removed 'watcher' in favor of 'scanner'

.vscode/launch.json

@@ -10,6 +10,7 @@
       "env":{
         "SLIDESHOW_INTERVAL": "10",
         "SLIDESHOW_DIRECTORY": "/home/velvettear/images",
+        "SLIDESHOW_SCANINTERVAL": "10",
         "SLIDESHOW_RESOLUTION": "600x1024",
         "SLIDESHOW_LOGLEVEL": "debug",
         "SLIDESHOW_PALETTE": "/tmp/.slideshow.palette",
@@ -27,6 +28,7 @@
       "env":{
         "SLIDESHOW_INTERVAL": "10",
         "SLIDESHOW_DIRECTORY": "/home/velvettear/images",
+        "SLIDESHOW_SCANINTERVAL": "10",
         "SLIDESHOW_LOGLEVEL": "debug",
         "SLIDESHOW_PALETTE": "/tmp/.slideshow.palette",
         "SLIDESHOW_PALETTE_ALGORITHM": "wsm",

README.md

@@ -15,6 +15,7 @@ configuration is entirely done via environment variables.
 | --------------------------- | ----------------- | -----------------------------------------------------------|
 | SLIDESHOW_INTERVAL          | 60                | the interval of the slideshow in seconds                   |
 | SLIDESHOW_DIRECTORY         | "$HOME"           | path to a directory containing images                      |
+| SLIDESHOW_SCANINTERVAL      | 60                | the interval for directory scans in seconds 
 | SLIDESHOW_RESOLUTION        |                   | the resolution to which images are scaled (i.e. 1920x1080) | 
 | SLIDESHOW_PALETTE           |                   | path to a file where the color palette will be stored      |
 | SLIDESHOW_PALETTE_ALGORITHM | "wsm"             | the algorithm used to generate the color palette           |

internal/config/config.go

@@ -11,6 +11,7 @@ import (
 
 var Interval time.Duration
 var Directory string
+var ScanInterval time.Duration
 var Resolution string
 var PaletteFile string
 var PaletteAlgorithm int
@@ -39,6 +40,11 @@ func Initialize() {
 	if !stats.IsDir() {
 		loggo.Fatal("configured directory '" + Directory + "' is not a valid directory")
 	}
+	tmpInt, _ = strconv.Atoi(os.Getenv("SLIDESHOW_SCANINTERVAL"))
+	if tmpInt <= 0 {
+		tmpInt = 60
+	}
+	ScanInterval = time.Duration(tmpInt) * time.Second
 	Resolution = os.Getenv("SLIDESHOW_RESOLUTION")
 	if len(Resolution) > 0 {
 		width, height, found := strings.Cut(Resolution, "x")

internal/slideshow/slideshow.go

@@ -11,7 +11,7 @@ import (
 
 	"git.velvettear.de/velvettear/loggo"
 	"git.velvettear.de/velvettear/slideshow/internal/config"
-	"git.velvettear.de/velvettear/slideshow/internal/watcher"
+	"git.velvettear.de/velvettear/slideshow/scanner"
 )
 
 // remember last shown image
@@ -28,7 +28,7 @@ func Start() {
 		var palette []color.Color
 		var data []byte
 		for {
-			image = watcher.GetRandomImage()
+			image = scanner.GetRandomImage()
 			if image != previousImage {
 				break
 			}
@@ -47,7 +47,7 @@ func Start() {
 			palette, _ = getColorPalette(image)
 		}
 		if sleepTime > 0 {
-			loggo.Debug("sleeping for " + strconv.FormatInt(sleepTime.Milliseconds(), 10) + "ms")
+			loggo.Debug("sleeping for " + strconv.FormatInt(sleepTime.Milliseconds(), 10) + "ms before next image will be displayed...")
 			time.Sleep(sleepTime)
 		}
 		go exportPalette(palette)

