forked from nuts/message-dispatcher
/
message-dispatcher.go
159 lines (137 loc) · 3.87 KB
/
message-dispatcher.go
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package main
import (
"flag"
"fmt"
"github.com/nuts/message-dispatcher/forwarders"
"github.com/streadway/amqp"
"log"
"net/url"
"os"
"os/signal"
"strings"
"sync"
"syscall"
"time"
)
var (
queueUrl string
queueName string
apiUrl string
numDispatchers uint
consumeTimeout time.Duration
requeueFailed bool
exitOnFailed bool
verbose bool
)
func init() {
flag.StringVar(&queueUrl, "from", queueUrl, "RabbitMQ url")
flag.StringVar(&queueName, "q", queueName, "queue name")
flag.StringVar(&apiUrl, "to", apiUrl, "forward to api url")
flag.UintVar(&numDispatchers, "#", 1, "number of concurrent dispatchers")
flag.DurationVar(&consumeTimeout, "t", consumeTimeout, "stop consuming when no messages arrive before the timeout")
flag.BoolVar(&requeueFailed, "requeue-failed", false, "requeue messages that failed to forward")
flag.BoolVar(&exitOnFailed, "exit-on-failed", false, "terminate the dispatcher when a forward fails")
flag.BoolVar(&verbose, "v", false, "verbose")
}
func main() {
flag.Parse()
forwarder, err := getForwarder(apiUrl)
if err != nil {
log.Fatal(err)
}
channel, err := getChannel(queueUrl)
if err != nil {
log.Fatal(err)
}
deliveries, err := getDeliveries(channel, queueName)
if err != nil {
log.Fatal(err)
}
if deliveries == nil {
os.Exit(1)
}
if verbose {
log.Printf("connected to: %q", queueUrl)
log.Printf("consuming queue: %s", queueName)
log.Printf("forwarding to: %#v\n", apiUrl)
log.Printf("number of dispatchers: %d", numDispatchers)
if consumeTimeout > 0 {
log.Printf("consume timeout: %v", consumeTimeout)
} else {
log.Printf("consume timeout: none")
}
log.Printf("requeuing messages on failure: %v", requeueFailed)
log.Printf("terminating dispatchers on failure: %v", requeueFailed)
}
errors := consumeDeliveries(deliveries, forwarder, numDispatchers, consumeTimeout, requeueFailed, exitOnFailed)
exitStatus := 0
for error := range errors {
exitStatus = 1
log.Printf("%s", error)
}
os.Exit(exitStatus)
}
func getForwarder(apiUrl string) (forwarders.Forwarder, error) {
apiEndpoint, err := url.Parse(apiUrl)
if err != nil {
return nil, err
}
switch apiEndpoint.Scheme {
case "unix":
return forwarders.NewSocketForwarder(apiEndpoint), nil
case "http", "https":
return forwarders.NewHttpForwarder(apiEndpoint), nil
}
return nil, fmt.Errorf("invalid api url: %s", apiUrl)
}
func getChannel(queueUrl string) (*amqp.Channel, error) {
conn, err := amqp.Dial(queueUrl)
if err != nil {
return nil, err
}
channel, err := conn.Channel()
if err != nil {
return nil, err
}
return channel, nil
}
func getDeliveries(channel *amqp.Channel, queueName string) (<-chan amqp.Delivery, error) {
deliveries, err := channel.Consume(queueName, "", false, true, true, false, nil)
if err != nil {
if err, ok := err.(*amqp.Error); ok {
if err.Code == amqp.AccessRefused && strings.HasSuffix(err.Reason, "in exclusive use") {
return nil, nil
}
}
return nil, err
}
return deliveries, nil
}
func consumeDeliveries(deliveries <-chan amqp.Delivery, forwarder forwarders.Forwarder, numDispatchers uint, consumeTimeout time.Duration, requeueFailed bool, returnOnFailed bool) <-chan error {
var wg sync.WaitGroup
errors := make(chan error)
quit := make(chan error)
handleSignals(numDispatchers, quit)
for i := uint(0); i < numDispatchers; i++ {
go func(consumerId uint) {
wg.Add(1)
forwarders.ForwardDeliveries(deliveries, forwarder, consumerId, consumeTimeout, requeueFailed, returnOnFailed, quit, errors)
wg.Done()
}(i)
}
go func() {
wg.Wait()
close(errors)
}()
return errors
}
func handleSignals(numDispatchers uint, quit chan<- error) {
signals := make(chan os.Signal, 1)
signal.Notify(signals, syscall.SIGQUIT, syscall.SIGINT)
go func() {
sig := <-signals
for i := uint(0); i < numDispatchers; i++ {
quit <- fmt.Errorf("quitting on %s signal\n", sig)
}
}()
}