return createUnsafeBuffer(size);
};

// If --zero-fill-buffers command line argument is set, a zero-filled
// buffer is returned.
function SlowBuffer(length) {
if (+length != length)
length = 0;
return createBuffer(+length, true);
return createUnsafeBuffer(+length);
}

Object.setPrototypeOf(SlowBuffer.prototype, Uint8Array.prototype);
Expand All @@ -200,7 +201,7 @@ Object.setPrototypeOf(SlowBuffer, Uint8Array);

function allocate(size) {
if (size <= 0) {
return createBuffer(0);
return new FastBuffer();
}
if (size < (Buffer.poolSize >>> 1)) {
if (size > (poolSize - poolOffset))
Expand All @@ -213,7 +214,7 @@ function allocate(size) {
// Even though this is checked above, the conditional is a safety net and
// sanity check to prevent any subsequent typed array allocation from not
// being zero filled.
return createBuffer(size, true);
return createUnsafeBuffer(size);
}
}

Expand All @@ -226,7 +227,7 @@ function fromString(string, encoding) {
throw new TypeError('"encoding" must be a valid string encoding');

if (string.length === 0)
return Buffer.alloc(0);
return new FastBuffer();

var length = byteLength(string, encoding);

Expand All @@ -246,18 +247,30 @@ function fromArrayLike(obj) {
const length = obj.length;
const b = allocate(length);
for (var i = 0; i < length; i++)
b[i] = obj[i] & 255;
b[i] = obj[i];
return b;
}

function fromArrayBuffer(obj, byteOffset, length) {
if (!isArrayBuffer(obj))
throw new TypeError('argument is not an ArrayBuffer');

byteOffset >>>= 0;

if (typeof length === 'undefined')
return binding.createFromArrayBuffer(obj, byteOffset);
const maxLength = obj.byteLength - byteOffset;

if (maxLength <= 0)
throw new RangeError("'offset' is out of bounds");

if (length === undefined) {
length = maxLength;
} else {
length >>>= 0;
if (length > maxLength)
throw new RangeError("'length' is out of bounds");
}

length >>>= 0;
return binding.createFromArrayBuffer(obj, byteOffset, length);
return new FastBuffer(obj, byteOffset, length);
}

function fromObject(obj) {
Expand All @@ -274,7 +287,7 @@ function fromObject(obj) {
if (obj) {
if (obj.buffer instanceof ArrayBuffer || 'length' in obj) {
if (typeof obj.length !== 'number' || obj.length !== obj.length) {
return allocate(0);
return new FastBuffer();
}
return fromArrayLike(obj);
}
Expand Down Expand Up @@ -341,7 +354,7 @@ Buffer.concat = function(list, length) {
throw new TypeError('"list" argument must be an Array of Buffers');

if (list.length === 0)
return Buffer.alloc(0);
return new FastBuffer();

if (length === undefined) {
length = 0;
Expand Down Expand Up @@ -818,10 +831,26 @@ Buffer.prototype.toJSON = function() {
};


function adjustOffset(offset, length) {
offset = +offset;
if (offset === 0 || Number.isNaN(offset)) {
return 0;
}
if (offset < 0) {
offset += length;
return offset > 0 ? offset : 0;
} else {
return offset < length ? offset : length;
}
}


Buffer.prototype.slice = function slice(start, end) {
const buffer = this.subarray(start, end);
Object.setPrototypeOf(buffer, Buffer.prototype);
return buffer;
const srcLength = this.length;
start = adjustOffset(start, srcLength);
end = end !== undefined ? adjustOffset(end, srcLength) : srcLength;
const newLength = end > start ? end - start : 0;
return new FastBuffer(this.buffer, this.byteOffset + start, newLength);
};


Expand Down
28 changes: 0 additions & 28 deletions src/node_buffer.cc
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Original file line number Diff line number Diff line change
Expand Up @@ -427,33 +427,6 @@ void CreateFromString(const FunctionCallbackInfo<Value>& args) {
}


void CreateFromArrayBuffer(const FunctionCallbackInfo<Value>& args) {
Environment* env = Environment::GetCurrent(args);
if (!args[0]->IsArrayBuffer())
return env->ThrowTypeError("argument is not an ArrayBuffer");
Local<ArrayBuffer> ab = args[0].As<ArrayBuffer>();

size_t ab_length = ab->ByteLength();
size_t offset;
size_t max_length;

CHECK_NOT_OOB(ParseArrayIndex(args[1], 0, &offset));
CHECK_NOT_OOB(ParseArrayIndex(args[2], ab_length - offset, &max_length));

if (offset >= ab_length)
return env->ThrowRangeError("'offset' is out of bounds");
if (max_length > ab_length - offset)
return env->ThrowRangeError("'length' is out of bounds");

Local<Uint8Array> ui = Uint8Array::New(ab, offset, max_length);
Maybe<bool> mb =
ui->SetPrototype(env->context(), env->buffer_prototype_object());
if (!mb.FromMaybe(false))
return env->ThrowError("Unable to set Object prototype");
args.GetReturnValue().Set(ui);
}


template <encoding encoding>
void StringSlice(const FunctionCallbackInfo<Value>& args) {
Environment* env = Environment::GetCurrent(args);
Expand Down Expand Up @@ -1246,7 +1219,6 @@ void Initialize(Local<Object> target,

env->SetMethod(target, "setupBufferJS", SetupBufferJS);
env->SetMethod(target, "createFromString", CreateFromString);
env->SetMethod(target, "createFromArrayBuffer", CreateFromArrayBuffer);

env->SetMethod(target, "byteLengthUtf8", ByteLengthUtf8);
env->SetMethod(target, "compare", Compare);
Expand Down