2 * Copyright (c) 2016, 2017 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.datastore;
10 import static java.util.Objects.requireNonNull;
12 import com.google.common.base.MoreObjects;
13 import com.google.common.base.Verify;
14 import java.util.ArrayDeque;
15 import java.util.Optional;
16 import java.util.Queue;
17 import org.eclipse.jdt.annotation.Nullable;
18 import org.opendaylight.controller.cluster.access.commands.IncrementTransactionSequenceRequest;
19 import org.opendaylight.controller.cluster.access.commands.IncrementTransactionSequenceSuccess;
20 import org.opendaylight.controller.cluster.access.commands.OutOfOrderRequestException;
21 import org.opendaylight.controller.cluster.access.commands.TransactionRequest;
22 import org.opendaylight.controller.cluster.access.commands.TransactionSuccess;
23 import org.opendaylight.controller.cluster.access.concepts.RequestEnvelope;
24 import org.opendaylight.controller.cluster.access.concepts.RequestException;
25 import org.opendaylight.controller.cluster.access.concepts.RuntimeRequestException;
26 import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
27 import org.opendaylight.yangtools.concepts.Identifiable;
28 import org.slf4j.Logger;
29 import org.slf4j.LoggerFactory;
32 * Frontend common transaction state as observed by the shard leader. This class is NOT thread-safe.
34 * @author Robert Varga
36 abstract class FrontendTransaction implements Identifiable<TransactionIdentifier> {
37 private static final Logger LOG = LoggerFactory.getLogger(FrontendTransaction.class);
39 private final AbstractFrontendHistory history;
40 private final TransactionIdentifier id;
43 * It is possible that after we process a request and send a response that response gets lost and the client
44 * initiates a retry. Since subsequent requests can mutate transaction state we need to retain the response until
45 * it is acknowledged by the client.
47 private final Queue<Object> replayQueue = new ArrayDeque<>();
48 private long firstReplaySequence;
49 private Long lastPurgedSequence;
50 private long expectedSequence;
52 private RequestException previousFailure;
54 FrontendTransaction(final AbstractFrontendHistory history, final TransactionIdentifier id) {
55 this.history = requireNonNull(history);
56 this.id = requireNonNull(id);
60 public final TransactionIdentifier getIdentifier() {
64 final AbstractFrontendHistory history() {
68 final String persistenceId() {
69 return history().persistenceId();
72 final Optional<TransactionSuccess<?>> replaySequence(final long sequence) throws RequestException {
73 // Fast path check: if the requested sequence is the next request, bail early
74 if (expectedSequence == sequence) {
75 return Optional.empty();
78 // Check sequencing: we do not need to bother with future requests
79 if (Long.compareUnsigned(expectedSequence, sequence) < 0) {
80 throw new OutOfOrderRequestException(expectedSequence);
83 // Sanity check: if we have purged sequences, this has to be newer
84 if (lastPurgedSequence != null && Long.compareUnsigned(lastPurgedSequence.longValue(), sequence) >= 0) {
85 // Client has sent a request sequence, which has already been purged. This is a hard error, which should
86 // never occur. Throwing an IllegalArgumentException will cause it to be wrapped in a
87 // RuntimeRequestException (which is not retriable) and report it back to the client.
88 throw new IllegalArgumentException(String.format("Invalid purged sequence %s (last purged is %s)",
89 sequence, lastPurgedSequence));
92 // At this point we have established that the requested sequence lies in the open interval
93 // (lastPurgedSequence, expectedSequence). That does not actually mean we have a response, as the commit
94 // machinery is asynchronous, hence a reply may be in the works and not available.
96 long replaySequence = firstReplaySequence;
97 for (Object replay : replayQueue) {
98 if (replaySequence == sequence) {
99 if (replay instanceof RequestException) {
100 throw (RequestException) replay;
103 Verify.verify(replay instanceof TransactionSuccess);
104 return Optional.of((TransactionSuccess<?>) replay);
111 return Optional.empty();
114 final void purgeSequencesUpTo(final long sequence) {
115 // FIXME: implement this
117 lastPurgedSequence = sequence;
120 // Request order has already been checked by caller and replaySequence()
121 @SuppressWarnings("checkstyle:IllegalCatch")
122 final @Nullable TransactionSuccess<?> handleRequest(final TransactionRequest<?> request,
123 final RequestEnvelope envelope, final long now) throws RequestException {
124 if (request instanceof IncrementTransactionSequenceRequest) {
125 final IncrementTransactionSequenceRequest incr = (IncrementTransactionSequenceRequest) request;
126 expectedSequence += incr.getIncrement();
128 return recordSuccess(incr.getSequence(),
129 new IncrementTransactionSequenceSuccess(incr.getTarget(), incr.getSequence()));
132 if (previousFailure != null) {
133 LOG.debug("{}: Rejecting request {} due to previous failure", persistenceId(), request, previousFailure);
134 throw previousFailure;
138 return doHandleRequest(request, envelope, now);
139 } catch (RuntimeException e) {
141 * The request failed to process, we should not attempt to ever
142 * apply it again. Furthermore we cannot accept any further requests
143 * from this connection, simply because the transaction state is
146 LOG.debug("{}: Request {} failed to process", persistenceId(), request, e);
147 previousFailure = new RuntimeRequestException("Request " + request + " failed to process", e);
148 throw previousFailure;
152 abstract @Nullable TransactionSuccess<?> doHandleRequest(TransactionRequest<?> request, RequestEnvelope envelope,
153 long now) throws RequestException;
155 abstract void retire();
157 private void recordResponse(final long sequence, final Object response) {
158 if (replayQueue.isEmpty()) {
159 firstReplaySequence = sequence;
161 replayQueue.add(response);
165 final <T extends TransactionSuccess<?>> T recordSuccess(final long sequence, final T success) {
166 recordResponse(sequence, success);
170 private long executionTime(final long startTime) {
171 return history.readTime() - startTime;
174 final void recordAndSendSuccess(final RequestEnvelope envelope, final long startTime,
175 final TransactionSuccess<?> success) {
176 recordResponse(success.getSequence(), success);
177 envelope.sendSuccess(success, executionTime(startTime));
180 final void recordAndSendFailure(final RequestEnvelope envelope, final long startTime,
181 final RuntimeRequestException failure) {
182 recordResponse(envelope.getMessage().getSequence(), failure);
183 envelope.sendFailure(failure, executionTime(startTime));
187 public final String toString() {
188 return MoreObjects.toStringHelper(this).omitNullValues().add("identifier", getIdentifier())
189 .add("expectedSequence", expectedSequence).add("firstReplaySequence", firstReplaySequence)
190 .add("lastPurgedSequence", lastPurgedSequence)