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/*
* 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 org.apache.commons.pool;
/**
* A "keyed" pooling interface.
*
* A keyed pool pools instances of multiple types. Each
* type may be accessed using an arbitrary key.
*
* Example of use:
*
* Object obj = null;
* Object key = "Key";
*
* try {
* obj = pool.borrowObject(key);
* //...use the object...
* } catch(Exception e) {
* //...handle any exceptions...
* } finally {
* // make sure the object is returned to the pool
* if(null != obj) {
* pool.returnObject(key,obj);
* }
* }
*
*
* {@link KeyedObjectPool} implementations may 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}).
*
*
* @see KeyedPoolableObjectFactory
* @see KeyedObjectPoolFactory
* @see ObjectPool
*
* @author Rodney Waldhoff
* @version $Revision: 1.14 $ $Date: 2004/02/28 12:16:21 $
*/
public interface KeyedObjectPool {
/**
* Obtain an instance from my pool
* for the specified key.
* By contract, clients MUST return
* the borrowed object using
* {@link #returnObject(java.lang.Object,java.lang.Object) returnObject},
* or a related method as defined in an implementation
* or sub-interface,
* using a key 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, obj MUST have been obtained
* using {@link #borrowObject(java.lang.Object) borrowObject}
* or a related method as defined in an implementation
* or sub-interface
* using a key that is equivalent to the one used to
* borrow the Object 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, obj MUST have been obtained
* using {@link #borrowObject borrowObject}
* or a related method as defined in an implementation
* or sub-interface
* using a key that is equivalent to the one used to
* borrow the Object in the first place.
*
* 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 key
* 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 key 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 key (optional operation).
* Throws {@link UnsupportedOperationException}
* if this information is not available.
*
* @param key the key
* @return the number of instances corresponding to the given key 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 key (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;
}