s4-core/src/main/java/org/apache/s4/processor/PrototypeWrapper.java

/**
 * 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.s4.processor;

import org.apache.s4.ft.SafeKeeper;
import org.apache.s4.persist.ConMapPersister;
import org.apache.s4.persist.Persister;
import org.apache.s4.util.clock.Clock;

import java.util.List;

import org.apache.log4j.Logger;

public class PrototypeWrapper {

    private static Logger logger = Logger.getLogger(PrototypeWrapper.class);
    private AbstractPE prototype;
    Persister lookupTable;

    public String getId() {
        return prototype.getId();
    }

    public PrototypeWrapper(AbstractPE prototype, Clock s4Clock) {
        this.prototype = prototype;
        lookupTable = new ConMapPersister(s4Clock);
        // TODO lookup table with PEIds
        System.out.println("Using ConMapPersister ..");
        // this bit of reflection is not a performance issue because it is only
        // invoked at configuration time
        try {
            ((ConMapPersister) lookupTable).setSelfClean(true);
            ((ConMapPersister) lookupTable).init();
            // set the persister in prototype
            prototype.setLookupTable(lookupTable);
            prototype.setPrototypeWrapper(this);
        } catch (Exception e) {
            // this is not expected
            Logger.getLogger("s4")
                  .error("Exception invoking setLookupTable on prototype", e);
        }
    }


    /**
     * Find PE corresponding to keyValue. If no such PE exists, then a new one
     * is created by cloning the prototype and this is returned. As a
     * side-effect, the last update time for the PE in the lookup table is
     * modified.
     * 
     * @param keyValue
     *            key value
     * @return PE corresponding to keyValue.
     */
    public AbstractPE getPE(String keyValue) {
        AbstractPE pe = null;
        try {
            pe = (AbstractPE) lookupTable.get(keyValue);
            if (pe == null) {
                pe = (AbstractPE) prototype.clone();
                pe.initInstance();
            }
            // update the last update time on the entry
            lookupTable.set(keyValue, pe, prototype.getTtl());

        } catch (Exception e) {
            logger.error("exception when looking up pe for key:" + keyValue, e);
        }

        return pe;
    }

    /**
     * Find PE corresponding to keyValue. If no such PE exists, then null is
     * returned. Note: the last update time is not modified in the lookup table.
     * 
     * @param keyValue
     *            key value
     * @return PE corresponding to keyValue, if such a PE exists. Null
     *         otherwise.
     */
    public AbstractPE lookupPE(String keyValue) {
        AbstractPE pe = null;

        try {
            pe = (AbstractPE) lookupTable.get(keyValue);

        } catch (Exception e) {
            logger.error("exception when looking up pe for key:" + keyValue, e);
        }

        return pe;
    }
    
    public void expire(String keyValue) {
        try {
           lookupTable.set(keyValue, null, 0);
        } catch (Exception e) {
            logger.error("exception when removing pe for key:" + keyValue, e);
        }
   
    }

    public int getPECount() {
        return lookupTable.keySet().size();
    }

    public List<EventAdvice> advise() {
        return prototype.advise();
    }

}