Java tutorial
/* * Copyright (c) 2016 Cisco Systems, Inc. and others. All rights reserved. * * This program and the accompanying materials are made available under the * terms of the Eclipse Public License v1.0 which accompanies this distribution, * and is available at http://www.eclipse.org/legal/epl-v10.html */ package org.opendaylight.controller.cluster.datastore; import com.google.common.base.MoreObjects; import com.google.common.base.Preconditions; import com.google.common.collect.ImmutableMap; import com.google.common.collect.Range; import com.google.common.collect.RangeSet; import com.google.common.primitives.UnsignedLong; import java.util.HashMap; import java.util.Map; import java.util.Optional; import javax.annotation.Nullable; import org.opendaylight.controller.cluster.access.commands.AbstractReadTransactionRequest; import org.opendaylight.controller.cluster.access.commands.ClosedTransactionException; import org.opendaylight.controller.cluster.access.commands.CommitLocalTransactionRequest; import org.opendaylight.controller.cluster.access.commands.DeadTransactionException; import org.opendaylight.controller.cluster.access.commands.IncrementTransactionSequenceRequest; import org.opendaylight.controller.cluster.access.commands.LocalHistorySuccess; import org.opendaylight.controller.cluster.access.commands.OutOfOrderRequestException; import org.opendaylight.controller.cluster.access.commands.TransactionPurgeRequest; import org.opendaylight.controller.cluster.access.commands.TransactionPurgeResponse; import org.opendaylight.controller.cluster.access.commands.TransactionRequest; import org.opendaylight.controller.cluster.access.commands.TransactionSuccess; import org.opendaylight.controller.cluster.access.concepts.LocalHistoryIdentifier; import org.opendaylight.controller.cluster.access.concepts.RequestEnvelope; import org.opendaylight.controller.cluster.access.concepts.RequestException; import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier; import org.opendaylight.yangtools.concepts.Identifiable; import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeModification; import org.slf4j.Logger; import org.slf4j.LoggerFactory; /** * Abstract class for providing logical tracking of frontend local histories. This class is specialized for * standalone transactions and chained transactions. * * @author Robert Varga */ abstract class AbstractFrontendHistory implements Identifiable<LocalHistoryIdentifier> { private static final Logger LOG = LoggerFactory.getLogger(AbstractFrontendHistory.class); private final Map<TransactionIdentifier, FrontendTransaction> transactions = new HashMap<>(); private final RangeSet<UnsignedLong> purgedTransactions; private final String persistenceId; private final ShardDataTree tree; /** * Transactions closed by the previous leader. Boolean indicates whether the transaction was committed (true) or * aborted (false). We only ever shrink these. */ private Map<UnsignedLong, Boolean> closedTransactions; AbstractFrontendHistory(final String persistenceId, final ShardDataTree tree, final Map<UnsignedLong, Boolean> closedTransactions, final RangeSet<UnsignedLong> purgedTransactions) { this.persistenceId = Preconditions.checkNotNull(persistenceId); this.tree = Preconditions.checkNotNull(tree); this.closedTransactions = Preconditions.checkNotNull(closedTransactions); this.purgedTransactions = Preconditions.checkNotNull(purgedTransactions); } final String persistenceId() { return persistenceId; } final long readTime() { return tree.readTime(); } @Nullable final TransactionSuccess<?> handleTransactionRequest(final TransactionRequest<?> request, final RequestEnvelope envelope, final long now) throws RequestException { if (request instanceof TransactionPurgeRequest) { return handleTransactionPurgeRequest(request, envelope, now); } final TransactionIdentifier id = request.getTarget(); final UnsignedLong ul = UnsignedLong.fromLongBits(id.getTransactionId()); if (purgedTransactions.contains(ul)) { LOG.warn("{}: Request {} is contained purged transactions {}", persistenceId, request, purgedTransactions); throw new DeadTransactionException(purgedTransactions); } final Boolean closed = closedTransactions.get(ul); if (closed != null) { final boolean successful = closed.booleanValue(); LOG.debug("{}: Request {} refers to a {} transaction", persistenceId, request, successful ? "successful" : "failed"); throw new ClosedTransactionException(successful); } FrontendTransaction tx = transactions.get(id); if (tx == null) { // The transaction does not exist and we are about to create it, check sequence number if (request.getSequence() != 0) { LOG.warn("{}: no transaction state present, unexpected request {}", persistenceId(), request); throw new OutOfOrderRequestException(0); } tx = createTransaction(request, id); transactions.put(id, tx); } else if (!