Bug 7521: Convert Snapshot to store a State instance

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

diff --git a/opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/datastore/persisted/ShardSnapshotState.java b/opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/datastore/persisted/ShardSnapshotState.java
new file mode 100644 (file)
index 0000000..d4556cd
--- /dev/null
+++ b/opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/datastore/persisted/ShardSnapshotState.java
@@ -0,0 +1,104 @@
+/*
+ * Copyright (c) 2017 Brocade Communications Systems, Inc. and others.  All rights reserved.
+ *
+ * This program and the accompanying materials are made available under the
+ * terms of the Eclipse Public License v1.0 which accompanies this distribution,
+ * and is available at http://www.eclipse.org/legal/epl-v10.html
+ */
+package org.opendaylight.controller.cluster.datastore.persisted;
+
+import com.google.common.base.Preconditions;
+import edu.umd.cs.findbugs.annotations.SuppressFBWarnings;
+import java.io.Externalizable;
+import java.io.IOException;
+import java.io.InputStream;
+import java.io.ObjectInput;
+import java.io.ObjectOutput;
+import java.io.OutputStream;
+import javax.annotation.Nonnull;
+import org.opendaylight.controller.cluster.raft.persisted.Snapshot;
+
+/**
+ * Encapsulates the snapshot State for a Shard.
+ *
+ * @author Thomas Pantelis
+ */
+public class ShardSnapshotState implements Snapshot.State {
+    private static final long serialVersionUID = 1L;
+
+    private static final class Proxy implements Externalizable {
+        private static final long serialVersionUID = 1L;
+
+        private ShardSnapshotState snapshotState;
+
+        // checkstyle flags the public modifier as redundant which really doesn't make sense since it clearly isn't
+        // redundant. It is explicitly needed for Java serialization to be able to create instances via reflection.
+        @SuppressWarnings("checkstyle:RedundantModifier")
+        public Proxy() {
+            // For Externalizable
+        }
+
+        Proxy(final ShardSnapshotState snapshotState) {
+            this.snapshotState = snapshotState;
+        }
+
+        @Override
+        public void writeExternal(final ObjectOutput out) throws IOException {
+            snapshotState.snapshot.serialize(toOutputStream(out));
+        }
+
+        private OutputStream toOutputStream(final ObjectOutput out) {
+            if (out instanceof OutputStream) {
+                return (OutputStream) out;
+            }
+
+            return new OutputStream() {
+                @Override
+                public void write(int value) throws IOException {
+                    out.write(value);
+                }
+            };
+        }
+
+        @Override
+        public void readExternal(final ObjectInput in) throws IOException, ClassNotFoundException {
+            snapshotState = new ShardSnapshotState(ShardDataTreeSnapshot.deserialize(toInputStream(in)));
+        }
+
+        private InputStream toInputStream(final ObjectInput in) {
+            if (in instanceof InputStream) {
+                return (InputStream) in;
+            }
+
+            return new InputStream() {
+                @Override
+                public int read() throws IOException {
+                    return in.read();
+                }
+            };
+        }
+
+        private Object readResolve() {
+            return snapshotState;
+        }
+    }
+
+    @SuppressFBWarnings(value = "SE_BAD_FIELD", justification = "This field is not Serializable but this class "
+            + "implements writeReplace to delegate serialization to a Proxy class and thus instances of this class "
+            + "aren't serialized. FindBugs does not recognize this.")
+    private final ShardDataTreeSnapshot snapshot;
+
+    public ShardSnapshotState(@Nonnull ShardDataTreeSnapshot snapshot) {
+        this.snapshot = Preconditions.checkNotNull(snapshot);
+    }
+
+    @Nonnull
+    public ShardDataTreeSnapshot getSnapshot() {
+        return snapshot;
+    }
+
+    @SuppressWarnings("static-method")
+    private Object writeReplace() {
+        return new Proxy(this);
+    }
+}