Added SoftSuspendLazy class

src/main/kotlin/org/koitharu/kotatsu/parsers/util/SoftSuspendLazy.kt

@@ -0,0 +1,33 @@
+package org.koitharu.kotatsu.parsers.util
+
+import kotlinx.coroutines.sync.Mutex
+import kotlinx.coroutines.sync.withLock
+import java.lang.ref.SoftReference
+
+/**
+ * Like a [SuspendLazy] but with [SoftReference] under the hood
+ */
+class SoftSuspendLazy<T : Any>(
+	private val initializer: suspend () -> T,
+) {
+
+	private val mutex = Mutex()
+	private var cachedValue: SoftReference<T>? = null
+
+	suspend fun get(): T {
+		// fast way
+		cachedValue?.get()?.let {
+			return it
+		}
+		return mutex.withLock {
+			cachedValue?.get()?.let {
+				return it
+			}
+			val result = initializer()
+			cachedValue = SoftReference(result)
+			result
+		}
+	}
+
+	suspend fun tryGet() = runCatchingCancellable { get() }
+}