main.go

/*
Permission is hereby granted, free of charge, to any person
obtaining a copy of this software and associated documentation
files (the "Software"), to deal in the Software without
restriction, including without limitation the rights to use,
copy, modify, merge, publish, distribute, sublicense, and/or sell
copies of the Software, and to permit persons to whom the
Software is furnished to do so, subject to the following
conditions:
The above copyright notice and this permission notice shall be
included in all copies or substantial portions of the Software.
THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND,
EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES
OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND
NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT
HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY,
WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR
OTHER DEALINGS IN THE SOFTWARE.

See http://formwork-io.github.io/ for more.
*/

package main

import "os"
import "os/signal"
import "fmt"
import "strings"
import "syscall"
import "time"
import zmq "github.com/pebbe/zmq4"
import . "github.com/formwork-io/greenline/internal"

func main() {
	info := "greenline: notoriously unreliable\n" +
		"https://github.com/formwork-io/greenline\n" +
		"This is free software with ABSOLUTELY NO WARRANTY."
	fmt.Printf("%s\n--\n", info)
	var rails []Rail
	if len(os.Args) == 2 {
		var err error
		rails, err = ReadConfigFile(os.Args[1])
		if err != nil {
			die(err.Error())
		}
	} else {
		var err error
		rails, err = ReadEnvironment()
		if err != nil {
			die(err.Error())
		}
	}
	pprint("configuring %d rails", len(rails))

	socketPairs := make(map[*zmq.Socket]*zmq.Socket)
	socketNames := make(map[*zmq.Socket]string)
	poller := zmq.NewPoller()

	railmsg := "%s protocol %s, %d -> %d"

	for _, rail := range rails {

		var ingress *zmq.Socket
		var egress *zmq.Socket
		switch rail.Protocol {
		case "broadcast":
			ingress, egress = railToPubSub(&rail, poller)
		case "request":
			ingress, egress = railToRouterDealer(&rail, poller)
		default:
			die("The protocol %s is not valid.", rail.Protocol)
		}

		titledProtocol := strings.Title(rail.Protocol)
		pprint(railmsg, titledProtocol, rail.Name, rail.Ingress, rail.Egress)

		socketPairs[ingress] = egress
		socketNames[ingress] = fmt.Sprintf("%s (ingress)", rail.Name)

		socketPairs[egress] = ingress
		socketNames[egress] = fmt.Sprintf("%s (egress)", rail.Name)

		defer ingress.Close()
		defer egress.Close()
	}

	pprint("greenline alive")
	exitchan := make(chan os.Signal, 0)
	signal.Notify(exitchan, syscall.SIGINT, syscall.SIGTERM, syscall.SIGQUIT)
	go func() {
		sig := <-exitchan
		out("received %s signal, exiting.\n", sig.String())
		os.Exit(0)
	}()

	reloadchan := make(chan int)
	go reloader(reloadchan)
	readychan := make(chan bool)
	pollchan := make(chan bool)
	go func() {
		for {
			sockets, err := poller.Poll(-1)
			if err != nil {
				// get EINTR while polling?
				if IsEINTR(err) {
					// Continue polling; EINTR is normal for us...
					continue
					// ... with our use of signals.
				}

				// otherwise shutdown
				readychan <- false
				break
			}
			if len(sockets) != 0 {
				readychan <- true
			}
			// wait to poll once msgs processed
			<-pollchan
		}
	}()
	pprint("greenline ready")
	for {
		select {
		case reloadOp := <-reloadchan:
			if reloadOp&BinReload == BinReload {
				pprint("new binary available, restarting greenline")
				for key, value := range socketPairs {
					key.Close()
					value.Close()
				}
				zmq.Term()
				// exec or die
				restart()
			} else if reloadOp&ConfigReload == ConfigReload {
				pprint("new configuration available, restarting greenline")
				for key, value := range socketPairs {
					key.Close()
					value.Close()
				}
				zmq.Term()
				// exec or die
				restart()
			}
		case ready := <-readychan:
			if !ready {
				die("ready set fail")
			}
			// ready set go
			sockets, err := poller.Poll(-1)
			if err != nil {
				die("poll returned err: %s", err.Error())
			}

			for _, polled := range sockets {
				socket := polled.Socket
				pairedSocket := socketPairs[socket]
				name := socketNames[socket]

				pprint("processing message for %s", name)
				for {
					msg, err := socket.Recv(0)
					if err != nil {
						die("failed on receive: %s", err.Error())
					}
					more, err := socket.GetRcvmore()
					if err != nil {
						die("failed on receive more: %s", err.Error())
					}
					if more {
						pairedSocket.Send(msg, zmq.SNDMORE)
					} else {
						pairedSocket.Send(msg, 0)
						break
					}
				}
			}
			pollchan <- true
		}
	}
}

func railToPubSub(rail *Rail, poller *zmq.Poller) (ingress *zmq.Socket, egress *zmq.Socket) {
	// CREATE EACH SOCKET...
	ingress = newSocket(zmq.SUB)
	ingress.SetSubscribe("")

	egress = newSocket(zmq.PUB)
	egress.SetLinger(1)

	// ... AND BIND
	bind(ingress, "tcp", "0.0.0.0", rail.Ingress)
	bind(egress, "tcp", "0.0.0.0", rail.Egress)

	poller.Add(ingress, zmq.POLLIN)
	return
}

func railToRouterDealer(rail *Rail, poller *zmq.Poller) (ingress *zmq.Socket, egress *zmq.Socket) {
	// CREATE EACH SOCKET...
	ingress = newSocket(zmq.ROUTER)

	egress = newSocket(zmq.DEALER)
	egress.SetLinger(1)

	// ... AND BIND
	bind(ingress, "tcp", "0.0.0.0", rail.Ingress)
	bind(egress, "tcp", "0.0.0.0", rail.Egress)

	poller.Add(ingress, zmq.POLLIN)
	poller.Add(egress, zmq.POLLIN)
	return
}

func newSocket(ztype zmq.Type) (socket *zmq.Socket) {
	socket, err := zmq.NewSocket(ztype)
	if err != nil {
		die("failed creating socket type %d: %s", ztype, err.Error())
	}
	return
}

func bind(socket *zmq.Socket, transport string, address string, port int) {
	endpoint := fmt.Sprintf("%s://%s:%d", transport, address, port)
	err := socket.Bind(endpoint)
	if err != nil {
		die("failed binding %s: %s", endpoint, err.Error())
	}
}

func makeMsg(msg string, args ...interface{}) string {
	const layout = "%d%02d%02d-%02d-%02d-%02d greenline[%d]: %s"
	now := time.Now()
	year := now.Year()
	month := now.Month()
	day := now.Day()
	hour := now.Hour()
	minute := now.Minute()
	seconds := now.Second()
	pid := os.Getpid()
	arg := fmt.Sprintf(msg, args...)
	ret := fmt.Sprintf(layout, year, month, day, hour, minute, seconds, pid, arg)
	return ret
}

func pprint(msg string, args ...interface{}) {
	msg = makeMsg(msg, args...)
	fmt.Fprintf(os.Stdout, msg+"\n")
}

func out(msg string, args ...interface{}) {
	msg = makeMsg(msg, args...)
	fmt.Fprintf(os.Stdout, msg)
	os.Stdout.Sync()
}

func die(msg string, args ...interface{}) {
	msg = makeMsg(msg, args...)
	fmt.Fprintf(os.Stderr, msg+"\n")
	os.Exit(1)
}

// vim: ts=4 noexpandtab