Parallelloop.java

package com.yahoo.dtf.actions.flowcontrol;

import com.yahoo.dtf.actions.flowcontrol.Loop;
import com.yahoo.dtf.actions.flowcontrol.Sequence;
import com.yahoo.dtf.distribution.Worker;
import com.yahoo.dtf.exception.BreakException;
import com.yahoo.dtf.exception.DTFException;
import com.yahoo.dtf.exception.InterruptionException;
import com.yahoo.dtf.range.Range;
import com.yahoo.dtf.range.RangeFactory;
import com.yahoo.dtf.state.DTFState;

/**
 * @dtf.tag parallelloop
 * 
 * @dtf.since 1.0
 * @dtf.author Rodney Gomes
 * 
 * @dtf.tag.desc The parallelloop tag will take the child tag and spawn as many 
 *               times as the number of items in the range expression and execute 
 *               those in parallel.
 * 
 * @dtf.tag.example
 * <parallelloop property="j" range="[1..6]">
 *     <parallelloop property="k" range="[1..6]">
 *         <log>Creating property property.${j}.${k}</log>
 *         <property name="property.${j}.${k}" value="${j}-${k}"/>
 *     </parallelloop>
 * </parallelloop>
 *   
 * @dtf.tag.example
 * <parallelloop property="var1" range="[1,2,3,4,5,6]">
 *     <log>Looping on ${var1}</log>
 * </parallelloop>
 */
public class Parallelloop extends Loop {

    public Parallelloop() { }
   
    public void execute() throws DTFException {
        Range range = RangeFactory.getRange(getRange());
        int workerCount = range.size();
        
        Sequence children = new Sequence();
        children.addActions(children());
       
        Worker[] workers =  new Worker[workerCount];
       
        int i = 0;
        while (range.hasMoreElements()) {
            String value = range.nextElement();
            DTFState state = getState().duplicate();
            state.getConfig().setProperty(getProperty(), value);
            workers[i++] = new Worker(children, state, value);
        }
        
        for(i = 0; i < workerCount; i++) 
            workers[i].start();
      
        /*
         * Wait for all underlying threads to terminate and log all of them 
         * except the last exception which we can throw to any parent tag to 
         * handle the error.
         */
        DTFException lastexception = null;
        boolean interrupted = false;
        for (int index = 0; index < workers.length; index++) {
            try { 
                workers[index].waitFor();
            } catch (InterruptionException e) { 
                if ( getLogger().isDebugEnabled() ) {
                    getLogger().debug("Thread interrupted [" + 
                                      workers[index].getName() + "]",e);
                }
                interrupted = true;
            } catch (BreakException e) { 
                // break point
                if ( getLogger().isDebugEnabled() )
                    getLogger().debug("Break point hit", e);
            } catch (DTFException e) { 
                if ( lastexception != null ) 
                    getLogger().error("Child failed.", lastexception);
                
                lastexception = e;
            }
        }
        
        if ( interrupted && getLogger().isDebugEnabled() ) 
            getLogger().debug("Execution interrupted.");
        
        if ( lastexception != null ) 
            throw lastexception;
    }
}