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 static java.util.Objects.requireNonNull;
  11
  12 import com.google.common.base.FinalizablePhantomReference;
  13 import com.google.common.base.FinalizableReferenceQueue;
  14 import java.util.Set;
  15 import java.util.concurrent.ConcurrentHashMap;
  16 import org.eclipse.jdt.annotation.NonNull;
  17 import org.eclipse.jdt.annotation.Nullable;
  18 import org.opendaylight.controller.cluster.access.concepts.TransactionIdentifier;
  19 import org.opendaylight.controller.cluster.databroker.actors.dds.AbstractClientHandle;
  20 import org.opendaylight.controller.cluster.databroker.actors.dds.ClientTransaction;
  21 import org.opendaylight.controller.sal.core.spi.data.AbstractDOMStoreTransaction;
  22 import org.slf4j.Logger;
  23 import org.slf4j.LoggerFactory;
  24
  25 /**
  26  * An implementation of {@link DOMStoreTransaction} backed by a {@link ClientTransaction}. It guards against user-level
  27  * leaks by maintaining a phantom reference on the backing transaction, which will ensure that the transaction will
  28  * be aborted, if it is not otherwise closed, just before this object is garbage-collected.
  29  *
  30  * @author Robert Varga
  31  */
  32 abstract class ClientBackedTransaction<T extends AbstractClientHandle<?>> extends
  33         AbstractDOMStoreTransaction<TransactionIdentifier> {
  34     private static final class Finalizer extends FinalizablePhantomReference<ClientBackedTransaction<?>> {
  35         private static final FinalizableReferenceQueue QUEUE = new FinalizableReferenceQueue();
  36         private static final Set<Finalizer> FINALIZERS = ConcurrentHashMap.newKeySet();
  37         private static final Logger LOG = LoggerFactory.getLogger(Finalizer.class);
  38
  39         private final AbstractClientHandle<?> transaction;
  40         private final Throwable allocationContext;
  41
  42         private Finalizer(final ClientBackedTransaction<?> referent, final AbstractClientHandle<?> transaction,
  43                 final Throwable allocationContext) {
  44             super(referent, QUEUE);
  45             this.transaction = requireNonNull(transaction);
  46             this.allocationContext = allocationContext;
  47         }
  48
  49         static <T extends AbstractClientHandle<?>> @NonNull T recordTransaction(
  50                 final @NonNull ClientBackedTransaction<T> referent, final @NonNull T transaction,
  51                 final @Nullable Throwable allocationContext) {
  52             FINALIZERS.add(new Finalizer(referent, transaction, allocationContext));
  53             return transaction;
  54         }
  55
  56         @Override
  57         public void finalizeReferent() {
  58             FINALIZERS.remove(this);
  59             if (transaction.abort()) {
  60                 LOG.info("Aborted orphan transaction {}", transaction, allocationContext);
  61             }
  62         }
  63     }
  64
  65     private final T delegate;
  66
  67     ClientBackedTransaction(final T delegate, final Throwable allocationContext) {
  68         super(delegate.getIdentifier());
  69         this.delegate = Finalizer.recordTransaction(this, delegate, allocationContext);
  70     }
  71
  72     final T delegate() {
  73         return delegate;
  74     }
  75
  76     @Override
  77     public void close() {
  78         delegate.abort();
  79     }
  80 }