2 * Copyright (c) 2016 Cisco Systems, Inc. and others. All rights reserved.
4 * This program and the accompanying materials are made available under the
5 * terms of the Eclipse Public License v1.0 which accompanies this distribution,
6 * and is available at http://www.eclipse.org/legal/epl-v10.html
8 package org.opendaylight.controller.cluster.databroker.actors.dds;
10 import com.google.common.annotations.Beta;
11 import com.google.common.base.Preconditions;
12 import com.google.common.collect.Iterables;
13 import com.google.common.util.concurrent.FluentFuture;
14 import java.util.Collection;
15 import java.util.Optional;
16 import org.eclipse.jdt.annotation.NonNull;
17 import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
18 import org.opendaylight.mdsal.dom.api.DOMDataTreeCursor;
19 import org.opendaylight.mdsal.dom.api.DOMDataTreeWriteCursor;
20 import org.opendaylight.mdsal.dom.spi.store.DOMStoreThreePhaseCommitCohort;
21 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
22 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
25 * Client-side view of a transaction.
28 * This interface is used by the world outside of the actor system and in the actor system it is manifested via
29 * its client actor. That requires some state transfer with {@link DistributedDataStoreClientBehavior}. In order to
30 * reduce request latency, all messages are carbon-copied (and enqueued first) to the client actor.
33 * It is internally composed of multiple {@link RemoteProxyTransaction}s, each responsible for a component shard.
36 * Implementation is quite a bit complex, and involves cooperation with {@link AbstractClientHistory} for tracking
37 * gaps in transaction identifiers seen by backends.
40 * These gaps need to be accounted for in the transaction setup message sent to a particular backend, so it can verify
41 * that the requested transaction is in-sequence. This is critical in ensuring that transactions (which are independent
42 * entities from message queueing perspective) do not get reodered -- thus allowing multiple in-flight transactions.
45 * Alternative would be to force visibility by sending an abort request to all potential backends, but that would mean
46 * that even empty transactions increase load on all shards -- which would be a scalability issue.
49 * Yet another alternative would be to introduce inter-transaction dependencies to the queueing layer in client actor,
50 * but that would require additional indirection and complexity.
52 * @author Robert Varga
55 public class ClientTransaction extends AbstractClientHandle<AbstractProxyTransaction> {
57 private ClientTransactionCursor cursor;
59 ClientTransaction(final AbstractClientHistory parent, final TransactionIdentifier transactionId) {
60 super(parent, transactionId);
63 private AbstractProxyTransaction ensureTransactionProxy(final YangInstanceIdentifier path) {
64 return ensureProxy(path);
67 public DOMDataTreeWriteCursor openCursor() {
68 Preconditions.checkState(cursor == null, "Transaction %s has open cursor", getIdentifier());
69 cursor = new ClientTransactionCursor(this);
73 public FluentFuture<Boolean> exists(final YangInstanceIdentifier path) {
74 return ensureTransactionProxy(path).exists(path);
77 public FluentFuture<Optional<NormalizedNode<?, ?>>> read(final YangInstanceIdentifier path) {
78 return ensureTransactionProxy(path).read(path);
81 public void delete(final YangInstanceIdentifier path) {
82 ensureTransactionProxy(path).delete(path);
85 public void merge(final YangInstanceIdentifier path, final NormalizedNode<?, ?> data) {
86 ensureTransactionProxy(path).merge(path, data);
89 public void write(final YangInstanceIdentifier path, final NormalizedNode<?, ?> data) {
90 ensureTransactionProxy(path).write(path, data);
93 public DOMStoreThreePhaseCommitCohort ready() {
94 final Collection<AbstractProxyTransaction> toReady = ensureClosed();
95 Preconditions.checkState(toReady != null, "Attempted to submit a closed transaction %s", this);
97 toReady.forEach(AbstractProxyTransaction::seal);
98 final AbstractTransactionCommitCohort cohort;
99 switch (toReady.size()) {
101 cohort = new EmptyTransactionCommitCohort(parent(), getIdentifier());
104 cohort = new DirectTransactionCommitCohort(parent(), getIdentifier(),
105 Iterables.getOnlyElement(toReady));
108 cohort = new ClientTransactionCommitCohort(parent(), getIdentifier(), toReady);
112 return parent().onTransactionReady(this, cohort);
116 final AbstractProxyTransaction createProxy(final Long shard) {
117 return parent().createTransactionProxy(getIdentifier(), shard);
120 void closeCursor(final @NonNull DOMDataTreeCursor cursorToClose) {
121 if (cursorToClose.equals(this.cursor)) {