/**
* Copyright 2010 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.base.evaluators;
import java.io.IOException;
import java.io.ObjectInput;
import java.io.ObjectOutput;
import java.util.Collections;
import java.util.HashMap;
import java.util.Map;
import org.drools.RuntimeDroolsException;
import org.drools.base.BaseEvaluator;
import org.drools.base.ValueType;
import org.drools.common.EventFactHandle;
import org.drools.common.InternalFactHandle;
import org.drools.common.InternalWorkingMemory;
import org.drools.rule.VariableRestriction.ObjectVariableContextEntry;
import org.drools.rule.VariableRestriction.VariableContextEntry;
import org.drools.spi.Evaluator;
import org.drools.spi.FieldValue;
import org.drools.spi.InternalReadAccessor;
import org.drools.time.Interval;
/**
* <p>The implementation of the <code>metby</code> evaluator definition.</p>
*
* <p>The <b><code>metby</code></b> evaluator correlates two events and matches when the current event's
* start timestamp happens at the same time as the correlated event's end timestamp.</p>
*
* <p>Lets look at an example:</p>
*
* <pre>$eventA : EventA( this metby $eventB )</pre>
*
* <p>The previous pattern will match if and only if the $eventA starts at the same time $eventB finishes.
* In other words:</p>
*
* <pre>
* abs( $eventA.startTimestamp - $eventB.endTimestamp ) == 0
* </pre>
*
* <p>The <b><code>metby</code></b> evaluator accepts one optional parameter. If it is defined, it determines
* the maximum distance between the end timestamp of the correlated event and the start timestamp of the current
* event in order for the operator to match. Example:</p>
*
* <pre>$eventA : EventA( this metby[ 5s ] $eventB )</pre>
*
* Will match if and only if:
*
* <pre>
* abs( $eventA.startTimestamp - $eventB.endTimestamp) <= 5s
* </pre>
*
* <p><b>NOTE:</b> it makes no sense to use a negative interval value for the parameter and the
* engine will raise an exception if that happens.</p>
*
* @author etirelli
* @author mgroch
*/
public class MetByEvaluatorDefinition
implements
EvaluatorDefinition {
public static final Operator MET_BY = Operator.addOperatorToRegistry( "metby",
false );
public static final Operator NOT_MET_BY = Operator.addOperatorToRegistry( "metby",
true );
private static final String[] SUPPORTED_IDS = {MET_BY.getOperatorString()};
private Map<String, MetByEvaluator> cache = Collections.emptyMap();
private volatile TimeIntervalParser parser = new TimeIntervalParser();
@SuppressWarnings("unchecked")
public void readExternal(ObjectInput in) throws IOException,
ClassNotFoundException {
cache = (Map<String, MetByEvaluator>) in.readObject();
}
public void writeExternal(ObjectOutput out) throws IOException {
out.writeObject( cache );
}
/**
* @inheridDoc
*/
public Evaluator getEvaluator(ValueType type,
Operator operator) {
return this.getEvaluator( type,
operator.getOperatorString(),
operator.isNegated(),
null );
}
/**
* @inheridDoc
*/
public Evaluator getEvaluator(ValueType type,
Operator operator,
String parameterText) {
return this.getEvaluator( type,
operator.getOperatorString(),
operator.isNegated(),
parameterText );
}
/**
* @inheritDoc
*/
public Evaluator getEvaluator(final ValueType type,
final String operatorId,
final boolean isNegated,
final String parameterText) {
return this.getEvaluator( type,
operatorId,
isNegated,
parameterText,
Target.HANDLE,
Target.HANDLE );
}
/**
* @inheritDoc
*/
public Evaluator getEvaluator(final ValueType type,
final String operatorId,
final boolean isNegated,
final String parameterText,
final Target left,
final Target right ) {
if ( this.cache == Collections.EMPTY_MAP ) {
this.cache = new HashMap<String, MetByEvaluator>();
}
String key = isNegated + ":" + parameterText;
MetByEvaluator eval = this.cache.get( key );
if ( eval == null ) {
Long[] params = parser.parse( parameterText );
eval = new MetByEvaluator( type,
isNegated,
params,
parameterText );
this.cache.put( key,
eval );
}
return eval;
}
/**
* @inheritDoc
*/
public String[] getEvaluatorIds() {
return SUPPORTED_IDS;
}
/**
* @inheritDoc
*/
public boolean isNegatable() {
return true;
}
/**
* @inheritDoc
*/
public Target getTarget() {
return Target.HANDLE;
}
/**
* @inheritDoc
*/
public boolean supportsType(ValueType type) {
// supports all types, since it operates over fact handles
// Note: should we change this interface to allow checking of event classes only?
