Github user dick-twocows commented on a diff in the pull request: https://github.com/apache/jena/pull/233#discussion_r110245267 --- Diff: jena-arq/src/main/java/org/apache/jena/sparql/core/mosaic/TransactionalDistributed.java --- @@ -0,0 +1,267 @@ +package org.apache.jena.sparql.core.mosaic; + +import java.util.LinkedList; +import java.util.List; +import java.util.Objects; +import java.util.Set; +import java.util.concurrent.Callable; +import java.util.concurrent.ConcurrentHashMap; +import java.util.concurrent.ConcurrentMap; +import java.util.concurrent.ForkJoinPool; +import java.util.concurrent.ForkJoinWorkerThread; +import java.util.concurrent.Future; +import java.util.concurrent.atomic.AtomicInteger; +import java.util.function.Supplier; +import java.util.stream.Collectors; + +import org.apache.jena.query.ReadWrite; +import org.apache.jena.shared.JenaException; +import org.apache.jena.sparql.core.DatasetGraph; +import org.apache.jena.sparql.core.Transactional; +import org.slf4j.Logger; +import org.slf4j.LoggerFactory; + +/** + * Class to support a distributed Transactional. + * + * Thread affinity is maintained by associating a Thread per DatasetGraph. + * + * A TransactionalDistributed should be declared via a ThreadLocal and thus provides a MRMW. + * + * @author dick + * + */ +public class TransactionalDistributed implements Transactional { + + private static final Logger LOGGER = LoggerFactory.getLogger(TransactionalDistributed.class); + + protected final ForkJoinPool forkJoinPool = new ForkJoinPool(Runtime.getRuntime().availableProcessors()); + + protected final String id = Thread.currentThread().toString(); + + protected final AtomicInteger readCount = new AtomicInteger(); + + protected final AtomicInteger writeCount = new AtomicInteger(); + + protected volatile ReadWrite readWrite = null; + + protected final Set<DatasetGraph> children = ConcurrentHashMap.newKeySet(32); + + protected final ConcurrentMap<DatasetGraph, ThreadProxy> workers = new ConcurrentHashMap<>(32); + + protected class FJWT extends ForkJoinWorkerThread { + + public FJWT(final ForkJoinPool pool) { + super(pool); + } + + } + + public TransactionalDistributed() { + super(); + } + + /** + * Execute the given Runnable. + */ + public void execute(final Runnable task) { + try { + forkJoinPool.submit(task).get(); + } catch (final Exception exception) { + throw new JenaException(exception); + } + } + + /** + * Submit the given Callable. + */ + public <T> Future<T> submit(final Callable<T> task) { + try { + return forkJoinPool.submit(task); + } catch (final Exception exception) { + throw new JenaException(exception); + } + } + + /* + * Distributed transactional methods. The general goal is to maintain transactions on the child DatasetGraph's. + */ + + public ReadWrite getType() { + return readWrite; + } + + public boolean isIn(final ReadWrite compare) { + return Objects.equals(readWrite, Objects.requireNonNull(compare)); + } + + protected Set<DatasetGraph> getChildren() { + return children; + } + + protected ConcurrentMap<DatasetGraph, ThreadProxy> getWorkers() { + return workers; + } + + /** + * Get the ThreadProxy for the given DatasetGraph. + */ + protected ThreadProxy getWorker(final DatasetGraph datasetGraph) { + return getWorkers().computeIfAbsent(datasetGraph, (dg) -> {return new ThreadProxy();}); + } + + /** + * Submit the given Runnable to the correct ThreadProxy based on the given datasetGraph. + */ + public void execute(final DatasetGraph datasetGraph, final Runnable runnable) { + getWorker(datasetGraph).execute(() -> { + begin(datasetGraph); + runnable.run(); + }); + } + + /** + * Submit the given Supplier to the correct ThreadProxy based on the given datasetGraph. + */ + public <T> Future<T> submit(final DatasetGraph datasetGraph, final Supplier<T> supplier) { + return getWorker(datasetGraph).submit(() -> { + begin(datasetGraph); + return supplier.get(); + }); + } + + /** + * Begin a transaction on the given DatasetGraph. + */ + protected DatasetGraph begin(final DatasetGraph datasetGraph) { + if (!isInTransaction()) { + throw new JenaException("No parent transaction"); + } + try { + if (!children.contains(datasetGraph)) { + if (datasetGraph.supportsTransactions()) { + datasetGraph.begin(readWrite); + } + children.add(datasetGraph); + } + return datasetGraph; + } catch (final Exception exception) { + throw new JenaException(exception); + } + } + + /* + * Transactional + */ + + @Override + public void begin(final ReadWrite readWrite) { + if (this.readWrite != null) { + throw new JenaException("Already in a transaction " + this.readWrite); + } + this.readWrite = readWrite; + } + + @Override + public void commit() { + List<Exception> threw = new LinkedList<>(); + children + .forEach(datasetGraph -> { + try { + getWorker(datasetGraph).execute(() -> { + if (datasetGraph.supportsTransactions()) { + datasetGraph.commit(); + } + }); + } catch (final Exception exception) { + threw.add(exception); + } + }); + this.children.clear(); + this.readWrite = null; + if (!threw.isEmpty()) { + final JenaException jenaException = new JenaException(); + threw.forEach((exception) -> {jenaException.addSuppressed(exception);}); + throw jenaException; + } + } + + @Override + public void abort() { + List<Exception> threw = new LinkedList<>(); + children + .forEach(datasetGraph -> { + try { + getWorker(datasetGraph).execute(() -> { + if (datasetGraph.supportsTransactions() && datasetGraph.supportsTransactionAbort()) { + datasetGraph.abort(); + } else { + LOGGER.warn("Attempt to call Transactional.abort().", datasetGraph.getClass()); + } + }); + } catch (final Exception exception) { + threw.add(exception); + } + }); + this.children.clear(); + this.readWrite = null; + if (!threw.isEmpty()) { + final JenaException jenaException = new JenaException(); + threw.forEach((exception) -> {jenaException.addSuppressed(exception);}); + throw jenaException; + } + } + + @Override + public void end() { + if (readWrite != null && readWrite.equals(ReadWrite.WRITE)) { + LOGGER.warn("End without commit/abort"); + } + List<Exception> threw = new LinkedList<>(); + children + .forEach(datasetGraph -> { + try { + getWorker(datasetGraph).execute(() -> { + if (datasetGraph.supportsTransactions()) { + datasetGraph.end(); + } + }); + } catch (final Exception exception) { + threw.add(exception); + } + }); + this.children.clear(); + this.workers.values().forEach(threadDelegate -> { --- End diff -- There'll be more of these ;-)
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