src: use subarray() in Buffer#slice() for speedup
Use the built-in Typed Array method subarray() to improve performance of Buffer#slice(). Benchmark improvements: benchmark/buffer-slice: 40% benchmark/buffer-creation (pool): 25% Additional tests also added. PR-URL: https://github.com/nodejs/node/pull/2777 Reviewed-By: Trevor Norris <trev.norris@gmail.com> Reviewed-By: Сковорода Никита Андреевич <chalkerx@gmail.com>
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@ -73,7 +73,7 @@ function allocate(size) {
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if (size < (Buffer.poolSize >>> 1)) {
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if (size > (poolSize - poolOffset))
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createPool();
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var b = binding.slice(allocPool, poolOffset, poolOffset + size);
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var b = allocPool.slice(poolOffset, poolOffset + size);
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poolOffset += size;
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alignPool();
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return b;
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@ -94,7 +94,7 @@ function fromString(string, encoding) {
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if (length > (poolSize - poolOffset))
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createPool();
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var actual = allocPool.write(string, poolOffset, encoding);
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var b = binding.slice(allocPool, poolOffset, poolOffset + actual);
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var b = allocPool.slice(poolOffset, poolOffset + actual);
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poolOffset += actual;
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alignPool();
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return b;
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@ -552,30 +552,9 @@ Buffer.prototype.toJSON = function() {
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// TODO(trevnorris): currently works like Array.prototype.slice(), which
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// doesn't follow the new standard for throwing on out of range indexes.
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Buffer.prototype.slice = function slice(start, end) {
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var len = this.length;
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start = ~~start;
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end = end === undefined ? len : ~~end;
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if (start < 0) {
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start += len;
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if (start < 0)
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start = 0;
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} else if (start > len) {
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start = len;
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}
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if (end < 0) {
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end += len;
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if (end < 0)
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end = 0;
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} else if (end > len) {
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end = len;
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}
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if (end < start)
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end = start;
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return binding.slice(this, start, end);
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const buffer = this.subarray(start, end);
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Object.setPrototypeOf(buffer, Buffer.prototype);
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return buffer;
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};
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@ -456,29 +456,6 @@ void CreateFromArrayBuffer(const FunctionCallbackInfo<Value>& args) {
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}
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void Slice(const FunctionCallbackInfo<Value>& args) {
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CHECK(args[0]->IsUint8Array());
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CHECK(args[1]->IsNumber());
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CHECK(args[2]->IsNumber());
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Environment* env = Environment::GetCurrent(args);
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Local<Uint8Array> ab_ui = args[0].As<Uint8Array>();
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Local<ArrayBuffer> ab = ab_ui->Buffer();
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ArrayBuffer::Contents ab_c = ab->GetContents();
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size_t offset = ab_ui->ByteOffset();
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size_t start = args[1]->NumberValue() + offset;
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size_t end = args[2]->NumberValue() + offset;
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CHECK_GE(end, start);
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size_t size = end - start;
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CHECK_GE(ab_c.ByteLength(), start + size);
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Local<Uint8Array> ui = Uint8Array::New(ab, start, size);
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Maybe<bool> mb =
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ui->SetPrototype(env->context(), env->buffer_prototype_object());
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if (!mb.FromMaybe(false))
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return env->ThrowError("Unable to set Object prototype");
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args.GetReturnValue().Set(ui);
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}
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template <encoding encoding>
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void StringSlice(const FunctionCallbackInfo<Value>& args) {
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Environment* env = Environment::GetCurrent(args);
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@ -1002,7 +979,6 @@ void Initialize(Local<Object> target,
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env->SetMethod(target, "createFromString", CreateFromString);
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env->SetMethod(target, "createFromArrayBuffer", CreateFromArrayBuffer);
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env->SetMethod(target, "slice", Slice);
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env->SetMethod(target, "byteLengthUtf8", ByteLengthUtf8);
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env->SetMethod(target, "compare", Compare);
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env->SetMethod(target, "fill", Fill);
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@ -1061,14 +1061,46 @@ assert.equal(buf.readInt8(0), -1);
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assert.equal(buf.slice(-10, 10), '0123456789');
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assert.equal(buf.slice(-20, 10), '0123456789');
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assert.equal(buf.slice(-20, -10), '');
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assert.equal(buf.slice(), '0123456789');
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assert.equal(buf.slice(0), '0123456789');
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assert.equal(buf.slice(0, 0), '');
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assert.equal(buf.slice(undefined), '0123456789');
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assert.equal(buf.slice('foobar'), '0123456789');
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assert.equal(buf.slice(undefined, undefined), '0123456789');
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assert.equal(buf.slice(2), '23456789');
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assert.equal(buf.slice(5), '56789');
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assert.equal(buf.slice(10), '');
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assert.equal(buf.slice(5, 8), '567');
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assert.equal(buf.slice(8, -1), '8');
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assert.equal(buf.slice(-10), '0123456789');
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assert.equal(buf.slice(0, -9), '0');
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assert.equal(buf.slice(0, -10), '');
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assert.equal(buf.slice(0, -1), '012345678');
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assert.equal(buf.slice(2, -2), '234567');
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assert.equal(buf.slice(0, 65536), '0123456789');
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assert.equal(buf.slice(65536, 0), '');
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assert.equal(buf.slice(-5, -8), '');
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assert.equal(buf.slice(-5, -3), '56');
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assert.equal(buf.slice(-10, 10), '0123456789');
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for (var i = 0, s = buf.toString(); i < buf.length; ++i) {
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assert.equal(buf.slice(i), s.slice(i));
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assert.equal(buf.slice(0, i), s.slice(0, i));
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assert.equal(buf.slice(-i), s.slice(-i));
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assert.equal(buf.slice(0, -i), s.slice(0, -i));
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}
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var utf16Buf = new Buffer('0123456789', 'utf16le');
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assert.deepEqual(utf16Buf.slice(0, 6), Buffer('012', 'utf16le'));
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assert.equal(buf.slice('0', '1'), '0');
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assert.equal(buf.slice('-5', '10'), '56789');
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assert.equal(buf.slice('-10', '10'), '0123456789');
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assert.equal(buf.slice('-10', '-5'), '01234');
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assert.equal(buf.slice('-10', '-0'), '');
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assert.equal(buf.slice('111'), '');
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assert.equal(buf.slice('0', '-111'), '');
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// try to slice a zero length Buffer
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// see https://github.com/joyent/node/issues/5881
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SlowBuffer(0).slice(0, 1);
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