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// Copyright 2017 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.
//go:build aix || linux || netbsd
package socket
import (
"net"
"os"
"sync"
"syscall"
)
type mmsghdrs []mmsghdr
func (hs mmsghdrs) unpack(ms []Message, parseFn func([]byte, string) (net.Addr, error), hint string) error {
for i := range hs {
ms[i].N = int(hs[i].Len)
ms[i].NN = hs[i].Hdr.controllen()
ms[i].Flags = hs[i].Hdr.flags()
if parseFn != nil {
var err error
ms[i].Addr, err = parseFn(hs[i].Hdr.name(), hint)
if err != nil {
return err
}
}
}
return nil
}
// mmsghdrsPacker packs Message-slices into mmsghdrs (re-)using pre-allocated buffers.
type mmsghdrsPacker struct {
// hs are the pre-allocated mmsghdrs.
hs mmsghdrs
// sockaddrs is the pre-allocated buffer for the Hdr.Name buffers.
// We use one large buffer for all messages and slice it up.
sockaddrs []byte
// vs are the pre-allocated iovecs.
// We allocate one large buffer for all messages and slice it up. This allows to reuse the buffer
// if the number of buffers per message is distributed differently between calls.
vs []iovec
}
func (p *mmsghdrsPacker) prepare(ms []Message) {
n := len(ms)
if n <= cap(p.hs) {
p.hs = p.hs[:n]
} else {
p.hs = make(mmsghdrs, n)
}
if n*sizeofSockaddrInet6 <= cap(p.sockaddrs) {
p.sockaddrs = p.sockaddrs[:n*sizeofSockaddrInet6]
} else {
p.sockaddrs = make([]byte, n*sizeofSockaddrInet6)
}
nb := 0
for _, m := range ms {
nb += len(m.Buffers)
}
if nb <= cap(p.vs) {
p.vs = p.vs[:nb]
} else {
p.vs = make([]iovec, nb)
}
}
func (p *mmsghdrsPacker) pack(ms []Message, parseFn func([]byte, string) (net.Addr, error), marshalFn func(net.Addr, []byte) int) mmsghdrs {
p.prepare(ms)
hs := p.hs
vsRest := p.vs
saRest := p.sockaddrs
for i := range hs {
nvs := len(ms[i].Buffers)
vs := vsRest[:nvs]
vsRest = vsRest[nvs:]
var sa []byte
if parseFn != nil {
sa = saRest[:sizeofSockaddrInet6]
saRest = saRest[sizeofSockaddrInet6:]
} else if marshalFn != nil {
n := marshalFn(ms[i].Addr, saRest)
if n > 0 {
sa = saRest[:n]
saRest = saRest[n:]
}
}
hs[i].Hdr.pack(vs, ms[i].Buffers, ms[i].OOB, sa)
}
return hs
}
// syscaller is a helper to invoke recvmmsg and sendmmsg via the RawConn.Read/Write interface.
// It is reusable, to amortize the overhead of allocating a closure for the function passed to
// RawConn.Read/Write.
type syscaller struct {
n int
operr error
hs mmsghdrs
flags int
boundRecvmmsgF func(uintptr) bool
boundSendmmsgF func(uintptr) bool
}
func (r *syscaller) init() {
r.boundRecvmmsgF = r.recvmmsgF
r.boundSendmmsgF = r.sendmmsgF
}
func (r *syscaller) recvmmsg(c syscall.RawConn, hs mmsghdrs, flags int) (int, error) {
r.n = 0
r.operr = nil
r.hs = hs
r.flags = flags
if err := c.Read(r.boundRecvmmsgF); err != nil {
return r.n, err
}
if r.operr != nil {
return r.n, os.NewSyscallError("recvmmsg", r.operr)
}
return r.n, nil
}
func (r *syscaller) recvmmsgF(s uintptr) bool {
r.n, r.operr = recvmmsg(s, r.hs, r.flags)
return ioComplete(r.flags, r.operr)
}
func (r *syscaller) sendmmsg(c syscall.RawConn, hs mmsghdrs, flags int) (int, error) {
r.n = 0
r.operr = nil
r.hs = hs
r.flags = flags
if err := c.Write(r.boundSendmmsgF); err != nil {
return r.n, err
}
if r.operr != nil {
return r.n, os.NewSyscallError("sendmmsg", r.operr)
}
return r.n, nil
}
func (r *syscaller) sendmmsgF(s uintptr) bool {
r.n, r.operr = sendmmsg(s, r.hs, r.flags)
return ioComplete(r.flags, r.operr)
}
// mmsgTmps holds reusable temporary helpers for recvmmsg and sendmmsg.
type mmsgTmps struct {
packer mmsghdrsPacker
syscaller syscaller
}
var defaultMmsgTmpsPool = mmsgTmpsPool{
p: sync.Pool{
New: func() interface{} {
tmps := new(mmsgTmps)
tmps.syscaller.init()
return tmps
},
},
}
type mmsgTmpsPool struct {
p sync.Pool
}
func (p *mmsgTmpsPool) Get() *mmsgTmps {
m := p.p.Get().(*mmsgTmps)
// Clear fields up to the len (not the cap) of the slice,
// assuming that the previous caller only used that many elements.
for i := range m.packer.sockaddrs {
m.packer.sockaddrs[i] = 0
}
m.packer.sockaddrs = m.packer.sockaddrs[:0]
for i := range m.packer.vs {
m.packer.vs[i] = iovec{}
}
m.packer.vs = m.packer.vs[:0]
for i := range m.packer.hs {
m.packer.hs[i].Len = 0
m.packer.hs[i].Hdr = msghdr{}
}
m.packer.hs = m.packer.hs[:0]
return m
}
func (p *mmsgTmpsPool) Put(tmps *mmsgTmps) {
p.p.Put(tmps)
}
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