org.jbpm.graph.node.Join.java Source code

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/*
 * JBoss, Home of Professional Open Source
 * Copyright 2005, JBoss Inc., and individual contributors as indicated
 * by the @authors tag. See the copyright.txt in the distribution for a
 * full listing of individual contributors.
 *
 * This is free software; you can redistribute it and/or modify it
 * under the terms of the GNU Lesser General Public License as
 * published by the Free Software Foundation; either version 2.1 of
 * the License, or (at your option) any later version.
 *
 * This software is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
 * Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with this software; if not, write to the Free
 * Software Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA
 * 02110-1301 USA, or see the FSF site: http://www.fsf.org.
 */
package org.jbpm.graph.node;

import java.util.Collection;
import java.util.Iterator;

import org.apache.commons.logging.Log;
import org.apache.commons.logging.LogFactory;
import org.dom4j.Element;
import org.hibernate.LockMode;
import org.hibernate.Session;
import org.jbpm.JbpmContext;
import org.jbpm.graph.action.Script;
import org.jbpm.graph.def.Node;
import org.jbpm.graph.exe.ExecutionContext;
import org.jbpm.graph.exe.Token;
import org.jbpm.jpdl.xml.JpdlXmlReader;
import org.jbpm.jpdl.xml.Parsable;

public class Join extends Node implements Parsable {

    private static final long serialVersionUID = 1L;

    /** specifies wether what type of hibernate lock should be acquired.  null value defaults to LockMode.Force */
    String parentLockMode;

    /**
     * specifies if this joinhandler is a discriminator.
     * a descriminator reactivates the parent when the first 
     * concurrent token enters the join. 
     */
    boolean isDiscriminator = false;

    /**
     * a fixed set of concurrent tokens.
     */
    Collection tokenNames = null;

    /**
     * a script that calculates concurrent tokens at runtime.
     */
    Script script = null;

    /**
     * reactivate the parent if the n-th token arrives in the join.
     */
    int nOutOfM = -1;

    public Join() {
    }

    public Join(String name) {
        super(name);
    }

    public void read(Element element, JpdlXmlReader jpdlReader) {
        String lock = element.attributeValue("lock");
        if ((lock != null) && (lock.equalsIgnoreCase("pessimistic"))) {
            parentLockMode = LockMode.UPGRADE.toString();
        }
    }

    public void execute(ExecutionContext executionContext) {
        Token token = executionContext.getToken();

        boolean isAbleToReactivateParent = token.isAbleToReactivateParent();

        if (!token.hasEnded()) {
            token.end(false);
        }

        // if this token is not able to reactivate the parent, 
        // we don't need to check anything
        if (isAbleToReactivateParent) {

            // the token arrived in the join and can only reactivate 
            // the parent once
            token.setAbleToReactivateParent(false);

            Token parentToken = token.getParent();

            if (parentToken != null) {

                JbpmContext jbpmContext = executionContext.getJbpmContext();
                Session session = (jbpmContext != null ? jbpmContext.getSession() : null);
                if (session != null) {
                    LockMode lockMode = LockMode.FORCE;
                    if (parentLockMode != null) {
                        lockMode = LockMode.parse(parentLockMode);
                    }
                    log.debug("forcing version increment on parent token " + parentToken);
                    session.flush();
                    session.lock(parentToken, lockMode);
                }

                boolean reactivateParent = true;

                // if this is a discriminator
                if (isDiscriminator) {
                    // reactivate the parent when the first token arrives in the 
                    // join.  this must be the first token arriving because otherwise
                    // the isAbleToReactivateParent() of this token should have been false
                    // above.
                    reactivateParent = true;

                    // if a fixed set of tokenNames is specified at design time...
                } else if (tokenNames != null) {
                    // check reactivation on the basis of those tokenNames
                    reactivateParent = mustParentBeReactivated(parentToken, tokenNames.iterator());

                    // if a script is specified
                } else if (script != null) {

                    // check if the script returns a collection or a boolean
                    Object result = null;
                    try {
                        result = script.eval(token);
                    } catch (Exception e) {
                        this.raiseException(e, executionContext);
                    }
                    // if the result is a collection 
                    if (result instanceof Collection) {
                        // it must be a collection of tokenNames 
                        Collection runtimeTokenNames = (Collection) result;
                        reactivateParent = mustParentBeReactivated(parentToken, runtimeTokenNames.iterator());

                        // if it's a boolean... 
                    } else if (result instanceof Boolean) {
                        // the boolean specifies if the parent needs to be reactivated
                        reactivateParent = ((Boolean) result).booleanValue();
                    }

                    // if a nOutOfM is specified
                } else if (nOutOfM != -1) {

                    int n = 0;
                    // wheck how many tokens already arrived in the join
                    Iterator iter = parentToken.getChildren().values().iterator();
                    while (iter.hasNext()) {
                        Token concurrentToken = (Token) iter.next();
                        if (this.equals(concurrentToken.getNode())) {
                            n++;
                        }
                    }
                    if (n < nOutOfM) {
                        reactivateParent = false;
                    }

                    // if no configuration is specified..
                } else {
                    // the default behaviour is to check all concurrent tokens and reactivate
                    // the parent if the last token arrives in the join
                    reactivateParent = mustParentBeReactivated(parentToken,
                            parentToken.getChildren().keySet().iterator());
                }

                // if the parent token needs to be reactivated from this join node
                if (reactivateParent) {

                    // write to all child tokens that the parent is already reactivated
                    Iterator iter = parentToken.getChildren().values().iterator();
                    while (iter.hasNext()) {
                        ((Token) iter.next()).setAbleToReactivateParent(false);
                    }

                    // write to all child tokens that the parent is already reactivated
                    ExecutionContext parentContext = new ExecutionContext(parentToken);
                    leave(parentContext);
                }
            }
        }
    }

    public boolean mustParentBeReactivated(Token parentToken, Iterator childTokenNameIterator) {
        boolean reactivateParent = true;
        while ((childTokenNameIterator.hasNext()) && (reactivateParent)) {
            String concurrentTokenName = (String) childTokenNameIterator.next();

            Token concurrentToken = parentToken.getChild(concurrentTokenName);

            if (concurrentToken.isAbleToReactivateParent()) {
                log.debug("join will not yet reactivate parent: found concurrent token '" + concurrentToken + "'");
                reactivateParent = false;
            }
        }
        return reactivateParent;
    }

    public Script getScript() {
        return script;
    }

    public void setScript(Script script) {
        this.script = script;
    }

    public Collection getTokenNames() {
        return tokenNames;
    }

    public void setTokenNames(Collection tokenNames) {
        this.tokenNames = tokenNames;
    }

    public boolean isDiscriminator() {
        return isDiscriminator;
    }

    public void setDiscriminator(boolean isDiscriminator) {
        this.isDiscriminator = isDiscriminator;
    }

    public int getNOutOfM() {
        return nOutOfM;
    }

    public void setNOutOfM(int nOutOfM) {
        this.nOutOfM = nOutOfM;
    }

    private static final Log log = LogFactory.getLog(Join.class);
}