From 88b60f2df01687b914167694d3f2892b3387446c Mon Sep 17 00:00:00 2001
From: KemoNine <kemonine@kemonine.info>
Date: Thu, 27 Aug 2020 10:02:44 -0400
Subject: [PATCH] Added inotify watcher for restarting slideshow when files are
 changed/deleted/added

---
 cmd/inotify/README.md  |  3 ++
 cmd/inotify/inotify.go | 68 ++++++++++++++++++++++++++++++++++++++++++
 watchdog/README.md     |  3 ++
 watchdog/watchdog.go   | 41 +++++++++++++++++++++++++
 4 files changed, 115 insertions(+)
 create mode 100644 cmd/inotify/README.md
 create mode 100644 cmd/inotify/inotify.go
 create mode 100644 watchdog/README.md
 create mode 100644 watchdog/watchdog.go

diff --git a/cmd/inotify/README.md b/cmd/inotify/README.md
new file mode 100644
index 0000000..05f19c5
--- /dev/null
+++ b/cmd/inotify/README.md
@@ -0,0 +1,3 @@
+# inotify
+
+This is the main source code for the inotify watcher that restarts the PiFrame slide show when files have changed (add/remove/etc).
diff --git a/cmd/inotify/inotify.go b/cmd/inotify/inotify.go
new file mode 100644
index 0000000..686cad6
--- /dev/null
+++ b/cmd/inotify/inotify.go
@@ -0,0 +1,68 @@
+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
+}
diff --git a/watchdog/README.md b/watchdog/README.md
new file mode 100644
index 0000000..2244211
--- /dev/null
+++ b/watchdog/README.md
@@ -0,0 +1,3 @@
+# watchdog
+
+A very simple watchdog timer implementation. Borrowed from [here](https://codereview.stackexchange.com/questions/144273/watchdog-in-golang) and tweaked slightly.
diff --git a/watchdog/watchdog.go b/watchdog/watchdog.go
new file mode 100644
index 0000000..fe60efc
--- /dev/null
+++ b/watchdog/watchdog.go
@@ -0,0 +1,41 @@
+// 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)
+}