internal/watcher/watcher.go

@@ -1,88 +0,0 @@
-package watcher
-
-import (
-	"io/fs"
-	"math/rand"
-	"path/filepath"
-	"strconv"
-	"strings"
-	"time"
-
-	"git.velvettear.de/velvettear/loggo"
-	"github.com/fsnotify/fsnotify"
-)
-
-// the watcher
-var watcher *fsnotify.Watcher
-
-// slice of images
-var images []string
-
-// initialize the watcher
-func Initialize(directory string) {
-	timestamp := time.Now().UnixMilli()
-	tmp, error := fsnotify.NewWatcher()
-	if error != nil {
-		loggo.FatalTimed("encountered an error initializing the watcher", timestamp, error.Error())
-	}
-	watcher = tmp
-	loggo.Info("scanning directory for images and subdirectories...", directory)
-	filepath.WalkDir(directory, checkDirectory)
-	loggo.InfoTimed("found "+strconv.Itoa(len(images))+" images "+strconv.Itoa(len(watcher.WatchList()))+" directories to watch", timestamp)
-	go func() {
-		for {
-			event := <-watcher.Events
-			if !isImage(event.Name) {
-				continue
-			}
-			if event.Has(fsnotify.Create) {
-				images = append(images, event.Name)
-				loggo.Debug("added image to slice of images", event.Name)
-			} else if event.Has(fsnotify.Remove) {
-				for index, tmp := range images {
-					if tmp != event.Name {
-						continue
-					}
-					images = append(images[:index], images[index+1:]...)
-					loggo.Debug("removed image from slice of images", event.Name)
-				}
-			}
-		}
-	}()
-}
-
-// stop the watcher
-func Stop() {
-	error := watcher.Close()
-	if error != nil {
-		loggo.Fatal("encountered an error closing the watcher", error.Error())
-	}
-}
-
-// get a random image
-func GetRandomImage() string {
-	return images[rand.Intn(len(images))]
-}
-
-// add image files to the slice of images and subdirectoies to the watcher
-func checkDirectory(path string, dir fs.DirEntry, err error) error {
-	if err != nil {
-		return err
-	}
-	if dir.IsDir() {
-		watcher.Add(path)
-		loggo.Debug("added directory to watcher", path)
-		return nil
-	}
-	if !isImage(path) {
-		return nil
-	}
-	images = append(images, path)
-	loggo.Debug("added image to slice of images", path)
-	return nil
-}
-
-// check if a file is an image
-func isImage(file string) bool {
-	return strings.HasSuffix(file, ".jpeg") || strings.HasSuffix(file, ".jpg") || strings.HasSuffix(file, ".png")
-}

main.go

@@ -7,7 +7,7 @@ import (
 	"git.velvettear.de/velvettear/loggo"
 	"git.velvettear.de/velvettear/slideshow/internal/config"
 	"git.velvettear.de/velvettear/slideshow/internal/slideshow"
-	"git.velvettear.de/velvettear/slideshow/internal/watcher"
+	"git.velvettear.de/velvettear/slideshow/scanner"
 )
 
 func main() {
@@ -16,7 +16,7 @@ func main() {
 	var waitgroup sync.WaitGroup
 	waitgroup.Add(1)
 	config.Initialize()
-	watcher.Initialize(config.Directory)
+	scanner.Initialize()
 	slideshow.Start()
 	waitgroup.Wait()
 	loggo.InfoTimed("slideshow is shutting down now!", timestamp)

scanner/scanner.go

@@ -0,0 +1,66 @@
+package scanner
+
+import (
+	"io/fs"
+	"math/rand"
+	"path/filepath"
+	"strconv"
+	"strings"
+	"time"
+
+	"git.velvettear.de/velvettear/loggo"
+	"git.velvettear.de/velvettear/slideshow/internal/config"
+)
+
+// slice of images
+var images []string
+
+// temporary slice of images
+var tmpImages []string
+
+// scan the specified directories for images
+func Initialize() {
+	directory := config.Directory
+	scan(directory)
+}
+
+// get a random image
+func GetRandomImage() string {
+	return images[rand.Intn(len(images))]
+}
+
+// scan the specified directory
+func scan(directory string) {
+	timestamp := time.Now().UnixMilli()
+	loggo.Info("scanning directory for images and subdirectories...", directory)
+	filepath.WalkDir(directory, checkDirectory)
+	images = tmpImages
+	tmpImages = nil
+	loggo.InfoTimed("found "+strconv.Itoa(len(images))+" image(s)", timestamp)
+	go scheduleRescan(directory)
+}
+
+// sleep the specified interval and then trigger a rescan of the specified directory
+func scheduleRescan(directory string) {
+	loggo.Debug("sleeping for " + strconv.FormatInt(config.Interval.Milliseconds(), 10) + "ms before next scan...")
+	time.Sleep(config.ScanInterval)
+	scan(directory)
+}
+
+// add image files to the slice of images and subdirectoies to the watcher
+func checkDirectory(path string, dir fs.DirEntry, err error) error {
+	if err != nil {
+		return err
+	}
+	if dir.IsDir() || !isImage(path) {
+		return nil
+	}
+	tmpImages = append(tmpImages, path)
+	loggo.Debug("added image to temporary slice of images", path)
+	return nil
+}
+
+// check if a file is an image
+func isImage(file string) bool {
+	return strings.HasSuffix(file, ".jpeg") || strings.HasSuffix(file, ".jpg") || strings.HasSuffix(file, ".png")
+}