ETLContext.java

/*******************************************************************************
 * Copyright (c) 2011 The Board of Trustees of the Leland Stanford Junior University
 * as Operator of the SLAC National Accelerator Laboratory.
 * Copyright (c) 2011 Brookhaven National Laboratory.
 * EPICS archiver appliance is distributed subject to a Software License Agreement found
 * in file LICENSE that is included with this distribution.
 *******************************************************************************/
package org.epics.archiverappliance.etl;

import java.util.HashMap;
import java.util.LinkedList;

import org.apache.log4j.Logger;
import org.epics.archiverappliance.common.BasicContext;

/**
 * A class to hold state for one run of ETL. 
 * A new ETL context is created for each run of ETL.
 * In addition, we also support the ability to execute code after completion of the entire run.
 * @author mshankar
 *
 */
public class ETLContext extends BasicContext {
	private static Logger logger = Logger.getLogger(ETLContext.class.getName());
	
	private HashMap<String, Object> state = new HashMap<String, Object>();
	private LinkedList<Runnable> postETLTasks = new LinkedList<Runnable>(); 
	
	public void put(String key, Object value) {
		state.put(key, value);
	}
	
	public Object get(String key) {
		return state.get(key);
	}
	
	public void putString(String key, String value) {
		state.put(key, value);
	}
	
	public String getString(String key) {
		return (String) state.get(key);
	}
	
	public void addPostETLTask(Runnable runnable) {
		postETLTasks.add(runnable);
	}
	
	public void executePostETLTasks() {
		for(Runnable runnable : postETLTasks) {
			try {
				runnable.run();
			} catch(Throwable t) {
				// We log but ignore throwables thrown by post ETL tasks.
				logger.error("Exception executing post ETL task", t);
			}
		}
	}
}