+++ /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.md.sal.dom.broker.impl;
-
-import com.google.common.base.Optional;
-import com.google.common.base.Preconditions;
-import com.google.common.util.concurrent.CheckedFuture;
-import com.google.common.util.concurrent.FutureCallback;
-import com.google.common.util.concurrent.Futures;
-import com.google.common.util.concurrent.ListenableFuture;
-import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
-import javax.annotation.Nonnull;
-import javax.annotation.concurrent.GuardedBy;
-import org.opendaylight.controller.md.sal.common.api.TransactionStatus;
-import org.opendaylight.controller.md.sal.common.api.data.AsyncTransaction;
-import org.opendaylight.controller.md.sal.common.api.data.LogicalDatastoreType;
-import org.opendaylight.controller.md.sal.common.api.data.ReadFailedException;
-import org.opendaylight.controller.md.sal.common.api.data.TransactionChain;
-import org.opendaylight.controller.md.sal.common.api.data.TransactionChainListener;
-import org.opendaylight.controller.md.sal.common.api.data.TransactionCommitFailedException;
-import org.opendaylight.controller.md.sal.dom.api.DOMDataBroker;
-import org.opendaylight.controller.md.sal.dom.api.DOMDataReadOnlyTransaction;
-import org.opendaylight.controller.md.sal.dom.api.DOMDataReadWriteTransaction;
-import org.opendaylight.controller.md.sal.dom.api.DOMDataWriteTransaction;
-import org.opendaylight.controller.md.sal.dom.api.DOMTransactionChain;
-import org.opendaylight.controller.md.sal.dom.spi.ForwardingDOMDataReadWriteTransaction;
-import org.opendaylight.yangtools.yang.common.RpcResult;
-import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
-import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
-import org.slf4j.Logger;
-import org.slf4j.LoggerFactory;
-
-/**
- * An implementation of {@link DOMTransactionChain}, which has a very specific
- * behavior, which some users may find surprising. If keeps the general
- * intent of the contract, but it makes sure there are never more than two
- * transactions allocated at any given time: one of them is being committed,
- * and while that is happening, the other one acts as the scratch pad. Once
- * the committing transaction completes successfully, the scratch transaction
- * is enqueued as soon as it is ready.
- *
- * This mode of operation means that there is no inherent isolation between
- * the front-end transactions and transactions cannot be reasonably cancelled.
- *
- * It furthermore means that the transactions returned by {@link #newReadOnlyTransaction()}
- * counts as an outstanding transaction and the user may not allocate multiple
- * read-only transactions at the same time.
- */
-public final class PingPongTransactionChain implements DOMTransactionChain {
- private static final Logger LOG = LoggerFactory.getLogger(PingPongTransactionChain.class);
- private final DOMTransactionChain delegate;
-
- @GuardedBy("this")
- private boolean failed;
-
- /**
- * This updater is used to manipulate the "ready" transaction. We perform only atomic
- * get-and-set on it.
- */
- private static final AtomicReferenceFieldUpdater<PingPongTransactionChain, PingPongTransaction> READY_UPDATER =
- AtomicReferenceFieldUpdater.newUpdater(PingPongTransactionChain.class, PingPongTransaction.class, "readyTx");
- private volatile PingPongTransaction readyTx;
-
- /**
- * This updater is used to manipulate the "locked" transaction. A locked transaction
- * means we know that the user still holds a transaction and should at some point call
- * us. We perform on compare-and-swap to ensure we properly detect when a user is
- * attempting to allocated multiple transactions concurrently.
- */
- private static final AtomicReferenceFieldUpdater<PingPongTransactionChain, PingPongTransaction> LOCKED_UPDATER =
- AtomicReferenceFieldUpdater.newUpdater(PingPongTransactionChain.class, PingPongTransaction.class, "lockedTx");
- private volatile PingPongTransaction lockedTx;
-
- /**
- * This updater is used to manipulate the "inflight" transaction. There can be at most
- * one of these at any given time. We perform only compare-and-swap on these.
