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