Fix amq router race condition (#59)

Add retries when starting AMQP server to deal with the race
condition when AMQP router starts later than cloud-event-proxy
service, for example when a node is rebooted.

Signed-off-by: Jack Ding <jackding@gmail.com>

v1/amqp/amqp.go

@@ -15,39 +15,58 @@
 package amqp
 
 import (
+	"context"
 	"sync"
+	"time"
 
 	"github.com/Azure/go-amqp"
 
 	cloudevents "github.com/cloudevents/sdk-go/v2"
 	"github.com/redhat-cne/sdk-go/pkg/channel"
 	"github.com/redhat-cne/sdk-go/pkg/errorhandler"
 	amqp1 "github.com/redhat-cne/sdk-go/pkg/protocol/amqp"
+	log "github.com/sirupsen/logrus"
 )
 
 var (
-	instance *AMQP
-	once     sync.Once
+	instance      *AMQP
+	retryTimeout  = 500 * time.Millisecond
+	cancelTimeout = 30 * time.Second
 )
 
-//AMQP exposes amqp api methods
+// AMQP exposes amqp api methods
 type AMQP struct {
 	Router *amqp1.Router
 }
 
-//GetAMQPInstance get event instance
+// GetAMQPInstance get event instance
 func GetAMQPInstance(amqpHost string, dataIn <-chan *channel.DataChan, dataOut chan<- *channel.DataChan, closeCh <-chan struct{}) (*AMQP, error) {
-	once.Do(func() {
-		router, err := amqp1.InitServer(amqpHost, dataIn, dataOut, closeCh)
-		if err == nil {
-			instance = &AMQP{
-				Router: router,
-			}
+	ctx, cancel := context.WithTimeout(context.Background(), cancelTimeout)
+	defer cancel()
+	var router *amqp1.Router
+	var err error
+	for {
+		select {
+		case <-ctx.Done():
+			return nil, errorhandler.AMQPConnectionError{}
+		default:
 		}
-	})
+		router, err = amqp1.InitServer(amqpHost, dataIn, dataOut, closeCh)
+		if err != nil {
+			log.Info("retrying connecting to amqp.")
+			time.Sleep(retryTimeout)
+			continue
+		}
+
+		instance = &AMQP{
+			Router: router,
+		}
+		break
+	}
 	if instance == nil || instance.Router == nil {
-		return nil, errorhandler.AMQPConnectionError{Desc: "amqp connection error"}
+		return nil, errorhandler.AMQPConnectionError{}
 	}
+
 	if instance.Router.Client == nil {
 		client, err := instance.Router.NewClient(amqpHost, []amqp.ConnOption{})
 		if err != nil {
@@ -58,12 +77,12 @@ func GetAMQPInstance(amqpHost string, dataIn <-chan *channel.DataChan, dataOut c
 	return instance, nil
 }
 
-//Start start amqp processors
+// Start start amqp processors
 func (a *AMQP) Start(wg *sync.WaitGroup) {
 	go instance.Router.QDRRouter(wg)
 }
 
-//NewSender - create new sender independent of the framework
+// NewSender - create new sender independent of the framework
 func NewSender(hostName string, port int, address string) (*amqp1.Protocol, error) {
 	return amqp1.NewSender(hostName, port, address)
 }
@@ -73,7 +92,7 @@ func NewReceiver(hostName string, port int, address string) (*amqp1.Protocol, er
 	return amqp1.NewReceiver(hostName, port, address)
 }
 
-//DeleteSender send publisher address information  on a channel to delete its sender object
+// DeleteSender send publisher address information  on a channel to delete its sender object
 func DeleteSender(inChan chan<- *channel.DataChan, address string) {
 	// go ahead and create QDR to this address
 	inChan <- &channel.DataChan{
@@ -83,7 +102,7 @@ func DeleteSender(inChan chan<- *channel.DataChan, address string) {
 	}
 }
 
-//CreateSender send publisher address information  on a channel to create it's sender object
+// CreateSender send publisher address information  on a channel to create it's sender object
 func CreateSender(inChan chan<- *channel.DataChan, address string) {
 	// go ahead and create QDR to this address
 	inChan <- &channel.DataChan{
@@ -93,7 +112,7 @@ func CreateSender(inChan chan<- *channel.DataChan, address string) {
 	}
 }
 
-//DeleteListener send subscription address information  on a channel to delete its listener object
+// DeleteListener send subscription address information  on a channel to delete its listener object
 func DeleteListener(inChan chan<- *channel.DataChan, address string) {
 	// go ahead and create QDR listener to this address
 	inChan <- &channel.DataChan{
@@ -103,7 +122,7 @@ func DeleteListener(inChan chan<- *channel.DataChan, address string) {
 	}
 }
 
-//CreateListener send subscription address information  on a channel to create its listener object
+// CreateListener send subscription address information  on a channel to create its listener object
 func CreateListener(inChan chan<- *channel.DataChan, address string) {
 	// go ahead and create QDR listener to this address
 	inChan <- &channel.DataChan{
@@ -113,7 +132,7 @@ func CreateListener(inChan chan<- *channel.DataChan, address string) {
 	}
 }
 
-//CreateNewStatusListener send status address information  on a channel to create its listener object
+// CreateNewStatusListener send status address information  on a channel to create its listener object
 func CreateNewStatusListener(inChan chan<- *channel.DataChan, address string,
 	onReceiveOverrideFn func(e cloudevents.Event, dataChan *channel.DataChan) error,
 	processEventFn func(e interface{}) error) {