Use a context for closing channels. (#10)

Reviewed-on: #10
Co-authored-by: Anna Rose Wiggins <annabunches@gmail.com>
Co-committed-by: Anna Rose Wiggins <annabunches@gmail.com>

cmd/joyful/main.go

@@ -1,6 +1,7 @@
 package main
 
 import (
+	"context"
 	"flag"
 	"fmt"
 	"os"
@@ -71,7 +72,7 @@ func main() {
 	// Initialize physical devices
 	pDevices := initPhysicalDevices(config)
 
-	rules, eventChannel, doneChannel, wg := loadRules(config, pDevices, getVirtualDevices(vBuffersByName))
+	rules, eventChannel, cancel, wg := loadRules(config, pDevices, getVirtualDevices(vBuffersByName))
 
 	// initialize the mode variable
 	mode := config.GetModes()[0]
@@ -115,12 +116,12 @@ func main() {
 		case ChannelEventReload:
 			// stop existing channels
 			fmt.Println("Reloading rules.")
-			doneChannel <- true
+			cancel()
 			fmt.Println("Waiting for existing listeners to exit. Provide input from each of your devices.")
 			wg.Wait()
 			fmt.Println("Listeners exited. Parsing config.")
 			config := readConfig(configDir) // reload the config
-			rules, eventChannel, doneChannel, wg = loadRules(config, pDevices, getVirtualDevices(vBuffersByName))
+			rules, eventChannel, cancel, wg = loadRules(config, pDevices, getVirtualDevices(vBuffersByName))
 			fmt.Println("Config re-loaded. Only rule changes applied. Device and Mode changes require restart.")
 		}
 	}
@@ -129,11 +130,11 @@ func main() {
 func loadRules(
 	config *config.ConfigParser,
 	pDevices map[string]*evdev.InputDevice,
-	vDevices map[string]*evdev.InputDevice) ([]mappingrules.MappingRule, <-chan ChannelEvent, chan bool, *sync.WaitGroup) {
+	vDevices map[string]*evdev.InputDevice) ([]mappingrules.MappingRule, <-chan ChannelEvent, func(), *sync.WaitGroup) {
 
 	var wg sync.WaitGroup
 	eventChannel := make(chan ChannelEvent, 1000)
-	doneChannel := make(chan bool)
+	ctx, cancel := context.WithCancel(context.Background())
 
 	// Initialize rules
 	rules := config.BuildRules(pDevices, vDevices)
@@ -142,20 +143,20 @@ func loadRules(
 	// start listening for events on devices and timers
 	for _, device := range pDevices {
 		wg.Add(1)
-		go eventWatcher(device, eventChannel, doneChannel, &wg)
+		go eventWatcher(device, eventChannel, ctx, &wg)
 	}
 
 	timerCount := 0
 	for _, rule := range rules {
 		if timedRule, ok := rule.(mappingrules.TimedEventEmitter); ok {
 			wg.Add(1)
-			go timerWatcher(timedRule, eventChannel, doneChannel, &wg)
+			go timerWatcher(timedRule, eventChannel, ctx, &wg)
 			timerCount++
 		}
 	}
 	logger.Logf("registered %d timers", timerCount)
 
-	go consoleWatcher(eventChannel, &wg)
+	go consoleWatcher(eventChannel)
 
-	return rules, eventChannel, doneChannel, &wg
+	return rules, eventChannel, cancel, &wg
 }

cmd/joyful/threads.go

@@ -2,6 +2,7 @@ package main
 
 import (
 	"bufio"
+	"context"
 	"os"
 	"sync"
 	"time"
@@ -19,26 +20,25 @@ const (
 func eventWatcher(
 	device *evdev.InputDevice,
 	channel chan<- ChannelEvent,
-	done chan bool,
+	ctx context.Context,
 	wg *sync.WaitGroup) {
 
 	defer wg.Done()
 
 	for {
-		select {
-		case cancel := <-done:
-			if cancel {
-				done <- true
-				return
-			}
-		default:
-		}
-
 		event, err := device.ReadOne()
 		if err != nil {
 			logger.LogError(err, "Error while reading event. Disconnecting device.")
 			return
 		}
+
+		select {
+		case <-ctx.Done():
+			return
+		default:
+			// Proceed
+		}
+
 		channel <- ChannelEvent{Device: device, Event: event, Type: ChannelEventInput}
 
 		if event.Type == evdev.EV_SYN {
@@ -50,19 +50,17 @@ func eventWatcher(
 func timerWatcher(
 	rule mappingrules.TimedEventEmitter,
 	channel chan<- ChannelEvent,
-	done chan bool,
+	ctx context.Context,
 	wg *sync.WaitGroup) {
 
 	defer wg.Done()
 
 	for {
 		select {
-		case cancel := <-done:
-			if cancel {
-				done <- true
-				return
-			}
+		case <-ctx.Done():
+			return
 		default:
+			// Proceed
 		}
 
 		event := rule.TimerEvent()
@@ -77,9 +75,9 @@ func timerWatcher(
 	}
 }
 
-// consoleWatcher reads input from stdin, and on receiving anything
-func consoleWatcher(channel chan<- ChannelEvent, wg *sync.WaitGroup) {
-	defer wg.Done()
+// consoleWatcher reads input from stdin, and on receiving anything,
+// closes the current threading context
+func consoleWatcher(channel chan<- ChannelEvent) {
 	stdin := bufio.NewReader(os.Stdin)
 	for {
 		_, err := stdin.ReadString('\n')