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channel.go
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/
channel.go
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package main
import (
"bufio"
"encoding/binary"
"io"
"log"
"os"
"github.com/gotoz/runq/pkg/vm"
"golang.org/x/sys/unix"
)
const headerSize = 4 + 1 // 4 byte payload size + 1 byte message type
// AckChannel to send acknowledge messages to proxy.
// MsgChannel to receive messages from proxy.
func mkChannel(path string) (chan uint8, <-chan vm.Msg, error) {
fd, err := os.OpenFile(path, unix.O_RDWR, 0600|os.ModeExclusive)
if err != nil {
return nil, nil, err
}
ackChan := make(chan uint8)
msgChan := make(chan vm.Msg, 1)
go func() {
for {
value := <-ackChan
if _, err := fd.Write([]byte{value}); err != nil {
log.Printf("Write: %v", err)
}
ackChan <- 0
}
}()
go func() {
for {
// read header
buf := make([]byte, headerSize)
if _, err := io.ReadFull(fd, buf); err != nil {
log.Panic(err)
}
payloadSize := int(binary.BigEndian.Uint32(buf[:4]))
msgType := vm.Msgtype(buf[4])
// read payload
buf = make([]byte, payloadSize)
rd := bufio.NewReaderSize(fd, payloadSize)
if _, err := io.ReadFull(rd, buf); err != nil {
log.Panic(err)
}
msgChan <- vm.Msg{
Type: msgType,
Data: buf,
}
}
}()
return ackChan, msgChan, nil
}