Modifications to https://github.com/vivo-project/Vitro/pull/14

Restore pause logic to IndexingChangeListener.
Adjust comments, remove compiler warnings and vestigial code items, rename method.

webapp/src/edu/cornell/mannlib/vitro/webapp/modules/searchIndexer/SearchIndexer.java

@@ -44,12 +44,13 @@ public interface SearchIndexer extends Application.Module {
 	void pause();
 
 	/**
-     * Stop processing new tasks. Requests will be ignored and the index rebuilt when unpaused.
+	 * Stop processing new tasks. If any request is received while the indexer
-     * Fires a PAUSED event to listeners.
+	 * is paused, the request will be ignored, but the index will be rebuilt
+	 * when unpaused. Fires a PAUSED event to listeners.
 	 * 
 	 * This call has no effect if already paused, or if called after shutdown.
 	 */
-    void pauseWithoutDeferring();
+	void pauseInAnticipationOfRebuild();
 
 	/**
 	 * Resume processing new tasks. Any requests that were received since the

webapp/src/edu/cornell/mannlib/vitro/webapp/reasoner/ABoxRecomputer.java

@@ -104,7 +104,7 @@ public class ABoxRecomputer {
         }
         try {
             if  (searchIndexer != null) {
-                searchIndexer.pauseWithoutDeferring();
+                searchIndexer.pauseInAnticipationOfRebuild();
             }
             recomputeABox();
         } finally {

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

@@ -15,10 +15,12 @@ import java.util.concurrent.Executors;
 import java.util.concurrent.ScheduledExecutorService;
 import java.util.concurrent.TimeUnit;
 
-import com.hp.hpl.jena.graph.Triple;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
+import org.apache.jena.riot.RDFLanguages;
+import org.apache.jena.riot.RiotReader;
 
+import com.hp.hpl.jena.graph.Triple;
 import com.hp.hpl.jena.rdf.model.Model;
 import com.hp.hpl.jena.rdf.model.ModelFactory;
 import com.hp.hpl.jena.rdf.model.Statement;
@@ -28,8 +30,6 @@ 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.
@@ -62,6 +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. */
@@ -78,20 +79,34 @@ public class IndexingChangeListener implements ChangeListener,
 
 	private synchronized void noteChange(Statement stmt) {
         changes.add(stmt); 
+		if (!paused) {
 			ticker.start();
 		}
+	}
 
 	@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 (!changes.isEmpty()) {
+		if (!paused && !changes.isEmpty()) {
 			searchIndexer.scheduleUpdatesForStatements(changes);
 			changes.clear();
 		}
 	}
 
+	private synchronized void discardChanges() {
+		changes.clear();
+	}
+
 	public void shutdown() {
 		ticker.shutdown();
 	}
@@ -128,13 +143,14 @@ public class IndexingChangeListener implements ChangeListener,
         try {
             // Use RiotReader to parse a Triple
             // NB A Triple can be serialized correctly with: FmtUtils.stringForTriple(triple, PrefixMapping.Factory.create()) + " .";
-            Iterator<Triple> it = RiotReader.createIteratorTriples(new ByteArrayInputStream(serializedTriple.getBytes("UTF-8")), RDFLanguages.NTRIPLES, null);
+            ByteArrayInputStream input = new ByteArrayInputStream(serializedTriple.getBytes("UTF-8"));
+			Iterator<Triple> it = RiotReader.createIteratorTriples(input, RDFLanguages.NTRIPLES, null);
 
             if (it.hasNext()) {
                 Triple triple = it.next();
 
                 if (it.hasNext()) {
-                    log.warn("More than one triple parsed from change event");
+                    log.warn("More than one triple parsed from change event: '" + serializedTriple + "'");
                 }
 
                 // Use the retained defaultModel instance to convert the Triple to a Statement
@@ -143,7 +159,7 @@ public class IndexingChangeListener implements ChangeListener,
                 // 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");
+                throw new RuntimeException("no triple parsed from change event: '" + serializedTriple + "'");
             }
         } catch (RuntimeException riot) {
             log.error("Failed to parse triple " + serializedTriple, riot);

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

@@ -28,12 +28,12 @@ import java.util.concurrent.atomic.AtomicReference;
 
 import javax.servlet.ServletContext;
 
-import edu.cornell.mannlib.vitro.webapp.dao.IndividualDao;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 
 import com.hp.hpl.jena.rdf.model.Statement;
 
+import edu.cornell.mannlib.vitro.webapp.dao.IndividualDao;
 import edu.cornell.mannlib.vitro.webapp.dao.WebappDaoFactory;
 import edu.cornell.mannlib.vitro.webapp.dao.filtering.WebappDaoFactoryFiltering;
 import edu.cornell.mannlib.vitro.webapp.dao.filtering.filters.VitroFilterUtils;
@@ -87,7 +87,7 @@ public class SearchIndexerImpl implements SearchIndexer {
 
 	private final ListenerList listeners = new ListenerList();
 	private final TaskQueue taskQueue = new TaskQueue();
-	private final Scheduler scheduler = new Scheduler(this, taskQueue);
+	private final Scheduler scheduler = new Scheduler(taskQueue);
 
 	private Integer threadPoolSize;
 	private WorkerThreadPool pool;
@@ -209,7 +209,7 @@ public class SearchIndexerImpl implements SearchIndexer {
 	}
 
