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 static com.google.common.base.Preconditions.checkState;
12 import com.google.common.annotations.Beta;
13 import com.google.common.util.concurrent.FluentFuture;
14 import java.util.Collection;
15 import java.util.Optional;
16 import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
17 import org.opendaylight.mdsal.dom.spi.store.DOMStoreThreePhaseCommitCohort;
18 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
19 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
22 * Client-side view of a transaction.
25 * This interface is used by the world outside of the actor system and in the actor system it is manifested via
26 * its client actor. That requires some state transfer with {@link DistributedDataStoreClientBehavior}. In order to
27 * reduce request latency, all messages are carbon-copied (and enqueued first) to the client actor.
30 * It is internally composed of multiple {@link RemoteProxyTransaction}s, each responsible for a component shard.
33 * Implementation is quite a bit complex, and involves cooperation with {@link AbstractClientHistory} for tracking
34 * gaps in transaction identifiers seen by backends.
37 * These gaps need to be accounted for in the transaction setup message sent to a particular backend, so it can verify
38 * that the requested transaction is in-sequence. This is critical in ensuring that transactions (which are independent
39 * entities from message queueing perspective) do not get reodered -- thus allowing multiple in-flight transactions.
42 * Alternative would be to force visibility by sending an abort request to all potential backends, but that would mean
43 * that even empty transactions increase load on all shards -- which would be a scalability issue.
46 * Yet another alternative would be to introduce inter-transaction dependencies to the queueing layer in client actor,
47 * but that would require additional indirection and complexity.
49 * @author Robert Varga
52 public class ClientTransaction extends AbstractClientHandle<AbstractProxyTransaction> {
53 ClientTransaction(final AbstractClientHistory parent, final TransactionIdentifier transactionId) {
54 super(parent, transactionId);
57 private AbstractProxyTransaction ensureTransactionProxy(final YangInstanceIdentifier path) {
58 return ensureProxy(path);
61 public FluentFuture<Boolean> exists(final YangInstanceIdentifier path) {
62 return ensureTransactionProxy(path).exists(path);
65 public FluentFuture<Optional<NormalizedNode>> read(final YangInstanceIdentifier path) {
66 return ensureTransactionProxy(path).read(path);
69 public void delete(final YangInstanceIdentifier path) {
70 ensureTransactionProxy(path).delete(path);
73 public void merge(final YangInstanceIdentifier path, final NormalizedNode data) {
74 ensureTransactionProxy(path).merge(path, data);
77 public void write(final YangInstanceIdentifier path, final NormalizedNode data) {
78 ensureTransactionProxy(path).write(path, data);
81 public DOMStoreThreePhaseCommitCohort ready() {
82 final Collection<AbstractProxyTransaction> toReady = ensureClosed();
83 checkState(toReady != null, "Attempted to submit a closed transaction %s", this);
85 toReady.forEach(AbstractProxyTransaction::seal);
86 final AbstractTransactionCommitCohort cohort;
87 switch (toReady.size()) {
89 cohort = new EmptyTransactionCommitCohort(parent(), getIdentifier());
92 cohort = new DirectTransactionCommitCohort(parent(), getIdentifier(), toReady.iterator().next());
95 cohort = new ClientTransactionCommitCohort(parent(), getIdentifier(), toReady);
99 return parent().onTransactionReady(this, cohort);
103 final AbstractProxyTransaction createProxy(final Long shard) {
104 return parent().createTransactionProxy(getIdentifier(), shard);