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-rw-r--r--WallpaperPicker/src/android/util/Pools.java165
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diff --git a/WallpaperPicker/src/android/util/Pools.java b/WallpaperPicker/src/android/util/Pools.java
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+/*
+ * Copyright (C) 2009 The Android Open Source Project
+ *
+ * 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 android.util;
+
+/**
+ * Helper class for crating pools of objects. An example use looks like this:
+ * <pre>
+ * public class MyPooledClass {
+ *
+ * private static final SynchronizedPool<MyPooledClass> sPool =
+ * new SynchronizedPool<MyPooledClass>(10);
+ *
+ * public static MyPooledClass obtain() {
+ * MyPooledClass instance = sPool.acquire();
+ * return (instance != null) ? instance : new MyPooledClass();
+ * }
+ *
+ * public void recycle() {
+ * // Clear state if needed.
+ * sPool.release(this);
+ * }
+ *
+ * . . .
+ * }
+ * </pre>
+ *
+ * @hide
+ */
+public final class Pools {
+
+ /**
+ * Interface for managing a pool of objects.
+ *
+ * @param <T> The pooled type.
+ */
+ public static interface Pool<T> {
+
+ /**
+ * @return An instance from the pool if such, null otherwise.
+ */
+ public T acquire();
+
+ /**
+ * Release an instance to the pool.
+ *
+ * @param instance The instance to release.
+ * @return Whether the instance was put in the pool.
+ *
+ * @throws IllegalStateException If the instance is already in the pool.
+ */
+ public boolean release(T instance);
+ }
+
+ private Pools() {
+ /* do nothing - hiding constructor */
+ }
+
+ /**
+ * Simple (non-synchronized) pool of objects.
+ *
+ * @param <T> The pooled type.
+ */
+ public static class SimplePool<T> implements Pool<T> {
+ private final Object[] mPool;
+
+ private int mPoolSize;
+
+ /**
+ * Creates a new instance.
+ *
+ * @param maxPoolSize The max pool size.
+ *
+ * @throws IllegalArgumentException If the max pool size is less than zero.
+ */
+ public SimplePool(int maxPoolSize) {
+ if (maxPoolSize <= 0) {
+ throw new IllegalArgumentException("The max pool size must be > 0");
+ }
+ mPool = new Object[maxPoolSize];
+ }
+
+ @Override
+ @SuppressWarnings("unchecked")
+ public T acquire() {
+ if (mPoolSize > 0) {
+ final int lastPooledIndex = mPoolSize - 1;
+ T instance = (T) mPool[lastPooledIndex];
+ mPool[lastPooledIndex] = null;
+ mPoolSize--;
+ return instance;
+ }
+ return null;
+ }
+
+ @Override
+ public boolean release(T instance) {
+ if (isInPool(instance)) {
+ throw new IllegalStateException("Already in the pool!");
+ }
+ if (mPoolSize < mPool.length) {
+ mPool[mPoolSize] = instance;
+ mPoolSize++;
+ return true;
+ }
+ return false;
+ }
+
+ private boolean isInPool(T instance) {
+ for (int i = 0; i < mPoolSize; i++) {
+ if (mPool[i] == instance) {
+ return true;
+ }
+ }
+ return false;
+ }
+ }
+
+ /**
+ * Synchronized) pool of objects.
+ *
+ * @param <T> The pooled type.
+ */
+ public static class SynchronizedPool<T> extends SimplePool<T> {
+ private final Object mLock = new Object();
+
+ /**
+ * Creates a new instance.
+ *
+ * @param maxPoolSize The max pool size.
+ *
+ * @throws IllegalArgumentException If the max pool size is less than zero.
+ */
+ public SynchronizedPool(int maxPoolSize) {
+ super(maxPoolSize);
+ }
+
+ @Override
+ public T acquire() {
+ synchronized (mLock) {
+ return super.acquire();
+ }
+ }
+
+ @Override
+ public boolean release(T element) {
+ synchronized (mLock) {
+ return super.release(element);
+ }
+ }
+ }
+} \ No newline at end of file