From f9477d5adc3223f53bf220649a67142fdf5f83af Mon Sep 17 00:00:00 2001
From: Tim Vossen <tim.vossen@intrafind.de>
Date: Thu, 18 Feb 2021 18:19:18 +0100
Subject: [PATCH] Reuse the same strategy instance. This avoids unecessary
 allocations when using the default constructor of ArrayLists or ArrayDeques.

---
 .../hppc/BoundedProportionalArraySizingStrategy.java     | 5 +++++
 .../templates/com/carrotsearch/hppc/KTypeArrayDeque.java | 9 ++++++++-
 .../templates/com/carrotsearch/hppc/KTypeArrayList.java  | 8 +++++++-
 3 files changed, 20 insertions(+), 2 deletions(-)

diff --git a/hppc/src/main/java/com/carrotsearch/hppc/BoundedProportionalArraySizingStrategy.java b/hppc/src/main/java/com/carrotsearch/hppc/BoundedProportionalArraySizingStrategy.java
index a0e02084..d524a9b1 100644
--- a/hppc/src/main/java/com/carrotsearch/hppc/BoundedProportionalArraySizingStrategy.java
+++ b/hppc/src/main/java/com/carrotsearch/hppc/BoundedProportionalArraySizingStrategy.java
@@ -22,6 +22,11 @@
  * </pre>
  */
 public final class BoundedProportionalArraySizingStrategy implements ArraySizingStrategy {
+
+  /** Instance of {@link BoundedProportionalArraySizingStrategy} with default values. */
+  public static final BoundedProportionalArraySizingStrategy DEFAULT_INSTANCE =
+      new BoundedProportionalArraySizingStrategy();
+
   /**
    * Maximum allocable array length (approximately the largest positive integer decreased by the
    * array's object header).
diff --git a/hppc/src/main/templates/com/carrotsearch/hppc/KTypeArrayDeque.java b/hppc/src/main/templates/com/carrotsearch/hppc/KTypeArrayDeque.java
index eac87343..001b8eba 100644
--- a/hppc/src/main/templates/com/carrotsearch/hppc/KTypeArrayDeque.java
+++ b/hppc/src/main/templates/com/carrotsearch/hppc/KTypeArrayDeque.java
@@ -19,6 +19,13 @@ public class KTypeArrayDeque<KType>
              Preallocable, 
              Cloneable,
              Accountable {
+
+  /**
+   * Reuse the same strategy instance.
+   */
+  private static final BoundedProportionalArraySizingStrategy DEFAULT_SIZING_STRATEGY =
+      BoundedProportionalArraySizingStrategy.DEFAULT_INSTANCE;
+
   /**
    * Internal array for storing elements of the deque.
    */
@@ -62,7 +69,7 @@ public KTypeArrayDeque() {
    *          expansion (inclusive).
    */
   public KTypeArrayDeque(int expectedElements) {
-    this(expectedElements, new BoundedProportionalArraySizingStrategy());
+    this(expectedElements, DEFAULT_SIZING_STRATEGY);
   }
 
   /**
diff --git a/hppc/src/main/templates/com/carrotsearch/hppc/KTypeArrayList.java b/hppc/src/main/templates/com/carrotsearch/hppc/KTypeArrayList.java
index 72d33d70..a15801d0 100644
--- a/hppc/src/main/templates/com/carrotsearch/hppc/KTypeArrayList.java
+++ b/hppc/src/main/templates/com/carrotsearch/hppc/KTypeArrayList.java
@@ -36,6 +36,12 @@ public class KTypeArrayList<KType>
           new Object [0]; 
       /*! #end !*/; 
 
+  /**
+   * Reuse the same strategy instance.
+   */
+  private static final BoundedProportionalArraySizingStrategy DEFAULT_SIZING_STRATEGY =
+      BoundedProportionalArraySizingStrategy.DEFAULT_INSTANCE;
+
   /**
    * Internal array for storing the list. The array may be larger than the current size
    * ({@link #size()}).
@@ -73,7 +79,7 @@ public KTypeArrayList() {
    *          expansion (inclusive).
    */
   public KTypeArrayList(int expectedElements) {
-    this(expectedElements, new BoundedProportionalArraySizingStrategy());
+    this(expectedElements, DEFAULT_SIZING_STRATEGY);
   }