(request instanceof IncrementTransactionSequenceRequest)) { final Optional<TransactionSuccess<?>> maybeReplay = tx.replaySequence(request.getSequence()); if (maybeReplay.isPresent()) { final TransactionSuccess<?> replay = maybeReplay.get(); LOG.debug("{}: envelope {} replaying response {}", persistenceId(), envelope, replay); return replay; } } return tx.handleRequest(request, envelope, now); } private TransactionSuccess<?> handleTransactionPurgeRequest(final TransactionRequest<?> request, final RequestEnvelope envelope, final long now) { final TransactionIdentifier id = request.getTarget(); final UnsignedLong ul = UnsignedLong.fromLongBits(id.getTransactionId()); if (purgedTransactions.contains(ul)) { // Retransmitted purge request: nothing to do LOG.debug("{}: transaction {} already purged", persistenceId, id); return new TransactionPurgeResponse(id, request.getSequence()); } // We perform two lookups instead of a straight remove, because once the map becomes empty we switch it // to an ImmutableMap, which does not allow remove(). if (closedTransactions.containsKey(ul)) { tree.purgeTransaction(id, () -> { closedTransactions.remove(ul); if (closedTransactions.isEmpty()) { closedTransactions = ImmutableMap.of(); } purgedTransactions.add(Range.closedOpen(ul, UnsignedLong.ONE.plus(ul))); LOG.debug("{}: finished purging inherited transaction {}", persistenceId(), id); envelope.sendSuccess(new TransactionPurgeResponse(id, request.getSequence()), readTime() - now); }); return null; } final FrontendTransaction tx = transactions.get(id); if (tx == null) { // This should never happen because the purge callback removes the transaction and puts it into // purged transactions in one go. If it does, we warn about the situation and LOG.warn("{}: transaction {} not tracked in {}, but not present in active transactions", persistenceId, id, purgedTransactions); purgedTransactions.add(Range.closedOpen(ul, UnsignedLong.ONE.plus(ul))); return new TransactionPurgeResponse(id, request.getSequence()); } tree.purgeTransaction(id, () -> { purgedTransactions.add(Range.closedOpen(ul, UnsignedLong.ONE.plus(ul))); transactions.remove(id); LOG.debug("{}: finished purging transaction {}", persistenceId(), id); envelope.sendSuccess(new TransactionPurgeResponse(id, request.getSequence()), readTime() - now); }); return null; } final void destroy(final long sequence, final RequestEnvelope envelope, final long now) { LOG.debug("{}: closing history {}", persistenceId(), getIdentifier()); tree.closeTransactionChain(getIdentifier(), () -> envelope.sendSuccess(new LocalHistorySuccess(getIdentifier(), sequence), readTime() - now)); } final void purge(final long sequence, final RequestEnvelope envelope, final long now) { LOG.debug("{}: purging history {}", persistenceId(), getIdentifier()); tree.purgeTransactionChain(getIdentifier(), () -> envelope.sendSuccess(new LocalHistorySuccess(getIdentifier(), sequence), readTime() - now)); } final void retire() { transactions.values().forEach(FrontendTransaction::retire); tree.removeTransactionChain(getIdentifier()); } private FrontendTransaction createTransaction(final TransactionRequest<?> request, final TransactionIdentifier id) throws RequestException { if (request instanceof CommitLocalTransactionRequest) { LOG.debug("{}: allocating new ready transaction {}", persistenceId(), id); tree.getStats().incrementReadWriteTransactionCount(); return createReadyTransaction(id, ((CommitLocalTransactionRequest) request).getModification()); } if (request instanceof AbstractReadTransactionRequest && ((AbstractReadTransactionRequest<?>) request).isSnapshotOnly()) { LOG.debug("{}: allocating new open snapshot {}", persistenceId(), id); tree.getStats().incrementReadOnlyTransactionCount(); return createOpenSnapshot(id); } LOG.debug("{}: allocating new open transaction {}", persistenceId(), id); tree.getStats().incrementReadWriteTransactionCount(); return createOpenTransaction(id); } abstract FrontendTransaction createOpenSnapshot(TransactionIdentifier id) throws RequestException; abstract FrontendTransaction createOpenTransaction(TransactionIdentifier id) throws RequestException; abstract FrontendTransaction createReadyTransaction(TransactionIdentifier id, DataTreeModification mod) throws RequestException; abstract ShardDataTreeCohort createFailedCohort(TransactionIdentifier id, DataTreeModification mod, Exception failure); abstract ShardDataTreeCohort createReadyCohort(TransactionIdentifier id, DataTreeModification mod); @Override public String toString() { return MoreObjects.toStringHelper(this).omitNullValues().add("identifier", getIdentifier()) .add("persistenceId", persistenceId).add("transactions", transactions).toString(); } }