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/*
* Copyright (C) 2012 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 com.android.volley.toolbox;
import java.io.ByteArrayOutputStream;
import java.io.IOException;
/**
* A variation of {@link java.io.ByteArrayOutputStream} that uses a pool of byte[] buffers instead
* of always allocating them fresh, saving on heap churn.
*/
public class PoolingByteArrayOutputStream extends ByteArrayOutputStream {
/**
* If the {@link #PoolingByteArrayOutputStream(ByteArrayPool)} constructor is called, this is
* the default size to which the underlying byte array is initialized.
*/
private static final int DEFAULT_SIZE = 256;
private final ByteArrayPool mPool;
/**
* Constructs a new PoolingByteArrayOutputStream with a default size. If more bytes are written
* to this instance, the underlying byte array will expand.
*/
public PoolingByteArrayOutputStream(ByteArrayPool pool) {
this(pool, DEFAULT_SIZE);
}
/**
* Constructs a new {@code ByteArrayOutputStream} with a default size of {@code size} bytes. If
* more than {@code size} bytes are written to this instance, the underlying byte array will
* expand.
*
* @param size initial size for the underlying byte array. The value will be pinned to a default
* minimum size.
*/
public PoolingByteArrayOutputStream(ByteArrayPool pool, int size) {
mPool = pool;
buf = mPool.getBuf(Math.max(size, DEFAULT_SIZE));
}
@Override
public void close() throws IOException {
mPool.returnBuf(buf);
buf = null;
super.close();
}
@Override
public void finalize() {
mPool.returnBuf(buf);
}
/** Ensures there is enough space in the buffer for the given number of additional bytes. */
@SuppressWarnings("UnsafeFinalization")
private void expand(int i) {
/* Can the buffer handle @i more bytes, if not expand it */
if (count + i <= buf.length) {
return;
}
byte[] newbuf = mPool.getBuf((count + i) * 2);
System.arraycopy(buf, 0, newbuf, 0, count);
mPool.returnBuf(buf);
buf = newbuf;
}
@Override
public synchronized void write(byte[] buffer, int offset, int len) {
expand(len);
super.write(buffer, offset, len);
}
@Override
public synchronized void write(int oneByte) {
expand(1);
super.write(oneByte);
}
}
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