1 /* 2 * Copyright (C) 2012 The Android Open Source Project 3 * 4 * Licensed under the Apache License, Version 2.0 (the "License"); 5 * you may not use this file except in compliance with the License. 6 * You may obtain a copy of 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, 12 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 13 * See the License for the specific language governing permissions and 14 * limitations under the License. 15 */ 16 17 package com.android.volley.toolbox; 18 19 import java.io.ByteArrayOutputStream; 20 import java.io.IOException; 21 22 /** 23 * A variation of {@link java.io.ByteArrayOutputStream} that uses a pool of byte[] buffers instead 24 * of always allocating them fresh, saving on heap churn. 25 */ 26 public class PoolingByteArrayOutputStream extends ByteArrayOutputStream { 27 /** 28 * If the {@link #PoolingByteArrayOutputStream(ByteArrayPool)} constructor is called, this is 29 * the default size to which the underlying byte array is initialized. 30 */ 31 private static final int DEFAULT_SIZE = 256; 32 33 private final ByteArrayPool mPool; 34 35 /** 36 * Constructs a new PoolingByteArrayOutputStream with a default size. If more bytes are written 37 * to this instance, the underlying byte array will expand. 38 */ 39 public PoolingByteArrayOutputStream(ByteArrayPool pool) { 40 this(pool, DEFAULT_SIZE); 41 } 42 43 /** 44 * Constructs a new {@code ByteArrayOutputStream} with a default size of {@code size} bytes. If 45 * more than {@code size} bytes are written to this instance, the underlying byte array will 46 * expand. 47 * 48 * @param size initial size for the underlying byte array. The value will be pinned to a default 49 * minimum size. 50 */ 51 public PoolingByteArrayOutputStream(ByteArrayPool pool, int size) { 52 mPool = pool; 53 buf = mPool.getBuf(Math.max(size, DEFAULT_SIZE)); 54 } 55 56 @Override 57 public void close() throws IOException { 58 mPool.returnBuf(buf); 59 buf = null; 60 super.close(); 61 } 62 63 @Override 64 public void finalize() { 65 mPool.returnBuf(buf); 66 } 67 68 /** 69 * Ensures there is enough space in the buffer for the given number of additional bytes. 70 */ 71 private void expand(int i) { 72 /* Can the buffer handle @i more bytes, if not expand it */ 73 if (count + i <= buf.length) { 74 return; 75 } 76 byte[] newbuf = mPool.getBuf((count + i) * 2); 77 System.arraycopy(buf, 0, newbuf, 0, count); 78 mPool.returnBuf(buf); 79 buf = newbuf; 80 } 81 82 @Override 83 public synchronized void write(byte[] buffer, int offset, int len) { 84 expand(len); 85 super.write(buffer, offset, len); 86 } 87 88 @Override 89 public synchronized void write(int oneByte) { 90 expand(1); 91 super.write(oneByte); 92 } 93 } 94
