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Fork of Esoteric Software's Kryo built by Nathan Sweet that replaces Minlog with slf4j as the logging facade. This contains the shaded reflectasm jar to prevent conflicts with other versions of asm.
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/* Copyright (c) 2008, Nathan Sweet
 * All rights reserved.
 * 
 * Redistribution and use in source and binary forms, with or without modification, are permitted provided that the following
 * conditions are met:
 * 
 * - Redistributions of source code must retain the above copyright notice, this list of conditions and the following disclaimer.
 * - Redistributions in binary form must reproduce the above copyright notice, this list of conditions and the following
 * disclaimer in the documentation and/or other materials provided with the distribution.
 * - Neither the name of Esoteric Software nor the names of its contributors may be used to endorse or promote products derived
 * from this software without specific prior written permission.
 * 
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING,
 * BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT
 * SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING
 * NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */

package com.esotericsoftware.kryo.pool;

import java.lang.ref.SoftReference;
import java.util.Queue;
import java.util.concurrent.Callable;
import java.util.concurrent.ConcurrentLinkedQueue;

import com.esotericsoftware.kryo.Kryo;

/**
 * A simple pool interface for {@link Kryo} instances. Use the {@link KryoPool.Builder} to
 * construct a pool instance.
 * 
 * Usage:
 *  * import com.esotericsoftware.kryo.Kryo;
 * import com.esotericsoftware.kryo.pool.*;
 * 
 * KryoFactory factory = new KryoFactory() {
 *   public Kryo create () {
 *     Kryo kryo = new Kryo();
 *     // configure kryo instance, customize settings
 *     return kryo;
 *   }
 * };
 * // Simple pool, you might also activate SoftReferences to fight OOMEs.
 * KryoPool pool = new KryoPool.Builder(factory).build();
 * Kryo kryo = pool.borrow();
 * // do s.th. with kryo here, and afterwards release it
 * pool.release(kryo);
 * 
 * // or use a callback to work with kryo (pool.run borrows+releases for you)
 * String value = pool.run(new KryoCallback() {
 *   public String execute(Kryo kryo) {
 *     return kryo.readObject(input, String.class);
 *   }
 * });
 *
 * 
 * 
 * @author Martin Grotzke
 */
public interface KryoPool {

	/**
	 * Takes a {@link Kryo} instance from the pool or creates a new one
	 * (using the factory) if the pool is empty.
	 */
	Kryo borrow ();

	/**
	 * Returns the given {@link Kryo} instance to the pool.
	 */
	void release (Kryo kryo);

	/**
	 * Runs the provided {@link KryoCallback} with a {@link Kryo} instance
	 * from the pool (borrow/release around {@link KryoCallback#execute(Kryo)}).
	 */
	 T run(KryoCallback callback);

	/**
	 * Builder for a {@link KryoPool} instance, constructs a {@link KryoPoolQueueImpl} instance.
	 */
	public static class Builder {

		private final KryoFactory factory;
		private Queue queue = new ConcurrentLinkedQueue();
		private boolean softReferences;

		public Builder(KryoFactory factory) {
			if(factory == null) {
				throw new IllegalArgumentException("factory must not be null");
			}
			this.factory = factory;
		}

		/**
		 * Use the given queue for pooling kryo instances (by default a {@link ConcurrentLinkedQueue}
		 * is used).
		 */
		public Builder queue(Queue queue) {
			if(queue == null) {
				throw new IllegalArgumentException("queue must not be null");
			}
			this.queue = queue;
			return this;
		}

		/**
		 * Use {@link SoftReference}s for pooled {@link Kryo} instances, so that
		 * instances may be garbage collected when there's memory demand (by default
		 * disabled).
		 */
		public Builder softReferences() {
			softReferences = true;
			return this;
		}

		/**
		 * Build the pool.
		 */
		public KryoPool build() {
			Queue q = softReferences ? new SoftReferenceQueue(queue) : queue;
			return new KryoPoolQueueImpl(factory, q);
		}

		@Override
		public String toString () {
			return getClass().getName() + "[queue.class=" + queue.getClass() + ", softReferences=" + softReferences + "]";
		}
	}

}