Define efficient serialization proxies

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

diff --git a/opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/datastore/persisted/MS.java b/opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/datastore/persisted/MS.java
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+++ b/opendaylight/md-sal/sal-distributed-datastore/src/main/java/org/opendaylight/controller/cluster/datastore/persisted/MS.java
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+/*
+ * Copyright (c) 2022 PANTHEON.tech, s.r.o. 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 static com.google.common.base.Preconditions.checkArgument;
+
+import com.google.common.collect.ImmutableMap;
+import java.io.Externalizable;
+import java.io.IOException;
+import java.io.ObjectInput;
+import java.io.ObjectOutput;
+import java.util.Map;
+import org.opendaylight.yangtools.yang.data.api.schema.NormalizedNode;
+import org.opendaylight.yangtools.yang.data.codec.binfmt.NormalizedNodeDataInput;
+import org.opendaylight.yangtools.yang.data.codec.binfmt.NormalizedNodeStreamVersion;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * Externalizable proxy for {@link MetadataShardDataTreeSnapshot}.
+ */
+final class MS implements Externalizable {
+    private static final Logger LOG = LoggerFactory.getLogger(MS.class);
+    private static final long serialVersionUID = 1L;
+
+    private Map<Class<? extends ShardDataTreeSnapshotMetadata<?>>, ShardDataTreeSnapshotMetadata<?>> metadata;
+    private NormalizedNodeStreamVersion version;
+    private NormalizedNode rootNode;
+
+    @SuppressWarnings("checkstyle:RedundantModifier")
+    public MS() {
+        // For Externalizable
+    }
+
+    MS(final MetadataShardDataTreeSnapshot snapshot) {
+        rootNode = snapshot.getRootNode().orElseThrow();
+        metadata = snapshot.getMetadata();
+        version = snapshot.version().getStreamVersion();
+    }
+
+    @Override
+    public void writeExternal(final ObjectOutput out) throws IOException {
+        out.writeInt(metadata.size());
+        for (var m : metadata.values()) {
+            out.writeObject(m);
+        }
+        try (var stream = version.newDataOutput(out)) {
+            stream.writeNormalizedNode(rootNode);
+        }
+    }
+
+    @Override
+    public void readExternal(final ObjectInput in) throws IOException, ClassNotFoundException {
+        final int metaSize = in.readInt();
+        checkArgument(metaSize >= 0, "Invalid negative metadata map length %s", metaSize);
+
+        // Default pre-allocate is 4, which should be fine
+        final var metaBuilder = ImmutableMap
+            .<Class<? extends ShardDataTreeSnapshotMetadata<?>>, ShardDataTreeSnapshotMetadata<?>>builder();
+        for (int i = 0; i < metaSize; ++i) {
+            final var m = (ShardDataTreeSnapshotMetadata<?>) in.readObject();
+            if (m != null) {
+                metaBuilder.put(m.getType(), m);
+            } else {
+                LOG.warn("Skipping null metadata");
+            }
+        }
+        metadata = metaBuilder.build();
+
+        final var stream = NormalizedNodeDataInput.newDataInput(in);
+        version = stream.getVersion();
+        rootNode = stream.readNormalizedNode();
+    }
+
+    private Object readResolve() {
+        return new MetadataShardDataTreeSnapshot(rootNode, metadata);
+    }
+}
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