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package main | |
import ( | |
"flag" | |
"net" | |
"os" | |
"syscall" | |
"github.com/golang/glog" | |
) | |
func main() { | |
flag.Parse() | |
ln, err := net.Listen("tcp", ":8080") | |
if err != nil { | |
glog.Fatalf("could not listen") | |
} | |
glog.Info("listening") | |
for { | |
conn, err := ln.Accept() | |
if err != nil { | |
glog.Error("error accepting connection") | |
continue | |
} | |
go handleConnection(conn, zeroCopy) | |
} | |
} | |
type spliceable interface { | |
File() (*os.File, error) | |
} | |
func handleConnection(iconn net.Conn, copyFunc func(in *os.File, ou *os.File)) { | |
in, ok := iconn.(spliceable) | |
if !ok { | |
glog.Errorf("not spliceable: %+v", iconn) | |
iconn.Close() | |
return | |
} | |
ifile, err := in.File() | |
iconn.Close() | |
if err != nil { | |
glog.Error("yolo out: %v", err) | |
return | |
} | |
oconn, err := net.Dial("tcp", "localhost:80") | |
if err != nil { | |
glog.Errorf("error getting file from spliceable") | |
return | |
} | |
out, ok := oconn.(spliceable) | |
if !ok { | |
glog.Errorf("not spliceable: %+v", oconn) | |
oconn.Close() | |
return | |
} | |
ofile, err := out.File() | |
oconn.Close() | |
if err != nil { | |
glog.Error("yolo out") | |
return | |
} | |
go copyFunc(ifile, ofile) | |
go copyFunc(ofile, ifile) | |
} | |
const txLength = 4098 | |
const ( | |
SPLICE_F_NONBLOCK = 0x02 | |
) | |
func zeroCopy(in *os.File, out *os.File) { | |
filedes := make([]int, 2) | |
err := syscall.Pipe(filedes) | |
if err != nil { | |
glog.Errorf("zero copy create pipe error: %v", err) | |
return | |
} | |
defer syscall.Close(filedes[0]) | |
defer syscall.Close(filedes[1]) | |
inFd := int(in.Fd()) | |
outFd := int(out.Fd()) | |
defer func() { | |
syscall.SetNonblock(int(inFd), true) | |
syscall.Close(inFd) | |
}() | |
defer func() { | |
syscall.SetNonblock(int(outFd), true) | |
syscall.Close(inFd) | |
}() | |
txLength := 2048 | |
for { | |
_, err := syscall.Splice(inFd, nil, filedes[1], nil, txLength, SPLICE_F_NONBLOCK) | |
if err != nil { | |
// if err == syscall.EAGAIN { | |
// runtime.Gosched() | |
// continue | |
// } | |
glog.Errorf("error splicing into pipe: %v", err) | |
return | |
} | |
sizeOut, err := syscall.Splice(filedes[0], nil, outFd, nil, txLength, SPLICE_F_NONBLOCK) | |
if err != nil { | |
// if err == syscall.EAGAIN { | |
// glog.Infof("caught") | |
// runtime.Gosched() | |
// return | |
// } | |
glog.Errorf("error splicing out of pipe: %+v", err) | |
return | |
} | |
if sizeOut == 0 { | |
glog.Info("done") | |
return | |
} | |
} | |
} | |
func copy(in *os.File, out *os.File) { | |
defer in.Close() | |
defer out.Close() | |
inFd := int(in.Fd()) | |
outFd := int(out.Fd()) | |
txLength := 2048 | |
buffer := make([]byte, txLength) | |
for { | |
_, err := syscall.Read(inFd, buffer) | |
if err != nil { | |
glog.Errorf("error reading: %v", err) | |
return | |
} | |
bytesWritten, err := syscall.Write(outFd, buffer) | |
if err != nil { | |
glog.Errorf("error writing: %v", err) | |
return | |
} | |
if bytesWritten < txLength { | |
glog.Info("done") | |
return | |
} | |
} | |
} |
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