- */
- private static final AtomicReferenceFieldUpdater<PingPongTransactionChain, PingPongTransaction> INFLIGHT_UPDATER =
- AtomicReferenceFieldUpdater.newUpdater(PingPongTransactionChain.class, PingPongTransaction.class, "inflightTx");
- private volatile PingPongTransaction inflightTx;
-
- PingPongTransactionChain(final DOMDataBroker broker, final TransactionChainListener listener) {
- this.delegate = broker.createTransactionChain(new TransactionChainListener() {
- @Override
- public void onTransactionChainFailed(final TransactionChain<?, ?> chain, final AsyncTransaction<?, ?> transaction, final Throwable cause) {
- LOG.debug("Delegate chain {} reported failure in {}", chain, transaction, cause);
-
- final DOMDataReadWriteTransaction frontend;
- final PingPongTransaction tx = inflightTx;
- if (tx == null) {
- LOG.warn("Transaction chain {} failed with no pending transactions", chain);
- frontend = null;
- } else {
- frontend = tx.getFrontendTransaction();
- }
-
- listener.onTransactionChainFailed(PingPongTransactionChain.this, frontend, cause);
- delegateFailed();
- }
-
- @Override
- public void onTransactionChainSuccessful(final TransactionChain<?, ?> chain) {
- listener.onTransactionChainSuccessful(PingPongTransactionChain.this);
- }
- });
- }
-
- private synchronized void delegateFailed() {
- failed = true;
-
- /*
- * If we do not have a locked transaction, we need to ensure that
- * the backend transaction is cancelled. Otherwise we can defer
- * until the user calls us.
- */
- if (lockedTx == null) {
- processIfReady();
- }
- }
-
- private synchronized PingPongTransaction slowAllocateTransaction() {
- final DOMDataReadWriteTransaction delegateTx = delegate.newReadWriteTransaction();
- final PingPongTransaction newTx = new PingPongTransaction(delegateTx);
-
- if (!LOCKED_UPDATER.compareAndSet(this, null, newTx)) {
- delegateTx.cancel();
- throw new IllegalStateException(String.format("New transaction %s raced with transacion %s", newTx, lockedTx));
- }
-
- return newTx;
- }
-
- private PingPongTransaction allocateTransaction() {
- // Step 1: acquire current state
- final PingPongTransaction oldTx = READY_UPDATER.getAndSet(this, null);
-
- // Slow path: allocate a delegate transaction
- if (oldTx == null) {
- return slowAllocateTransaction();
- }
-
- // Fast path: reuse current transaction. We will check
- // failures and similar on submit().
- if (!LOCKED_UPDATER.compareAndSet(this, null, oldTx)) {
- // Ouch. Delegate chain has not detected a duplicate
- // transaction allocation. This is the best we can do.
- oldTx.getTransaction().cancel();
- throw new IllegalStateException(String.format("Reusable transaction %s raced with transaction %s", oldTx, lockedTx));
- }
-
- return oldTx;
- }
-
- /*
- * This forces allocateTransaction() on a slow path, which has to happen after
- * this method has completed executing.
- */
- @GuardedBy("this")
- private void processIfReady() {
- final PingPongTransaction tx = READY_UPDATER.getAndSet(this, null);
- if (tx != null) {
- processTransaction(tx);
- }
- }
-
- /**
- * Process a ready transaction. The caller needs to ensure that
- * each transaction is seen only once by this method.
- *
- * @param tx Transaction which needs processing.
