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/*
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* Copyright (C) 2012 The Android Open Source Project
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*
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* Licensed under the Apache License, Version 2.0 (the "License");
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* you may not use this file except in compliance with the License.
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* You may obtain a copy of the License at
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*
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* http://www.apache.org/licenses/LICENSE-2.0
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*
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* Unless required by applicable law or agreed to in writing, software
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* distributed under the License is distributed on an "AS IS" BASIS,
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* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
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* See the License for the specific language governing permissions and
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* limitations under the License.
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*/
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package com.android.volley.toolbox;
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import java.io.ByteArrayOutputStream;
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import java.io.IOException;
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/**
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* A variation of {@link java.io.ByteArrayOutputStream} that uses a pool of byte[] buffers instead
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* of always allocating them fresh, saving on heap churn.
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*/
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public class PoolingByteArrayOutputStream extends ByteArrayOutputStream {
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/**
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* If the {@link #PoolingByteArrayOutputStream(ByteArrayPool)} constructor is called, this is
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* the default size to which the underlying byte array is initialized.
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*/
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private static final int DEFAULT_SIZE = 256;
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private final ByteArrayPool mPool;
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/**
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* Constructs a new PoolingByteArrayOutputStream with a default size. If more bytes are written
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* to this instance, the underlying byte array will expand.
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*/
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public PoolingByteArrayOutputStream(ByteArrayPool pool) {
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this(pool, DEFAULT_SIZE);
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}
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/**
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* Constructs a new {@code ByteArrayOutputStream} with a default size of {@code size} bytes. If
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* more than {@code size} bytes are written to this instance, the underlying byte array will
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* expand.
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*
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* @param size initial size for the underlying byte array. The value will be pinned to a default
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* minimum size.
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*/
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public PoolingByteArrayOutputStream(ByteArrayPool pool, int size) {
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mPool = pool;
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buf = mPool.getBuf(Math.max(size, DEFAULT_SIZE));
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}
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@Override
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public void close() throws IOException {
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mPool.returnBuf(buf);
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buf = null;
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super.close();
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}
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@Override
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public void finalize() {
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mPool.returnBuf(buf);
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}
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/**
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* Ensures there is enough space in the buffer for the given number of additional bytes.
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*/
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private void expand(int i) {
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/* Can the buffer handle @i more bytes, if not expand it */
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if (count + i <= buf.length) {
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return;
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}
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byte[] newbuf = mPool.getBuf((count + i) * 2);
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System.arraycopy(buf, 0, newbuf, 0, count);
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mPool.returnBuf(buf);
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buf = newbuf;
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}
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@Override
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public synchronized void write(byte[] buffer, int offset, int len) {
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expand(len);
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super.write(buffer, offset, len);
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}
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@Override
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public synchronized void write(int oneByte) {
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expand(1);
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super.write(oneByte);
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}
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}
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