Synchronize libGDX Pool operations, try to fix better font issues

src/main/java/com/badlogic/gdx/utils/Pool.java

@@ -0,0 +1,144 @@
+/*******************************************************************************
+ * Copyright 2011 See AUTHORS file.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *   http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ ******************************************************************************/
+
+package com.badlogic.gdx.utils;
+
+/** A pool of objects that can be reused to avoid allocation.
+ * @see Pools
+ * @author Nathan Sweet */
+abstract public class Pool<T> {
+    /** The maximum number of objects that will be pooled. */
+    public final int max;
+    /** The highest number of free objects. Can be reset any time. */
+    public int peak;
+
+    private final Array<T> freeObjects;
+
+    /** Creates a pool with an initial capacity of 16 and no maximum. */
+    public Pool () {
+        this(16, Integer.MAX_VALUE);
+    }
+
+    /** Creates a pool with the specified initial capacity and no maximum. */
+    public Pool (int initialCapacity) {
+        this(initialCapacity, Integer.MAX_VALUE);
+    }
+
+    /** @param initialCapacity The initial size of the array supporting the pool. No objects are created/pre-allocated. Use
+     *           {@link #fill(int)} after instantiation if needed.
+     * @param max The maximum number of free objects to store in this pool. */
+    public Pool (int initialCapacity, int max) {
+        freeObjects = new Array(false, initialCapacity);
+        this.max = max;
+    }
+
+    abstract protected T newObject ();
+
+    /** Returns an object from this pool. The object may be new (from {@link #newObject()}) or reused (previously
+     * {@link #free(Object) freed}). */
+    public T obtain () {
+        synchronized (freeObjects) {
+            return freeObjects.size == 0 ? newObject() : freeObjects.pop();
+        }
+    }
+
+    /** Puts the specified object in the pool, making it eligible to be returned by {@link #obtain()}. If the pool already contains
+     * {@link #max} free objects, the specified object is {@link #discard(Object) discarded}, it is not reset and not added to the
+     * pool.
+     * <p>
+     * The pool does not check if an object is already freed, so the same object must not be freed multiple times. */
+    public void free (T object) {
+        synchronized (freeObjects) {
+            if (object == null) throw new IllegalArgumentException("object cannot be null.");
+            if (freeObjects.size < max) {
+                freeObjects.add(object);
+                peak = Math.max(peak, freeObjects.size);
+                reset(object);
+            } else
+                discard(object);
+        }
+    }
+
+    /** Adds the specified number of new free objects to the pool. Usually called early on as a pre-allocation mechanism but can be
+     * used at any time.
+     *
+     * @param size the number of objects to be added */
+    public void fill (int size) {
+        synchronized (freeObjects) {
+            for (int i = 0; i < size; i++)
+                if (freeObjects.size < max) freeObjects.add(newObject());
+            peak = Math.max(peak, freeObjects.size);
+        }
+    }
+
+    /** Called when an object is freed to clear the state of the object for possible later reuse. The default implementation calls
+     * {@link Poolable#reset()} if the object is {@link Poolable}. */
+    protected void reset (T object) {
+        if (object instanceof Poolable) ((Poolable)object).reset();
+    }
+
+    /** Called when an object is discarded. This is the case when an object is freed, but the maximum capacity of the pool is
+     * reached, and when the pool is {@link #clear() cleared} */
+    protected void discard (T object) {
+        reset(object);
+    }
+
+    /** Puts the specified objects in the pool. Null objects within the array are silently ignored.
+     * <p>
+     * The pool does not check if an object is already freed, so the same object must not be freed multiple times.
+     * @see #free(Object) */
+    public void freeAll (Array<T> objects) {
+        synchronized (freeObjects) {
+            if (objects == null) throw new IllegalArgumentException("objects cannot be null.");
+            Array<T> freeObjects = this.freeObjects;
+            int max = this.max;
+            for (int i = 0, n = objects.size; i < n; i++) {
+                T object = objects.get(i);
+                if (object == null) continue;
+                if (freeObjects.size < max) {
+                    freeObjects.add(object);
+                    reset(object);
+                } else {
+                    discard(object);
+                }
+            }
+            peak = Math.max(peak, freeObjects.size);
+        }
+    }
+
+    /** Removes and discards all free objects from this pool. */
+    public void clear () {
+        synchronized (freeObjects) {
+            Array<T> freeObjects = this.freeObjects;
+            for (int i = 0, n = freeObjects.size; i < n; i++)
+                discard(freeObjects.get(i));
+            freeObjects.clear();
+        }
+    }
+
+    /** The number of objects available to be obtained. */
+    public int getFree () {
+        synchronized (freeObjects) {
+            return freeObjects.size;
+        }
+    }
+
+    /** Objects implementing this interface will have {@link #reset()} called when passed to {@link Pool#free(Object)}. */
+    static public interface Poolable {
+        /** Resets the object for reuse. Object references should be nulled and fields may be set to default values. */
+        public void reset ();
+    }
+}