/*
* Copyright 1999-2004 The Apache Software Foundation.
*
* 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 com.frameworkset.commons.pool;
/**
* A "keyed" pooling interface.
* <p>
* A keyed pool pools instances of multiple types. Each
* type may be accessed using an arbitrary key.
* <p>
* Example of use:
* <table border="1" cellspacing="0" cellpadding="3" align="center" bgcolor="#FFFFFF"><tr><td><pre>
* Object obj = <font color="#0000CC">null</font>;
* Object key = <font color="#CC0000">"Key"</font>;
*
* <font color="#0000CC">try</font> {
* obj = pool.borrowObject(key);
* <font color="#00CC00">//...use the object...</font>
* } <font color="#0000CC">catch</font>(Exception e) {
* <font color="#00CC00">//...handle any exceptions...</font>
* } <font color="#0000CC">finally</font> {
* <font color="#00CC00">// make sure the object is returned to the pool</font>
* <font color="#0000CC">if</font>(<font color="#0000CC">null</font> != obj) {
* pool.returnObject(key,obj);
* }
* }</pre></td></tr></table>
*
* <p>
* {@link KeyedObjectPool} implementations <i>may</i> choose to store at most
* one instance per key value, or may choose to maintain a pool of instances
* for each key (essentially creating a {@link java.util.Map Map} of
* {@link ObjectPool pools}).
* </p>
*
* @see KeyedPoolableObjectFactory
* @see KeyedObjectPoolFactory
* @see ObjectPool
*
* @author Rodney Waldhoff
* @version $Revision: 155430 $ $Date: 2005-02-26 08:13:28 -0500 (Sat, 26 Feb 2005) $
*/
public interface KeyedObjectPool {
/**
* Obtain an instance from my pool
* for the specified <i>key</i>.
* By contract, clients MUST return
* the borrowed object using
* {@link #returnObject(java.lang.Object,java.lang.Object) <tt>returnObject</tt>},
* or a related method as defined in an implementation
* or sub-interface,
* using a <i>key</i> that is equivalent to the one used to
* borrow the instance in the first place.
*
* @param key the key used to obtain the object
* @return an instance from my pool.
*/
Object borrowObject(Object key) throws Exception;
/**
* Return an instance to my pool.
* By contract, <i>obj</i> MUST have been obtained
* using {@link #borrowObject(java.lang.Object) <tt>borrowObject</tt>}
* or a related method as defined in an implementation
* or sub-interface
* using a <i>key</i> that is equivalent to the one used to
* borrow the <tt>Object</tt> in the first place.
*
* @param key the key used to obtain the object
* @param obj a {@link #borrowObject(java.lang.Object) borrowed} instance to be returned.
*/
void returnObject(Object key, Object obj) throws Exception;
/**
* Invalidates an object from the pool
* By contract, <i>obj</i> MUST have been obtained
* using {@link #borrowObject borrowObject}
* or a related method as defined in an implementation
* or sub-interface
* using a <i>key</i> that is equivalent to the one used to
* borrow the <tt>Object</tt> in the first place.
* <p>
* This method should be used when an object that has been borrowed
* is determined (due to an exception or other problem) to be invalid.
* If the connection should be validated before or after borrowing,
* then the {@link PoolableObjectFactory#validateObject} method should be
* used instead.
*
* @param obj a {@link #borrowObject borrowed} instance to be returned.
*/
void invalidateObject(Object key, Object obj) throws Exception;
/**
* Create an object using my {@link #setFactory factory} or other
* implementation dependent mechanism, and place it into the pool.
* addObject() is useful for "pre-loading" a pool with idle objects.
* (Optional operation).
*/
void addObject(Object key) throws Exception;
/**
* Returns the number of instances
* corresponding to the given <i>key</i>
* currently idle in my pool (optional operation).
* Throws {@link UnsupportedOperationException}
* if this information is not available.
*
* @param key the key
* @return the number of instances corresponding to the given <i>key</i> currently idle in my pool
* @throws UnsupportedOperationException when this implementation doesn't support the operation
*/
int getNumIdle(Object key) throws UnsupportedOperationException;
/**
* Returns the number of instances
* currently borrowed from but not yet returned
* to my pool corresponding to the
* given <i>key</i> (optional operation).
* Throws {@link UnsupportedOperationException}
* if this information is not available.
*
* @param key the key
* @return the number of instances corresponding to the given <i>key</i> currently borrowed in my pool
* @throws UnsupportedOperationException when this implementation doesn't support the operation
*/
int getNumActive(Object key) throws UnsupportedOperationException;
/**
* Returns the total number of instances
* currently idle in my pool (optional operation).
* Throws {@link UnsupportedOperationException}
* if this information is not available.
*
* @return the total number of instances currently idle in my pool
* @throws UnsupportedOperationException when this implementation doesn't support the operation
*/
int getNumIdle() throws UnsupportedOperationException;
/**
* Returns the total number of instances
* current borrowed from my pool but not
* yet returned (optional operation).
* Throws {@link UnsupportedOperationException}
* if this information is not available.
*
* @return the total number of instances currently borrowed from my pool
* @throws UnsupportedOperationException when this implementation doesn't support the operation
*/
int getNumActive() throws UnsupportedOperationException;
/**
* Clears my pool, removing all pooled instances
* (optional operation).
* Throws {@link UnsupportedOperationException}
* if the pool cannot be cleared.
* @throws UnsupportedOperationException when this implementation doesn't support the operation
*/
void clear() throws Exception, UnsupportedOperationException;
/**
* Clears the specified pool, removing all
* pooled instances corresponding to
* the given <i>key</i> (optional operation).
* Throws {@link UnsupportedOperationException}
* if the pool cannot be cleared.
* @param key the key to clear
* @throws UnsupportedOperationException when this implementation doesn't support the operation
*/
void clear(Object key) throws Exception, UnsupportedOperationException;
/**
* Close this pool, and free any resources associated with it.
*/
void close() throws Exception;
/**
* Sets the {@link KeyedPoolableObjectFactory factory} I use
* to create new instances (optional operation).
* @param factory the {@link KeyedPoolableObjectFactory} I use to create new instances.
* @throws IllegalStateException when the factory cannot be set at this time
* @throws UnsupportedOperationException when this implementation doesn't support the operation
*/
void setFactory(KeyedPoolableObjectFactory factory) throws IllegalStateException, UnsupportedOperationException;
}