2 * Copyright (c) 2014 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.sal.core.spi.data;
10 import com.google.common.annotations.Beta;
11 import com.google.common.base.Preconditions;
12 import java.util.AbstractMap.SimpleEntry;
13 import java.util.Map.Entry;
14 import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
15 import org.opendaylight.controller.sal.core.spi.data.SnapshotBackedWriteTransaction.TransactionReadyPrototype;
16 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeModification;
17 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeSnapshot;
18 import org.slf4j.Logger;
19 import org.slf4j.LoggerFactory;
22 * Abstract implementation of the {@link DOMStoreTransactionChain} interface relying on {@link DataTreeSnapshot} supplier
23 * and backend commit coordinator.
25 * @param <T> transaction identifier type
28 public abstract class AbstractSnapshotBackedTransactionChain<T> extends TransactionReadyPrototype<T> implements DOMStoreTransactionChain {
29 private static abstract class State {
31 * Allocate a new snapshot.
33 * @return A new snapshot
35 protected abstract DataTreeSnapshot getSnapshot(Object transactionId);
38 private static final class Idle extends State {
39 private final AbstractSnapshotBackedTransactionChain<?> chain;
41 Idle(final AbstractSnapshotBackedTransactionChain<?> chain) {
42 this.chain = Preconditions.checkNotNull(chain);
46 protected DataTreeSnapshot getSnapshot(Object transactionId) {
47 return chain.takeSnapshot();
52 * We have a transaction out there.
54 private static final class Allocated extends State {
55 private static final AtomicReferenceFieldUpdater<Allocated, DataTreeSnapshot> SNAPSHOT_UPDATER =
56 AtomicReferenceFieldUpdater.newUpdater(Allocated.class, DataTreeSnapshot.class, "snapshot");
57 private final DOMStoreWriteTransaction transaction;
58 private volatile DataTreeSnapshot snapshot;
60 Allocated(final DOMStoreWriteTransaction transaction) {
61 this.transaction = Preconditions.checkNotNull(transaction);
64 public DOMStoreWriteTransaction getTransaction() {
69 protected DataTreeSnapshot getSnapshot(Object transactionId) {
70 final DataTreeSnapshot ret = snapshot;
71 Preconditions.checkState(ret != null, "Could not get snapshot for transaction %s - previous transaction %s is not ready yet",
72 transactionId, transaction.getIdentifier());
76 void setSnapshot(final DataTreeSnapshot snapshot) {
77 final boolean success = SNAPSHOT_UPDATER.compareAndSet(this, null, snapshot);
78 Preconditions.checkState(success, "Transaction %s has already been marked as ready", transaction.getIdentifier());
83 * Chain is logically shut down, no further allocation allowed.
85 private static final class Shutdown extends State {
86 private final String message;
88 Shutdown(final String message) {
89 this.message = Preconditions.checkNotNull(message);
93 protected DataTreeSnapshot getSnapshot(Object transactionId) {
94 throw new IllegalStateException(message);
98 @SuppressWarnings("rawtypes")
99 private static final AtomicReferenceFieldUpdater<AbstractSnapshotBackedTransactionChain, State> STATE_UPDATER =
100 AtomicReferenceFieldUpdater.newUpdater(AbstractSnapshotBackedTransactionChain.class, State.class, "state");
101 private static final Logger LOG = LoggerFactory.getLogger(AbstractSnapshotBackedTransactionChain.class);
102 private static final Shutdown CLOSED = new Shutdown("Transaction chain is closed");
103 private static final Shutdown FAILED = new Shutdown("Transaction chain has failed");
104 private final Idle idleState;
105 private volatile State state;
107 protected AbstractSnapshotBackedTransactionChain() {
108 idleState = new Idle(this);
112 private Entry<State, DataTreeSnapshot> getSnapshot(T transactionId) {
113 final State localState = state;
114 return new SimpleEntry<>(localState, localState.getSnapshot(transactionId));
117 private boolean recordTransaction(final State expected, final DOMStoreWriteTransaction transaction) {
118 final State state = new Allocated(transaction);
119 return STATE_UPDATER.compareAndSet(this, expected, state);
123 public final DOMStoreReadTransaction newReadOnlyTransaction() {
124 return newReadOnlyTransaction(nextTransactionIdentifier());
127 protected DOMStoreReadTransaction newReadOnlyTransaction(T transactionId) {
128 final Entry<State, DataTreeSnapshot> entry = getSnapshot(transactionId);
129 return SnapshotBackedTransactions.newReadTransaction(transactionId, getDebugTransactions(), entry.getValue());
133 public final DOMStoreReadWriteTransaction newReadWriteTransaction() {
134 return newReadWriteTransaction(nextTransactionIdentifier());
137 protected DOMStoreReadWriteTransaction newReadWriteTransaction(T transactionId) {
138 Entry<State, DataTreeSnapshot> entry;
139 DOMStoreReadWriteTransaction ret;
142 entry = getSnapshot(transactionId);
