cat to ZeroMQ in Go

cat-zmq.go

package main

import (
	"bufio"
	"flag"
	"github.com/alecthomas/gozmq"
	"io"
	"log"
	"os"
)

const ReadBufferSize = 128 << 10

func main() {
	endpoint := flag.String("endpoint", "", "")
	flag.Parse()
	paths := flag.Args()
	if len(paths) == 0 {
		paths = make([]string, 1)
		paths[0] = "-"
	}

	zmqContext, err := gozmq.NewContext()
	if err != nil {
		log.Fatalln(err)
	}
	sender, err := zmqContext.NewSocket(gozmq.DEALER)
	if err != nil {
		log.Fatalln("zmq.Socket:", err)
	}
	if err := sender.SetSockOptInt(gozmq.LINGER, 5*1000); err != nil {
		log.Fatalln("zmq.SetSockOpt:", err)
	}
	if err := sender.Connect(*endpoint); err != nil {
		log.Fatalln("zmq.Connect:", err)
	}

	for _, path := range paths {
		var f *os.File
		if path != "-" {
			f, err = os.Open(path)
			if err != nil {
				log.Fatalln("os.Open:", path, err)
			}
		} else {
			f = os.Stdin
		}
		br := bufio.NewReaderSize(f, ReadBufferSize)
		for {
			line, err := br.ReadBytes('\n')
			if err != nil && err != io.EOF {
				log.Fatalln("file.ReadBytes:", err)
			}
			if len(line) > 0 {
				if err := sender.Send(line, 0); err != nil {
					log.Fatalln("zmq.Send:", err)
				}
			}
			if err != nil || len(line) == 0 {
				break
			}
		}
		if path != "-" {
			if err := f.Close(); err != nil {
				log.Fatalln("file.Close:", err)
			}
		}
	}
	// Send empty message to denote end of stream.
	if err := sender.Send([]byte{}, 0); err != nil {
		log.Fatalln("zmq.Send:", err)
	}
	if err := sender.Close(); err != nil {
		log.Fatalln("zmq.socket.Close:", err)
	}
	zmqContext.Close()
}