abstractrulebase.java

jboss规则引擎

package org.drools.common;

/*
 * Copyright 2005 JBoss Inc
 * 
 * Licensed 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.
 */

import java.io.ByteArrayInputStream;
import java.io.ByteArrayOutputStream;
import java.io.Externalizable;
import java.io.IOException;
import java.io.InputStream;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.io.ObjectOutputStream;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Iterator;
import java.util.List;
import java.util.Map;
import java.util.Set;
import java.util.WeakHashMap;

import org.drools.FactException;
import org.drools.PackageIntegrationException;
import org.drools.RuleBase;
import org.drools.RuleBaseConfiguration;
import org.drools.RuleIntegrationException;
import org.drools.WorkingMemory;
import org.drools.rule.CompositePackageClassLoader;
import org.drools.rule.InvalidPatternException;
import org.drools.rule.Package;
import org.drools.rule.PackageCompilationData;
import org.drools.rule.Rule;
import org.drools.spi.FactHandleFactory;

/**
 * Implementation of <code>RuleBase</code>.
 * 
 * @author <a href="mailto:[e-mail]">bob mcwhirter</a>
 * @author <a href="mailto:[e-mail]">Mark Proctor</a> 
 * 
 * @version $Id: RuleBaseImpl.java,v 1.5 2005/08/14 22:44:12 mproctor Exp $
 */
abstract public class AbstractRuleBase
    implements
    InternalRuleBase,
    Externalizable {
    // ------------------------------------------------------------
    // Instance members
    // ------------------------------------------------------------
    protected RuleBaseConfiguration                 config;

    protected Map                                   pkgs;

    protected transient CompositePackageClassLoader packageClassLoader;

    /** The fact handle factory. */
    protected FactHandleFactory                     factHandleFactory;

    protected Map                                   globals;

    /**
     * WeakHashMap to keep references of WorkingMemories but allow them to be
     * garbage collected
     */
    protected transient Map                         workingMemories;

    /** Special value when adding to the underlying map. */
    protected static final Object                   PRESENT = new Object();

    // ------------------------------------------------------------
    // Constructors
    // ------------------------------------------------------------

    /**
     * Construct.
     * 
     * @param rete
     *            The rete network.
     */
    public AbstractRuleBase(final RuleBaseConfiguration config,
                            final FactHandleFactory factHandleFactory) {
        this.config = (config != null) ? config : new RuleBaseConfiguration();
        this.config.makeImmutable();
        this.factHandleFactory = factHandleFactory;

        this.packageClassLoader = new CompositePackageClassLoader( Thread.currentThread().getContextClassLoader() );
        this.pkgs = new HashMap();
        this.globals = new HashMap();
        this.workingMemories = new WeakHashMap();
    }

    // ------------------------------------------------------------
    // Instance methods
    // ------------------------------------------------------------

    /**
     * Handles the write serialization of the Package. Patterns in Rules may reference generated data which cannot be serialized by default methods.
     * The Package uses PackageCompilationData to hold a reference to the generated bytecode. The generated bytecode must be restored before any Rules.
     * 
     */
    public void doWriteExternal(final ObjectOutput stream,
                                final Object[] objects) throws IOException {
        stream.writeObject( this.pkgs );

        // Rules must be restored by an ObjectInputStream that can resolve using a given ClassLoader to handle seaprately by storing as
        // a byte[]
        final ByteArrayOutputStream bos = new ByteArrayOutputStream();
        final ObjectOutput out = new ObjectOutputStream( bos );
        out.writeObject( this.factHandleFactory );
        out.writeObject( this.globals );
        out.writeObject( this.config );

        for ( int i = 0, length = objects.length; i < length; i++ ) {
            out.writeObject( objects[i] );
        }

        stream.writeObject( bos.toByteArray() );
    }

    /**
     * Handles the read serialization of the Package. Patterns in Rules may reference generated data which cannot be serialized by default methods.
     * The Package uses PackageCompilationData to hold a reference to the generated bytecode; which must be restored before any Rules.
     * A custom ObjectInputStream, able to resolve classes against the bytecode in the PackageCompilationData, is used to restore the Rules.
     * 
     */
    public void doReadExternal(final ObjectInput stream,
                               final Object[] objects) throws IOException,
                                                      ClassNotFoundException {
        // PackageCompilationData must be restored before Rules as it has the ClassLoader needed to resolve the generated code references in Rules
        this.pkgs = (Map) stream.readObject();

        this.packageClassLoader = new CompositePackageClassLoader( Thread.currentThread().getContextClassLoader() );
        for ( final Iterator it = this.pkgs.values().iterator(); it.hasNext(); ) {
            this.packageClassLoader.addClassLoader( ((Package) it.next()).getPackageCompilationData().getClassLoader() );
        }

        // Return the rules stored as a byte[]
        final byte[] bytes = (byte[]) stream.readObject();

        //  Use a custom ObjectInputStream that can resolve against a given classLoader
        final ObjectInputStreamWithLoader streamWithLoader = new ObjectInputStreamWithLoader( new ByteArrayInputStream( bytes ),
                                                                                              this.packageClassLoader );

        this.factHandleFactory = (FactHandleFactory) streamWithLoader.readObject();
        this.globals = (Map) streamWithLoader.readObject();

        this.config = (RuleBaseConfiguration) streamWithLoader.readObject();

        this.workingMemories = new WeakHashMap();

        for ( int i = 0, length = objects.length; i < length; i++ ) {
            objects[i] = streamWithLoader.readObject();
        }
    }

    /**
     * @see RuleBase
     */
    public WorkingMemory newWorkingMemory() {
        return newWorkingMemory( true );
    }

    /**
     * @see RuleBase
     */
    abstract public WorkingMemory newWorkingMemory(boolean keepReference);

    public void disposeWorkingMemory(final WorkingMemory workingMemory) {
        this.workingMemories.remove( workingMemory );
    }

    /**
     * @see RuleBase
     */
    public FactHandleFactory getFactHandleFactory() {
        return this.factHandleFactory;
    }

    public FactHandleFactory newFactHandleFactory() {
        return this.factHandleFactory.newInstance();
    }

    public Package[] getPackages() {
        return (Package[]) this.pkgs.values().toArray( new Package[this.pkgs.size()] );
    }

    public Map getGlobals() {
        return this.globals;
    }

    /**
     * Add a <code>Package</code> to the network. Iterates through the
     * <code>Package</code> adding Each individual <code>Rule</code> to the
     * network. Before update network each referenced <code>WorkingMemory</code>
     * is locked.
     * 
     * @param pkg
     *            The package to add.
     * @throws PackageIntegrationException 
     *