dom/mdsal-dom-broker/src/main/java/org/opendaylight/mdsal/dom/broker/DOMForwardedWriteTransaction.java

   1 /*
   2  * Copyright (c) 2014 Cisco Systems, Inc. and others.  All rights reserved.
   3  *
   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
   7  */
   8 package org.opendaylight.mdsal.dom.broker;
   9
  10 import com.google.common.base.Preconditions;
  11 import com.google.common.util.concurrent.CheckedFuture;
  12 import com.google.common.util.concurrent.Futures;
  13 import java.util.ArrayList;
  14 import java.util.Collection;
  15 import java.util.Map;
  16 import java.util.concurrent.Future;
  17 import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
  18 import org.opendaylight.mdsal.common.api.LogicalDatastoreType;
  19 import org.opendaylight.mdsal.common.api.TransactionCommitFailedException;
  20 import org.opendaylight.mdsal.dom.api.DOMDataTreeWriteTransaction;
  21 import org.opendaylight.mdsal.dom.spi.store.DOMStoreThreePhaseCommitCohort;
  22 import org.opendaylight.mdsal.dom.spi.store.DOMStoreWriteTransaction;
  23 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
  24 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
  25 import org.slf4j.Logger;
  26 import org.slf4j.LoggerFactory;
  27
  28 /**
  29  * Read-Write Transaction, which is composed of several
  30  * {@link DOMStoreWriteTransaction} transactions. A sub-transaction is selected by
  31  * {@link LogicalDatastoreType} type parameter in:
  32  *
  33  * <ul>
  34  * <li>{@link #put(LogicalDatastoreType, YangInstanceIdentifier, NormalizedNode)}
  35  * <li>{@link #delete(LogicalDatastoreType, YangInstanceIdentifier)}
  36  * <li>{@link #merge(LogicalDatastoreType, YangInstanceIdentifier, NormalizedNode)}
  37  * </ul>
  38  *
  39  * <p>
  40  * {@link #submit()} will result in invocation of
  41  * {@link DOMDataCommitImplementation#submit(org.opendaylight.mdsal.dom.api.DOMDataTreeWriteTransaction, Iterable)}
  42  * invocation with all
  43  * {@link org.opendaylight.mdsal.dom.spi.store.DOMStoreThreePhaseCommitCohort} for
  44  * underlying transactions.
  45  *
  46  * @param <T> Subtype of {@link DOMStoreWriteTransaction} which is used as subtransaction.
  47  */
  48 class DOMForwardedWriteTransaction<T extends DOMStoreWriteTransaction> extends
  49         AbstractDOMForwardedCompositeTransaction<LogicalDatastoreType, T> implements DOMDataTreeWriteTransaction {
  50     @SuppressWarnings("rawtypes")
  51     private static final AtomicReferenceFieldUpdater<DOMForwardedWriteTransaction,
  52         AbstractDOMForwardedTransactionFactory> IMPL_UPDATER = AtomicReferenceFieldUpdater.newUpdater(
  53                 DOMForwardedWriteTransaction.class, AbstractDOMForwardedTransactionFactory.class, "commitImpl");
  54     @SuppressWarnings("rawtypes")
  55     private static final AtomicReferenceFieldUpdater<DOMForwardedWriteTransaction, Future> FUTURE_UPDATER =
  56             AtomicReferenceFieldUpdater.newUpdater(DOMForwardedWriteTransaction.class, Future.class, "commitFuture");
  57     private static final Logger LOG = LoggerFactory.getLogger(DOMForwardedWriteTransaction.class);
  58     private static final Future<?> CANCELLED_FUTURE = Futures.immediateCancelledFuture();
  59
  60     /**
  61      * Implementation of real commit. It also acts as an indication that
  62      * the transaction is running -- which we flip atomically using
  63      * {@link #IMPL_UPDATER}.
  64      */
  65     private volatile AbstractDOMForwardedTransactionFactory<?> commitImpl;
  66
  67     /**
  68      * Future task of transaction commit. It starts off as null, but is
  69      * set appropriately on {@link #submit()} and {@link #cancel()} via
  70      * {@link AtomicReferenceFieldUpdater#lazySet(Object, Object)}.
  71      *
  72      *<p>
  73      * Lazy set is safe for use because it is only referenced to in the
  74      * {@link #cancel()} slow path, where we will busy-wait for it. The
  75      * fast path gets the benefit of a store-store barrier instead of the
  76      * usual store-load barrier.
  77      */
  78     private volatile Future<?> commitFuture;
  79
  80     protected DOMForwardedWriteTransaction(final Object identifier,
  81             final Map<LogicalDatastoreType, T> backingTxs, final AbstractDOMForwardedTransactionFactory<?> commitImpl) {
  82         super(identifier, backingTxs);
  83         this.commitImpl = Preconditions.checkNotNull(commitImpl, "commitImpl must not be null.");
  84     }
  85
  86     @Override
  87     public void put(final LogicalDatastoreType store, final YangInstanceIdentifier path,
  88             final NormalizedNode<?, ?> data) {
  89         checkRunning(commitImpl);
  90         getSubtransaction(store).write(path, data);
  91     }
  92
  93     @Override
  94     public void delete(final LogicalDatastoreType store, final YangInstanceIdentifier path) {
  95         checkRunning(commitImpl);
  96         getSubtransaction(store).delete(path);
  97     }
  98
  99     @Override
 100     public void merge(final LogicalDatastoreType store, final YangInstanceIdentifier path,
 101             final NormalizedNode<?, ?> data) {
 102         checkRunning(commitImpl);
 103         getSubtransaction(store).merge(path, data);
 104     }
 105
 106     @Override
 107     public boolean cancel() {
 108         final AbstractDOMForwardedTransactionFactory<?> impl = IMPL_UPDATER.getAndSet(this, null);
 109         if (impl != null) {
 110             LOG.trace("Transaction {} cancelled before submit", getIdentifier());
 111             FUTURE_UPDATER.lazySet(this, CANCELLED_FUTURE);
 112             closeSubtransactions();
 113             return true;
 114         }
 115
 116         // The transaction is in process of being submitted or cancelled. Busy-wait
 117         // for the corresponding future.
 118         Future<?> future;
 119         do {
 120             future = commitFuture;
 121         } while (future == null);
 122
 123         return future.cancel(false);
 124     }
 125
 126     @Override
 127     public CheckedFuture<Void, TransactionCommitFailedException> submit() {
 128         final AbstractDOMForwardedTransactionFactory<?> impl = IMPL_UPDATER.getAndSet(this, null);
 129         checkRunning(impl);
 130
 131         final Collection<T> txns = getSubtransactions();
 132         final Collection<DOMStoreThreePhaseCommitCohort> cohorts = new ArrayList<>(txns.size());
 133
 134         // FIXME: deal with errors thrown by backed (ready and submit can fail in theory)
 135         for (final DOMStoreWriteTransaction txn : txns) {
 136             cohorts.add(txn.ready());
 137         }
 138
 139         final CheckedFuture<Void, TransactionCommitFailedException> ret = impl.submit(this, cohorts);
 140         FUTURE_UPDATER.lazySet(this, ret);
 141         return ret;
 142     }
 143
 144     private void checkRunning(final AbstractDOMForwardedTransactionFactory<?> impl) {
 145         Preconditions.checkState(impl != null, "Transaction %s is no longer running", getIdentifier());
 146     }
 147 }