Add continuous polling execution

This state polls the device states with 500 milliseconds period and
publishes the state on every poll.

1 files changed, 39 insertions, 9 deletions

diff --git a/main.go b/main.go
index f0dfb95..6ef4c63 100644
--- a/main.go
+++ b/main.go
@@ -3,6 +3,9 @@ package main
 import (
 	"fmt"
 	"log"
+	"os"
+	"os/signal"
+	"syscall"
 	"time"
 
 	mqtt "github.com/eclipse/paho.mqtt.golang"
@@ -18,22 +21,33 @@ const (
 	RETAINED                   = false
 	MQTT_CONNECT_TIMEOUT       = time.Second * 5
 	MQTT_DISCONNECT_TIMEOUT_US = 500
+	POLLING_PERIOD             = 500 * time.Millisecond
 )
 
 func main() {
 	log.Println("+++ Started Sia server +++")
 	defer log.Println("--- Stopped Sia server ---")
 
-	req, inventory, client, err := Start()
-	defer Stop(client)
-	if err != nil {
-		log.Fatalf("Failed startup process: %v", err)
-	}
+	go func() {
+		req, inventory, client, err := Start()
+		defer Stop(client)
+		if err != nil {
+			log.Fatalf("Failed startup process: %v", err)
+		}
 
-	err = Poll(req, inventory, client)
-	if err != nil {
-		log.Fatalf("Failed to poll states: %v", err)
-	}
+		for {
+			start := time.Now()
+
+			err = Poll(req, inventory, client)
+			if err != nil {
+				log.Fatalf("Failed to poll states: %v", err)
+			}
+
+			WaitUntil(start.Add(POLLING_PERIOD))
+		}
+	}()
+
+	Await(syscall.SIGTERM, syscall.SIGINT)
 }
 
 func ConnectMQTT(broker string, id string) (mqtt.Client, error) {
@@ -104,3 +118,19 @@ func Poll(req homematic.Requester, inventory homematic.Devices, client mqtt.Clie
 
 	return nil
 }
+
+func Await(signals ...syscall.Signal) {
+	listener := make(chan os.Signal)
+	for _, s := range signals {
+		signal.Notify(listener, s)
+	}
+	sig := <-listener
+	log.Printf("Received OS signal '%v'\n", sig)
+}
+
+func WaitUntil(deadline time.Time) {
+	duration := time.Until(deadline)
+	if duration > 0 {
+		time.Sleep(duration)
+	}
+}