opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/datastore/persisted/ShardSnapshotState.java

   1 /*
   2  * Copyright (c) 2017 Brocade Communications 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.datastore.persisted;
   9
  10 import com.google.common.base.Preconditions;
  11 import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
  12 import java.io.Externalizable;
  13 import java.io.IOException;
  14 import java.io.InputStream;
  15 import java.io.ObjectInput;
  16 import java.io.ObjectOutput;
  17 import java.io.OutputStream;
  18 import javax.annotation.Nonnull;
  19 import org.opendaylight.controller.cluster.raft.persisted.Snapshot;
  20
  21 /**
  22  * Encapsulates the snapshot State for a Shard.
  23  *
  24  * @author Thomas Pantelis
  25  */
  26 public class ShardSnapshotState implements Snapshot.State {
  27     private static final long serialVersionUID = 1L;
  28
  29     private static final class Proxy implements Externalizable {
  30         private static final long serialVersionUID = 1L;
  31
  32         private ShardSnapshotState snapshotState;
  33
  34         // checkstyle flags the public modifier as redundant which really doesn't make sense since it clearly isn't
  35         // redundant. It is explicitly needed for Java serialization to be able to create instances via reflection.
  36         @SuppressWarnings("checkstyle:RedundantModifier")
  37         public Proxy() {
  38             // For Externalizable
  39         }
  40
  41         Proxy(final ShardSnapshotState snapshotState) {
  42             this.snapshotState = snapshotState;
  43         }
  44
  45         @Override
  46         public void writeExternal(final ObjectOutput out) throws IOException {
  47             snapshotState.snapshot.serialize(toOutputStream(out));
  48         }
  49
  50         private static OutputStream toOutputStream(final ObjectOutput out) {
  51             if (out instanceof OutputStream) {
  52                 return (OutputStream) out;
  53             }
  54
  55             return new OutputStream() {
  56                 @Override
  57                 public void write(final int value) throws IOException {
  58                     out.write(value);
  59                 }
  60             };
  61         }
  62
  63         @Override
  64         public void readExternal(final ObjectInput in) throws IOException, ClassNotFoundException {
  65             snapshotState = new ShardSnapshotState(ShardDataTreeSnapshot.deserialize(toInputStream(in)));
  66         }
  67
  68         private static InputStream toInputStream(final ObjectInput in) {
  69             if (in instanceof InputStream) {
  70                 return (InputStream) in;
  71             }
  72
  73             return new InputStream() {
  74                 @Override
  75                 public int read() throws IOException {
  76                     return in.read();
  77                 }
  78             };
  79         }
  80
  81         private Object readResolve() {
  82             return snapshotState;
  83         }
  84     }
  85
  86     @SuppressFBWarnings(value = "SE_BAD_FIELD", justification = "This field is not Serializable but this class "
  87             + "implements writeReplace to delegate serialization to a Proxy class and thus instances of this class "
  88             + "aren't serialized. FindBugs does not recognize this.")
  89     private final ShardDataTreeSnapshot snapshot;
  90
  91     public ShardSnapshotState(@Nonnull final ShardDataTreeSnapshot snapshot) {
  92         this.snapshot = Preconditions.checkNotNull(snapshot);
  93     }
  94
  95     @Nonnull
  96     public ShardDataTreeSnapshot getSnapshot() {
  97         return snapshot;
  98     }
  99
 100     private Object writeReplace() {
 101         return new Proxy(this);
 102     }
 103 }