Java tutorial
/** * CloudGraph Community Edition (CE) License * * This is a community release of CloudGraph, a dual-license suite of * Service Data Object (SDO) 2.1 services designed for relational and * big-table style "cloud" databases, such as HBase and others. * This particular copy of the software is released under the * version 2 of the GNU General Public License. CloudGraph was developed by * TerraMeta Software, Inc. * * Copyright (c) 2013, TerraMeta Software, Inc. All rights reserved. * * General License information can be found below. * * This distribution may include materials developed by third * parties. For license and attribution notices for these * materials, please refer to the documentation that accompanies * this distribution (see the "Licenses for Third-Party Components" * appendix) or view the online documentation at * <http://cloudgraph.org/licenses/>. */ package org.cloudgraph.cassandra.graph; import static com.google.common.util.concurrent.Uninterruptibles.awaitUninterruptibly; import java.util.ArrayList; import java.util.Iterator; import java.util.List; import java.util.Map; import java.util.Set; import java.util.concurrent.CountDownLatch; import java.util.concurrent.RejectedExecutionException; import org.apache.commons.logging.Log; import org.apache.commons.logging.LogFactory; import org.cloudgraph.common.concurrent.SubgraphTask; import org.cloudgraph.common.concurrent.Traversal; import org.cloudgraph.store.lang.AssemblerSupport; import org.cloudgraph.store.lang.DefaultAssembler; import org.cloudgraph.store.lang.StatementExecutor; import org.cloudgraph.store.lang.StatementFactory; import org.plasma.query.collector.SelectionCollector; import org.plasma.sdo.PlasmaDataObject; import org.plasma.sdo.PlasmaProperty; import org.plasma.sdo.PlasmaType; import org.plasma.sdo.access.provider.common.PropertyPair; import commonj.sdo.Property; /** * A concurrent task which processes a portion of a data graph or sub-graph while leveraging * shared resources, such as the data graph being assembled and the thread pool, through the * shared parent {@link ParallelGraphAssembler}. * * @see ParallelGraphAssembler * @see LangStoreGraphAssembler * * @author Scott Cinnamond * @since 0.6.2 */ public class ParallelSubgraphTask extends AssemblerSupport implements SubgraphTask { private static Log log = LogFactory.getLog(ParallelSubgraphTask.class); protected PlasmaType subrootType; protected PlasmaDataObject source; protected PlasmaProperty sourceProperty; protected List<PropertyPair> subrootChildKeyPairs; protected int level; protected int sequence; private final CountDownLatch shutdownLatch = new CountDownLatch(1); private ParallelGraphAssembler sharedAssembler; public ParallelSubgraphTask(PlasmaType subrootType, PlasmaDataObject source, SelectionCollector selection, StatementFactory statementFactory, StatementExecutor statementExecutor, PlasmaProperty sourceProperty, List<PropertyPair> childKeyPairs, int level, int sequence, ParallelGraphAssembler assembler) { super(selection, statementFactory, statementExecutor); this.subrootType = subrootType; this.source = source; this.sourceProperty = sourceProperty; this.subrootChildKeyPairs = childKeyPairs; this.level = level; this.sequence = sequence; this.sharedAssembler = assembler; if (log.isDebugEnabled()) log.debug(String.valueOf(level) + ":process: " + source.getType().getName() + "." + sourceProperty.getName() + "->" + subrootType.getName() + ": " + childKeyPairs); } @Override public void start() { if (log.isDebugEnabled()) log.debug("start-" + level + "." + sequence); try { sharedAssembler.getExecutorService().execute(new Runnable() { @Override public void run() { // begin a breadth first traversal from the given node assemble(); shutdown(); } }); } catch (RejectedExecutionException e) { log.error(e.getMessage(), e); } } protected void shutdown() { this.shutdownLatch.countDown(); } @Override public void join() { if (log.isDebugEnabled()) log.debug("join-" + level + "." + sequence); //Uninterruptibles.joinUninterruptibly(this.runner); awaitUninterruptibly(shutdownLatch); } public void