Manage prefetch cache memory

app/src/main/java/org/koitharu/kotatsu/core/AppModule.kt

@@ -190,12 +190,12 @@ interface AppModule {
 		@Provides
 		@Singleton
 		fun provideContentCache(
-			@ApplicationContext context: Context,
+			application: Application,
 		): ContentCache {
-			return if (context.activityManager?.isLowRamDevice == true) {
+			return if (application.activityManager?.isLowRamDevice == true) {
 				StubContentCache()
 			} else {
-				MemoryContentCache()
+				MemoryContentCache(application)
 			}
 		}
 	}

app/src/main/java/org/koitharu/kotatsu/core/cache/ContentCache.kt

@@ -7,6 +7,8 @@ import org.koitharu.kotatsu.parsers.model.MangaSource
 
 interface ContentCache {
 
+	val isCachingEnabled: Boolean
+
 	suspend fun getDetails(source: MangaSource, url: String): Manga?
 
 	fun putDetails(source: MangaSource, url: String, details: Deferred<Manga>)

app/src/main/java/org/koitharu/kotatsu/core/cache/MemoryContentCache.kt

@@ -1,15 +1,24 @@
 package org.koitharu.kotatsu.core.cache
 
+import android.app.Application
+import android.content.ComponentCallbacks2
+import android.content.res.Configuration
 import kotlinx.coroutines.Deferred
 import org.koitharu.kotatsu.parsers.model.Manga
 import org.koitharu.kotatsu.parsers.model.MangaPage
 import org.koitharu.kotatsu.parsers.model.MangaSource
 
 @Suppress("DeferredResultUnused")
-class MemoryContentCache : ContentCache {
+class MemoryContentCache(application: Application) : ContentCache, ComponentCallbacks2 {
 
-	private val detailsCache = DeferredLruCache<Manga>(10)
-	private val pagesCache = DeferredLruCache<List<MangaPage>>(10)
+	init {
+		application.registerComponentCallbacks(this)
+	}
+
+	private val detailsCache = DeferredLruCache<Manga>(4)
+	private val pagesCache = DeferredLruCache<List<MangaPage>>(4)
+
+	override val isCachingEnabled: Boolean = true
 
 	override suspend fun getDetails(source: MangaSource, url: String): Manga? {
 		return detailsCache[ContentCache.Key(source, url)]?.await()
@@ -26,4 +35,27 @@ class MemoryContentCache : ContentCache {
 	override fun putPages(source: MangaSource, url: String, pages: Deferred<List<MangaPage>>) {
 		pagesCache.put(ContentCache.Key(source, url), pages)
 	}
+
+	override fun onConfigurationChanged(newConfig: Configuration) = Unit
+
+	override fun onLowMemory() = Unit
+
+	override fun onTrimMemory(level: Int) {
+		trimCache(detailsCache, level)
+		trimCache(pagesCache, level)
+	}
+
+	private fun trimCache(cache: DeferredLruCache<*>, level: Int) {
+		when (level) {
+			ComponentCallbacks2.TRIM_MEMORY_RUNNING_CRITICAL,
+			ComponentCallbacks2.TRIM_MEMORY_COMPLETE,
+			ComponentCallbacks2.TRIM_MEMORY_MODERATE -> cache.evictAll()
+
+			ComponentCallbacks2.TRIM_MEMORY_UI_HIDDEN,
+			ComponentCallbacks2.TRIM_MEMORY_RUNNING_LOW,
+			ComponentCallbacks2.TRIM_MEMORY_BACKGROUND -> cache.trimToSize(1)
+
+			else -> cache.trimToSize(cache.maxSize() / 2)
+		}
+	}
 }

app/src/main/java/org/koitharu/kotatsu/core/cache/StubContentCache.kt

@@ -7,6 +7,8 @@ import org.koitharu.kotatsu.parsers.model.MangaSource
 
 class StubContentCache : ContentCache {
 
+	override val isCachingEnabled: Boolean = false
+
 	override suspend fun getDetails(source: MangaSource, url: String): Manga? = null
 
 	override fun putDetails(source: MangaSource, url: String, details: Deferred<Manga>) = Unit

app/src/main/java/org/koitharu/kotatsu/details/service/MangaPrefetchService.kt

@@ -9,7 +9,6 @@ import kotlinx.coroutines.coroutineScope
 import kotlinx.coroutines.launch
 import org.koitharu.kotatsu.base.ui.CoroutineIntentService
 import org.koitharu.kotatsu.core.cache.ContentCache
-import org.koitharu.kotatsu.core.cache.StubContentCache
 import org.koitharu.kotatsu.core.model.parcelable.ParcelableManga
 import org.koitharu.kotatsu.core.model.parcelable.ParcelableMangaChapters
 import org.koitharu.kotatsu.core.parser.MangaRepository
@@ -87,10 +86,7 @@ class MangaPrefetchService : CoroutineIntentService() {
 				return false
 			}
 			val entryPoint = EntryPointAccessors.fromApplication(context, PrefetchCompanionEntryPoint::class.java)
-			if (entryPoint.contentCache is StubContentCache) {
-				return false
-			}
-			return entryPoint.settings.isContentPrefetchEnabled()
+			return entryPoint.contentCache.isCachingEnabled && entryPoint.settings.isContentPrefetchEnabled()
 		}
 	}
 }