opendaylight/md-sal/sal-dom-spi/src/main/java/org/opendaylight/controller/sal/core/spi/data/SnapshotBackedReadTransaction.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.controller.sal.core.spi.data;
   9
  10 import static com.google.common.base.Preconditions.checkNotNull;
  11
  12 import com.google.common.annotations.Beta;
  13 import com.google.common.base.Optional;
  14 import com.google.common.base.Preconditions;
  15 import com.google.common.util.concurrent.CheckedFuture;
  16 import com.google.common.util.concurrent.Futures;
  17 import java.util.concurrent.atomic.AtomicReferenceFieldUpdater;
  18 import org.opendaylight.controller.md.sal.common.api.data.ReadFailedException;
  19 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
  20 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
  21 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeSnapshot;
  22 import org.slf4j.Logger;
  23 import org.slf4j.LoggerFactory;
  24
  25 /**
  26  * Implementation of read-only transaction backed by {@link DataTreeSnapshot}.
  27  *
  28  * <p>
  29  * Implementation of read-only transaction backed by {@link DataTreeSnapshot}
  30  * which delegates most of its calls to similar methods provided by underlying snapshot.
  31  *
  32  * @param <T> identifier type
  33  *
  34  * @deprecated Use {@link org.opendaylight.mdsal.dom.spi.store.SnapshotBackedReadTransaction} instead.
  35  */
  36 @Deprecated
  37 @Beta
  38 public final class SnapshotBackedReadTransaction<T> extends AbstractDOMStoreTransaction<T>
  39         implements DOMStoreReadTransaction {
  40     private static final Logger LOG = LoggerFactory.getLogger(SnapshotBackedReadTransaction.class);
  41
  42     @SuppressWarnings("rawtypes")
  43     private static final AtomicReferenceFieldUpdater<SnapshotBackedReadTransaction, DataTreeSnapshot> SNAPSHOT_UPDATER =
  44             AtomicReferenceFieldUpdater.newUpdater(SnapshotBackedReadTransaction.class, DataTreeSnapshot.class,
  45                 "stableSnapshot");
  46
  47     // Guarded by stableSnapshot CAS, hence it does not need to be volatile
  48     private TransactionClosePrototype<T> closeImpl;
  49     private volatile DataTreeSnapshot stableSnapshot;
  50
  51     /**
  52      * Creates a new read-only transaction.
  53      *
  54      * @param identifier Transaction Identifier
  55      * @param debug Enable transaction debugging
  56      * @param snapshot Snapshot which will be modified.
  57      */
  58     SnapshotBackedReadTransaction(final T identifier, final boolean debug, final DataTreeSnapshot snapshot,
  59             final TransactionClosePrototype<T> closeImpl) {
  60         super(identifier, debug);
  61         this.stableSnapshot = Preconditions.checkNotNull(snapshot);
  62         this.closeImpl = closeImpl;
  63         LOG.debug("ReadOnly Tx: {} allocated with snapshot {}", identifier, snapshot);
  64     }
  65
  66     @Override
  67     public void close() {
  68         final DataTreeSnapshot prev = SNAPSHOT_UPDATER.getAndSet(this, null);
  69         if (prev == null) {
  70             LOG.debug("Store transaction: {} : previously closed", getIdentifier());
  71             return;
  72         }
  73
  74         LOG.debug("Store transaction: {} : Closed", getIdentifier());
  75         if (closeImpl != null) {
  76             closeImpl.transactionClosed(this);
  77             closeImpl = null;
  78         }
  79     }
  80
  81     @Override
  82     @SuppressWarnings("checkstyle:IllegalCatch")
  83     public CheckedFuture<Optional<NormalizedNode<?,?>>, ReadFailedException> read(final YangInstanceIdentifier path) {
  84         LOG.debug("Tx: {} Read: {}", getIdentifier(), path);
  85         checkNotNull(path, "Path must not be null.");
  86
  87         final DataTreeSnapshot snapshot = stableSnapshot;
  88         if (snapshot == null) {
  89             return Futures.immediateFailedCheckedFuture(new ReadFailedException("Transaction is closed"));
  90         }
  91
  92         try {
  93             return Futures.immediateCheckedFuture(Optional.fromJavaUtil(snapshot.readNode(path)));
  94         } catch (RuntimeException e) {
  95             LOG.error("Tx: {} Failed Read of {}", getIdentifier(), path, e);
  96             return Futures.immediateFailedCheckedFuture(new ReadFailedException("Read failed",e));
  97         }
  98     }
  99
 100     @Override
 101     public CheckedFuture<Boolean, ReadFailedException> exists(final YangInstanceIdentifier path) {
 102         LOG.debug("Tx: {} Exists: {}", getIdentifier(), path);
 103         checkNotNull(path, "Path must not be null.");
 104
 105         try {
 106             return Futures.immediateCheckedFuture(read(path).checkedGet().isPresent());
 107         } catch (ReadFailedException e) {
 108             return Futures.immediateFailedCheckedFuture(e);
 109         }
 110     }
 111
 112     /**
 113      * Prototype implementation of {@link SnapshotBackedReadTransaction#close()}.
 114      *
 115      * <p>
 116      * This class is intended to be implemented by Transaction factories responsible for allocation
 117      * of {@link org.opendaylight.mdsal.dom.spi.store.SnapshotBackedReadTransaction} and
 118      * providing underlying logic for applying implementation.
 119      *
 120      * @param <T> identifier type
 121      */
 122     public interface TransactionClosePrototype<T> {
 123         /**
 124          * Called when a transaction is closed. This is not invoked at most once for every transaction.
 125          *
 126          * @param tx Transaction which got closed.
 127          */
 128         void transactionClosed(SnapshotBackedReadTransaction<T> tx);
 129     }
 130 }