package org.apache.fulcrum.pool;
   
   import java.util.HashMap;
   
   /*
    * 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.
   */
  
  import java.util.Map;
  
  import org.apache.avalon.framework.activity.Disposable;
  import org.apache.avalon.framework.activity.Initializable;
  import org.apache.avalon.framework.configuration.Configurable;
  import org.apache.avalon.framework.configuration.Configuration;
  import org.apache.avalon.framework.logger.AbstractLogEnabled;
  import org.apache.avalon.framework.service.ServiceManager;
  import org.apache.avalon.framework.service.Serviceable;
  import org.apache.fulcrum.factory.FactoryException;
  import org.apache.fulcrum.factory.FactoryService;
  
  /**
   * The Pool Service extends the Factory Service by adding support for pooling
   * instantiated objects. When a new instance is requested, the service first
   * checks its pool if one is available. If the the pool is empty, a new instance
   * will be requested from the FactoryService.
   *
   * For objects implementing the Recyclable interface, a recycle method will be
   * called, when they taken from the pool, and a dispose method, when they are
   * returned to the pool.
   *
   * @author <a href="mailto:ilkka.priha@simsoft.fi">Ilkka Priha</a>
   * @author <a href="mailto:mcconnell@apache.org">Stephen McConnell</a>
   * @version $Id$
   *
   * avalon.component name="pool" lifestyle="transient"
   * avalon.service type="org.apache.fulcrum.pool.PoolService"
   */
  public class DefaultPoolService extends AbstractLogEnabled
  		implements PoolService, Serviceable, Disposable, Initializable, Configurable {
  	/**
  	 * The property specifying the pool capacity.
  	 */
  	public static final String POOL_CAPACITY = "capacity";
  	
  	/**
  	 * The default capacity of pools.
  	 */
  	private int poolCapacity = DEFAULT_POOL_CAPACITY;
  	
  	/**
  	 * The pool repository, one pool for each class.
  	 */
  	private HashMap<String, PoolBuffer> poolRepository = new HashMap<>();
  	private Map<String, Integer> capacityMap;
  	private FactoryService factoryService;
  	private ServiceManager manager;
  
  	/**
  	 * Gets an instance of a named class either from the pool or by calling the
  	 * Factory Service if the pool is empty.
  	 *
  	 * @param className the name of the class.
  	 * @return the instance.
  	 * @throws PoolException if recycling fails.
  	 */
  	public <T> T getInstance(String className) throws PoolException 
  	{
  		try 
  		{
  			T instance = pollInstance(className, null, null);
  			return instance == null ? getFactory().getInstance(className) : instance;
  		} 
  		catch (FactoryException fe) 
  		{
  			throw new PoolException(fe);
  		}
  	}
  
  	/**
  	 * Gets an instance of a named class either from the pool or by calling the
  	 * Factory Service if the pool is empty. The specified class loader will be
  	 * passed to the Factory Service.
  	 *
  	 * @param className the name of the class.
 	 * @param loader    the class loader.
 	 * @return the instance.
 	 * @throws PoolException if recycling fails.
 	 */
 	public Object getInstance(String className, ClassLoader loader) throws PoolException 
 	{
 		try 
 		{
 			Object instance = pollInstance(className, null, null);
 			return instance == null ? getFactory().getInstance(className, loader) : instance;
 		} 
 		catch (FactoryException fe) 
 		{
 			throw new PoolException(fe);
 		}
 	}
 
 	/**
 	 * Gets an instance of a named class either from the pool or by calling the
 	 * Factory Service if the pool is empty. Parameters for its constructor are
 	 * given as an array of objects, primitive types must be wrapped with a
 	 * corresponding class.
 	 *
 	 * @param className the name of the class.
 	 * @param params    an array containing the parameters of the constructor.
 	 * @param signature an array containing the signature of the constructor.
 	 * @return the instance.
 	 * @throws PoolException if recycling fails.
 	 */
 	public Object getInstance(String className, Object[] params, String[] signature) throws PoolException 
 	{
 		try 
 		{
 			Object instance = pollInstance(className, params, signature);
 			return instance == null ? getFactory().getInstance(className, params, signature) : instance;
 		} 
 		catch (FactoryException fe) 
 		{
 			throw new PoolException(fe);
 		}
 	}
 
