Initial commit.

nats/exported.go

@@ -0,0 +1,87 @@
+package nats
+
+import (
+	// stdlib
+	"log"
+	"sync"
+
+	// local
+	"github.com/pztrn/ffmpeger/config"
+
+	// other
+	"github.com/nats-io/nats.go"
+)
+
+const (
+	Topic = "ffmpeger.v1"
+)
+
+var (
+	natsConn         *nats.Conn
+	natsSubscription *nats.Subscription
+
+	// Handlers.
+	handlers      []*Handler
+	handlersMutex sync.Mutex
+)
+
+// AddHandler adds handler for received NATS messages.
+func AddHandler(hndl *Handler) {
+	handlersMutex.Lock()
+	handlers = append(handlers, hndl)
+	handlersMutex.Unlock()
+}
+
+// Initialize initializes package.
+func Initialize() {
+	log.Println("Initializing NATS handler...")
+
+	handlers = make([]*Handler, 0, 8)
+}
+
+// Handler for NATS messages.
+func messageHandler(msg *nats.Msg) {
+	log.Println("Received message:", string(msg.Data))
+
+	handlersMutex.Lock()
+	for _, hndl := range handlers {
+		hndl.Func(msg.Data)
+	}
+	handlersMutex.Unlock()
+}
+
+// Shutdown unsubscribes from topic and disconnects from NATS.
+func Shutdown() {
+	log.Println("Unsuscribing from NATS topic...")
+	err := natsSubscription.Unsubscribe()
+	if err != nil {
+		log.Println("ERROR unsubscribing", Topic, "topic:", err.Error())
+	}
+
+	if natsConn != nil {
+		log.Println("Closing connection to NATS...")
+		natsConn.Close()
+	} else {
+		log.Println("Connection to NATS wasn't established")
+	}
+}
+
+// StartListening connects to NATS and starts to listen for messages.
+func StartListening() {
+	nc, err := nats.Connect(config.Cfg.NATS.ConnectionString)
+	if err != nil {
+		log.Fatalln("Failed to connect to NATS:", err.Error())
+	}
+
+	natsConn = nc
+	log.Println("NATS connection established")
+
+	// Beware - if ffmpeger will be launched more than once and subscribed
+	// to same topic (which is hardcoded here) then ALL instances of
+	// ffmpeger will receive this message!
+	sub, err1 := nc.Subscribe(Topic, messageHandler)
+	if err1 != nil {
+		log.Fatalln("Failed to subscribe to", Topic, "topic:", err1.Error())
+	}
+	natsSubscription = sub
+}

nats/handler.go

@@ -0,0 +1,6 @@
+package nats
+
+type Handler struct {
+	Name string
+	Func func(data []byte)
+}