music: introduce library revisions

Will be used to maintain image loading consistency even during loads.

app/src/main/java/org/oxycblt/auxio/music/MusicRepository.kt

@@ -43,6 +43,7 @@ import org.oxycblt.musikr.playlist.db.PlaylistDatabase
 import org.oxycblt.musikr.playlist.db.StoredPlaylists
 import org.oxycblt.musikr.tag.interpret.Naming
 import org.oxycblt.musikr.tag.interpret.Separators
+import java.util.UUID
 import timber.log.Timber as L
 
 /**
@@ -57,7 +58,8 @@ import timber.log.Timber as L
  *   configurations
  */
 interface MusicRepository {
-    val library: Library?
+    /** The current library */
+    val library: RevisionedLibrary?
 
     /** The current state of music loading. Null if no load has occurred yet. */
     val indexingState: IndexingState?
@@ -222,7 +224,7 @@ constructor(
     private val indexingListeners = mutableListOf<MusicRepository.IndexingListener>()
     @Volatile private var indexingWorker: MusicRepository.IndexingWorker? = null
 
-    @Volatile override var library: MutableLibrary? = null
+    @Volatile override var library: MutableRevisionedLibrary? = null
     @Volatile private var previousCompletedState: IndexingState.Completed? = null
     @Volatile private var currentIndexingState: IndexingState? = null
     override val indexingState: IndexingState?
@@ -362,17 +364,19 @@ constructor(
             }
         val locations = musicSettings.musicLocations
 
-        val storage =
+        val revision: UUID
+        val storage: Storage
             if (withCache) {
-                Storage(
+                revision = this.library?.revision ?: musicSettings.revision
+                storage = Storage(
                     Cache.full(cacheDatabase),
-                    StoredCovers.from(context, "covers"),
+                    StoredCovers.from(context, "covers_$revision"),
                     StoredPlaylists.from(playlistDatabase))
             } else {
-                // TODO: Revisioned cache (as a stateful extension of musikr)
-                Storage(
+                revision = UUID.randomUUID()
+                storage = Storage(
                     Cache.writeOnly(cacheDatabase),
-                    StoredCovers.from(context, "covers"),
+                    StoredCovers.from(context, "covers_$revision"),
                     StoredPlaylists.from(playlistDatabase))
             }
 
@@ -381,6 +385,9 @@ constructor(
         val newLibrary =
             Musikr.new(context, storage, interpretation).run(locations, ::emitIndexingProgress)
 
+        val revisionedLibrary =
+            MutableRevisionedLibrary(revision, newLibrary)
+
         emitIndexingCompletion(null)
 
         // We want to make sure that all reads and writes are synchronized due to the sheer
@@ -402,7 +409,7 @@ constructor(
                 return
             }
 
-            this.library = newLibrary
+            this.library = revisionedLibrary
         }
 
         // Consumers expect their updates to be on the main thread (notably PlaybackService),
@@ -410,6 +417,11 @@ constructor(
         withContext(Dispatchers.Main) {
             dispatchLibraryChange(deviceLibraryChanged, userLibraryChanged)
         }
+
+        // Quietly update the revision if needed (this way we don't disrupt any new loads)
+        if (!withCache) {
+            musicSettings.revision = revisionedLibrary.revision
+        }
     }
 
     private suspend fun emitIndexingProgress(progress: IndexingProgress) {

app/src/main/java/org/oxycblt/auxio/music/MusicSettings.kt

@@ -25,6 +25,7 @@ import javax.inject.Inject
 import org.oxycblt.auxio.R
 import org.oxycblt.auxio.settings.Settings
 import org.oxycblt.musikr.fs.MusicLocation
+import java.util.UUID
 import timber.log.Timber as L
 
 /**
@@ -33,6 +34,8 @@ import timber.log.Timber as L
  * @author Alexander Capehart (OxygenCobalt)
  */
 interface MusicSettings : Settings<MusicSettings.Listener> {
+    /** The current library revision. */
+    var revision: UUID
     /** The locations of music to load. */
     var musicLocations: List<MusicLocation>
     /** Whether to exclude non-music audio files from the music library. */
@@ -55,6 +58,17 @@ interface MusicSettings : Settings<MusicSettings.Listener> {
 class MusicSettingsImpl @Inject constructor(@ApplicationContext private val context: Context) :
     Settings.Impl<MusicSettings.Listener>(context), MusicSettings {
 
+    override var revision: UUID
+        get() = UUID.fromString(
+            sharedPreferences.getString(getString(R.string.set_key_library_revision), null)
+                ?: UUID.randomUUID().toString())
+        set(value) {
+            sharedPreferences.edit {
+                putString(getString(R.string.set_key_library_revision), value.toString())
+                apply()
+            }
+        }
+
     override var musicLocations: List<MusicLocation>
         get() {
             val locations =

app/src/main/java/org/oxycblt/auxio/music/RevisionedLibrary.kt

@@ -0,0 +1,32 @@
+package org.oxycblt.auxio.music
+
+import org.oxycblt.musikr.Library
+import org.oxycblt.musikr.MutableLibrary
+import org.oxycblt.musikr.Playlist
+import org.oxycblt.musikr.Song
+import java.util.UUID
+
+interface RevisionedLibrary : Library {
+    val revision: UUID
+}
+
+class MutableRevisionedLibrary(
+    override val revision: UUID,
+    private val inner: MutableLibrary
+) : RevisionedLibrary, Library by inner, MutableLibrary {
+    override suspend fun createPlaylist(name: String, songs: List<Song>) =
+        MutableRevisionedLibrary(revision, inner.createPlaylist(name, songs))
+
+    override suspend fun renamePlaylist(playlist: Playlist, name: String) =
+        MutableRevisionedLibrary(revision, inner.renamePlaylist(playlist, name))
+
+    override suspend fun addToPlaylist(playlist: Playlist, songs: List<Song>) =
+        MutableRevisionedLibrary(revision, inner.addToPlaylist(playlist, songs))
+
+    override suspend fun rewritePlaylist(playlist: Playlist, songs: List<Song>) =
+        MutableRevisionedLibrary(revision, inner.rewritePlaylist(playlist, songs))
+
+    override suspend fun deletePlaylist(playlist: Playlist) =
+        MutableRevisionedLibrary(revision, inner.deletePlaylist(playlist))
+
+}

app/src/main/res/values/settings.xml

@@ -53,6 +53,8 @@
     <string name="set_key_artist_songs_sort" translatable="false">auxio_artist_sort</string>
     <string name="set_key_genre_songs_sort" translatable="false">auxio_genre_sort</string>
 
+    <string name="set_key_library_revision" translatable="false">auxio_library_revision</string>
+
     <string-array name="entries_theme">
         <item>@string/set_theme_auto</item>
         <item>@string/set_theme_day</item>