opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/databroker/actors/dds/EmptyTransactionCommitCohort.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.actors.dds;
   9
  10 import com.google.common.util.concurrent.ListenableFuture;
  11 import org.opendaylight.controller.sal.core.spi.data.DOMStoreThreePhaseCommitCohort;
  12
  13 /**
  14  * An {@link AbstractTransactionCommitCohort} for use with empty transactions. This relies on the fact that no backends
  15  * have been touched, hence all state book-keeping needs to happen only locally and shares fate with the coordinator.
  16  *
  17  * <p>
  18  * Therefore all methods can finish immediately without any effects.
  19  *
  20  * @author Robert Varga
  21  */
  22 final class EmptyTransactionCommitCohort extends AbstractTransactionCommitCohort {
  23     static final DOMStoreThreePhaseCommitCohort INSTANCE = new EmptyTransactionCommitCohort();
  24
  25     private EmptyTransactionCommitCohort() {
  26         // Hidden
  27     }
  28
  29     @Override
  30     public ListenableFuture<Boolean> canCommit() {
  31         return TRUE_FUTURE;
  32     }
  33
  34     @Override
  35     public ListenableFuture<Void> preCommit() {
  36         return VOID_FUTURE;
  37     }
  38
  39     @Override
  40     public ListenableFuture<Void> abort() {
  41         return VOID_FUTURE;
  42     }
  43
  44     @Override
  45     public ListenableFuture<Void> commit() {
  46         return VOID_FUTURE;
  47     }
  48 }