| /* |
| * 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. |
| */ |
| |
| package org.apache.ode.utils; |
| |
| import java.util.ArrayList; |
| import java.util.Collections; |
| import java.util.HashSet; |
| import java.util.List; |
| import java.util.Set; |
| |
| import org.apache.commons.collections.map.LRUMap; |
| import org.apache.commons.collections.map.MultiKeyMap; |
| |
| |
| /** |
| * A key value based cache that internalizes immutable values |
| * so that they can be shared across various BPEL objects. |
| * |
| */ |
| public class InternPool { |
| private static MultiKeyMap cachedValues = MultiKeyMap.decorate(new LRUMap()); |
| private static Set<String> cachedBlocks = Collections.synchronizedSet(new HashSet<String>()); |
| |
| /** |
| * Creates a new KeyValueCache object. |
| */ |
| protected InternPool() { |
| } |
| |
| /** |
| * Runs the given block in the context of a cache. |
| * If you do not run your block this way, the caching |
| * mechanism will be disabled. |
| * |
| * @param block block |
| */ |
| public static void runBlock(InternableBlock block) { |
| String processId = getProcessId(); |
| cachedBlocks.add(processId); |
| block.run(); |
| cachedBlocks.remove(processId); |
| clearAll(processId); |
| } |
| |
| /** |
| * Returns an internalized value if it already exists in the cache |
| * |
| * @param value value |
| * |
| * @return the internalized value |
| */ |
| public static Object intern(Object key, Object value) { |
| String processId = getProcessId(); |
| |
| if (!cachedBlocks.contains(processId)) { |
| return value; |
| } |
| |
| synchronized (cachedValues) { |
| List values = (List) cachedValues.get(processId, key); |
| if (values == null) { |
| cachedValues.put(processId, key, (values = new ArrayList())); |
| } |
| |
| Object intern; |
| if (values.contains(value)) { |
| intern = values.get(values.indexOf(value)); |
| } else { |
| values.add(intern = value); |
| } |
| |
| return intern; |
| } |
| } |
| |
| /** |
| * Clears all the values corresponding to the given process |
| * |
| * @param processId processId |
| */ |
| protected static void clearAll(String processId) { |
| synchronized (cachedValues) { |
| cachedValues.remove(processId); |
| } |
| } |
| |
| /** |
| * Returns the current thread id as the process id. |
| * |
| * @return the "process id" |
| */ |
| private static String getProcessId() { |
| return String.valueOf(Thread.currentThread().getId()); |
| } |
| |
| /** |
| * An interface that clients should implement to run their |
| * blocks of code in the context of this caching mechanism. |
| */ |
| public interface InternableBlock { |
| /** |
| * The block to run |
| */ |
| public void run(); |
| } |
| } |