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/*
 * ====================================================================
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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
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 * KIND, either express or implied.  See the License for the
 * specific language governing permissions and limitations
 * under the License.
 * ====================================================================
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 * This software consists of voluntary contributions made by many
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package org.apache.http.nio.util;

import java.nio.ByteBuffer;

import org.apache.http.annotation.NotThreadSafe;
import org.apache.http.io.BufferInfo;
import org.apache.http.util.Args;

/**
 * A buffer that expand its capacity on demand using {@link ByteBufferAllocator}
 * interface. Internally, this class is backed by an instance of
 * {@link ByteBuffer}.
 * 

* This class is not thread safe. * * @since 4.0 */ @SuppressWarnings("deprecation") @NotThreadSafe public class ExpandableBuffer implements BufferInfo, org.apache.http.nio.util.BufferInfo { public final static int INPUT_MODE = 0; public final static int OUTPUT_MODE = 1; private final ByteBufferAllocator allocator; private int mode; protected ByteBuffer buffer = null; /** * Allocates buffer of the given size using the given allocator. * * @param buffersize the buffer size. * @param allocator allocator to be used to allocate {@link ByteBuffer}s. */ public ExpandableBuffer(final int buffersize, final ByteBufferAllocator allocator) { super(); Args.notNull(allocator, "ByteBuffer allocator"); this.allocator = allocator; this.buffer = allocator.allocate(buffersize); this.mode = INPUT_MODE; } /** * Returns the current mode: *

* {@link #INPUT_MODE}: the buffer is in the input mode. *

* {@link #OUTPUT_MODE}: the buffer is in the output mode. * * @return current input/output mode. */ protected int getMode() { return this.mode; } /** * Sets output mode. The buffer can now be read from. */ protected void setOutputMode() { if (this.mode != OUTPUT_MODE) { this.buffer.flip(); this.mode = OUTPUT_MODE; } } /** * Sets input mode. The buffer can now be written into. */ protected void setInputMode() { if (this.mode != INPUT_MODE) { if (this.buffer.hasRemaining()) { this.buffer.compact(); } else { this.buffer.clear(); } this.mode = INPUT_MODE; } } private void expandCapacity(final int capacity) { final ByteBuffer oldbuffer = this.buffer; this.buffer = allocator.allocate(capacity); oldbuffer.flip(); this.buffer.put(oldbuffer); } /** * Expands buffer's capacity. */ protected void expand() { int newcapacity = (this.buffer.capacity() + 1) << 1; if (newcapacity < 0) { newcapacity = Integer.MAX_VALUE; } expandCapacity(newcapacity); } /** * Ensures the buffer can accommodate the required capacity. */ protected void ensureCapacity(final int requiredCapacity) { if (requiredCapacity > this.buffer.capacity()) { expandCapacity(requiredCapacity); } } /** * Returns the total capacity of this buffer. * * @return total capacity. */ @Override public int capacity() { return this.buffer.capacity(); } /** * Determines if the buffer contains data. * * @return {@code true} if there is data in the buffer, * {@code false} otherwise. */ public boolean hasData() { setOutputMode(); return this.buffer.hasRemaining(); } /** * Returns the length of this buffer. * * @return buffer length. */ @Override public int length() { setOutputMode(); return this.buffer.remaining(); } /** * Returns available capacity of this buffer. * * @return buffer length. */ @Override public int available() { setInputMode(); return this.buffer.remaining(); } /** * Clears buffer. */ protected void clear() { this.buffer.clear(); this.mode = INPUT_MODE; } @Override public String toString() { final StringBuilder sb = new StringBuilder(); sb.append("[mode="); if (getMode() == INPUT_MODE) { sb.append("in"); } else { sb.append("out"); } sb.append(" pos="); sb.append(this.buffer.position()); sb.append(" lim="); sb.append(this.buffer.limit()); sb.append(" cap="); sb.append(this.buffer.capacity()); sb.append("]"); return sb.toString(); } }





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