image: make bitmap provider use generation system

Make BitmapProvider leverage the generation system used in Indexer.

This helps reduce the surface for instruction-by-instruction race
conditions.

CHANGELOG.md

@@ -2,7 +2,11 @@
 
 ## dev [v2.3.2, v2.4.0, or v3.0.0]
 
+#### What's Improved
+- Genre parsing now handles multiple integer values and cover/remix indicators
+
 #### Dev/Meta
+- New translations [Fjuro -> Czech]
 - Moved music loading to a foreground service
 
 ## v2.3.1

app/src/main/java/org/oxycblt/auxio/image/BitmapProvider.kt

@@ -25,6 +25,7 @@ import coil.request.Disposable
 import coil.request.ImageRequest
 import coil.size.Size
 import org.oxycblt.auxio.music.Song
+import org.oxycblt.auxio.util.logD
 
 /**
  * A utility to provide bitmaps in a manner less prone to race conditions.
@@ -33,15 +34,15 @@ import org.oxycblt.auxio.music.Song
  * request with some target callbacks could result in overlapping requests causing unrelated
  * updates. This class (to an extent) resolves this by keeping track of the current request and
  * disposing of it every time a new request is created. This greatly reduces the surface for race
- * conditions save the case of instruction-by-instruction data races, which are effectively
- * impossible to solve.
+ * conditions.
  *
  * @author OxygenCobalt
  */
 class BitmapProvider(private val context: Context) {
     private var currentRequest: Request? = null
+    private var currentGeneration = 0L
 
-    /* If this provider is currently attempting to load something. */
+    /** If this provider is currently attempting to load something. */
     val isBusy: Boolean
         get() = currentRequest?.run { !disposable.isDisposed } ?: false
 
@@ -50,6 +51,10 @@ class BitmapProvider(private val context: Context) {
      * callback.
      */
     fun load(song: Song, target: Target) {
+        // Increment the generation value so that previous requests are invalidated.
+        // This is a second safeguard to mitigate instruction-by-instruction race conditions.
+        val generation = synchronized(this) { ++currentGeneration }
+
         currentRequest?.run { disposable.dispose() }
         currentRequest = null
 
@@ -59,8 +64,16 @@ class BitmapProvider(private val context: Context) {
                     .data(song)
                     .size(Size.ORIGINAL)
                     .target(
-                        onSuccess = { target.onCompleted(it.toBitmap()) },
-                        onError = { target.onCompleted(null) })
+                        onSuccess = {
+                            if (generation == currentGeneration) {
+                                target.onCompleted(it.toBitmap())
+                            }
+                        },
+                        onError = {
+                            if (generation == currentGeneration) {
+                                target.onCompleted(null)
+                            }
+                        })
                     .transformations(SquareFrameTransform.INSTANCE))
 
         currentRequest = Request(context.imageLoader.enqueue(request.build()), target)

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

@@ -57,7 +57,7 @@ class Indexer {
     private var lastResponse: Response? = null
     private var loadingState: Loading? = null
 
-    private var currentGeneration: Long = 0
+    private var currentGeneration = 0L
     private val callbacks = mutableListOf<Callback>()
 
     fun addCallback(callback: Callback) {

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

@@ -88,10 +88,10 @@ class IndexerService : Service(), Indexer.Callback {
     override fun onIndexerStateChanged(state: Indexer.State?) {
         when (state) {
             is Indexer.State.Complete -> {
-                if (state.response is Indexer.Response.Ok && musicStore.library == null) {
+                if (state.response is Indexer.Response.Ok &&
+                    state.response.library != musicStore.library) {
                     // Load was completed successfully, so apply the new library if we
                     // have not already.
-                    // TODO: Change null check for equality check [automatic rescanning]
                     musicStore.library = state.response.library
                 }
 

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

@@ -108,6 +108,8 @@ private fun String.parseId3v1Genre(): String? =
         // CR and RX are not technically ID3v1, but are formatted similarly to a plain number.
         this == "CR" -> "Cover"
         this == "RX" -> "Remix"
+
+        // Current name is fine.
         else -> null
     }
 
@@ -119,7 +121,7 @@ private fun String.parseId3v2Genre(): String? {
     // You can read the spec for it here: https://id3.org/id3v2.3.0#TCON
     // This implementation in particular is based off Mutagen's genre parser.
 
-    // Case 1: Genre IDs in the format (DIGITS|RX|CR). If these exist, parse them as
+    // Case 1: Genre IDs in the format (INT|RX|CR). If these exist, parse them as
     // ID3v1 tags.
     val genreIds = groups[1]
     if (genreIds != null && genreIds.value.isNotEmpty()) {
@@ -143,6 +145,7 @@ private fun String.parseId3v2Genre(): String? {
     return genres.distinctBy { it }.joinToString(separator = ", ").ifEmpty { null }
 }
 
+/** Regex that implements matching for ID3v2's genre format. */
 private val GENRE_RE = Regex("((?:\\(([0-9]+|RX|CR)\\))*)(.+)?")
 
 /**