From b8aea094a48f180fed5e4459be5bb54fa265564b Mon Sep 17 00:00:00 2001 From: Ingvar Stepanyan Date: Fri, 20 May 2016 10:50:53 +0100 Subject: [PATCH] buffer: improve creation performance. MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Improves performance of allocating unsafe buffers, creating buffers from an existing ArrayBuffer and creating .slice(...) from existing Buffer by avoiding deoptimizing change of prototype after Uint8Array allocation in favor of ES6 native subclassing. This is done through an internal ES6 class that extends Uint8Array and is used for allocations, but the regular Buffer function is exposed, so calling Buffer(...) with or without `new` continues to work as usual and prototype chains are also preserved. Performance wins for .slice are +120% (2.2x), and, consequently, for unsafe allocations up to +95% (1.9x) for small buffers, and for safe allocations (zero-filled) up to +30% (1.3x). PR-URL: https://github.com/nodejs/node/pull/6893 Reviewed-By: Anna Henningsen Reviewed-By: Сковорода Никита Андреевич --- lib/buffer.js | 87 ++++++++++++++++++++++++++++++---------------- src/node_buffer.cc | 28 --------------- 2 files changed, 58 insertions(+), 57 deletions(-) diff --git a/lib/buffer.js b/lib/buffer.js index 2472390086057c..08575c10890c63 100644 --- a/lib/buffer.js +++ b/lib/buffer.js @@ -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; @@ -62,12 +68,10 @@ 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; } @@ -75,7 +79,7 @@ function createBuffer(size, noZeroFill) { function createPool() { poolSize = Buffer.poolSize; - allocPool = createBuffer(poolSize, true); + allocPool = createUnsafeBuffer(poolSize); poolOffset = 0; } createPool(); @@ -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) { @@ -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); }; /** @@ -183,7 +184,7 @@ 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 @@ -191,7 +192,7 @@ Buffer.allocUnsafeSlow = function(size) { function SlowBuffer(length) { if (+length != length) length = 0; - return createBuffer(+length, true); + return createUnsafeBuffer(+length); } Object.setPrototypeOf(SlowBuffer.prototype, Uint8Array.prototype); @@ -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)) @@ -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); } } @@ -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); @@ -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) { @@ -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); } @@ -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; @@ -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); }; diff --git a/src/node_buffer.cc b/src/node_buffer.cc index bb77387e8f87b7..345e6fe4c5b782 100644 --- a/src/node_buffer.cc +++ b/src/node_buffer.cc @@ -427,33 +427,6 @@ void CreateFromString(const FunctionCallbackInfo& args) { } -void CreateFromArrayBuffer(const FunctionCallbackInfo& args) { - Environment* env = Environment::GetCurrent(args); - if (!args[0]->IsArrayBuffer()) - return env->ThrowTypeError("argument is not an ArrayBuffer"); - Local ab = args[0].As(); - - 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 ui = Uint8Array::New(ab, offset, max_length); - Maybe 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 void StringSlice(const FunctionCallbackInfo& args) { Environment* env = Environment::GetCurrent(args); @@ -1246,7 +1219,6 @@ void Initialize(Local 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);