     @Override
-    public void pauseWithoutDeferring() {
+    public void pauseInAnticipationOfRebuild() {
         if (!isPaused() && !isShutdown()) {
             ignoreTasksWhilePaused = true;
             rebuildOnUnpause = false;
@@ -398,12 +398,10 @@ public class SearchIndexerImpl implements SearchIndexer {
 	private static class Scheduler {
 		private final TaskQueue taskQueue;
 		private final List<Task> deferredQueue;
-        private final SearchIndexerImpl indexer;
 		private volatile boolean started;
 		private volatile boolean paused;
 
-		public Scheduler(SearchIndexerImpl indexer, TaskQueue taskQueue) {
+		public Scheduler(TaskQueue taskQueue) {
-            this.indexer = indexer;
 			this.taskQueue = taskQueue;
 			this.deferredQueue = new ArrayList<Task>();
 		}
@@ -449,8 +447,6 @@ public class SearchIndexerImpl implements SearchIndexer {
                 taskQueue.scheduleTask(task);
 				log.debug("moved task from deferred queue to task queue: " + task);
 			}
-
-            // Empty out the deferred queue as we've now processed it
 			deferredQueue.clear();
 		}
 
@@ -559,29 +555,59 @@ public class SearchIndexerImpl implements SearchIndexer {
 	 */
 	public static interface IndexerConfig {
 		public IndexingUriFinderList uriFinderList();
+
 		public SearchIndexExcluderList excluderList();
+
 		public DocumentModifierList documentModifierList();
+
 		public IndividualDao individualDao();
+
 		public ListenerList listenerList();
+
 		public WorkerThreadPool workerThreadPool();
 	}
 
 	/**
-     * Implementation of IndexerConfig
+	 * Implementation of IndexerConfig Defers access to the configuration until
-     * Defers access to the configuration until the task is running, so a Task
+	 * the task is running, so a Task created and deferred before the indexer is
-     * created and deferred before the indexer is started will not cause a NullPointerException
+	 * started will not cause a NullPointerException
 	 */
 	private static class IndexerConfigImpl implements IndexerConfig {
 		private final SearchIndexerImpl sii;
 
-        public IndexerConfigImpl(SearchIndexerImpl sii) { this.sii = sii; }
+		public IndexerConfigImpl(SearchIndexerImpl sii) {
+			this.sii = sii;
+		}
 
-        public IndexingUriFinderList uriFinderList()       { return sii.createFindersList(); }
+		@Override
-        public SearchIndexExcluderList excluderList()      { return sii.createExcludersList(); }
+		public IndexingUriFinderList uriFinderList() {
-        public DocumentModifierList documentModifierList() { return sii.createModifiersList(); }
+			return sii.createFindersList();
-        public IndividualDao individualDao()               { return sii.wadf.getIndividualDao(); }
+		}
-        public ListenerList listenerList()                 { return sii.listeners; }
+
-        public WorkerThreadPool workerThreadPool()         { return sii.pool; }
+		@Override
+		public SearchIndexExcluderList excluderList() {
+			return sii.createExcludersList();
+		}
+
+		@Override
+		public DocumentModifierList documentModifierList() {
+			return sii.createModifiersList();
+		}
+
+		@Override
+		public IndividualDao individualDao() {
+			return sii.wadf.getIndividualDao();
+		}
+
+		@Override
+		public ListenerList listenerList() {
+			return sii.listeners;
+		}
+
+		@Override
+		public WorkerThreadPool workerThreadPool() {
+			return sii.pool;
+		}
 	}
 
 	public static interface Task extends Runnable {
@@ -688,28 +714,4 @@ public class SearchIndexerImpl implements SearchIndexer {
 		}
 
 	}
-
-    private static class StatementList {
-        List<Statement> changes;
-
-        public StatementList() {
-            changes = new ArrayList<Statement>();
-        }
-
-        public synchronized void addStatement(Statement stmt) {
-            changes.add(stmt);
-        }
-
-        public synchronized List<Statement> getStatements() {
-            try {
-                return new ArrayList<>(changes);
-            } finally {
-                changes.clear();
-            }
-        }
-
-        public synchronized int size() {
-            return changes.size();
-        }
-    };
 }

webapp/src/edu/cornell/mannlib/vitro/webapp/searchindex/tasks/UpdateStatementsTask.java

@@ -14,7 +14,6 @@ import java.util.HashSet;
 import java.util.List;
 import java.util.Set;
 
-import edu.cornell.mannlib.vitro.webapp.searchindex.SearchIndexerImpl;
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;
 

webapp/src/edu/cornell/mannlib/vitro/webapp/searchindex/tasks/UpdateUrisTask.java

@@ -7,7 +7,10 @@ import static edu.cornell.mannlib.vitro.webapp.modules.searchIndexer.SearchIndex
 import static edu.cornell.mannlib.vitro.webapp.modules.searchIndexer.SearchIndexer.Event.Type.STOP_URIS;
 import static edu.cornell.mannlib.vitro.webapp.modules.searchIndexer.SearchIndexerStatus.State.PROCESSING_URIS;
 
-import java.util.*;
+import java.util.Collection;
+import java.util.Date;
+import java.util.HashSet;
+import java.util.List;
 
 import org.apache.commons.logging.Log;
 import org.apache.commons.logging.LogFactory;

webapp/test/stubs/edu/cornell/mannlib/vitro/webapp/modules/searchIndexer/SearchIndexerStub.java

@@ -32,7 +32,7 @@ public class SearchIndexerStub implements SearchIndexer {
 	}
 
     @Override
-    public void pauseWithoutDeferring() {
+    public void pauseInAnticipationOfRebuild() {
         paused = true;
     }