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/**
 *  Copyright 2015 Peter Nerg
 *
 *  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 simplepool;

import java.time.Duration;

import javascalautils.Try;
import javascalautils.Unit;

/**
 * Represents a pool of objects.
 * 
 * @author Peter Nerg
 * @param 
 *            The type returned by the pool
 * @since 1.0
 */
public interface Pool {

	/**
	 * Request a object instance from the pool. 

	 * If no free objects this method waits until an object is returned. 

	 * Warning! This means that the thread may be held here forever.
	 * 
	 * @return The object instance
	 * @since 1.0
	 */
	default Try getInstance() {
		return getInstance(Duration.ofMillis(Long.MAX_VALUE));
	}

	/**
	 * Request a object instance from the pool. 

	 * If no free objects this method waits (for the provided time) until an object is returned.
	 * 
	 * @param maxWaitTime
	 *            The time to wait for a free object
	 * @return The object instance
	 * @since 1.0
	 */
	Try getInstance(Duration maxWaitTime);

	/**
	 * Returns a borrowed instance to the pool. 

	 * Should the pool be full and an attempt is made to return an instance the operation will result in a {@link javascalautils.Failure}.
	 * 
	 * @param instance
	 *            The instance to return
	 * @return The result of returning the instance
	 * @since 1.0
	 */
	Try returnInstance(T instance);
}