Added inotify watcher for restarting slideshow when files are changed/deleted/added

cmd/inotify/README.md

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+# inotify
+
+This is the main source code for the inotify watcher that restarts the PiFrame slide show when files have changed (add/remove/etc).

cmd/inotify/inotify.go

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+package main
+
+import (
+	"log"
+	"os/exec"
+	"time"
+
+	"github.com/dietsche/rfsnotify"
+
+	"git.kemonine.info/PiFrame/watchdog"
+)
+
+const (
+	CMD_SYSTEMCTL = "/usr/bin/systemctl"
+	PATH_PICTURES = "/tank/pictures"
+	TIMEOUT       = 5 * time.Second
+)
+
+func main() {
+	// Create watchdog timer that restarts fim.service on timeout
+	watchdog := watchdog.New(TIMEOUT, func() {
+		err := exec.Command(CMD_SYSTEMCTL, "restart", "fim.service").Run()
+		if err != nil {
+			log.Fatalf("Error running %s : %s", CMD_SYSTEMCTL, err)
+		}
+	})
+	watchdog.DeferredStart()
+
+	// Create fswatcher
+	watcher, err := rfsnotify.NewWatcher()
+	if err != nil {
+		log.Fatal("Error setting up rfsnotify")
+	}
+
+	// Ensure we clean stuff up no matter what
+	defer watcher.Close()
+
+	// Setup goroutine and listen for events
+	done := make(chan bool)
+	go func() {
+		for {
+			select {
+			case event, ok := <-watcher.Events:
+				if !ok {
+					return
+				}
+				// Print out event (this is where logic will go eventually))
+				log.Printf("event: %#v\n", event)
+				// [Re]Start timer to restart slideshow after the fs events die down
+				watchdog.Kick()
+			case err, ok := <-watcher.Errors:
+				if !ok {
+					return
+				}
+				log.Println("Error: ", err)
+			}
+		}
+	}()
+
+	// Setup paths to watch
+	err = watcher.AddRecursive(PATH_PICTURES)
+	if err != nil {
+		log.Fatalf("Error setting up recursive watch of %s", PATH_PICTURES)
+	}
+
+	// Drain done channel...
+	<-done
+}

watchdog/README.md

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+# watchdog
+
+A very simple watchdog timer implementation. Borrowed from [here](https://codereview.stackexchange.com/questions/144273/watchdog-in-golang) and tweaked slightly.

watchdog/watchdog.go

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+// Adapted from https://codereview.stackexchange.com/questions/144273/watchdog-in-golang
+
+package watchdog
+
+import (
+	"time"
+)
+
+type watchdog struct {
+	interval time.Duration
+	callback func()
+	timer    *time.Timer
+}
+
+func New(interval time.Duration, callback func()) *watchdog {
+	w := watchdog{
+		interval: interval,
+		callback: callback,
+		timer:    nil,
+	}
+	return &w
+}
+
+func (w *watchdog) Start() {
+	w.timer = time.AfterFunc(w.interval, w.callback)
+}
+
+// Helper to allow the watchdog to be started by a call to Kick directly
+func (w *watchdog) DeferredStart() {
+	w.Start()
+	w.Stop()
+}
+
+func (w *watchdog) Stop() {
+	w.timer.Stop()
+}
+
+func (w *watchdog) Kick() {
+	w.Stop()
+	w.timer.Reset(w.interval)
+}