packet.go

// Copyright 2014-2015 Matthew Endsley
// All rights reserved
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted providing that the following conditions
// are met:
// 1. Redistributions of source code must retain the above copyright
//    notice, this list of conditions and the following disclaimer.
// 2. Redistributions in binary form must reproduce the above copyright
//    notice, this list of conditions and the following disclaimer in the
//    documentation and/or other materials provided with the distribution.
//
// THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
// IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
// WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
// ARE DISCLAIMED.  IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY
// DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
// OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
// HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
// STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
// IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
// POSSIBILITY OF SUCH DAMAGE.

package mnet

import (
	"sync"
	"sync/atomic"
)

type refBuffer struct {
	refcnt int32
	data   [256]byte
}

var bufferFreeList = &sync.Pool{
	New: func() interface{} { return new(refBuffer) },
}

func newRefBuffer() *refBuffer {
	buffer := bufferFreeList.Get().(*refBuffer)
	buffer.refcnt = 1
	return buffer
}

func (rb *refBuffer) addref() {
	atomic.AddInt32(&rb.refcnt, 1)
}

func (rb *refBuffer) release() {
	if atomic.AddInt32(&rb.refcnt, -1) == 0 {
		bufferFreeList.Put(rb)
	}
}

type Packet struct {
	buf *refBuffer
	D   []byte
}

func NewPacket(sz int) Packet {
	buf := newRefBuffer()
	p := Packet{
		buf: buf,
		D:   buf.data[:0],
	}
	if len(buf.data) < sz {
		p.D = make([]byte, sz)
	}
	p.D = p.D[:sz]
	return p
}

func (p Packet) Reset() {
	p.D = p.buf.data[:0]
}

func (p Packet) Addref() {
	p.buf.addref()
}

func (p Packet) Free() {
	p.buf.release()
}