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/***********************************************************************************************************************
 * Copyright (C) 2010-2014 by the Stratosphere project (http://stratosphere.eu)
 *
 * 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 eu.stratosphere.runtime.io;

import eu.stratosphere.core.memory.MemorySegment;

import java.util.concurrent.atomic.AtomicInteger;

public class Buffer {

	private final MemorySegment memorySegment;

	private final BufferRecycler recycler;

	// -----------------------------------------------------------------------------------------------------------------

	private final AtomicInteger referenceCounter;

	private int size;

	// -----------------------------------------------------------------------------------------------------------------

	public Buffer(MemorySegment memorySegment, int size, BufferRecycler recycler) {
		this.memorySegment = memorySegment;
		this.size = size;
		this.recycler = recycler;

		// we are the first, so we start with reference count of one
		this.referenceCounter = new AtomicInteger(1);
	}

	/**
	 * @param toDuplicate Buffer instance to duplicate
	 */
	private Buffer(Buffer toDuplicate) {
		if (toDuplicate.referenceCounter.getAndIncrement() == 0) {
			throw new IllegalStateException("Buffer was released before duplication.");
		}
		
		this.memorySegment = toDuplicate.memorySegment;
		this.size = toDuplicate.size;
		this.recycler = toDuplicate.recycler;
		this.referenceCounter = toDuplicate.referenceCounter;
	}

	// -----------------------------------------------------------------------------------------------------------------

	public MemorySegment getMemorySegment() {
		return this.memorySegment;
	}

	public int size() {
		return this.size;
	}

	public void limitSize(int size) {
		if (size >= 0 && size <= this.memorySegment.size()) {
			this.size = size;
		} else {
			throw new IllegalArgumentException();
		}
	}

	public void recycleBuffer() {
		int refCount = this.referenceCounter.decrementAndGet();
		if (refCount == 0) {
			this.recycler.recycle(this.memorySegment);
		}
	}

	public Buffer duplicate() {
		return new Buffer(this);
	}

	public void copyToBuffer(Buffer destinationBuffer) {
		if (size() > destinationBuffer.size()) {
			throw new IllegalArgumentException("Destination buffer is too small to store content of source buffer.");
		}

		this.memorySegment.copyTo(0, destinationBuffer.memorySegment, 0, size);
	}
}