001 /** 002 * Licensed to the Apache Software Foundation (ASF) under one or more 003 * contributor license agreements. See the NOTICE file distributed with 004 * this work for additional information regarding copyright ownership. 005 * The ASF licenses this file to You under the Apache License, Version 2.0 006 * (the "License"); you may not use this file except in compliance with 007 * the License. You may obtain a copy of the License at 008 * 009 * http://www.apache.org/licenses/LICENSE-2.0 010 * 011 * Unless required by applicable law or agreed to in writing, software 012 * distributed under the License is distributed on an "AS IS" BASIS, 013 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. 014 * See the License for the specific language governing permissions and 015 * limitations under the License. 016 */ 017 package org.apache.camel.spi; 018 019 /** 020 * A service pool is like a connection pool but can pool any kind of objects. 021 * <p/> 022 * Services that is capable of being pooled should implement the marker interface 023 * {@link org.apache.camel.ServicePoolAware}. 024 * <p/> 025 * Notice the capacity is <b>per key</b> which means that each key can contain at most 026 * (the capacity) services. The pool can contain an unbounded number of keys. 027 * <p/> 028 * By default the capacity is set to 100. 029 * 030 * @version 031 */ 032 public interface ServicePool<Key, Service> { 033 034 /** 035 * Sets the capacity, which is capacity <b>per key</b>. 036 * 037 * @param capacity the capacity per key 038 */ 039 void setCapacity(int capacity); 040 041 /** 042 * Gets the capacity per key. 043 * 044 * @return the capacity per key 045 */ 046 int getCapacity(); 047 048 /** 049 * Adds the given service to the pool and acquires it. 050 * 051 * @param key the key 052 * @param service the service 053 * @return the acquired service, is newer <tt>null</tt> 054 * @throws IllegalStateException if the queue is full (capacity has been reached) 055 */ 056 Service addAndAcquire(Key key, Service service); 057 058 /** 059 * Tries to acquire the service with the given key 060 * 061 * @param key the key 062 * @return the acquired service, or <tt>null</tt> if no free in pool 063 */ 064 Service acquire(Key key); 065 066 /** 067 * Releases the service back to the pool 068 * 069 * @param key the key 070 * @param service the service 071 */ 072 void release(Key key, Service service); 073 074 /** 075 * Returns the current size of the pool 076 * 077 * @return the current size of the pool 078 */ 079 int size(); 080 081 /** 082 * Purges the pool. 083 */ 084 void purge(); 085 086 }