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.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.util.HashSet;
import java.util.Iterator;
import java.util.Set;
import org.drools.FactException;
import org.drools.marshalling.impl.MarshallerReaderContext;
import org.drools.marshalling.impl.MarshallerWriteContext;
import org.drools.rule.Rule;
import org.drools.spi.Activation;
import org.drools.spi.PropagationContext;
import org.drools.util.ObjectHashMap;
/**
* The Truth Maintenance System is responsible for tracking two things. Firstly
* It maintains a Map to track the classes with the same Equality, using the
* EqualityKey. The EqualityKey has an internal datastructure which references
* all the handles which are equal. Secondly It maintains another map tracking
* the justificiations for logically asserted facts.
*
* @author <a href="mailto:mark.proctor@jboss.com">Mark Proctor</a>
*
*/
public class TruthMaintenanceSystem {
private static final long serialVersionUID = 400L;
private AbstractWorkingMemory workingMemory;
private ObjectHashMap justifiedMap;
private ObjectHashMap assertMap;
public TruthMaintenanceSystem() {
}
public TruthMaintenanceSystem(final AbstractWorkingMemory workingMemory) {
this.workingMemory = workingMemory;
this.justifiedMap = new ObjectHashMap();
this.assertMap = new ObjectHashMap();
this.assertMap.setComparator( EqualityKeyComparator.getInstance() );
}
// public void write(WMSerialisationOutContext context) throws IOException {
// ObjectOutputStream stream = context.stream;
//
// EqualityKey[] keys = new EqualityKey[ this.assertMap.size() ];
// org.drools.util.Iterator it = this.assertMap.iterator();
// int i = 0;
// for ( ObjectEntry entry = ( ObjectEntry ) it.next(); entry != null; entry = ( ObjectEntry ) it.next() ) {
// EqualityKey key = ( EqualityKey ) entry.getKey();
// keys[i++] = key;
// }
//
// Arrays.sort( keys, EqualityKeySorter.instance );
//
// // write the assert map of Equality keys
// for ( EqualityKey key : keys ) {
// stream.writeInt( PersisterEnums.EQUALITY_KEY );
// stream.writeInt( key.getStatus() );
// InternalFactHandle handle = key.getFactHandle();
// stream.writeInt( handle.getId() );
// context.out.println( "EqualityKey int:" + key.getStatus() + " int:" + handle.getId() );
// if ( key.getOtherFactHandle() != null && !key.getOtherFactHandle().isEmpty() ) {
// for ( InternalFactHandle handle2 : key.getOtherFactHandle() ) {
// stream.writeInt( PersisterEnums.FACT_HANDLE );
// stream.writeInt( handle2.getId() );
// context.out.println( "OtherHandle int:" + handle2.getId() );
// }
// }
// stream.writeInt( PersisterEnums.END );
// }
// stream.writeInt( PersisterEnums.END );
// }
//
// public static class EqualityKeySorter implements Comparator<EqualityKey> {
// public static final EqualityKeySorter instance = new EqualityKeySorter();
// public int compare(EqualityKey key1,
// EqualityKey key2) {
// return key1.getFactHandle().getId() - key2.getFactHandle().getId();
// }
// }
//
// public void read(WMSerialisationInContext context) throws IOException {
// ObjectInputStream stream = context.stream;
//
// while ( stream.readInt() == PersisterEnums.EQUALITY_KEY ) {
// int status = stream.readInt();
// InternalFactHandle handle = ( InternalFactHandle ) context.handles.get( stream.readInt() );
// EqualityKey key = new EqualityKey(handle, status);
// handle.setEqualityKey( key );
// while ( stream.readInt() == PersisterEnums.FACT_HANDLE ) {
// handle = ( InternalFactHandle ) context.wm.getFactHandle( stream.readInt() );
// key.addFactHandle( handle );
// handle.setEqualityKey( key );
// }
// put( key );
// }
// }
// public void readExternal(ObjectInput in) throws IOException, ClassNotFoundException {
// workingMemory = (AbstractWorkingMemory)in.readObject();
// justifiedMap = (PrimitiveLongMap)in.readObject();
// assertMap = (ObjectHashMap)in.readObject();
// }
//
// public void writeExternal(ObjectOutput out) throws IOException {
// out.writeObject(workingMemory);
// out.writeObject(justifiedMap);
// out.writeObject(assertMap);
// }
public ObjectHashMap getJustifiedMap() {
return this.justifiedMap;
}
public ObjectHashMap getAssertMap() {
return this.assertMap;
}
public Object put(final EqualityKey key) {
return this.assertMap.put( key,
key,
false );
}
public EqualityKey get(final EqualityKey key) {
return (EqualityKey) this.assertMap.get( key );
}
public EqualityKey get(final Object object) {
return (EqualityKey) this.assertMap.get( object );
}
public EqualityKey remove(final EqualityKey key) {
return (EqualityKey) this.assertMap.remove( key );
}
/**
* An Activation is no longer true so it no longer justifies any of the logical facts
* it logically asserted. It iterates over the Activation's LinkedList of DependencyNodes
* it retrieves the justitication set for each DependencyNode's FactHandle and removes
* itself. If the Set is empty it retracts the FactHandle from the WorkingMemory.