return true;
}
/**
* Implements the 'metby' evaluator itself
*/
public static class MetByEvaluator extends BaseEvaluator {
private static final long serialVersionUID = 510l;
private long finalRange;
private String paramText;
public MetByEvaluator() {
}
public MetByEvaluator(final ValueType type,
final boolean isNegated,
final Long[] parameters,
final String paramText) {
super( type,
isNegated ? NOT_MET_BY : MET_BY );
this.paramText = paramText;
this.setParameters( parameters );
}
public void readExternal(ObjectInput in) throws IOException,
ClassNotFoundException {
super.readExternal( in );
finalRange = in.readLong();
paramText = (String) in.readObject();
}
public void writeExternal(ObjectOutput out) throws IOException {
super.writeExternal( out );
out.writeLong( finalRange );
out.writeObject( paramText );
}
@Override
public Object prepareLeftObject(InternalFactHandle handle) {
return handle;
}
@Override
public boolean isTemporal() {
return true;
}
@Override
public Interval getInterval() {
if ( this.getOperator().isNegated() ) {
return new Interval( Interval.MIN,
Interval.MAX );
}
return new Interval( Interval.MIN,
0 );
}
public boolean evaluate(InternalWorkingMemory workingMemory,
final InternalReadAccessor extractor,
final Object object1,
final FieldValue object2) {
throw new RuntimeDroolsException( "The 'metby' operator can only be used to compare one event to another, and never to compare to literal constraints." );
}
public boolean evaluateCachedRight(InternalWorkingMemory workingMemory,
final VariableContextEntry context,
final Object left) {
if ( context.rightNull ) {
return false;
}
long rightStartTS = ((EventFactHandle) ((ObjectVariableContextEntry) context).right).getStartTimestamp();
long dist = Math.abs( rightStartTS - ((EventFactHandle) left).getEndTimestamp() );
return this.getOperator().isNegated() ^ ( dist <= this.finalRange );
}
public boolean evaluateCachedLeft(InternalWorkingMemory workingMemory,
final VariableContextEntry context,
final Object right) {
if ( context.extractor.isNullValue( workingMemory,
right ) ) {
return false;
}
long rightStartTS = ((EventFactHandle) right).getStartTimestamp();
long dist = Math.abs( rightStartTS - ((EventFactHandle) ((ObjectVariableContextEntry) context).left).getEndTimestamp() );
return this.getOperator().isNegated() ^ ( dist <= this.finalRange );
}
public boolean evaluate(InternalWorkingMemory workingMemory,
final InternalReadAccessor extractor1,
final Object object1,
final InternalReadAccessor extractor2,
final Object object2) {
if ( extractor1.isNullValue( workingMemory,
object1 ) ) {
return false;
}
long obj1StartTS = ((EventFactHandle) object1).getStartTimestamp();
long dist = Math.abs( obj1StartTS - ((EventFactHandle) object2).getEndTimestamp() );
return this.getOperator().isNegated() ^ ( dist <= this.finalRange );
}
public String toString() {
return "metby[" + ((paramText != null) ? paramText : "") + "]";
}
/* (non-Javadoc)
* @see java.lang.Object#hashCode()
*/
@Override
public int hashCode() {
final int PRIME = 31;
int result = super.hashCode();
result = PRIME * result + (int) (finalRange ^ (finalRange >>> 32));
return result;
}
/* (non-Javadoc)
* @see java.lang.Object#equals(java.lang.Object)
*/
@Override
public boolean equals(Object obj) {
if ( this == obj ) return true;
if ( !super.equals( obj ) ) return false;
if ( getClass() != obj.getClass() ) return false;
final MetByEvaluator other = (MetByEvaluator) obj;
return finalRange == other.finalRange;
}
/**
* This methods sets the parameters appropriately.
*
* @param parameters
*/
private void setParameters(Long[] parameters) {
if ( parameters == null || parameters.length == 0 ) {
this.finalRange = 0;
} else if ( parameters.length == 1 ) {
if ( parameters[0].longValue() >= 0 ) {
// defined max distance
this.finalRange = parameters[0].longValue();
} else {
throw new RuntimeDroolsException( "[MetBy Evaluator]: Not possible to use negative parameter: '" + paramText + "'" );
}
} else {
throw new RuntimeDroolsException( "[MetBy Evaluator]: Not possible to use " + parameters.length + " parameters: '" + paramText + "'" );
}
}
}
}