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package quic
import (
"sync"
"github.com/quic-go/quic-go/internal/protocol"
)
type packetBuffer struct {
Data []byte
// refCount counts how many packets Data is used in.
// It doesn't support concurrent use.
// It is > 1 when used for coalesced packet.
refCount int
}
// Split increases the refCount.
// It must be called when a packet buffer is used for more than one packet,
// e.g. when splitting coalesced packets.
func (b *packetBuffer) Split() {
b.refCount++
}
// Decrement decrements the reference counter.
// It doesn't put the buffer back into the pool.
func (b *packetBuffer) Decrement() {
b.refCount--
if b.refCount < 0 {
panic("negative packetBuffer refCount")
}
}
// MaybeRelease puts the packet buffer back into the pool,
// if the reference counter already reached 0.
func (b *packetBuffer) MaybeRelease() {
// only put the packetBuffer back if it's not used any more
if b.refCount == 0 {
b.putBack()
}
}
// Release puts back the packet buffer into the pool.
// It should be called when processing is definitely finished.
func (b *packetBuffer) Release() {
b.Decrement()
if b.refCount != 0 {
panic("packetBuffer refCount not zero")
}
b.putBack()
}
// Len returns the length of Data
func (b *packetBuffer) Len() protocol.ByteCount { return protocol.ByteCount(len(b.Data)) }
func (b *packetBuffer) Cap() protocol.ByteCount { return protocol.ByteCount(cap(b.Data)) }
func (b *packetBuffer) putBack() {
if cap(b.Data) == protocol.MaxPacketBufferSize {
bufferPool.Put(b)
return
}
if cap(b.Data) == protocol.MaxLargePacketBufferSize {
largeBufferPool.Put(b)
return
}
panic("putPacketBuffer called with packet of wrong size!")
}
var bufferPool, largeBufferPool sync.Pool
func getPacketBuffer() *packetBuffer {
buf := bufferPool.Get().(*packetBuffer)
buf.refCount = 1
buf.Data = buf.Data[:0]
return buf
}
func getLargePacketBuffer() *packetBuffer {
buf := largeBufferPool.Get().(*packetBuffer)
buf.refCount = 1
buf.Data = buf.Data[:0]
return buf
}
func init() {
bufferPool.New = func() any {
return &packetBuffer{Data: make([]byte, 0, protocol.MaxPacketBufferSize)}
}
largeBufferPool.New = func() any {
return &packetBuffer{Data: make([]byte, 0, protocol.MaxLargePacketBufferSize)}
}
}
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