76 lines
1.5 KiB
Go
76 lines
1.5 KiB
Go
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package main
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import (
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"fmt"
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"github.com/rcrowley/goagain"
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"log"
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"net"
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"syscall"
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"time"
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)
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func init() {
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log.SetFlags(log.Lmicroseconds | log.Lshortfile)
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log.SetPrefix(fmt.Sprintf("pid:%d ", syscall.Getpid()))
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}
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func main() {
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// Get the listener and ppid from the environment. If this is successful,
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// this process is a child that's inheriting and open listener from ppid.
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l, ppid, err := goagain.GetEnvs()
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if nil != err {
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// Listen on a TCP or a UNIX domain socket (TCP here).
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l, err = net.Listen("tcp", "127.0.0.1:48879")
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if nil != err {
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log.Fatalln(err)
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}
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log.Println("listening on", l.Addr())
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// Accept connections in a new goroutine.
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go serve(l)
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} else {
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// Resume listening and accepting connections in a new goroutine.
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log.Println("resuming listening on", l.Addr())
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go serve(l)
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// Kill the parent, now that the child has started successfully.
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if err := goagain.KillParent(ppid); nil != err {
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log.Fatalln(err)
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}
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}
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// Block the main goroutine awaiting signals.
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if err := goagain.AwaitSignals(l); nil != err {
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log.Fatalln(err)
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}
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// Do whatever's necessary to ensure a graceful exit like waiting for
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// goroutines to terminate or a channel to become closed.
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// In this case, we'll simply stop listening and wait one second.
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if err := l.Close(); nil != err {
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log.Fatalln(err)
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}
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time.Sleep(1e9)
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}
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func serve(l net.Listener) {
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for {
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c, err := l.Accept()
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if nil != err {
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if goagain.IsErrClosing(err) {
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break
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}
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log.Fatalln(err)
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}
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c.Write([]byte("Hello, world!\n"))
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c.Close()
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}
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}
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