143 ret = new SnapshotBackedReadWriteTransaction<>(transactionId, getDebugTransactions(), entry.getValue(),
145 } while (!recordTransaction(entry.getKey(), ret));
151 public final DOMStoreWriteTransaction newWriteOnlyTransaction() {
152 return newWriteOnlyTransaction(nextTransactionIdentifier());
155 protected DOMStoreWriteTransaction newWriteOnlyTransaction(T transactionId) {
156 Entry<State, DataTreeSnapshot> entry;
157 DOMStoreWriteTransaction ret;
160 entry = getSnapshot(transactionId);
161 ret = new SnapshotBackedWriteTransaction<>(transactionId, getDebugTransactions(), entry.getValue(), this);
162 } while (!recordTransaction(entry.getKey(), ret));
168 protected final void transactionAborted(final SnapshotBackedWriteTransaction<T> tx) {
169 final State localState = state;
170 if (localState instanceof Allocated) {
171 final Allocated allocated = (Allocated)localState;
172 if (allocated.getTransaction().equals(tx)) {
173 final boolean success = STATE_UPDATER.compareAndSet(this, localState, idleState);
175 LOG.warn("Transaction {} aborted, but chain {} state already transitioned from {} to {}, very strange",
176 tx, this, localState, state);
183 protected final DOMStoreThreePhaseCommitCohort transactionReady(
184 final SnapshotBackedWriteTransaction<T> tx,
185 final DataTreeModification tree,
186 final Exception readyError) {
188 final State localState = state;
190 if (localState instanceof Allocated) {
191 final Allocated allocated = (Allocated)localState;
192 final DOMStoreWriteTransaction transaction = allocated.getTransaction();
193 Preconditions.checkState(tx.equals(transaction), "Mis-ordered ready transaction %s last allocated was %s", tx, transaction);
194 allocated.setSnapshot(tree);
196 LOG.debug("Ignoring transaction {} readiness due to state {}", tx, localState);
199 return createCohort(tx, tree, readyError);
203 public final void close() {
204 final State localState = state;
207 Preconditions.checkState(!CLOSED.equals(localState), "Transaction chain %s has been closed", this);
209 if (FAILED.equals(localState)) {
210 LOG.debug("Ignoring user close in failed state");
213 } while (!STATE_UPDATER.compareAndSet(this, localState, CLOSED));
217 * Notify the base logic that a previously-submitted transaction has been committed successfully.
219 * @param transaction Transaction which completed successfully.
221 protected final void onTransactionCommited(final SnapshotBackedWriteTransaction<T> transaction) {
222 // If the committed transaction was the one we allocated last,
223 // we clear it and the ready snapshot, so the next transaction
224 // allocated refers to the data tree directly.
225 final State localState = state;
227 if (!(localState instanceof Allocated)) {
228 // This can legally happen if the chain is shut down before the transaction was committed
230 LOG.debug("Ignoring successful transaction {} in state {}", transaction, localState);
234 final Allocated allocated = (Allocated)localState;
235 final DOMStoreWriteTransaction tx = allocated.getTransaction();
236 if (!tx.equals(transaction)) {
237 LOG.debug("Ignoring non-latest successful transaction {} in state {}", transaction, allocated);
241 if (!STATE_UPDATER.compareAndSet(this, localState, idleState)) {
242 LOG.debug("Transaction chain {} has already transitioned from {} to {}, not making it idle", this, localState, state);
247 * Notify the base logic that a previously-submitted transaction has failed.
249 * @param transaction Transaction which failed.
250 * @param cause Failure cause
252 protected final void onTransactionFailed(final SnapshotBackedWriteTransaction<T> transaction, final Throwable cause) {
253 LOG.debug("Transaction chain {} failed on transaction {}", this, transaction, cause);
258 * Return the next transaction identifier.
260 * @return transaction identifier.
262 protected abstract T nextTransactionIdentifier();
265 * Inquire as to whether transactions should record their allocation context.
267 * @return True if allocation context should be recorded.
269 protected abstract boolean getDebugTransactions();
272 * Take a fresh {@link DataTreeSnapshot} from the backend.
274 * @return A new snapshot.
276 protected abstract DataTreeSnapshot takeSnapshot();
279 * Create a cohort for driving the transaction through the commit process.
281 * @param transaction Transaction handle
282 * @param modification {@link DataTreeModification} which needs to be applied to the backend
283 * @param operationError Any previous error that could be reported through three phase commit
284 * @return A {@link DOMStoreThreePhaseCommitCohort} cohort.
286 protected abstract DOMStoreThreePhaseCommitCohort createCohort(final SnapshotBackedWriteTransaction<T> transaction,
287 final DataTreeModification modification,
288 final Exception operationError);