Fix for deserilization bug in weighted round robin metadata

CHANGELOG.md

@@ -105,6 +105,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 ### Removed
 
 ### Fixed
+- Fix for deserilization bug in weighted round-robin metadata ([#11679](https://github.com/opensearch-project/OpenSearch/pull/11679))
 
 ### Security
 

server/src/internalClusterTest/java/org/opensearch/cluster/routing/WeightedRoutingIT.java

@@ -13,12 +13,14 @@
 import org.opensearch.action.admin.cluster.shards.routing.weighted.delete.ClusterDeleteWeightedRoutingResponse;
 import org.opensearch.action.admin.cluster.shards.routing.weighted.get.ClusterGetWeightedRoutingResponse;
 import org.opensearch.action.admin.cluster.shards.routing.weighted.put.ClusterPutWeightedRoutingResponse;
+import org.opensearch.action.admin.cluster.state.ClusterStateRequest;
 import org.opensearch.cluster.health.ClusterHealthStatus;
 import org.opensearch.common.settings.Settings;
 import org.opensearch.core.rest.RestStatus;
 import org.opensearch.discovery.ClusterManagerNotDiscoveredException;
 import org.opensearch.plugins.Plugin;
 import org.opensearch.snapshots.mockstore.MockRepository;
+import org.opensearch.test.InternalTestCluster;
 import org.opensearch.test.OpenSearchIntegTestCase;
 import org.opensearch.test.disruption.NetworkDisruption;
 import org.opensearch.test.transport.MockTransportService;
@@ -715,4 +717,144 @@ public void testClusterHealthResponseWithEnsureNodeWeighedInParam() throws Excep
         assertFalse(nodeLocalHealth.isTimedOut());
         assertTrue(nodeLocalHealth.hasDiscoveredClusterManager());
     }
+
+    public void testReadWriteWeightedRoutingMetadataOnNodeRestart() throws Exception {
+        Settings commonSettings = Settings.builder()
+            .put("cluster.routing.allocation.awareness.attributes", "zone")
+            .put("cluster.routing.allocation.awareness.force.zone.values", "a,b,c")
+            .build();
+
+        internalCluster().startClusterManagerOnlyNode(Settings.builder().put(commonSettings).build());
+
+        logger.info("--> starting 1 nodes on zones 'a' & 'b' & 'c'");
+        List<String> nodes_in_zone_a = internalCluster().startDataOnlyNodes(
+            1,
+            Settings.builder().put(commonSettings).put("node.attr.zone", "a").build()
+        );
+        List<String> nodes_in_zone_b = internalCluster().startDataOnlyNodes(
+            1,
+            Settings.builder().put(commonSettings).put("node.attr.zone", "b").build()
+        );
+        List<String> nodes_in_zone_c = internalCluster().startDataOnlyNodes(
+            1,
+            Settings.builder().put(commonSettings).put("node.attr.zone", "c").build()
+        );
+
+        logger.info("--> waiting for nodes to form a cluster");
+        ClusterHealthResponse health = client().admin().cluster().prepareHealth().setWaitForNodes("4").execute().actionGet();
+        assertThat(health.isTimedOut(), equalTo(false));
+
+        ensureGreen();
+
+        logger.info("--> setting shard routing weights for weighted round robin");
+        Map<String, Double> weights = Map.of("a", 1.0, "b", 2.0, "c", 3.0);
+        WeightedRouting weightedRouting = new WeightedRouting("zone", weights);
+
+        ClusterPutWeightedRoutingResponse response = client().admin()
+            .cluster()
+            .prepareWeightedRouting()
+            .setWeightedRouting(weightedRouting)
+            .setVersion(-1)
+            .get();
+        assertEquals(response.isAcknowledged(), true);
+
+        ClusterDeleteWeightedRoutingResponse deleteResponse = client().admin().cluster().prepareDeleteWeightedRouting().setVersion(0).get();
+        assertTrue(deleteResponse.isAcknowledged());
+
+        // check weighted routing metadata after node restart, ensure node comes healthy after restart
+        internalCluster().restartNode(nodes_in_zone_a.get(0), new InternalTestCluster.RestartCallback());
+        ensureGreen();
+        assertNotNull(internalCluster().clusterService().state().metadata().weightedRoutingMetadata());
+
+        // make sure restarted node joins the cluster
+        assertEquals(3, internalCluster().clusterService().state().nodes().getDataNodes().size());
+        assertNotNull(
+            internalCluster().client(nodes_in_zone_a.get(0))
+                .admin()
+                .cluster()
+                .state(new ClusterStateRequest().local(true))
+                .get()
+                .getState()
+                .metadata()
+                .weightedRoutingMetadata()
+        );
+        assertNotNull(
+            internalCluster().client(nodes_in_zone_b.get(0))
+                .admin()
+                .cluster()
+                .state(new ClusterStateRequest().local(true))
+                .get()
+                .getState()
+                .metadata()
+                .weightedRoutingMetadata()
+        );
+        assertNotNull(
+            internalCluster().client(nodes_in_zone_c.get(0))
+                .admin()
+                .cluster()
+                .state(new ClusterStateRequest().local(true))
+                .get()
+                .getState()
+                .metadata()
+                .weightedRoutingMetadata()
+        );
+        assertNotNull(
+            internalCluster().client(internalCluster().getClusterManagerName())
+                .admin()
+                .cluster()
+                .state(new ClusterStateRequest().local(true))
+                .get()
+                .getState()
+                .metadata()
+                .weightedRoutingMetadata()
+        );
+
+        internalCluster().restartNode(internalCluster().getClusterManagerName(), new InternalTestCluster.RestartCallback());
+        ensureGreen();
+        assertNotNull(internalCluster().clusterService().state().metadata().weightedRoutingMetadata());
+
+        // make sure restarted node joins the cluster
+        assertEquals(3, internalCluster().clusterService().state().nodes().getDataNodes().size());
+        assertNotNull(
+            internalCluster().client(nodes_in_zone_a.get(0))
+                .admin()
+                .cluster()
+                .state(new ClusterStateRequest().local(true))
+                .get()
+                .getState()
+                .metadata()
+                .weightedRoutingMetadata()
+        );
+        assertNotNull(
+            internalCluster().client(nodes_in_zone_b.get(0))
+                .admin()
+                .cluster()
+                .state(new ClusterStateRequest().local(true))
+                .get()
+                .getState()
+                .metadata()
+                .weightedRoutingMetadata()
+        );
+        assertNotNull(
+            internalCluster().client(nodes_in_zone_c.get(0))
+                .admin()
+                .cluster()
+                .state(new ClusterStateRequest().local(true))
+                .get()
+                .getState()
+                .metadata()
+                .weightedRoutingMetadata()
+        );
+        assertNotNull(
+            internalCluster().client(internalCluster().getClusterManagerName())
+                .admin()
+                .cluster()
+                .state(new ClusterStateRequest().local(true))
+                .get()
+                .getState()
+                .metadata()
+                .weightedRoutingMetadata()
+        );
+
+    }
 }

