From 11cfeeddedd61d3c4aa40945fef0bc2d87c7559d Mon Sep 17 00:00:00 2001
From: Bobby Georgescu <georgescu@google.com>
Date: Tue, 19 Feb 2013 15:49:14 -0800
Subject: Replace various BitmapPools with a smarter unified pool

Make all of gallery use a single shared pool, and pave the
way for making the pool more adaptive based on the current
workload.

Change-Id: Ia32561ad50b1b9716ebe2fd32a7bf02737685dac
---
 src/android/util/Pools.java | 165 ++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 165 insertions(+)
 create mode 100644 src/android/util/Pools.java

(limited to 'src/android')

diff --git a/src/android/util/Pools.java b/src/android/util/Pools.java
new file mode 100644
index 000000000..40bab1eae
--- /dev/null
+++ b/src/android/util/Pools.java
@@ -0,0 +1,165 @@
+/*
+ * 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);
+            }
+        }
+    }
+}
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