Simplify Listener, allowing tasks to be submitted to the Indexer even when paused

webapp/src/edu/cornell/mannlib/vitro/webapp/searchindex/IndexingChangeListener.java

@@ -9,30 +9,27 @@ import static edu.cornell.mannlib.vitro.webapp.modules.searchIndexer.SearchIndex
 import java.io.ByteArrayInputStream;
 import java.io.UnsupportedEncodingException;
 import java.util.ArrayList;
+import java.util.Iterator;
 import java.util.List;
 import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 
-import org.apache.commons.lang.StringUtils;
+import com.hp.hpl.jena.graph.Triple;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
-import com.hp.hpl.jena.rdf.model.Literal;
 import com.hp.hpl.jena.rdf.model.Model;
 import com.hp.hpl.jena.rdf.model.ModelFactory;
-import com.hp.hpl.jena.rdf.model.Property;
-import com.hp.hpl.jena.rdf.model.RDFNode;
-import com.hp.hpl.jena.rdf.model.Resource;
-import com.hp.hpl.jena.rdf.model.ResourceFactory;
 import com.hp.hpl.jena.rdf.model.Statement;
-import com.hp.hpl.jena.rdf.model.StmtIterator;
 
 import edu.cornell.mannlib.vitro.webapp.dao.jena.event.EditEvent;
 import edu.cornell.mannlib.vitro.webapp.modules.searchIndexer.SearchIndexer;
 import edu.cornell.mannlib.vitro.webapp.modules.searchIndexer.SearchIndexer.Event;
 import edu.cornell.mannlib.vitro.webapp.rdfservice.ChangeListener;
 import edu.cornell.mannlib.vitro.webapp.utils.threads.VitroBackgroundThread;
+import org.apache.jena.riot.RDFLanguages;
+import org.apache.jena.riot.RiotReader;
 
 /**
  * When a change is heard, wait for an interval to see if more changes come in.
@@ -65,7 +62,7 @@ public class IndexingChangeListener implements ChangeListener,
 
 	private final SearchIndexer searchIndexer;
 	private final Ticker ticker;
-	private volatile boolean paused = true;
+    private final Model defaultModel;
 
 	/** All access to the list must be synchronized. */
 	private final List<Statement> changes;
@@ -73,82 +70,28 @@ public class IndexingChangeListener implements ChangeListener,
 	public IndexingChangeListener(SearchIndexer searchIndexer) {
 		this.searchIndexer = searchIndexer;
 		this.ticker = new Ticker();
+        this.defaultModel = ModelFactory.createDefaultModel();
 		this.changes = new ArrayList<>();
 
 		searchIndexer.addListener(this);
 	}
 
 	private synchronized void noteChange(Statement stmt) {
-		try {
+        changes.add(stmt);
-			changes.add(sanitize(stmt));
-			if (!paused) {
         ticker.start();
 	}
-		} catch (Exception e) {
-			log.warn("Failed to sanitize this statement: " + stmt);
-		}
-	}
-
-	private Statement sanitize(Statement rawStmt) {
-		return ResourceFactory.createStatement(
-				sanitizeSubject(rawStmt.getSubject()),
-				sanitizePredicate(rawStmt.getPredicate()),
-				sanitizeObject(rawStmt.getObject()));
-	}
-
-	private Resource sanitizeSubject(Resource rawSubject) {
-		if (rawSubject.isURIResource()) {
-			return ResourceFactory.createResource(rawSubject.getURI());
-		}
-		return ResourceFactory.createResource();
-	}
-
-	private Property sanitizePredicate(Property rawPredicate) {
-		return ResourceFactory.createProperty(rawPredicate.getURI());
-	}
-
-	private RDFNode sanitizeObject(RDFNode rawObject) {
-		if (rawObject.isURIResource()) {
-			return ResourceFactory.createResource(rawObject.asResource()
-					.getURI());
-		}
-		if (rawObject.isResource()) {
-			return ResourceFactory.createResource();
-		}
-		Literal l = rawObject.asLiteral();
-		if (StringUtils.isNotEmpty(l.getLanguage())) {
-			return ResourceFactory.createLangLiteral(l.getString(),
-					l.getLanguage());
-		}
-		if (null != l.getDatatype()) {
-			return ResourceFactory.createTypedLiteral(l.getValue());
-		}
-		return ResourceFactory.createPlainLiteral(l.getString());
-	}
 
 	@Override
 	public void receiveSearchIndexerEvent(Event event) {
-		if (event.getType() == PAUSE) {
-			paused = true;
-		} else if (event.getType() == UNPAUSE) {
-			paused = false;
-			ticker.start();
-		} else if (event.getType() == START_REBUILD) {
-			discardChanges();
-		}
 	}
 
 	private synchronized void respondToTicker() {
-		if (!paused && !changes.isEmpty()) {
+		if (!changes.isEmpty()) {
 			searchIndexer.scheduleUpdatesForStatements(changes);
 			changes.clear();
 		}
 	}
 
-	private synchronized void discardChanges() {
-		changes.clear();
-	}
-
 	public void shutdown() {
 		ticker.shutdown();
 	}
@@ -180,22 +123,27 @@ public class IndexingChangeListener implements ChangeListener,
 		}
 	}
 
-	// TODO avoid overhead of Model.
 	// TODO avoid duplication with JenaChangeListener
 	private Statement parseTriple(String serializedTriple) {
         try {
-			Model m = ModelFactory.createDefaultModel();
+            // Use RiotReader to parse a Triple
-			m.read(new ByteArrayInputStream(serializedTriple.getBytes("UTF-8")),
+            // NB A Triple can be serialized correctly with: FmtUtils.stringForTriple(triple, PrefixMapping.Factory.create()) + " .";
-					null, "N3");
+            Iterator<Triple> it = RiotReader.createIteratorTriples(new ByteArrayInputStream(serializedTriple.getBytes("UTF-8")), RDFLanguages.NTRIPLES, null);
-			StmtIterator sit = m.listStatements();
+
-			if (!sit.hasNext()) {
+            if (it.hasNext()) {
-				throw new RuntimeException("no triple parsed from change event");
+                Triple triple = it.next();
-			} else {
+
-				Statement s = sit.nextStatement();
+                if (it.hasNext()) {
-				if (sit.hasNext()) {
                     log.warn("More than one triple parsed from change event");
                 }
-				return s;
+
+                // Use the retained defaultModel instance to convert the Triple to a Statement
+                // This does not add the Statement to the Model, so the Statement can be disposed when unused
+                // And whilst the Model is attached to the Statement, using a single instance means only one Model
+                // is created and attached to all of the Statements created by this instance
+                return defaultModel.asStatement(triple);
+            } else {
+                throw new RuntimeException("no triple parsed from change event");
             }
         } catch (RuntimeException riot) {
             log.error("Failed to parse triple " + serializedTriple, riot);