server/src/main/java/org/opensearch/cluster/metadata/WeightedRoutingMetadata.java

@@ -26,6 +26,7 @@
 import java.util.EnumSet;
 import java.util.HashMap;
 import java.util.Map;
+import java.util.Objects;
 
 /**
  * Contains metadata for weighted routing
@@ -99,7 +100,7 @@ public static NamedDiff<Metadata.Custom> readDiffFrom(StreamInput in) throws IOE
     public static WeightedRoutingMetadata fromXContent(XContentParser parser) throws IOException {
         String attrKey = null;
         Double attrValue;
-        String attributeName = null;
+        String attributeName = "";
         Map<String, Double> weights = new HashMap<>();
         WeightedRouting weightedRouting;
         XContentParser.Token token;
@@ -162,12 +163,12 @@ public boolean equals(Object o) {
         if (this == o) return true;
         if (o == null || getClass() != o.getClass()) return false;
         WeightedRoutingMetadata that = (WeightedRoutingMetadata) o;
-        return weightedRouting.equals(that.weightedRouting);
+        return weightedRouting.equals(that.weightedRouting) && version == that.version;
     }
 
     @Override
     public int hashCode() {
-        return weightedRouting.hashCode();
+        return Objects.hash(weightedRouting.hashCode(), version);
     }
 
     @Override

server/src/main/java/org/opensearch/cluster/routing/WeightedRouting.java

@@ -54,6 +54,7 @@ public boolean isSet() {
 
     @Override
     public void writeTo(StreamOutput out) throws IOException {
+
         out.writeString(attributeName);
         out.writeGenericValue(weights);
     }

server/src/test/java/org/opensearch/cluster/metadata/WeightedRoutingMetadataTests.java

@@ -8,29 +8,60 @@
 
 package org.opensearch.cluster.metadata;
 
+import org.opensearch.cluster.ClusterModule;
+import org.opensearch.cluster.Diff;
 import org.opensearch.cluster.routing.WeightedRouting;
+import org.opensearch.core.common.io.stream.NamedWriteableRegistry;
+import org.opensearch.core.common.io.stream.Writeable;
 import org.opensearch.core.xcontent.XContentParser;
-import org.opensearch.test.AbstractXContentTestCase;
+import org.opensearch.test.AbstractDiffableSerializationTestCase;
 
 import java.io.IOException;
+import java.util.HashMap;
 import java.util.Map;
 
-public class WeightedRoutingMetadataTests extends AbstractXContentTestCase<WeightedRoutingMetadata> {
+public class WeightedRoutingMetadataTests extends AbstractDiffableSerializationTestCase<Metadata.Custom> {
+
+    @Override
+    protected Writeable.Reader<Metadata.Custom> instanceReader() {
+        return WeightedRoutingMetadata::new;
+    }
+
     @Override
     protected WeightedRoutingMetadata createTestInstance() {
+        String attributeName = "zone";
         Map<String, Double> weights = Map.of("a", 1.0, "b", 1.0, "c", 0.0);
-        WeightedRouting weightedRouting = new WeightedRouting("zone", weights);
+        if (randomBoolean()) {
+            weights = new HashMap<>();
+            attributeName = "";
+        }
+        WeightedRouting weightedRouting = new WeightedRouting(attributeName, weights);
         WeightedRoutingMetadata weightedRoutingMetadata = new WeightedRoutingMetadata(weightedRouting, -1);
+
         return weightedRoutingMetadata;
     }
 
+    @Override
+    protected NamedWriteableRegistry getNamedWriteableRegistry() {
+        return new NamedWriteableRegistry(ClusterModule.getNamedWriteables());
+    }
+
     @Override
     protected WeightedRoutingMetadata doParseInstance(XContentParser parser) throws IOException {
         return WeightedRoutingMetadata.fromXContent(parser);
     }
 
     @Override
-    protected boolean supportsUnknownFields() {
-        return false;
+    protected Metadata.Custom makeTestChanges(Metadata.Custom testInstance) {
+
+        WeightedRouting weightedRouting = new WeightedRouting("", new HashMap<>());
+        WeightedRoutingMetadata weightedRoutingMetadata = new WeightedRoutingMetadata(weightedRouting, -1);
+        return weightedRoutingMetadata;
     }
+
+    @Override
+    protected Writeable.Reader<Diff<Metadata.Custom>> diffReader() {
+        return WeightedRoutingMetadata::readDiffFrom;
+    }
+
 }