Fix ability to implement DefaultPool in common

Author: Sergey Mashkov

kotlinx-io-js/src/main/kotlin/kotlinx/io/pool/DefaultPool.kt

@@ -1,6 +1,6 @@
 package kotlinx.io.pool
 
-actual abstract class DefaultPool<T : Any>(actual final override val capacity: Int) : ObjectPool<T> {
+actual abstract class DefaultPool<T : Any> actual constructor(actual final override val capacity: Int) : ObjectPool<T> {
     private val instances = arrayOfNulls<Any?>(capacity)
     private var size = 0
 
@@ -10,7 +10,7 @@ actual abstract class DefaultPool<T : Any>(actual final override val capacity: I
     protected actual open fun clearInstance(instance: T): T = instance
     protected actual open fun validateInstance(instance: T) {}
 
-    final override fun borrow(): T {
+    actual final override fun borrow(): T {
         if (size == 0) return produceInstance()
         val idx = --size
 
@@ -21,13 +21,13 @@ actual abstract class DefaultPool<T : Any>(actual final override val capacity: I
         return clearInstance(instance)
     }
 
-    final override fun recycle(instance: T) {
+    actual final override fun recycle(instance: T) {
         validateInstance(instance)
         if (size == capacity) disposeInstance(instance)
         instances[size++] = instance
     }
 
-    final override fun dispose() {
+    actual final override fun dispose() {
         for (i in 0 until size) {
             @Suppress("UNCHECKED_CAST")
             val instance = instances[i] as T
@@ -36,4 +36,4 @@ actual abstract class DefaultPool<T : Any>(actual final override val capacity: I
         }
         size = 0
     }
-}
+}

kotlinx-io-jvm/src/main/kotlin/kotlinx/io/pool/DefaultPool.kt

@@ -9,7 +9,7 @@ private const val PROBE_COUNT = 8 // number of attempts to find a slot
 private const val MAGIC = 2654435769.toInt() // fractional part of golden ratio
 private const val MAX_CAPACITY = Int.MAX_VALUE / MULTIPLIER
 
-actual abstract class DefaultPool<T : Any>(actual final override val capacity: Int) : ObjectPool<T> {
+actual abstract class DefaultPool<T : Any> actual constructor(actual final override val capacity: Int) : ObjectPool<T> {
     init {
         require(capacity > 0) { "capacity should be positive but it is $capacity" }
         require(capacity <= MAX_CAPACITY) { "capacity should be less or equal to $MAX_CAPACITY but it is $capacity"}
@@ -31,15 +31,15 @@ actual abstract class DefaultPool<T : Any>(actual final override val capacity: I
     private val instances = AtomicReferenceArray<T?>(maxIndex + 1)
     private val next = IntArray(maxIndex + 1)
 
-    final override fun borrow(): T =
+    actual final override fun borrow(): T =
             tryPop()?.let { clearInstance(it) } ?: produceInstance()
 
-    final override fun recycle(instance: T) {
+    actual final override fun recycle(instance: T) {
         validateInstance(instance)
         if (!tryPush(instance)) disposeInstance(instance)
     }
 
-    final override fun dispose() {
+    actual final override fun dispose() {
         while (true) {
             val instance = tryPop() ?: return
             disposeInstance(instance)
@@ -92,4 +92,4 @@ actual abstract class DefaultPool<T : Any>(actual final override val capacity: I
         // todo: replace with atomicfu, remove companion object
         private val Top = longUpdater(DefaultPool<*>::top)
     }
-}
+}

kotlinx-io-native/src/main/kotlin/kotlinx/io/pool/DefaultPool.kt

@@ -1,6 +1,6 @@
 package kotlinx.io.pool
 
-actual abstract class DefaultPool<T : Any>(actual override final val capacity: Int) : ObjectPool<T> {
+actual abstract class DefaultPool<T : Any> actual constructor(actual override final val capacity: Int) : ObjectPool<T> {
     private val instances = arrayOfNulls<Any?>(capacity)
     private var size = 0
 
@@ -10,7 +10,7 @@ actual abstract class DefaultPool<T : Any>(actual override final val capacity: I
     actual protected open fun clearInstance(instance: T): T = instance
     actual protected open fun validateInstance(instance: T) {}
 
-    override final fun borrow(): T {
+    actual final override fun borrow(): T {
         if (size == 0) return produceInstance()
         val idx = --size
 
@@ -21,13 +21,13 @@ actual abstract class DefaultPool<T : Any>(actual override final val capacity: I
         return clearInstance(instance)
     }
 
-    override final fun recycle(instance: T) {
+    actual final override fun recycle(instance: T) {
         validateInstance(instance)
         if (size == capacity) disposeInstance(instance)
         instances[size++] = instance
     }
 
-    override final fun dispose() {
+    actual final override fun dispose() {
         for (i in 0 until size) {
             @Suppress("UNCHECKED_CAST")
             val instance = instances[i] as T
@@ -36,4 +36,4 @@ actual abstract class DefaultPool<T : Any>(actual override final val capacity: I
         }
         size = 0
     }
-}
+}

src/main/kotlin/kotlinx/io/pool/Pool.kt

@@ -109,9 +109,12 @@ abstract class SingleInstancePool<T : Any> : ObjectPool<T> {
 }
 
 /**
- * Default object pool implementation
+ * Default object pool implementation.
  */
-expect abstract class DefaultPool<T : Any> : ObjectPool<T> {
+expect abstract class DefaultPool<T : Any>(capacity: Int) : ObjectPool<T> {
+    /**
+     * Pool capacity.
+     */
     final override val capacity: Int
 
     /**
@@ -133,6 +136,12 @@ expect abstract class DefaultPool<T : Any> : ObjectPool<T> {
      * Validate [instance] of [T]. Could verify that the object has been borrowed from this pool
      */
     protected open fun validateInstance(instance: T)
+
+    final override fun borrow(): T
+
+    final override fun recycle(instance: T)
+
+    final override fun dispose()
 }
 
 /**

src/test/kotlin/kotlinx/io/tests/DefaultPoolImplementationTest.kt

@@ -0,0 +1,15 @@
+package kotlinx.io.tests
+
+import kotlinx.io.pool.*
+import kotlin.test.*
+
+class DefaultPoolImplementationTest {
+    @Test
+    fun instantiateTest() {
+        assertEquals(1, Impl().borrow())
+    }
+
+    private class Impl : DefaultPool<Int>(10) {
+        override fun produceInstance() = 1
+    }
+}