/*
Copyright (C) SYSTAP, LLC DBA Blazegraph 2006-2016. All rights reserved.
Contact:
SYSTAP, LLC DBA Blazegraph
2501 Calvert ST NW #106
Washington, DC 20008
licenses@blazegraph.com
This program is free software; you can redistribute it and/or modify
it under the terms of the GNU General Public License as published by
the Free Software Foundation; version 2 of the License.
This program 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 General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*/
/*
* Created on Jun 30, 2008
*/
package com.bigdata.relation.rule.eval;
import java.util.Iterator;
import com.bigdata.relation.rule.IProgram;
import com.bigdata.relation.rule.IStep;
/**
* Support for determining how and where a program should be executed.
*
* @author <a href="mailto:thompsonbry@users.sourceforge.net">Bryan Thompson</a>
* @version $Id$
*/
public class ProgramUtility {
// final protected static Logger log = Logger.getLogger(ProgramUtility.class);
// private final IResourceLocator resourceLocator;
// private final long readTimestamp;
// public ProgramUtility(IJoinNexus joinNexus) {
//
// this(joinNexus.getRelationLocator());//, joinNexus.getReadTimestamp());
//
// }
// /**
// *
// * @param resourceLocator
// */
public ProgramUtility() {//IResourceLocator resourceLocator) {
// if (resourceLocator == null)
// throw new IllegalArgumentException();
//
// this.resourceLocator = resourceLocator;
}
// /**
// * Return the {@link IIndexManager} that is capable of resolving all
// * relations (and their indices) used in the {@link IStep} -or-
// * <code>null</code> if some relations or indices are not resolvable from
// * the current context (in general, either because they do not exist or
// * because they rely on machine or JVM local resources not accessible from
// * the current execution context).
// * <p>
// * Note: If the returned {@link IIndexManager} is an {@link AbstractJournal},
// * an {@link LocalDataServiceFederation} then various optimizations are
// * possible, including running program as an {@link AbstractTask} within the
// * {@link LocalDataServiceImpl}, including the case where there is access
// * to local resources.
// *
// * @param step
// * The program.
// * @param timestamp
// * The timestamp is relatively arbitrary. We do not actually use
// * the relation objects that are being created other than to
// * inquire after the names of their indices.
// *
// * @return The {@link IBigdataFederation} -or- <code>null</code> if the
// * indices are all hosted by <strong>local</strong> resources
// * outside of {@link IBigdataFederation} control, such as a
// * {@link Journal} or {@link TemporaryStore}.
// *
// * @throws IllegalArgumentException
// * if <i>program</i> is <code>null</code>
// *
// * @throws IllegalArgumentException
// * if <i>program</i> is empty (not an {@link IRule} and having
// * no {@link IProgram#steps()}).
// *
// * @throws IllegalStateException
// * if some of the indices are hosted on local resources and
// * {@link IBigdataFederation#isDistributed()} is
// * <code>true</code> (this implies that those resources MAY be
// * unreachable from at least some of the {@link DataService}s
// * in the federation).
// *
// * @throws IllegalStateException
// * if there are relations belonging to different
// * {@link IBigdataFederation}s.
// */
// public IBigdataFederation getFederation(IIndexManager indexManager,
// IStep step, long timestamp) {
//
// if (step == null)
// throw new IllegalArgumentException();
//
// if(!step.isRule() && ((IProgram)step).stepCount()==0)
// throw new IllegalArgumentException("empty program");
//
// /*
// * The set of distinct relations.
// */
// final Map<String, IRelation> relations = getRelations(indexManager, step,
// timestamp);
//
// if(relations.isEmpty()) {
//
// // Note: this is either an empty program or a bug.
// throw new IllegalArgumentException();
//
// }
//
// // set of distinct index managers (IBigdataFederation, TemporaryStore, Journal, etc).
// final Set<IIndexManager> indexManagers = new HashSet<IIndexManager>();
//
// IBigdataFederation fed = null;
//
// final Set<IIndexManager> localResources = new HashSet<IIndexManager>();
//
// final Set<IBigdataFederation> feds = new HashSet<IBigdataFederation>();
//
// for(IRelation relation : relations.values()) {
//
// final IIndexManager tmp = relation.getIndexManager();
//
// indexManagers.add( tmp );
//
// if(tmp instanceof IBigdataFederation) {
//
// feds.add( (IBigdataFederation)tmp );
//
// if(fed == null) {
//
// fed = (IBigdataFederation)tmp;
//
// }
//
// } else {
//
// localResources.add(tmp);
//
// }
//
// }
//
// assert !indexManagers.isEmpty();
//
// if(fed == null) {
//
// /*
// * No federation, so all resources must be local.
// */
//
// assert ! localResources.isEmpty();
//
// // Note: [null] indicates non-federation based operation.
// return null;
//
// }
//
// if (feds.size() > 2) {
//
// throw new IllegalStateException(
// "Program uses more than one federation: #feds="
// + feds.size());
//
// }
//
// if(!localResources.isEmpty() && fed.isDistributed()) {
//
// throw new IllegalStateException("Program uses local resources but federation is distributed.");
//
// }
//
// return fed;
//
// }
/**
* <code>true</code> iff the program contains an embedded closure
* operation. <code>false</code> if the program is a rule or is itself a
* closure operation.
*
* @param step
* The program.
*
* @return
*/
public boolean isClosureProgram(IStep step) {
if (step == null)
throw new IllegalArgumentException();
if(step.isRule()) return false;
final IProgram program = (IProgram)step;
if (program.isClosure())
return false;
final Iterator<IStep> itr = program.steps();
while (itr.hasNext()) {
if (isClosureProgram2(itr.next()))
return true;
}
return false;
}
/**
* <code>true</code> iff this program is or contains a closure operation.
*/
private boolean isClosureProgram2(IStep step) {
if (step == null)
throw new IllegalArgumentException();
if (step.isRule()) return false;
final IProgram program = (IProgram)step;
if (program.isClosure())
return true;
final Iterator<IStep> itr = program.steps();
while (itr.hasNext()) {
if (isClosureProgram2(itr.next()))
return true;
}
return false;
}
}