- */
- @GuardedBy("this")
- private void processTransaction(final @Nonnull PingPongTransaction tx) {
- if (failed) {
- LOG.debug("Cancelling transaction {}", tx);
- tx.getTransaction().cancel();
- return;
- }
-
- LOG.debug("Submitting transaction {}", tx);
- if (!INFLIGHT_UPDATER.compareAndSet(this, null, tx)) {
- LOG.warn("Submitting transaction {} while {} is still running", tx, inflightTx);
- }
-
- Futures.addCallback(tx.getTransaction().submit(), new FutureCallback<Void>() {
- @Override
- public void onSuccess(final Void result) {
- transactionSuccessful(tx, result);
- }
-
- @Override
- public void onFailure(final Throwable t) {
- transactionFailed(tx, t);
- }
- });
- }
-
- private void transactionSuccessful(final PingPongTransaction tx, final Void result) {
- LOG.debug("Transaction {} completed successfully", tx);
-
- final boolean success = INFLIGHT_UPDATER.compareAndSet(this, tx, null);
- Preconditions.checkState(success, "Successful transaction %s while %s was submitted", tx, inflightTx);
-
- synchronized (this) {
- processIfReady();
- }
-
- // Can run unsynchronized
- tx.onSuccess(result);
- }
-
- private void transactionFailed(final PingPongTransaction tx, final Throwable t) {
- LOG.debug("Transaction {} failed", tx, t);
-
- final boolean success = INFLIGHT_UPDATER.compareAndSet(this, tx, null);
- Preconditions.checkState(success, "Failed transaction %s while %s was submitted", tx, inflightTx);
-
- tx.onFailure(t);
- }
-
- private void readyTransaction(final @Nonnull PingPongTransaction tx) {
- // First mark the transaction as not locked.
- final boolean lockedMatch = LOCKED_UPDATER.compareAndSet(this, tx, null);
- Preconditions.checkState(lockedMatch, "Attempted to submit transaction %s while we have %s", tx, lockedTx);
- LOG.debug("Transaction {} unlocked", tx);
-
- /*
- * The transaction is ready. It will then be picked up by either next allocation,
- * or a background transaction completion callback.
- */
- final boolean success = READY_UPDATER.compareAndSet(this, null, tx);
- Preconditions.checkState(success, "Transaction %s collided on ready state", tx, readyTx);
- LOG.debug("Transaction {} readied", tx);
-
- /*
- * We do not see a transaction being in-flight, so we need to take care of dispatching
- * the transaction to the backend. We are in the ready case, we cannot short-cut
- * the checking of readyTx, as an in-flight transaction may have completed between us
- * setting the field above and us checking.
- */
- if (inflightTx == null) {
- synchronized (this) {
- processIfReady();
- }
- }
- }
-
- @Override
- public void close() {
- final PingPongTransaction notLocked = lockedTx;
- Preconditions.checkState(notLocked == null, "Attempted to close chain with outstanding transaction %s", notLocked);
-
- synchronized (this) {
- processIfReady();
- delegate.close();
- }
- }
-
- @Override
- public DOMDataReadOnlyTransaction newReadOnlyTransaction() {
- final PingPongTransaction tx = allocateTransaction();
-
- return new DOMDataReadOnlyTransaction() {
- @Override
- public CheckedFuture<Optional<NormalizedNode<?, ?>>, ReadFailedException> read(final LogicalDatastoreType store,
- final YangInstanceIdentifier path) {
- return tx.getTransaction().read(store, path);
- }
-
- @Override
- public CheckedFuture<Boolean, ReadFailedException> exists(final LogicalDatastoreType store,
- final YangInstanceIdentifier path) {
- return tx.getTransaction().exists(store, path);
- }
-
- @Override
- public Object getIdentifier() {
- return tx.getTransaction().getIdentifier();
- }
-
- @Override
- public void close() {
- readyTransaction(tx);
- }
- };
- }
-
- @Override
- public DOMDataReadWriteTransaction newReadWriteTransaction() {
- final PingPongTransaction tx = allocateTransaction();
- final DOMDataReadWriteTransaction ret = new ForwardingDOMDataReadWriteTransaction() {
- @Override
- protected DOMDataReadWriteTransaction delegate() {
- return tx.getTransaction();
- }
-
- @Override
- public CheckedFuture<Void, TransactionCommitFailedException> submit() {
- readyTransaction(tx);
- return tx.getSubmitFuture();
- }
-
- @Override
- public ListenableFuture<RpcResult<TransactionStatus>> commit() {
- readyTransaction(tx);
- return tx.getCommitFuture();
- }
-
- @Override
- public boolean cancel() {
- throw new UnsupportedOperationException("Transaction cancellation is not supported");
- }
- };
-
- tx.recordFrontendTransaction(ret);
- return ret;
- }
-
- @Override
- public DOMDataWriteTransaction newWriteOnlyTransaction() {
- return newReadWriteTransaction();
- }
-}
Code Review / controller.git / blobdiff