 	/**
 	 * Gets an instance of a named class either from the pool or by calling the
 	 * Factory Service if the pool is empty. Parameters for its constructor are
 	 * given as an array of objects, primitive types must be wrapped with a
 	 * corresponding class. The specified class loader will be passed to the Factory
 	 * Service.
 	 *
 	 * @param className the name of the class.
 	 * @param loader    the class loader.
 	 * @param params    an array containing the parameters of the constructor.
 	 * @param signature an array containing the signature of the constructor.
 	 * @return the instance.
 	 * @throws PoolException if recycling fails.
 	 */
 	public Object getInstance(String className, ClassLoader loader, Object[] params, String[] signature)
 			throws PoolException 
 	{
 		try 
 		{
 			Object instance = pollInstance(className, params, signature);
 			return instance == null ? getFactory().getInstance(className, loader, params, signature) : instance;
 		} 
 		catch (FactoryException fe) 
 		{
 			throw new PoolException(fe);
 		}
 	}
 
 	/**
 	 * Tests if specified class loaders are supported for a named class.
 	 *
 	 * @param className the name of the class.
 	 * @return true if class loaders are supported, false otherwise.
 	 * @throws FactoryException if test fails.
 	 */
 	public boolean isLoaderSupported(String className) throws FactoryException 
 	{
 		return getFactory().isLoaderSupported(className);
 	}
 
 	/**
 	 * Gets an instance of a specified class either from the pool or by instatiating
 	 * from the class if the pool is empty.
 	 *
 	 * @param <T> type of the class
 	 * @param clazz the class.
 	 * @return the instance.
 	 * @throws PoolException if recycling fails.
 	 */
 	@SuppressWarnings("unchecked")
 	public <T> T getInstance(Class<?> clazz) throws PoolException 
 	{
 		try 
 		{
 			T instance = pollInstance(clazz.getName(), null, null);
 			return instance == null ? (T) factoryService.getInstance(clazz) : instance;
 		} 
 		catch (FactoryException fe) 
 		{
 			throw new PoolException(fe);
 		}
 	}
 
 	/**
 	 * Gets an instance of a specified class either from the pool or by instatiating
 	 * from the class if the pool is empty.
 	 *
 	 * @param clazz     the class.
 	 * @param params    an array containing the parameters of the constructor.
 	 * @param signature an array containing the signature of the constructor.
 	 * @return the instance.
 	 * @throws PoolException if recycling fails.
 	 */
 	public <T> T getInstance(Class<?> clazz, Object params[], String signature[]) throws PoolException 
 	{
 		try 
 		{
 			T instance = pollInstance(clazz.getName(), params, signature);
 			
 			// TODO There is a whacky .toString() on the clazz object, 
 			// but otherwise it won't compile
 			return instance == null ? getFactory().getInstance(clazz.toString(), params, signature) : instance;
 			
 		} 
 		catch (FactoryException fe) 
 		{
 			throw new PoolException(fe);
 		}
 	}
 
 	/**
 	 * Puts a used object back to the pool. Objects implementing the Recyclable
 	 * interface can provide a recycle method to be called when they are reused and
 	 * a dispose method to be called when they are returned to the pool.
 	 *
 	 * @param instance the object instance to recycle.
 	 * @return true if the instance was accepted.
 	 */
 	@SuppressWarnings("unchecked")
 	public boolean putInstance(Object instance) 
 	{
 		if (instance != null) 
 		{
 			HashMap<String, PoolBuffer> repository = poolRepository;
 			String className = instance.getClass().getName();
 			PoolBuffer pool = (PoolBuffer) repository.get(className);
 			if (pool == null) 
 			{
 				pool = new PoolBuffer(getCapacity(className));
 				repository = (HashMap<String, PoolBuffer>) repository.clone();
 				repository.put(className, pool);
 				poolRepository = repository;
 				if (instance instanceof ArrayCtorRecyclable) 
 				{
 					pool.setArrayCtorRecyclable(true);
 				}
 			}
 			return pool.offer(instance);
 		} else {
 			return false;
 		}
 	}
 
 	/**
 	 * Gets the capacity of the pool for a named class.
 	 *
 	 * @param className the name of the class.
 	 */
 	public int getCapacity(String className) 
 	{
 		PoolBuffer pool = (PoolBuffer) poolRepository.get(className);
 		if (pool == null) 
 		{
 			/* Check class specific capacity. */
 			int capacity = poolCapacity;
 			if (capacityMap != null) 
 			{
 				Integer cap = (Integer) capacityMap.get(className);
 				if (cap != null) 
 				{
 					capacity = cap.intValue();
 				}
 			}
 			return capacity;
 		} else {
 			return pool.capacity();
 		}
 	}
 
