opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/databroker/ClientBackedTransaction.java

   1 /*
   2  * Copyright (c) 2016 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.cluster.databroker;
   9
  10 import com.google.common.base.FinalizablePhantomReference;
  11 import com.google.common.base.FinalizableReferenceQueue;
  12 import com.google.common.base.Preconditions;
  13 import java.util.Set;
  14 import java.util.concurrent.ConcurrentHashMap;
  15 import javax.annotation.Nonnull;
  16 import javax.annotation.Nullable;
  17 import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
  18 import org.opendaylight.controller.cluster.databroker.actors.dds.AbstractClientHandle;
  19 import org.opendaylight.controller.cluster.databroker.actors.dds.ClientTransaction;
  20 import org.opendaylight.controller.sal.core.spi.data.AbstractDOMStoreTransaction;
  21 import org.slf4j.Logger;
  22 import org.slf4j.LoggerFactory;
  23
  24 /**
  25  * An implementation of {@link DOMStoreTransaction} backed by a {@link ClientTransaction}. It guards against user-level
  26  * leaks by maintaining a phantom reference on the backing transaction, which will ensure that the transaction will
  27  * be aborted, if it is not otherwise closed, just before this object is garbage-collected.
  28  *
  29  * @author Robert Varga
  30  */
  31 abstract class ClientBackedTransaction<T extends AbstractClientHandle<?>> extends
  32         AbstractDOMStoreTransaction<TransactionIdentifier> {
  33     private static final class Finalizer extends FinalizablePhantomReference<ClientBackedTransaction<?>> {
  34         private static final FinalizableReferenceQueue QUEUE = new FinalizableReferenceQueue();
  35         private static final Set<Finalizer> FINALIZERS = ConcurrentHashMap.newKeySet();
  36         private static final Logger LOG = LoggerFactory.getLogger(Finalizer.class);
  37
  38         private final AbstractClientHandle<?> transaction;
  39         private final Throwable allocationContext;
  40
  41         private Finalizer(final ClientBackedTransaction<?> referent, final AbstractClientHandle<?> transaction,
  42                 final Throwable allocationContext) {
  43             super(referent, QUEUE);
  44             this.transaction = Preconditions.checkNotNull(transaction);
  45             this.allocationContext = allocationContext;
  46         }
  47
  48         static @Nonnull <T extends AbstractClientHandle<?>> T recordTransaction(
  49                 @Nonnull final ClientBackedTransaction<T> referent, @Nonnull final T transaction,
  50                 @Nullable final Throwable allocationContext) {
  51             FINALIZERS.add(new Finalizer(referent, transaction, allocationContext));
  52             return transaction;
  53         }
  54
  55         @Override
  56         public void finalizeReferent() {
  57             FINALIZERS.remove(this);
  58             if (transaction.abort()) {
  59                 LOG.info("Aborted orphan transaction {}", transaction, allocationContext);
  60             }
  61         }
  62     }
  63
  64     private final T delegate;
  65
  66     ClientBackedTransaction(final T delegate, final Throwable allocationContext) {
  67         super(delegate.getIdentifier());
  68         this.delegate = Finalizer.recordTransaction(this, delegate, allocationContext);
  69     }
  70
  71     final T delegate() {
  72         return delegate;
  73     }
  74
  75     @Override
  76     public void close() {
  77         delegate.abort();
  78     }
  79 }