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.Optional;
12 import com.google.common.base.Preconditions;
13 import com.google.common.collect.Iterables;
14 import com.google.common.util.concurrent.CheckedFuture;
15 import java.util.HashMap;
17 import java.util.concurrent.atomic.AtomicIntegerFieldUpdater;
18 import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
19 import org.opendaylight.controller.md.sal.common.api.data.ReadFailedException;
20 import org.opendaylight.controller.sal.core.spi.data.DOMStoreThreePhaseCommitCohort;
21 import org.opendaylight.yangtools.concepts.Identifiable;
22 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
23 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
24 import org.slf4j.Logger;
25 import org.slf4j.LoggerFactory;
28 * Client-side view of a free-standing transaction.
30 * This interface is used by the world outside of the actor system and in the actor system it is manifested via
31 * its client actor. That requires some state transfer with {@link DistributedDataStoreClientBehavior}. In order to
32 * reduce request latency, all messages are carbon-copied (and enqueued first) to the client actor.
34 * 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.
39 * These gaps need to be accounted for in the transaction setup message sent to a particular backend, so it can verify
40 * that the requested transaction is in-sequence. This is critical in ensuring that transactions (which are independent
41 * entities from message queueing perspective) do not get reodered -- thus allowing multiple in-flight transactions.
43 * Alternative would be to force visibility by sending an abort request to all potential backends, but that would mean
44 * 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 final class ClientTransaction extends LocalAbortable implements Identifiable<TransactionIdentifier> {
53 private static final Logger LOG = LoggerFactory.getLogger(ClientTransaction.class);
54 private static final AtomicIntegerFieldUpdater<ClientTransaction> STATE_UPDATER =
55 AtomicIntegerFieldUpdater.newUpdater(ClientTransaction.class, "state");
56 private static final int OPEN_STATE = 0;
57 private static final int CLOSED_STATE = 1;
59 private final Map<Long, AbstractProxyTransaction> proxies = new HashMap<>();
60 private final TransactionIdentifier transactionId;
61 private final AbstractClientHistory parent;
63 private volatile int state = OPEN_STATE;
65 ClientTransaction(final AbstractClientHistory parent, final TransactionIdentifier transactionId) {
66 this.transactionId = Preconditions.checkNotNull(transactionId);
67 this.parent = Preconditions.checkNotNull(parent);
70 private void checkNotClosed() {
71 Preconditions.checkState(state == OPEN_STATE, "Transaction %s is closed", transactionId);
74 private AbstractProxyTransaction createProxy(final Long shard) {
75 return parent.createTransactionProxy(transactionId, shard);
78 private AbstractProxyTransaction ensureProxy(final YangInstanceIdentifier path) {
81 final ModuleShardBackendResolver resolver = parent.getClient().resolver();
82 final Long shard = resolver.resolveShardForPath(path);
83 return proxies.computeIfAbsent(shard, this::createProxy);
87 public TransactionIdentifier getIdentifier() {
91 public CheckedFuture<Boolean, ReadFailedException> exists(final YangInstanceIdentifier path) {
92 return ensureProxy(path).exists(path);
95 public CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> read(final YangInstanceIdentifier path) {
96 return ensureProxy(path).read(path);
99 public void delete(final YangInstanceIdentifier path) {
100 ensureProxy(path).delete(path);
103 public void merge(final YangInstanceIdentifier path, final NormalizedNode<?, ?> data) {
104 ensureProxy(path).merge(path, data);
107 public void write(final YangInstanceIdentifier path, final NormalizedNode<?, ?> data) {
108 ensureProxy(path).write(path, data);
111 private boolean ensureClosed() {
112 final int local = state;
113 if (local != CLOSED_STATE) {
114 final boolean success = STATE_UPDATER.compareAndSet(this, OPEN_STATE, CLOSED_STATE);
115 Preconditions.checkState(success, "Transaction %s raced during close", this);
122 public DOMStoreThreePhaseCommitCohort ready() {
123 Preconditions.checkState(ensureClosed(), "Attempted to submit a closed transaction %s", this);
125 for (AbstractProxyTransaction p : proxies.values()) {
128 parent.onTransactionReady(this);
130 switch (proxies.size()) {
132 return EmptyTransactionCommitCohort.INSTANCE;
134 return new DirectTransactionCommitCohort(Iterables.getOnlyElement(proxies.values()));
136 return new ClientTransactionCommitCohort(proxies.values());
141 * Release all state associated with this transaction.
143 public void abort() {
144 if (ensureClosed()) {
145 for (AbstractProxyTransaction proxy : proxies.values()) {
153 void localAbort(final Throwable cause) {
154 LOG.debug("Aborting transaction {}", getIdentifier(), cause);