*
* @param activation
* @param context
* @param rule
* @throws FactException
*/
public void removeLogicalDependencies(final Activation activation,
final PropagationContext context,
final Rule rule) throws FactException {
final org.drools.util.LinkedList list = activation.getLogicalDependencies();
if ( list == null || list.isEmpty() ) {
return;
}
for ( LogicalDependency node = (LogicalDependency) list.getFirst(); node != null; node = (LogicalDependency) node.getNext() ) {
final InternalFactHandle handle = (InternalFactHandle) node.getFactHandle();
final Set set = (Set) this.justifiedMap.get( handle.getId() );
if ( set != null ) {
set.remove( node );
WorkingMemoryAction action = new LogicalRetractCallback( this,
node,
set,
handle,
context,
activation );
workingMemory.queueWorkingMemoryAction( action );
}
}
}
public static class LogicalRetractCallback
implements
WorkingMemoryAction {
private TruthMaintenanceSystem tms;
private LogicalDependency node;
private Set set;
private InternalFactHandle handle;
private PropagationContext context;
private Activation activation;
public LogicalRetractCallback() {
}
public LogicalRetractCallback(final TruthMaintenanceSystem tms,
final LogicalDependency node,
final Set set,
final InternalFactHandle handle,
final PropagationContext context,
final Activation activation) {
this.tms = tms;
this.node = node;
this.set = set;
this.handle = handle;
this.context = context;
}
public LogicalRetractCallback(MarshallerReaderContext context) throws IOException {
this.tms = context.wm.getTruthMaintenanceSystem();
this.handle = context.handles.get( context.readInt() );
this.context = context.propagationContexts.get( context.readLong() );
this.activation = context.terminalTupleMap.get( context.readInt() ).getActivation();
this.set = ( Set ) this.tms.getJustifiedMap().get( handle.getId() );
for ( Iterator it = this.set.iterator(); it.hasNext(); ) {
LogicalDependency node = ( LogicalDependency ) it.next();
if ( node.getJustifier() == this.activation ) {
this.node = node;
break;
}
}
}
public void write(MarshallerWriteContext context) throws IOException {
context.writeInt( WorkingMemoryAction.LogicalRetractCallback );
context.writeInt( this.handle.getId() );
context.writeLong( this.context.getPropagationNumber() );
context.writeInt( context.terminalTupleMap.get( this.activation.getTuple() ) );
}
public void readExternal(ObjectInput in) throws IOException,
ClassNotFoundException {
tms = (TruthMaintenanceSystem) in.readObject();
node = (LogicalDependency) in.readObject();
set = (Set) in.readObject();
handle = (InternalFactHandle) in.readObject();
context = (PropagationContext) in.readObject();
activation = (Activation) in.readObject();
}
public void writeExternal(ObjectOutput out) throws IOException {
out.writeObject( tms );
out.writeObject( node );
out.writeObject( set );
out.writeObject( handle );
out.writeObject( context );
out.writeObject( activation );
}
public void execute(InternalWorkingMemory workingMemory) {
if ( set.isEmpty() ) {
this.tms.getJustifiedMap().remove( handle.getId() );
// this needs to be scheduled so we don't upset the current
// working memory operation
workingMemory.retract( this.handle,
false,
true,
(Rule) context.getRuleOrigin(),
this.activation );
}
}
}
/**
* The FactHandle is being removed from the system so remove any logical dependencies
* between the justified FactHandle and its justifiers. Removes the FactHandle key
* from the justifiedMap. It then iterates over all the LogicalDependency nodes, if any,
* in the returned Set and removes the LogicalDependency node from the LinkedList maintained
* by the Activation.
*
* @see LogicalDependency
*
* @param handle - The FactHandle to be removed
* @throws FactException
*/
public void removeLogicalDependencies(final InternalFactHandle handle) throws FactException {
final Set set = (Set) this.justifiedMap.remove( handle.getId() );
if ( set != null && !set.isEmpty() ) {
for ( final Iterator it = set.iterator(); it.hasNext(); ) {
final LogicalDependency node = (LogicalDependency) it.next();
node.getJustifier().getLogicalDependencies().remove( node );
}
}
}
/**
* Adds a justification for the FactHandle to the justifiedMap.
*
* @param handle
* @param activation
* @param context
* @param rule
* @throws FactException
*/
public void addLogicalDependency(final InternalFactHandle handle,
final Activation activation,
final PropagationContext context,
final Rule rule) throws FactException {
final LogicalDependency node = new LogicalDependency( activation,
handle );
activation.getRule().setHasLogicalDependency( true );
activation.addLogicalDependency( node );
Set set = (Set) this.justifiedMap.get( handle.getId() );
if ( set == null ) {
if ( context.getType() == PropagationContext.MODIFICATION ) {
// if this was a update, chances are its trying to retract a logical assertion
}
set = new HashSet();
this.justifiedMap.put( handle.getId(),
set );
}
set.add( node );
}
public void clear() {
this.justifiedMap.clear();
this.assertMap.clear();
}
}