--- /dev/null
+/*
+ * Copyright (c) 2014 Cisco Systems, Inc. and others. All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+package org.opendaylight.controller.sal.core.spi.data;
+
+import com.google.common.annotations.Beta;
+import com.google.common.base.Preconditions;
+import java.util.AbstractMap.SimpleEntry;
+import java.util.Map.Entry;
+import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
+import org.opendaylight.controller.sal.core.spi.data.SnapshotBackedWriteTransaction.TransactionReadyPrototype;
+import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeModification;
+import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeSnapshot;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Abstract implementation of the {@link DOMStoreTransactionChain} interface relying on {@link DataTreeSnapshot} supplier
+ * and backend commit coordinator.
+ *
+ * @param <T> transaction identifier type
+ */
+@Beta
+public abstract class AbstractSnapshotBackedTransactionChain<T> extends TransactionReadyPrototype<T> implements DOMStoreTransactionChain {
+ private static abstract class State {
+ /**
+ * Allocate a new snapshot.
+ *
+ * @return A new snapshot
+ */
+ protected abstract DataTreeSnapshot getSnapshot();
+ }
+
+ private static final class Idle extends State {
+ private final AbstractSnapshotBackedTransactionChain<?> chain;
+
+ Idle(final AbstractSnapshotBackedTransactionChain<?> chain) {
+ this.chain = Preconditions.checkNotNull(chain);
+ }
+
+ @Override
+ protected DataTreeSnapshot getSnapshot() {
+ return chain.takeSnapshot();
+ }
+ }
+
+ /**
+ * We have a transaction out there.
+ */
+ private static final class Allocated extends State {
+ private static final AtomicReferenceFieldUpdater<Allocated, DataTreeSnapshot> SNAPSHOT_UPDATER =
+ AtomicReferenceFieldUpdater.newUpdater(Allocated.class, DataTreeSnapshot.class, "snapshot");
+ private final DOMStoreWriteTransaction transaction;
+ private volatile DataTreeSnapshot snapshot;
+
+ Allocated(final DOMStoreWriteTransaction transaction) {
+ this.transaction = Preconditions.checkNotNull(transaction);
+ }
+
+ public DOMStoreWriteTransaction getTransaction() {
+ return transaction;
+ }
+
+ @Override
+ protected DataTreeSnapshot getSnapshot() {
+ final DataTreeSnapshot ret = snapshot;
+ Preconditions.checkState(ret != null, "Previous transaction %s is not ready yet", transaction.getIdentifier());
+ return ret;
+ }
+
+ void setSnapshot(final DataTreeSnapshot snapshot) {
+ final boolean success = SNAPSHOT_UPDATER.compareAndSet(this, null, snapshot);
+ Preconditions.checkState(success, "Transaction %s has already been marked as ready", transaction.getIdentifier());
+ }
+ }
+
+ /**
+ * Chain is logically shut down, no further allocation allowed.
+ */
+ private static final class Shutdown extends State {
+ private final String message;
+
+ Shutdown(final String message) {
+ this.message = Preconditions.checkNotNull(message);
+ }
+
+ @Override
+ protected DataTreeSnapshot getSnapshot() {
+ throw new IllegalStateException(message);
+ }
+ }
+
+ @SuppressWarnings("rawtypes")
+ private static final AtomicReferenceFieldUpdater<AbstractSnapshotBackedTransactionChain, State> STATE_UPDATER =
+ AtomicReferenceFieldUpdater.newUpdater(AbstractSnapshotBackedTransactionChain.class, State.class, "state");
+ private static final Logger LOG = LoggerFactory.getLogger(AbstractSnapshotBackedTransactionChain.class);
+ private static final Shutdown CLOSED = new Shutdown("Transaction chain is closed");
+ private static final Shutdown FAILED = new Shutdown("Transaction chain has failed");
+ private final Idle idleState;
+ private volatile State state;
+
+ protected AbstractSnapshotBackedTransactionChain() {
+ idleState = new Idle(this);
+ state = idleState;
+ }
+
+ private Entry<State, DataTreeSnapshot> getSnapshot() {
+ final State localState = state;
+ return new SimpleEntry<>(localState, localState.getSnapshot());
+ }
+
+ private boolean recordTransaction(final State expected, final DOMStoreWriteTransaction transaction) {
+ final State state = new Allocated(transaction);
+ return STATE_UPDATER.compareAndSet(this, expected, state);
+ }
+
+ @Override
+ public final DOMStoreReadTransaction newReadOnlyTransaction() {
+ final Entry<State, DataTreeSnapshot> entry = getSnapshot();
+ return SnapshotBackedTransactions.newReadTransaction(nextTransactionIdentifier(), getDebugTransactions(), entry.getValue());
+ }
+
+ @Override
+ public final DOMStoreReadWriteTransaction newReadWriteTransaction() {
+ Entry<State, DataTreeSnapshot> entry;
+ DOMStoreReadWriteTransaction ret;
+
+ do {
+ entry = getSnapshot();
+ ret = new SnapshotBackedReadWriteTransaction<T>(nextTransactionIdentifier(),
