Add ContextWithCancel for better termination pending response

Author: d2r2

dht.go

@@ -6,10 +6,14 @@ import "C"
 
 import (
 	"bytes"
+	"context"
+	"errors"
 	"fmt"
 	"reflect"
 	"time"
 	"unsafe"
+
+	"github.com/d2r2/go-shell/shell"
 )
 
 type SensorType int
@@ -55,7 +59,7 @@ func dialDHTxxAndGetResponse(pin int, boostPerfFlag bool) ([]Pulse, error) {
 	// Return array: [pulse, duration, pulse, duration, ...]
 	r := C.dial_DHTxx_and_read(C.int32_t(pin), boost, &arr, &arrLen)
 	if r == -1 {
-		err := fmt.Errorf("Error during call C.dial_DHTxx_and_read()")
+		err := errors.New("Error during call C.dial_DHTxx_and_read()")
 		return nil, err
 	}
 	defer C.free(unsafe.Pointer(arr))
@@ -159,7 +163,7 @@ func decodeDHTxxPulses(sensorType SensorType, pulses []Pulse) (temperature float
 		return -1, -1, err
 	}
 	// Debug output for 5 bytes
-	log.Debugf("Five bytes from DHTxx: [%d, %d, %d, %d, %d]", b0, b1, b2, b3, sum)
+	lg.Debugf("Five bytes from DHTxx: [%d, %d, %d, %d, %d]", b0, b1, b2, b3, sum)
 	// Extract temprature and humidity depending on sensor type
 	temperature, humidity = 0.0, 0.0
 	if sensorType == DHT11 {
@@ -186,7 +190,7 @@ func printPulseArrayForDebug(pulses []Pulse) {
 		buf.WriteString(fmt.Sprintf("pulse %3d: %v, %v\n", i,
 			pulse.Value, pulse.Duration))
 	}
-	log.Debugf("Pulse count %d:\n%v", len(pulses), buf.String())
+	lg.Debugf("Pulse count %d:\n%v", len(pulses), buf.String())
 }
 
 // Send activation request to DHTxx sensor via specific pin.
@@ -238,17 +242,25 @@ func ReadDHTxx(sensorType SensorType, pin int,
 // 4) error if present.
 func ReadDHTxxWithRetry(sensorType SensorType, pin int, boostPerfFlag bool,
 	retry int) (temperature float32, humidity float32, retried int, err error) {
+	ctx, cancel := context.WithCancel(context.Background())
+	shell.CloseContextOnKillSignal(cancel)
 	retried = 0
 	for {
 		temp, hum, err := ReadDHTxx(sensorType, pin, boostPerfFlag)
 		if err != nil {
 			if retry > 0 {
-				log.Warningf("%v", err)
+				lg.Warning(err)
 				retry--
 				retried++
-				// Sleep before new attempt
-				time.Sleep(1500 * time.Millisecond)
-				continue
+				select {
+				case <-ctx.Done():
+					// Interrupt loop, if pending termination
+					return -1, -1, retried, errors.New("Termination pending...")
+				default:
+					// Sleep before new attempt
+					time.Sleep(1500 * time.Millisecond)
+					continue
+				}
 			}
 			return -1, -1, retried, err
 		}

examples/example1.go

@@ -1,10 +1,13 @@
 package main
 
 import (
-	"fmt"
-	"log"
-
 	"github.com/d2r2/go-dht"
+	logger "github.com/d2r2/go-logger"
+)
+
+var lg = logger.NewPackageLogger("main",
+	logger.DebugLevel,
+	// logger.InfoLevel,
 )
 
 func main() {
@@ -13,15 +16,16 @@ func main() {
 	// as Raspberry PI 1 (this will require root privileges). You can switch off
 	// "boost GPIO performance" parameter for old devices, but it may increase
 	// retry attempts. Play with this parameter.
+	defer logger.FinalizeLogger()
 	sensorType := dht.DHT22
 	for {
 		temperature, humidity, retried, err :=
 			dht.ReadDHTxxWithRetry(sensorType, 4, false, 10)
 		if err != nil {
-			log.Fatal(err)
+			lg.Fatal(err)
 		}
 		// print temperature and humidity
-		fmt.Printf("Sensor = %v: Temperature = %v*C, Humidity = %v%% (retried %d times)\n",
+		lg.Infof("Sensor = %v: Temperature = %v*C, Humidity = %v%% (retried %d times)",
 			sensorType, temperature, humidity, retried)
 	}
 }

examples/example2.go

@@ -8,6 +8,12 @@ import (
 	"time"
 
 	"github.com/d2r2/go-dht"
+	logger "github.com/d2r2/go-logger"
+)
+
+var lg = logger.NewPackageLogger("main",
+	logger.DebugLevel,
+	// logger.InfoLevel,
 )
 
 var (
@@ -38,7 +44,7 @@ func main() {
 	temperature, humidity, retried, err :=
 		dht.ReadDHTxxWithRetry(sensorType, pin, boostPerfFlag, 10)
 	if err != nil {
-		panic(err)
+		lg.Fatal(err)
 	}
 
 	//fmt.Printf("Sensor = %v: Temperature = %v*C, Humidity = %v%% (retried %d times)\n",

logger.go

@@ -1,41 +1,10 @@
 package dht
 
-import (
-	"os"
+import logger "github.com/d2r2/go-logger"
 
-	"github.com/op/go-logging"
+// You can manage verbosity of log output
+// in the package by changing last parameter value.
+var lg = logger.NewPackageLogger("dht",
+	logger.DebugLevel,
+	// logger.InfoLevel,
 )
-
-// Comment INFO and uncomment DEBUG if you want detail debug output in library.
-var log *logging.Logger = buildLogger("dht",
-	//	logging.DEBUG,
-	logging.INFO,
-)
-
-var terminalBackend logging.LeveledBackend = nil
-
-func buildLogger(module string, level logging.Level) *logging.Logger {
-	// Set the backends to be used.
-	if terminalBackend == nil {
-		// Everything except the message has a custom color
-		// which is dependent on the log level. Many fields have a custom output
-		// formatting too, eg. the time returns the hour down to the milli second.
-		var format = logging.MustStringFormatter(
-			"%{time:2006-01-02T15:04:05.000} [%{module}] " +
-				"%{color}%{level:.4s}%{color:reset}  %{message}",
-		)
-		// Create backend for os.Stderr.
-		var backend logging.Backend = logging.NewLogBackend(os.Stderr, "", 0)
-
-		// For messages written to backend we want to add some additional
-		// information to the output, including the used log level and the name of
-		// the function.
-		var backendFormatter logging.Backend = logging.NewBackendFormatter(backend, format)
-		var backendLeveled logging.LeveledBackend = logging.AddModuleLevel(backendFormatter)
-		terminalBackend = backendLeveled
-		logging.SetBackend(terminalBackend)
-	}
-	log := logging.MustGetLogger(module)
-	terminalBackend.SetLevel(level, module)
-	return log
-}