1 /* 2 * Copyright (C) 2011 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); you may not 5 * use this file except in compliance with the License. You may obtain a copy of 6 * the License at 7 * 8 * http://www.apache.org/licenses/LICENSE-2.0 9 * 10 * Unless required by applicable law or agreed to in writing, software 11 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT 12 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the 13 * License for the specific language governing permissions and limitations under 14 * the License. 15 */ 16 17 package com.android.inputmethod.latin; 18 19 import java.util.ArrayList; 20 import java.util.Collections; 21 import java.util.List; 22 23 /** 24 * A pool of string builders to be used from anywhere. 25 */ 26 public class StringBuilderPool { 27 // Singleton 28 private static final StringBuilderPool sInstance = new StringBuilderPool(); 29 private static final boolean DEBUG = false; 30 private StringBuilderPool() {} 31 // TODO: Make this a normal array with a size of 20, or a ConcurrentQueue 32 private final List<StringBuilder> mPool = 33 Collections.synchronizedList(new ArrayList<StringBuilder>()); 34 35 public static StringBuilder getStringBuilder(final int initialSize) { 36 // TODO: although the pool is synchronized, the following is not thread-safe. 37 // Two threads entering this at the same time could take the same size of the pool and the 38 // second to attempt removing this index from the pool would crash with an 39 // IndexOutOfBoundsException. 40 // At the moment this pool is only used in Suggest.java and only in one thread so it's 41 // okay. The simplest thing to do here is probably to replace the ArrayList with a 42 // ConcurrentQueue. 43 final int poolSize = sInstance.mPool.size(); 44 final StringBuilder sb = poolSize > 0 ? (StringBuilder) sInstance.mPool.remove(poolSize - 1) 45 : new StringBuilder(initialSize); 46 sb.setLength(0); 47 return sb; 48 } 49 50 public static void recycle(final StringBuilder garbage) { 51 if (DEBUG) { 52 final int gid = garbage.hashCode(); 53 for (final StringBuilder q : sInstance.mPool) { 54 if (gid == q.hashCode()) throw new RuntimeException("Duplicate id " + gid); 55 } 56 } 57 sInstance.mPool.add(garbage); 58 } 59 60 public static void ensureCapacity(final int capacity, final int initialSize) { 61 for (int i = sInstance.mPool.size(); i < capacity; ++i) { 62 final StringBuilder sb = new StringBuilder(initialSize); 63 sInstance.mPool.add(sb); 64 } 65 } 66 67 public static int getSize() { 68 return sInstance.mPool.size(); 69 } 70 } 71