 	/**
 	 * Sets the capacity of the pool for a named class. Note that the pool will be
 	 * cleared after the change.
 	 *
 	 * @param className the name of the class.
 	 * @param capacity  the new capacity.
 	 */
 	@SuppressWarnings("unchecked")
 	public void setCapacity(String className, int capacity) 
 	{
 		HashMap<String, PoolBuffer> repository = poolRepository;
 		repository = repository != null ? (HashMap<String, PoolBuffer>) repository.clone()
 				: new HashMap<String, PoolBuffer>();
 		repository.put(className, new PoolBuffer(capacity));
 		poolRepository = repository;
 	}
 
 	/**
 	 * Gets the current size of the pool for a named class.
 	 *
 	 * @param className the name of the class.
 	 */
 	public int getSize(String className) 
 	{
 		PoolBuffer pool = (PoolBuffer) poolRepository.get(className);
 		return pool != null ? pool.size() : 0;
 	}
 
 	/**
 	 * Clears instances of a named class from the pool.
 	 *
 	 * @param className the name of the class.
 	 */
 	@SuppressWarnings("unchecked")
 	public void clearPool(String className) 
 	{
 		HashMap<String, PoolBuffer> repository = poolRepository;
 		if (repository.get(className) != null) 
 		{
 			repository = (HashMap<String, PoolBuffer>) repository.clone();
 			repository.remove(className);
 			poolRepository = repository;
 		}
 	}
 
 	/**
 	 * Clears all instances from the pool.
 	 */
 	public void clearPool() 
 	{
 		poolRepository = new HashMap<String, PoolBuffer>();
 	}
 
 	/**
 	 * Polls and recycles an object of the named class from the pool.
 	 *
 	 * @param className the name of the class.
 	 * @param params    an array containing the parameters of the constructor.
 	 * @param signature an array containing the signature of the constructor.
 	 * @return the object or null.
 	 * @throws PoolException if recycling fails.
 	 */
 	private <T> T pollInstance(String className, Object[] params, String[] signature) throws PoolException 
 	{
 		PoolBuffer pool = (PoolBuffer) poolRepository.get(className);
 		return pool != null ? pool.poll(params, signature, factoryService) : null;
 	}
 
 	/**
 	 * Gets the factory service.
 	 *
 	 * @return the factory service.
 	 */
 	protected FactoryService getFactory() 
 	{
 		return factoryService;
 	}
 
 	// ---------------- Avalon Lifecycle Methods ---------------------
 	/* (non-Javadoc)
 	 * Avalon component lifecycle method
 	 * @see org.apache.avalon.framework.configuration.Configurable#configure(org.apache.avalon.framework.configuration.Configuration)
 	 */
 	public void configure(Configuration conf) 
 	{
 		final Configuration capacities = conf.getChild(POOL_CAPACITY, false);
 		if (capacities != null) 
 		{
 			Configuration defaultConf = capacities.getChild("default");
 			int capacity = defaultConf.getValueAsInteger(DEFAULT_POOL_CAPACITY);
 			if (capacity <= 0) 
 			{
 				throw new IllegalArgumentException("Capacity must be >0");
 			}
 			poolCapacity = capacity;
 			Configuration[] nameVal = capacities.getChildren();
 			for (int i = 0; i < nameVal.length; i++) 
 			{
 				String key = nameVal[i].getName();
 				if (!"default".equals(key)) 
 				{
 					capacity = nameVal[i].getValueAsInteger(poolCapacity);
 					if (capacity < 0) 
 					{
 						capacity = poolCapacity;
 					}
 					
 					if (capacityMap == null) 
 					{
 						capacityMap = new HashMap<String, Integer>();
 					}
 					
 					capacityMap.put(key, capacity);
 				}
 			}
 		}
 	}
 
 	/**
 	 * Avalon component lifecycle method
 	 * 
 	 * {@link org.apache.fulcrum.factory.FactoryService}
 	 * 
 	 * @param manager the service manager
 	 */
 	public void service(ServiceManager manager) 
 	{
 		this.manager = manager;
 	}
 
 	/**
 	 * Avalon component lifecycle method Initializes the service by loading default
 	 * class loaders and customized object factories.
 	 *
 	 * @throws Exception if initialization fails.
 	 */
 	public void initialize() throws Exception 
 	{
 		try 
 		{
 			factoryService = (FactoryService) manager.lookup(FactoryService.ROLE);
 		} 
 		catch (Exception e) 
 		{
 			throw new Exception("DefaultPoolService.initialize: Failed to get a Factory object", e);
 		}
 	}
 
 	/**
 	 * Avalon component lifecycle method
 	 */
 	public void dispose() 
 	{
 		if (factoryService != null) 
 		{
 			manager.release(factoryService);
 		}
 		factoryService = null;
 		manager = null;
 	}
 }