Free discarded pool objects by default. #476

CHANGELOG.md

@@ -2,6 +2,9 @@ _See also: [the official libGDX changelog](https://github.com/libgdx/libgdx/blob
 
 #### 1.12.1-SNAPSHOT
 
+- **[CHANGE]** (`ktx-assets`) The `pool` factory method now attempts to reset `Poolable` objects with the default `discard` lambda
+to match the default libGDX pool behavior. Pass a custom function to override it.
+
 #### 1.12.1-rc1
 
 - **[UPDATE]** Updated to libGDX 1.12.1.

assets/src/main/kotlin/ktx/assets/pools.kt

@@ -2,6 +2,7 @@ package ktx.assets
 
 import com.badlogic.gdx.utils.Disposable
 import com.badlogic.gdx.utils.Pool
+import com.badlogic.gdx.utils.Pool.Poolable
 
 /**
  * Allows to use a [Pool] instance as a functional object. When invoked with no parameters, [Pool] will provide an
@@ -14,7 +15,7 @@ operator fun <Type> Pool<Type>.invoke(): Type = this.obtain()
 /**
  * Allows to use a [Pool] instance as a functional object. When invoked with a parameter, [Pool] will treat the passed
  * parameter as an object freed to the pool.
- * @param free will be returned to the pool. Might be reset if it implements the Poolable interface.
+ * @param free will be returned to the pool. Might be reset if it implements the [Poolable] interface.
  * @see Pool.free
  */
 operator fun <Type> Pool<Type>.invoke(free: Type) = this.free(free)
@@ -24,14 +25,19 @@ operator fun <Type> Pool<Type>.invoke(free: Type) = this.free(free)
  * @param max max amount stored in the pool. When exceeded, freed objects are no longer accepted.
  * @param discard invoked each time an object is rejected or removed from the pool. This might happen if an object is
  * freed with [Pool.free] or [Pool.freeAll] if the pool is full, or when [Pool.clear] is called. Optional, defaults
- * to no operation. If the objects are [Disposable], this lambda might be used to dispose of them.
+ * to resetting the objects implementing the [Poolable] interface to replicate the default behavior. If the objects are
+ * [Disposable], this lambda should be used to dispose of them.
  * @param provider creates instances of the requested objects.
  * @return a new [Pool] instance, creating the object with the passed provider.
  */
 inline fun <Type> pool(
   initialCapacity: Int = 16,
   max: Int = Int.MAX_VALUE,
-  crossinline discard: (Type) -> Unit = {},
+  crossinline discard: (Type) -> Unit = {
+    if (it is Poolable) {
+      it.reset()
+    }
+  },
   crossinline provider: () -> Type,
 ): Pool<Type> =
   object : Pool<Type>(initialCapacity, max) {

assets/src/test/kotlin/ktx/assets/PoolsTest.kt

@@ -1,9 +1,11 @@
 package ktx.assets
 
 import com.badlogic.gdx.utils.Pool
+import com.badlogic.gdx.utils.Pool.Poolable
 import org.junit.Assert.assertEquals
 import org.junit.Assert.assertNotNull
 import org.junit.Assert.assertSame
+import org.junit.Assert.assertTrue
 import org.junit.Test
 
 /**
@@ -76,6 +78,30 @@ class PoolsTest {
     assertEquals(listOf("Value6", "Value7", "Value8", "Value9", "Value10"), discarded)
   }
 
+  @Test
+  fun `should create new pools that reset discarded objects by default`() {
+    // Given:
+    val pool = pool(max = 1) { SamplePoolable() }
+    val freed = pool()
+    val discarded = pool()
+    pool.free(freed)
+
+    // When:
+    pool.free(discarded)
+
+    // Then:
+    assertTrue(discarded.isReset)
+  }
+
+  /**
+   * A simple data object implementing the [Poolable] interface.
+   */
+  private class SamplePoolable(var isReset: Boolean = false) : Poolable {
+    override fun reset() {
+      this.isReset = true
+    }
+  }
+
   /**
    * Provides new [Any] instances.
    */