PKGBUILD/pkg/daemon/daemon.go

package daemon

import (
	"context"
	"fmt"
	"os"
	"os/signal"
	"sync"
	"syscall"

	"github.com/go-flucky/flucky/pkg/config"
	"github.com/go-flucky/flucky/pkg/sensor"
	"github.com/go-flucky/flucky/pkg/types"
	"github.com/volker-raschek/go-logger/pkg/logger"
)

var (
	flogger = logger.NewDefaultLogger(logger.LogLevelDebug)
)

// Start the daemon
func Start(cnf *config.Configuration, cacheSize uint, compression bool, round float64) error {

	storageEndpointURL, err := cnf.GetStorageEndpointURL()
	if err != nil {
		return err
	}

	cache := &cacheStore{
		compression: compression,
		cache:       make([]*types.MeasuredValue, 0),
		mux:         new(sync.Mutex),
		round:       round,
		URL:         storageEndpointURL,
	}

	// Context
	parentCtx := context.Background()
	ctx, cancel := context.WithCancel(parentCtx)

	// channels
	debugChannel := make(chan string, 0)
	infoChannel := make(chan string, 0)
	warnChannel := make(chan string, 0)
	errorChannel := make(chan error, 0)
	fatalChannel := make(chan error, 1)
	interruptChannel := make(chan os.Signal, 1)
	signal.Notify(interruptChannel, os.Interrupt, os.Kill, syscall.SIGTERM)
	measuredValueChannel := make(chan *types.MeasuredValue, 0)

	// Info
	flogger.Debug("Use compression: %v", compression)
	flogger.Debug("Round values to: %v", round)

	// Init semaphoreChannel
	semaphoreChannels := make(map[string]chan struct{})
	for _, sensor := range cnf.GetSensors(config.ENABLED) {
		semaphoreChannels[sensor.GetID()] = 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():
					return
				case <-semaphoreChannels[sensor.GetID()]:
					measuredValues, err := sensor.Read()
					if err != nil {
						errorChannel <- err
						return
					}
					for _, measuredValue := range measuredValues {
						measuredValueChannel <- measuredValue
					}
				}
			}
		}(s)

		// start ticker for each sensor
		go func(sensor sensor.Sensor) {
			for {
				select {
				case <-ctx.Done():
					return
				case <-sensor.GetTicker().C:
					semaphoreChannels[sensor.GetID()] <- struct{}{}
				}
			}
		}(s)
	}

	go func() {
		for {
			select {
			case <-ctx.Done():
				debugChannel <- fmt.Sprintf("Stop consumer of measured values: Closed context: %v", ctx.Err().Error())
				return
			case measuredValue := <-measuredValueChannel:
				cache.Add(measuredValue)
				debugChannel <- fmt.Sprintf("CacheStore ID: %v, Sensor ID: %v, Type: %v, Value: %v", cache.Size(), measuredValue.SensorID, measuredValue.ValueType, measuredValue.Value)
				if cache.Size() >= int(cacheSize) {
					debugChannel <- fmt.Sprint("Write cache into storage endpoint")
					err := cache.WriteToEndpoint()
					if err != nil {
						errorChannel <- err
					}
				}
			}
		}

	}()

	for {
		select {
		case debug, _ := <-debugChannel:
			flogger.Debug("%v", debug)
		case info, _ := <-infoChannel:
			flogger.Info("%v", info)
		case warn, _ := <-warnChannel:
			flogger.Warn("%v", warn)
		case err, _ := <-errorChannel:
			flogger.Error("%v", err)
		case fatal, _ := <-fatalChannel:
			flogger.Fatal("Received a fatal error: %v", fatal)
		case <-interruptChannel:
			flogger.Debug("Write %v cached values into storage endpoint", cache.Size())
			cache.WriteToEndpoint()
			flogger.Debug("Close context")
			cancel()
			flogger.Debug("Close channels")
			close(debugChannel)
			close(infoChannel)
			close(warnChannel)
			close(errorChannel)
			close(interruptChannel)
			return nil
		}
	}
}

// func checkDeviceInDatabase(ctx context.Context, device *types.Device, database db.Database) {
// 	_, err := database.SelectDeviceByID(ctx, device.ID)
// 	if err != nil {
// 		flogger.Debug("It's seems the current device is not registered in the database. Register the device now")
// 		err2 := database.InsertDevices(ctx, []*types.Device{device})
// 		if err2 != nil {
// 			flogger.Fatal("Can not register device into database: %v", err2)
// 		}
// 		flogger.Debug("Device successfully registered into the database")
// 		return
// 	}
// 	flogger.Debug("Device already registered into the database")
// }

// func checkSensorsInDatabase(ctx context.Context, sensors []*types.Sensor, database db.Database) {
// 	for _, sensor := range sensors {
// 		_, err := database.SelectSensorByID(ctx, sensor.ID)
// 		if err != nil {
// 			flogger.Debug("It's seems the sensor %v is not registered in the database. Register the sensor now", sensor.Name)
// 			err2 := database.InsertSensors(ctx, []*types.Sensor{sensor})
// 			if err2 != nil {
// 				flogger.Fatal("Can not register sensor %v into database: %v", sensor.Name, err2)
// 			}
// 			flogger.Debug("Sensor %v successfully registered into the database", sensor.Name)
// 			continue
// 		}
// 		flogger.Debug("Sensor %v is already registered into the database", sensor.Name)
// 	}
// }