fix(pkg/sensor): reduce interface functions for better error handling

pkg/daemon/daemon.go

@@ -2,6 +2,7 @@ package daemon
 
 import (
 	"context"
+	"fmt"
 	"os"
 	"os/signal"
 	"syscall"
@@ -59,8 +60,49 @@ func Start(cnf *config.Configuration, cleanCacheInterval time.Duration, compress
 	measuredValuesCache := make([]*types.MeasuredValue, 0)
 	// measuredValuesLogfile := logfile.New(cnf.Logfile)
 
-	// Producer
-	go sensor.ReadContinuously(ctx, cnf.GetSensors(config.ENABLED), measuredValueChannel, errorChannel)
+	// Init semaphoreChannel
+	semaphoreChannels := make(map[string]chan struct{})
+	for _, sensor := range cnf.GetSensors(config.ENABLED) {
+		semaphoreChannels[sensor.ID()] = make(chan struct{}, 1)
+	}
+
+	// Start producers
+	for _, s := range cnf.GetSensors(config.ENABLED) {
+
+		// start go routine for each sensor
+		go func(sensor sensor.Sensor) {
+			// run forever
+			for {
+				select {
+				case <-ctx.Done():
+					errorChannel <- fmt.Errorf("Closed context: %v", ctx.Err().Error())
+					return
+				case <-semaphoreChannels[sensor.ID()]:
+					measuredValues, err := sensor.Read()
+					if err != nil {
+						errorChannel <- err
+						return
+					}
+					for _, measmeasuredValue := range measuredValues {
+						measuredValueChannel <- measmeasuredValue
+					}
+				}
+			}
+		}(s)
+
+		// start ticker for each sensor
+		go func(sensor sensor.Sensor) {
+			for {
+				select {
+				case <-ctx.Done():
+					errorChannel <- fmt.Errorf("Closed context: %v", ctx.Err().Error())
+					return
+				case <-sensor.Ticker().C:
+					semaphoreChannels[sensor.ID()] <- struct{}{}
+				}
+			}
+		}(s)
+	}
 
 	// Distributor
 	//measuredValueChannels := distribute.MeasuredValues(ctx, 5, measuredValueChannel)
@@ -105,7 +147,11 @@ func Start(cnf *config.Configuration, cleanCacheInterval time.Duration, compress
 
 			measuredValuesCache = make([]*types.MeasuredValue, 0)
 
-		case measuredValue, _ := <-measuredValueChannel:
+		case measuredValue, open := <-measuredValueChannel:
+			if !open {
+				errorChannel <- fmt.Errorf("MeasuredValue channel closed")
+				cancel()
+			}
 			measuredValuesCache = append(measuredValuesCache, measuredValue)
 		}
 	}