Fix concurrent manga downloading #154

app/src/main/java/org/koitharu/kotatsu/download/domain/DownloadManager.kt

@@ -1,7 +1,6 @@
 package org.koitharu.kotatsu.download.domain
 
 import android.content.Context
-import android.graphics.drawable.Drawable
 import android.net.ConnectivityManager
 import android.webkit.MimeTypeMap
 import coil.ImageLoader
@@ -75,10 +74,12 @@ class DownloadManager(
 	): Job = coroutineScope.launch(Dispatchers.Default + errorStateHandler(outState)) {
 		@Suppress("NAME_SHADOWING") var manga = manga
 		val chaptersIdsSet = chaptersIds?.toMutableSet()
+		val cover = loadCover(manga)
+		outState.value = DownloadState.Queued(startId, manga, cover)
+		localMangaRepository.lockManga(manga.id)
 		semaphore.acquire()
 		coroutineContext[WakeLockNode]?.acquire()
 		outState.value = DownloadState.Preparing(startId, manga, null)
-		var cover: Drawable? = null
 		val destination = localMangaRepository.getOutputDir()
 		checkNotNull(destination) { context.getString(R.string.cannot_find_available_storage) }
 		val tempFileName = "${manga.id}_$startId.tmp"
@@ -88,16 +89,6 @@ class DownloadManager(
 				manga = localMangaRepository.getRemoteManga(manga) ?: error("Cannot obtain remote manga instance")
 			}
 			val repo = MangaRepository(manga.source)
-			cover = runCatching {
-				imageLoader.execute(
-					ImageRequest.Builder(context)
-						.data(manga.coverUrl)
-						.referer(manga.publicUrl)
-						.size(coverWidth, coverHeight)
-						.scale(Scale.FILL)
-						.build()
-				).drawable
-			}.getOrNull()
 			outState.value = DownloadState.Preparing(startId, manga, cover)
 			val data = if (manga.chapters.isNullOrEmpty()) repo.getDetails(manga) else manga
 			output = CbzMangaOutput.get(destination, data)
@@ -176,6 +167,7 @@ class DownloadManager(
 			}
 			coroutineContext[WakeLockNode]?.release()
 			semaphore.release()
+			localMangaRepository.unlockManga(manga.id)
 		}
 	}
 
@@ -208,6 +200,17 @@ class DownloadManager(
 			)
 		}
 
+	private suspend fun loadCover(manga: Manga) = runCatching {
+		imageLoader.execute(
+			ImageRequest.Builder(context)
+				.data(manga.coverUrl)
+				.referer(manga.publicUrl)
+				.size(coverWidth, coverHeight)
+				.scale(Scale.FILL)
+				.build()
+		).drawable
+	}.getOrNull()
+
 	class Factory(
 		private val context: Context,
 		private val imageLoader: ImageLoader,

app/src/main/java/org/koitharu/kotatsu/local/domain/LocalMangaRepository.kt

@@ -18,6 +18,7 @@ import org.koitharu.kotatsu.parsers.model.*
 import org.koitharu.kotatsu.parsers.util.longHashCode
 import org.koitharu.kotatsu.parsers.util.toCamelCase
 import org.koitharu.kotatsu.utils.AlphanumComparator
+import org.koitharu.kotatsu.utils.CompositeMutex
 import org.koitharu.kotatsu.utils.ext.deleteAwait
 import org.koitharu.kotatsu.utils.ext.readText
 import org.koitharu.kotatsu.utils.ext.resolveName
@@ -34,6 +35,7 @@ class LocalMangaRepository(private val storageManager: LocalStorageManager) : Ma
 
 	override val source = MangaSource.LOCAL
 	private val filenameFilter = CbzFilter()
+	private val locks = CompositeMutex<Long>()
 
 	override suspend fun getList(
 		offset: Int,
@@ -112,12 +114,19 @@ class LocalMangaRepository(private val storageManager: LocalStorageManager) : Ma
 		return file.deleteAwait()
 	}
 
