Jean-Baptiste Queru | d56b88a | 2012-11-07 07:48:57 -0800 | [diff] [blame] | 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 | } |