assemble() { assemble(this.subrootType, this.source, this.sourceProperty, this.subrootChildKeyPairs, this.level); } /** * Assembles a data object of the given target type by first forming a query using the * given key/property pairs. If an existing data object is mapped for the given * key pairs, the existing data object is linked. * @param targetType the type for the data object to be assembled * @param source the source data object * @param sourceProperty the source property * @param childKeyPairs the key pairs for the data object to be assembled */ private void assemble(PlasmaType targetType, PlasmaDataObject source, PlasmaProperty sourceProperty, List<PropertyPair> childKeyPairs, int level) { Set<Property> props = this.collector.getProperties(targetType, level); if (props == null) { props = DefaultAssembler.EMPTY_PROPERTY_SET; } if (log.isDebugEnabled()) log.debug(String.valueOf(level) + ":assemble: " + source.getType().getName() + "." + sourceProperty.getName() + "->" + targetType.getName() + ": " + props); List<List<PropertyPair>> result = this.getPredicateResult(targetType, sourceProperty, props, childKeyPairs); if (log.isDebugEnabled()) log.debug(String.valueOf(level) + ":results: " + result.size()); Map<PlasmaDataObject, List<PropertyPair>> resultMap = this.sharedAssembler.collectResults(targetType, source, sourceProperty, result); // now traverse Iterator<PlasmaDataObject> iter = resultMap.keySet().iterator(); while (iter.hasNext()) { PlasmaDataObject target = iter.next(); List<PropertyPair> row = resultMap.get(target); List<Traversal> traversals = new ArrayList<Traversal>(); // traverse singular results props for (PropertyPair pair : row) { if (pair.getProp().isMany() || pair.getProp().getType().isDataType()) continue; // only singular reference props if (!pair.isQueryProperty()) continue; // property is a key or other property not explicitly cited in the source query, don't traverse it List<PropertyPair> nextKeyPairs = this.getNextKeyPairs(target, pair, level); if (log.isDebugEnabled()) log.debug(String.valueOf(level) + ":traverse: (" + pair.getProp().isMany() + ") " + pair.getProp().toString() + ":" + String.valueOf(pair.getValue())); Traversal trav = new Traversal((PlasmaType) pair.getProp().getType(), target, pair.getProp(), nextKeyPairs, level + 1); traversals.add(trav); } // traverse multi props based, not on the results // row, but on keys within this data object for (Property p : props) { PlasmaProperty prop = (PlasmaProperty) p; if (!prop.isMany() || prop.getType().isDataType()) continue; // only many reference props List<PropertyPair> childKeyProps = this.getChildKeyProps(target, targetType, prop); if (log.isDebugEnabled()) log.debug(String.valueOf(level) + ":traverse: (" + prop.isMany() + ") " + prop.toString() + " - " + childKeyProps.toArray().toString()); Traversal trav = new Traversal((PlasmaType) prop.getType(), target, prop, childKeyProps, level + 1); traversals.add(trav); } // create concurrent tasks based on pool availability and // traversal depth this.sharedAssembler.logPoolStatistics(); int available = 0; if (level <= this.sharedAssembler.getConfig().getMaxThreadDepth()) { available = this.sharedAssembler.numThreadsAvailable(); if (available > traversals.size()) available = traversals.size(); } List<SubgraphTask> concurrentTasks = null; for (int i = 0; i < available; i++) { Traversal trav = traversals.get(i); SubgraphTask task = new ParallelSubgraphTask(trav.getSubrootType(), trav.getSource(), this.collector, this.getStatementFactory(), this.getStatementExecutor(), trav.getSourceProperty(), trav.getChildKeyPairs(), trav.getLevel(), i, this.sharedAssembler); if (concurrentTasks == null) concurrentTasks = new ArrayList<SubgraphTask>(); concurrentTasks.add(task); } // start any asynchronous assemblers if (concurrentTasks != null) { for (SubgraphTask task : concurrentTasks) task.start(); for (SubgraphTask task : concurrentTasks) task.join(); } // add remainder // continue with traversals for this thread for (int i = available; i < traversals.size(); i++) { Traversal trav = traversals.get(i); assemble(trav.getSubrootType(), trav.getSource(), trav.getSourceProperty(), trav.getChildKeyPairs(), trav.getLevel()); } } } }