musicindex: cache tarballs by default

overridable with the -r command line option

musicindex/index.go

@@ -2,7 +2,6 @@ package musicindex
 
 import (
 	"errors"
-	"fmt"
 	"io/fs"
 	"log"
 	"os"
@@ -58,13 +57,26 @@ func indexArtists() {
 		util.Die("%s", err.Error())
 	}
 
-	err = os.RemoveAll(TempDir)
-	if err != nil {
-		util.Die("cannot remove temporary directory %s: %s", TempDir, err.Error())
+	if (regenerateTarballs) {
+		err = os.RemoveAll(TempDir)
+		if err != nil {
+			util.Die("cannot remove temporary directory %s: %s", TempDir, err.Error())
+		}
 	}
-	err = os.Mkdir(TempDir, 0711)
+
+	f, err := os.Stat(TempDir)
 	if err != nil {
-		util.Die("cannot make temporary directory %s: %s", TempDir, err.Error())
+		err = os.Mkdir(TempDir, 0711)
+		if err != nil {
+			util.Die("cannot make temporary directory %s: %s", TempDir,
+				err.Error())
+		}
+		log.Println("generating new tarball index")
+	} else {
+		if !f.IsDir() {
+			util.Die("cannot make temporary directory %s: %s", TempDir,
+				"not a directory")
+		}
 	}
 
 	artists = make(map[string]Artist)
@@ -148,42 +160,32 @@ func indexAlbum(artist *Artist, albumName, albumDir string) (a Album, err error)
 	slices.Sort(tracks)
 	a.TrackFiles = tracks
 
+	generate := false
 	hash := util.HashOf(a.Artist.Name + "::" + a.Name)
-	path := TempDir + "/" + hash
+	a.Tarball = TempDir + "/" + hash
 
-	if _, err = os.Stat(path); errors.Is(err, os.ErrNotExist) {
-		a.Tarball = path
-	} else if err == nil {
-		a.Tarball = ""
-		for i := range 9 {
-			if _, err = os.Stat(fmt.Sprintf("%s.%d", path, i)); err == nil {
-				continue
-			} else if errors.Is(err, os.ErrNotExist) {
-				a.Tarball = path
-			} else {
-				err = errors.New("cannot create tarball in filesystem: " +
-					err.Error())
-				return
-			}
+	if _, err = os.Stat(a.Tarball); errors.Is(err, os.ErrNotExist) {
+		// if the file isn't there we definitely want to generate one
+		generate = true
+	} else { // if the file exists or if it's some other error
+		if regenerateTarballs {
+			// not sure why this is here since we deleted the whole
+			// directory beforehand but let's try overwrite it anyway
+			generate = true
 		}
-		if len(a.Tarball) == 0 {
-			err = errors.New("cannot create tarball in filesystem; " +
-				"please clean out " + TempDir)
-			return
-		}
-	} else {
-		err = errors.New("cannot create tarball in filesystem: " + err.Error())
-		return
 	}
 
-	a.Tarball = path
-	err = targz.Compress(a.Directory(), a.Tarball)
-	if err != nil {
-		return
+	if generate {
+		err = targz.Compress(a.Directory(), a.Tarball)
+		if err != nil {
+			a.Tarball = ""
+			return
+		}
 	}
 
 	tarball, err := os.Stat(a.Tarball)
 	if err != nil {
+		a.Tarball = ""
 		return
 	}
 	a.TarballSize = tarball.Size()