opendaylight/md-sal/sal-inmemory-datastore/src/main/java/org/opendaylight/controller/md/sal/dom/store/impl/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.md.sal.dom.store.impl;
   9
  10 import com.google.common.base.Optional;
  11 import com.google.common.base.Preconditions;
  12 import com.google.common.util.concurrent.CheckedFuture;
  13 import com.google.common.util.concurrent.Futures;
  14 import org.opendaylight.controller.md.sal.common.api.data.ReadFailedException;
  15 import org.opendaylight.controller.sal.core.spi.data.DOMStoreReadTransaction;
  16 import org.opendaylight.yangtools.yang.data.api.YangInstanceIdentifier;
  17 import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
  18 import org.opendaylight.yangtools.yang.data.api.schema.tree.DataTreeSnapshot;
  19 import org.slf4j.Logger;
  20 import org.slf4j.LoggerFactory;
  21
  22 import static com.google.common.base.Preconditions.checkNotNull;
  23
  24 /**
  25  *
  26  * Implementation of read-only transaction backed by {@link DataTreeSnapshot}
  27  *
  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  */
  32 final class SnapshotBackedReadTransaction extends AbstractDOMStoreTransaction
  33                                           implements DOMStoreReadTransaction {
  34
  35     private static final Logger LOG = LoggerFactory.getLogger(SnapshotBackedReadTransaction.class);
  36     private volatile DataTreeSnapshot stableSnapshot;
  37
  38     public SnapshotBackedReadTransaction(final Object identifier, final DataTreeSnapshot snapshot) {
  39         super(identifier);
  40         this.stableSnapshot = Preconditions.checkNotNull(snapshot);
  41         LOG.debug("ReadOnly Tx: {} allocated with snapshot {}", identifier, snapshot);
  42     }
  43
  44     @Override
  45     public void close() {
  46         LOG.debug("Store transaction: {} : Closed", getIdentifier());
  47         stableSnapshot = null;
  48     }
  49
  50     @Override
  51     public CheckedFuture<Optional<NormalizedNode<?,?>>, ReadFailedException> read(final YangInstanceIdentifier path) {
  52         LOG.debug("Tx: {} Read: {}", getIdentifier(), path);
  53         checkNotNull(path, "Path must not be null.");
  54
  55         final DataTreeSnapshot snapshot = stableSnapshot;
  56         if (snapshot == null) {
  57             return Futures.immediateFailedCheckedFuture(new ReadFailedException("Transaction is closed"));
  58         }
  59
  60         try {
  61             return Futures.immediateCheckedFuture(snapshot.readNode(path));
  62         } catch (Exception e) {
  63             LOG.error("Tx: {} Failed Read of {}", getIdentifier(), path, e);
  64             return Futures.immediateFailedCheckedFuture(new ReadFailedException("Read failed",e));
  65         }
  66     }
  67
  68     @Override
  69     public CheckedFuture<Boolean, ReadFailedException> exists(YangInstanceIdentifier path) {
  70         LOG.debug("Tx: {} Exists: {}", getIdentifier(), path);
  71         checkNotNull(path, "Path must not be null.");
  72
  73         try {
  74             return Futures.immediateCheckedFuture(
  75                 read(path).checkedGet().isPresent());
  76         } catch (ReadFailedException e) {
  77             return Futures.immediateFailedCheckedFuture(e);
  78         }
  79     }
  80 }