info.zhoumin.dat.util.ResizableIntArray.java Source code

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Here is the source code for info.zhoumin.dat.util.ResizableIntArray.java

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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 "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 info.zhoumin.dat.util;

import io.netty.buffer.ByteBuf;
import io.netty.buffer.PooledByteBufAllocator;

import java.nio.ByteOrder;

/**
 * @author Min Zhou (coderplay AT gmail.com)
 */
public final class ResizableIntArray {

    static final int INT_SIZE = 4; // 4 bytes
    static final int INT_SIZE_BITS = 2; // 4 bytes

    private ByteBuf buffer;

    public ResizableIntArray() {
        buffer = PooledByteBufAllocator.DEFAULT.directBuffer().order(ByteOrder.nativeOrder());
    }

    public ResizableIntArray(int initialCapacity) {
        buffer = PooledByteBufAllocator.DEFAULT.directBuffer(initialCapacity << INT_SIZE_BITS)
                .order(ByteOrder.nativeOrder());
    }

    public void capacity(int capacity) {
        buffer.capacity(capacity << INT_SIZE_BITS);
    }

    public int capacity() {
        /* In netty4, ByteBuf will be cleared after enlarge it
         * By changing the writer index, this bug would be coped*/
        buffer.writerIndex(buffer.capacity());
        return buffer.capacity() >> INT_SIZE_BITS;
    }

    /**
     * Returns the integer at the specified position in this array.
     *
     * @param index index of the integer to return
     * @return the integer at the specified position in this array.
     * @throws IndexOutOfBoundsException if the index is out of range
     *         (<tt>index &lt; 0 || index &gt;= length()</tt>)
     */
    public int get(int index) {
        return buffer.getInt(index << INT_SIZE_BITS);
    }

    /**
     */
    public void set(int index, int value) {
        int address = index << INT_SIZE_BITS;
        buffer.setInt(address, value);
    }

}