org.bpmscript.process.lock.LockingInstanceManager.java Source code

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Here is the source code for org.bpmscript.process.lock.LockingInstanceManager.java

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/*
 * 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.bpmscript.process.lock;

import java.util.List;
import java.util.Map;
import java.util.concurrent.ConcurrentHashMap;
import java.util.concurrent.atomic.AtomicInteger;

import org.bpmscript.BpmScriptException;
import org.bpmscript.IExecutorResult;
import org.bpmscript.paging.IPagedResult;
import org.bpmscript.paging.IQuery;
import org.bpmscript.process.IInstance;
import org.bpmscript.process.IInstanceCallback;
import org.bpmscript.process.IInstanceManager;

/**
 * Locks instances in memory
 */
public class LockingInstanceManager implements IInstanceManager {

    private final org.apache.commons.logging.Log log = org.apache.commons.logging.LogFactory
            .getLog(LockingInstanceManager.class);

    private IInstanceManager instanceManager;

    private static Map<String, AtomicInteger> locks = new ConcurrentHashMap<String, AtomicInteger>();

    public LockingInstanceManager(IInstanceManager instanceManager) {
        this.instanceManager = instanceManager;
    }

    public LockingInstanceManager() {

    }

    /**
     * Locks on the processInstanceId
     */
    public IExecutorResult doWithInstance(final String processInstanceId, final IInstanceCallback callback)
            throws Exception {
        AtomicInteger lock = null;
        synchronized (locks) {
            lock = locks.get(processInstanceId);
            if (lock == null) {
                lock = new AtomicInteger(1);
                locks.put(processInstanceId, lock);
            } else {
                lock.set(lock.get() + 1);
            }
        }
        IExecutorResult result = null;
        synchronized (lock) {
            try {
                log.debug("locking " + processInstanceId + " " + lock);
                result = instanceManager.doWithInstance(processInstanceId, callback);
            } finally {
                log.debug("unlocking " + processInstanceId);
                lock.set(lock.get() - 1);
                if (lock.get() == 0) {
                    locks.remove(processInstanceId);
                }
            }
        }
        return result;
    }

    /**
     * Delegates
     */
    public String createInstance(String parentProcessInstanceId, String definitionId, String definitionName,
            String definitionType, String operation) throws BpmScriptException {
        return instanceManager.createInstance(parentProcessInstanceId, definitionId, definitionName, definitionType,
                operation);
    }

    /**
     * Delegates
     */
    public List<IInstance> getChildInstances(String processInstanceId) throws BpmScriptException {
        return instanceManager.getChildInstances(processInstanceId);
    }

    /**
     * Delegates
     */
    public IInstance getInstance(String processInstanceId) throws BpmScriptException {
        return instanceManager.getInstance(processInstanceId);
    }

    /**
     * Delegates
     */
    public IPagedResult<IInstance> getInstances(IQuery query) throws BpmScriptException {
        return instanceManager.getInstances(query);
    }

    /**
     * The Instance Manager to delegate to
     */
    public void setInstanceManager(IInstanceManager instanceManager) {
        this.instanceManager = instanceManager;
    }

    /**
     * Delegates
     */
    public IPagedResult<IInstance> getInstancesForDefinition(IQuery query, String definitionId)
            throws BpmScriptException {
        return instanceManager.getInstancesForDefinition(query, definitionId);
    }

}