/**
* 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.
*/
package org.drools.reteoo;
import java.io.Externalizable;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import org.drools.common.BaseNode;
import org.drools.common.InternalWorkingMemory;
import org.drools.common.RuleBasePartitionId;
import org.drools.spi.PropagationContext;
/**
* A source of <code>ReteTuple</code> s for a <code>TupleSink</code>.
*
* <p>
* Nodes that propagate <code>Tuples</code> extend this class.
* </p>
*
* @see LeftTupleSource
* @see LeftTuple
*
* @author <a href="mailto:mark.proctor@jboss.com">Mark Proctor</a>
* @author <a href="mailto:bob@werken.com">Bob McWhirter</a>
*/
public abstract class LeftTupleSource extends BaseNode
implements
Externalizable {
// ------------------------------------------------------------
// Instance members
// ------------------------------------------------------------
/** The destination for <code>Tuples</code>. */
protected LeftTupleSinkPropagator sink;
// ------------------------------------------------------------
// Constructors
// ------------------------------------------------------------
public LeftTupleSource() {
}
/**
* Single parameter constructor that specifies the unique id of the node.
*
* @param id
*/
LeftTupleSource(final int id, final RuleBasePartitionId partitionId, final boolean partitionsEnabled ) {
super( id, partitionId, partitionsEnabled );
this.sink = EmptyLeftTupleSinkAdapter.getInstance();
}
// ------------------------------------------------------------
// Instance methods
// ------------------------------------------------------------
public void readExternal(ObjectInput in) throws IOException,
ClassNotFoundException {
super.readExternal( in );
sink = (LeftTupleSinkPropagator) in.readObject();
}
public void writeExternal(ObjectOutput out) throws IOException {
super.writeExternal( out );
out.writeObject( sink );
}
/**
* Adds the <code>TupleSink</code> so that it may receive
* <code>Tuples</code> propagated from this <code>TupleSource</code>.
*
* @param tupleSink
* The <code>TupleSink</code> to receive propagated
* <code>Tuples</code>.
*/
public void addTupleSink(final LeftTupleSink tupleSink) {
if ( this.sink instanceof EmptyLeftTupleSinkAdapter ) {
if( this.partitionsEnabled && ! this.partitionId.equals( tupleSink.getPartitionId() ) ) {
// if partitions are enabled and the next node belongs to a different partition,
// we need to use the asynchronous propagator
this.sink = new AsyncSingleLeftTupleSinkAdapter( this.getPartitionId(), tupleSink );
} else {
// otherwise, we use the lighter synchronous propagator
this.sink = new SingleLeftTupleSinkAdapter( this.getPartitionId(), tupleSink );
}
} else if ( this.sink instanceof SingleLeftTupleSinkAdapter ) {
final CompositeLeftTupleSinkAdapter sinkAdapter;
if( this.partitionsEnabled ) {
// a composite propagator may propagate to both nodes in the same partition
// as well as in a different partition, so, if partitions are enabled, we
// must use the asynchronous version
sinkAdapter = new AsyncCompositeLeftTupleSinkAdapter( this.getPartitionId() );
} else {
// if partitions are disabled, then it is safe to use the lighter synchronous propagator
sinkAdapter = new CompositeLeftTupleSinkAdapter( this.getPartitionId() );
}
sinkAdapter.addTupleSink( this.sink.getSinks()[0] );
sinkAdapter.addTupleSink( tupleSink );
this.sink = sinkAdapter;
} else {
((CompositeLeftTupleSinkAdapter) this.sink).addTupleSink( tupleSink );
}
}
/**
* Removes the <code>TupleSink</code>
*
* @param tupleSink
* The <code>TupleSink</code> to remove
*/
protected void removeTupleSink(final LeftTupleSink tupleSink) {
if ( this.sink instanceof EmptyLeftTupleSinkAdapter ) {
throw new IllegalArgumentException( "Cannot remove a sink, when the list of sinks is null" );
}
if ( this.sink instanceof SingleLeftTupleSinkAdapter ) {
this.sink = EmptyLeftTupleSinkAdapter.getInstance();
} else {
final CompositeLeftTupleSinkAdapter sinkAdapter = (CompositeLeftTupleSinkAdapter) this.sink;
sinkAdapter.removeTupleSink( tupleSink );
if ( sinkAdapter.size() == 1 ) {
if( this.partitionsEnabled && ! this.partitionId.equals( tupleSink.getPartitionId() ) ) {
// if partitions are enabled and the next node belongs to a different partition,
// we need to use the asynchronous propagator
this.sink = new AsyncSingleLeftTupleSinkAdapter( this.getPartitionId(), sinkAdapter.getSinks()[0] );
} else {
// otherwise, we use the lighter synchronous propagator
this.sink = new SingleLeftTupleSinkAdapter( this.getPartitionId(), sinkAdapter.getSinks()[0] );
}
}
}
}
public LeftTupleSinkPropagator getSinkPropagator() {
return this.sink;
}
public abstract void updateSink(LeftTupleSink sink,
PropagationContext context,
InternalWorkingMemory workingMemory);
public boolean isInUse() {
return this.sink.size() > 0;
}
}