-	suspend fun deleteChapters(manga: Manga, ids: Set<Long>) = runInterruptible(Dispatchers.IO) {
+	suspend fun deleteChapters(manga: Manga, ids: Set<Long>) {
+		lockManga(manga.id)
+		try {
+			runInterruptible(Dispatchers.IO) {
 				val uri = Uri.parse(manga.url)
 				val file = uri.toFile()
 				val cbz = CbzMangaOutput(file, manga)
 				CbzMangaOutput.filterChapters(cbz, ids)
 			}
+		} finally {
+			unlockManga(manga.id)
+		}
+	}
 
 	@WorkerThread
 	@SuppressLint("DefaultLocale")
@@ -278,6 +287,14 @@ class LocalMangaRepository(private val storageManager: LocalStorageManager) : Ma
 		}
 	}
 
+	suspend fun lockManga(id: Long) {
+		locks.lock(id)
+	}
+
+	suspend fun unlockManga(id: Long) {
+		locks.unlock(id)
+	}
+
 	private suspend fun getAllFiles() = storageManager.getReadableDirs().flatMap { dir ->
 		dir.listFiles(filenameFilter)?.toList().orEmpty()
 	}

app/src/main/java/org/koitharu/kotatsu/utils/CompositeMutex.kt

@@ -0,0 +1,66 @@
+package org.koitharu.kotatsu.utils
+
+import kotlinx.coroutines.CancellableContinuation
+import kotlinx.coroutines.suspendCancellableCoroutine
+import kotlinx.coroutines.sync.Mutex
+import kotlinx.coroutines.sync.withLock
+import java.util.*
+import kotlin.coroutines.resume
+
+class CompositeMutex<T : Any> : Set<T> {
+
+	private val data = HashMap<T, MutableList<CancellableContinuation<Unit>>>()
+	private val mutex = Mutex()
+
+	override val size: Int
+		get() = data.size
+
+	override fun contains(element: T): Boolean {
+		return data.containsKey(element)
+	}
+
+	override fun containsAll(elements: Collection<T>): Boolean {
+		return elements.all { x -> data.containsKey(x) }
+	}
+
+	override fun isEmpty(): Boolean {
+		return data.isEmpty()
+	}
+
+	override fun iterator(): Iterator<T> {
+		return data.keys.iterator()
+	}
+
+	suspend fun lock(element: T) {
+		waitForRemoval(element)
+		mutex.withLock {
+			val lastValue = data.put(element, LinkedList<CancellableContinuation<Unit>>())
+			check(lastValue == null) {
+				"CompositeMutex is double-locked for $element"
+			}
+		}
+	}
+
+	suspend fun unlock(element: T) {
+		val continuations = mutex.withLock {
+			checkNotNull(data.remove(element)) {
+				"CompositeMutex is not locked for $element"
+			}
+		}
+		continuations.forEach { c ->
+			if (c.isActive) {
+				c.resume(Unit)
+			}
+		}
+	}
+
+	private suspend fun waitForRemoval(element: T) {
+		val list = data[element] ?: return
+		suspendCancellableCoroutine<Unit> { continuation ->
+			list.add(continuation)
+			continuation.invokeOnCancellation {
+				list.remove(continuation)
+			}
+		}
+	}
+}

app/src/main/java/org/koitharu/kotatsu/utils/progress/TimeLeftEstimator.kt

@@ -1,6 +1,7 @@
 package org.koitharu.kotatsu.utils.progress
 
 import android.os.SystemClock
+import java.util.concurrent.TimeUnit
 import kotlin.math.roundToInt
 import kotlin.math.roundToLong
 
@@ -11,6 +12,7 @@ class TimeLeftEstimator {
 
 	private var times = ArrayList<Int>()
 	private var lastTick: Tick? = null
+	private val tooLargeTime = TimeUnit.DAYS.toMillis(1)
 
 	fun tick(value: Int, total: Int) {
 		if (total < 0) {
@@ -36,7 +38,8 @@ class TimeLeftEstimator {
 		}
 		val timePerTick = times.average()
 		val ticksLeft = progress.total - progress.value
-		return (ticksLeft * timePerTick).roundToLong()
+		val eta = (ticksLeft * timePerTick).roundToLong()
+		return if (eta < tooLargeTime) eta else NO_TIME
 	}
 
 	private class Tick(