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 static com.google.common.base.Preconditions.checkNotNull;
  11
  12 import com.google.common.base.Optional;
  13 import com.google.common.base.Preconditions;
  14 import com.google.common.util.concurrent.CheckedFuture;
  15 import com.google.common.util.concurrent.Futures;
  16
  17 import org.opendaylight.controller.md.sal.common.api.data.ReadFailedException;
  18 import org.opendaylight.controller.sal.core.spi.data.DOMStoreReadTransaction;
  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  *
  27  * Implementation of read-only transaction backed by {@link DataTreeSnapshot}
  28  *
  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  */
  33 final class SnapshotBackedReadTransaction extends AbstractDOMStoreTransaction
  34                                           implements DOMStoreReadTransaction {
  35
  36     private static final Logger LOG = LoggerFactory.getLogger(SnapshotBackedReadTransaction.class);
  37     private volatile DataTreeSnapshot stableSnapshot;
  38
  39     public SnapshotBackedReadTransaction(final Object identifier, final boolean debug, final DataTreeSnapshot snapshot) {
  40         super(identifier, debug);
  41         this.stableSnapshot = Preconditions.checkNotNull(snapshot);
  42         LOG.debug("ReadOnly Tx: {} allocated with snapshot {}", identifier, snapshot);
  43     }
  44
  45     @Override
  46     public void close() {
  47         LOG.debug("Store transaction: {} : Closed", getIdentifier());
  48         stableSnapshot = null;
  49     }
  50
  51     @Override
  52     public CheckedFuture<Optional<NormalizedNode<?,?>>, ReadFailedException> read(final YangInstanceIdentifier path) {
  53         LOG.debug("Tx: {} Read: {}", getIdentifier(), path);
  54         checkNotNull(path, "Path must not be null.");
  55
  56         final DataTreeSnapshot snapshot = stableSnapshot;
  57         if (snapshot == null) {
  58             return Futures.immediateFailedCheckedFuture(new ReadFailedException("Transaction is closed"));
  59         }
  60
  61         try {
  62             return Futures.immediateCheckedFuture(snapshot.readNode(path));
  63         } catch (Exception e) {
  64             LOG.error("Tx: {} Failed Read of {}", getIdentifier(), path, e);
  65             return Futures.immediateFailedCheckedFuture(new ReadFailedException("Read failed",e));
  66         }
  67     }
  68
  69     @Override
  70     public CheckedFuture<Boolean, ReadFailedException> exists(final YangInstanceIdentifier path) {
  71         LOG.debug("Tx: {} Exists: {}", getIdentifier(), path);
  72         checkNotNull(path, "Path must not be null.");
  73
  74         try {
  75             return Futures.immediateCheckedFuture(
  76                 read(path).checkedGet().isPresent());
  77         } catch (ReadFailedException e) {
  78             return Futures.immediateFailedCheckedFuture(e);
  79         }
  80     }
  81 }