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