+ getDebugTransactions(), entry.getValue(), this);
+ } while (!recordTransaction(entry.getKey(), ret));
+
+ return ret;
+ }
+
+ @Override
+ public final DOMStoreWriteTransaction newWriteOnlyTransaction() {
+ Entry<State, DataTreeSnapshot> entry;
+ DOMStoreWriteTransaction ret;
+
+ do {
+ entry = getSnapshot();
+ ret = new SnapshotBackedWriteTransaction<T>(nextTransactionIdentifier(),
+ getDebugTransactions(), entry.getValue(), this);
+ } while (!recordTransaction(entry.getKey(), ret));
+
+ return ret;
+ }
+
+ @Override
+ protected final void transactionAborted(final SnapshotBackedWriteTransaction<T> tx) {
+ final State localState = state;
+ if (localState instanceof Allocated) {
+ final Allocated allocated = (Allocated)localState;
+ if (allocated.getTransaction().equals(tx)) {
+ final boolean success = STATE_UPDATER.compareAndSet(this, localState, idleState);
+ if (!success) {
+ LOG.warn("Transaction {} aborted, but chain {} state already transitioned from {} to {}, very strange",
+ tx, this, localState, state);
+ }
+ }
+ }
+ }
+
+ @Override
+ protected final DOMStoreThreePhaseCommitCohort transactionReady(final SnapshotBackedWriteTransaction<T> tx, final DataTreeModification tree) {
+ final State localState = state;
+
+ if (localState instanceof Allocated) {
+ final Allocated allocated = (Allocated)localState;
+ final DOMStoreWriteTransaction transaction = allocated.getTransaction();
+ Preconditions.checkState(tx.equals(transaction), "Mis-ordered ready transaction %s last allocated was %s", tx, transaction);
+ allocated.setSnapshot(tree);
+ } else {
+ LOG.debug("Ignoring transaction {} readiness due to state {}", tx, localState);
+ }
+
+ return createCohort(tx, tree);
+ }
+
+ @Override
+ public final void close() {
+ final State localState = state;
+
+ do {
+ Preconditions.checkState(!CLOSED.equals(localState), "Transaction chain {} has been closed", this);
+
+ if (FAILED.equals(localState)) {
+ LOG.debug("Ignoring user close in failed state");
+ return;
+ }
+ } while (!STATE_UPDATER.compareAndSet(this, localState, CLOSED));
+ }
+
+ /**
+ * Notify the base logic that a previously-submitted transaction has been committed successfully.
+ *
+ * @param transaction Transaction which completed successfully.
+ */
+ protected final void onTransactionCommited(final SnapshotBackedWriteTransaction<T> transaction) {
+ // If the committed transaction was the one we allocated last,
+ // we clear it and the ready snapshot, so the next transaction
+ // allocated refers to the data tree directly.
+ final State localState = state;
+
+ if (!(localState instanceof Allocated)) {
+ // This can legally happen if the chain is shut down before the transaction was committed
+ // by the backend.
+ LOG.debug("Ignoring successful transaction {} in state {}", transaction, localState);
+ return;
+ }
+
+ final Allocated allocated = (Allocated)localState;
+ final DOMStoreWriteTransaction tx = allocated.getTransaction();
+ if (!tx.equals(transaction)) {
+ LOG.debug("Ignoring non-latest successful transaction {} in state {}", transaction, allocated);
+ return;
+ }
+
+ if (!STATE_UPDATER.compareAndSet(this, localState, idleState)) {
+ LOG.debug("Transaction chain {} has already transitioned from {} to {}, not making it idle", this, localState, state);
+ }
+ }
+
+ /**
+ * Notify the base logic that a previously-submitted transaction has failed.
+ *
+ * @param transaction Transaction which failed.
+ * @param cause Failure cause
+ */
+ protected final void onTransactionFailed(final SnapshotBackedWriteTransaction<T> transaction, final Throwable cause) {
+ LOG.debug("Transaction chain {} failed on transaction {}", this, transaction, cause);
+ state = FAILED;
+ }
+
+ /**
+ * Return the next transaction identifier.
+ *
+ * @return transaction identifier.
+ */
+ protected abstract T nextTransactionIdentifier();
+
+ /**
+ * Inquire as to whether transactions should record their allocation context.
+ *
+ * @return True if allocation context should be recorded.
+ */
+ protected abstract boolean getDebugTransactions();
+
+ /**
+ * Take a fresh {@link DataTreeSnapshot} from the backend.
+ *
+ * @return A new snapshot.
+ */
+ protected abstract DataTreeSnapshot takeSnapshot();
+
+ /**
+ * Create a cohort for driving the transaction through the commit process.
+ *
+ * @param transaction Transaction handle
+ * @param modification {@link DataTreeModification} which needs to be applied to the backend
+ * @return A {@link DOMStoreThreePhaseCommitCohort} cohort.
+ */
+ protected abstract DOMStoreThreePhaseCommitCohort createCohort(final SnapshotBackedWriteTransaction<T> transaction, final DataTreeModification modification);
+}
Code Review / controller.git / blobdiff