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/*
 * 
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS HEADER.
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 * Copyright 2007-2008 Sun Microsystems, Inc. All rights reserved.
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 * General Public License Version 2 only ("GPL") or the Common Development
 * and Distribution License("CDDL") (collectively, the "License").  You
 * may not use this file except in compliance with the License. You can obtain
 * a copy of the License at https://glassfish.dev.java.net/public/CDDL+GPL.html
 * or glassfish/bootstrap/legal/LICENSE.txt.  See the License for the specific
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 * file and include the License file at glassfish/bootstrap/legal/LICENSE.txt.
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package com.sun.grizzly.arp;

import com.sun.grizzly.http.ProcessorTask;
import com.sun.grizzly.util.ClassLoaderUtil;
import java.util.ArrayList;
import java.util.StringTokenizer;
import java.util.concurrent.atomic.AtomicBoolean;

/**
 * Default implementation of the {@link AsyncExecutor}. This class will
 * execute a {@link ProcessorTask} asynchronously, by interrupting the 
 * process based on the logic defined in its associated {@link AsyncFilter}
 * If no {@link AsyncFilter} are defined, the {@link ProcessorTask}
 * will not be interrupted and executed synchronously.
 *
 * @author Jeanfrancois Arcand
 */
public class DefaultAsyncExecutor implements AsyncExecutor{
    
    private final static String ASYNC_FILTER = 
            "com.sun.grizzly.asyncFilters";
    
    /**
     * The AsyncFilter to execute asynchronous operations on 
     * a ProcessorTask.
     */
    private final static ArrayList sharedAsyncFilters = loadFilters();
    
    
    /**
     * The {@link AsyncTask} used to wrap the 
     * {@link ProcessorTask}
     */
    private AsyncTask asyncProcessorTask;
       
    
    /**
     * The associated {@link ProcessorTask}
     */
    private ProcessorTask processorTask;
    
    
    /**
     * The {@link AsyncFilter} to execute asynchronous operations on 
     * a {@link ProcessorTask}.
     */
    private final ArrayList asyncFilters = new ArrayList(sharedAsyncFilters);
    
    
    /**
     * The {@link AsyncHandler} associated with this object.
     */
    private AsyncHandler asyncHandler;

    /**
     * Only one execution of every steps are allowed.
     */
    private AtomicBoolean parseHeaderPhase = new AtomicBoolean(false);
    private AtomicBoolean executeAdapterPhase = new AtomicBoolean(false);
    private AtomicBoolean commitResponsePhase = new AtomicBoolean(false);

    
    // --------------------------------------------------------------------- //
    
    public DefaultAsyncExecutor(){
    }
    
    
    
    // ------------------------------------------------Asynchrounous Execution --/    
    /**
     * Pre-execute a {@link ProcessorTask} by parsing the request 
     * line.
     */
    public boolean preExecute() throws Exception{
        if (!parseHeaderPhase.getAndSet(true)){
            processorTask.preProcess();

            // True when there is an error or when the (@link FileCache} is enabled
            if (processorTask.parseRequest()){
                finishResponse();
                return false;
            }
            return true;
        }
        return false;
    }
    
    
    /**
     * Interrupt the {@link ProcessorTask} if {@link AsyncFilter}
     * has been defined.
     * @return true if the execution can continue, false if delayed.
     */
    public boolean interrupt() throws Exception{
        if (asyncFilters.size() == 0 ) {
            execute();
            return false;
        } else {
            return invokeFilters();
        }
    }
    
    
    /**
     * Execute the associated {@link Adapter} or {@link GrizzlyAdapter}
     * @return true if the execution can continue, false if delayed.
     */
    public boolean execute() throws Exception{
        if (!executeAdapterPhase.getAndSet(true)){
            processorTask.invokeAdapter();
            return true;
        }
        return false;
    }

    
    /**
     * Invoke the {@link AsyncFilter}
     */
    private boolean invokeFilters(){
        boolean continueExec = true;
        for (int i=0;iAsynchFilter.
     */
    protected static ArrayList loadFilters(){
        ArrayList al = new ArrayList();
        if ( System.getProperty(ASYNC_FILTER) != null){
            StringTokenizer st = new StringTokenizer(
                    System.getProperty(ASYNC_FILTER),",");
            while (st.hasMoreTokens()){
                al.add((AsyncFilter)ClassLoaderUtil.load(st.nextToken()));
            } 
        }
        return al;
    }

    /**
     * Reset
     */
    void recycle(){
        parseHeaderPhase.getAndSet(false);
        executeAdapterPhase.getAndSet(false);
        commitResponsePhase.getAndSet(false);
    }
}