Fix Snapshot Shard Status Request Deduplication (#50788) (#50840)

* Fix Snapshot Shard Status Request Deduplication

The request deduplication didn't actually work for these requests
since they had no `equals` and `hashCode` so the deduplicator wouldn't
actually recognize equal requests.

server/src/main/java/org/elasticsearch/snapshots/SnapshotShardsService.java

@@ -77,6 +77,7 @@
 import java.util.Iterator;
 import java.util.List;
 import java.util.Map;
+import java.util.Objects;
 import java.util.function.Function;
 import java.util.stream.Collectors;
 
@@ -391,9 +392,9 @@ private void syncShardStatsOnNewMaster(ClusterChangedEvent event) {
      * Internal request that is used to send changes in snapshot status to master
      */
     public static class UpdateIndexShardSnapshotStatusRequest extends MasterNodeRequest<UpdateIndexShardSnapshotStatusRequest> {
-        private Snapshot snapshot;
-        private ShardId shardId;
-        private ShardSnapshotStatus status;
+        private final Snapshot snapshot;
+        private final ShardId shardId;
+        private final ShardSnapshotStatus status;
 
         public UpdateIndexShardSnapshotStatusRequest(StreamInput in) throws IOException {
             super(in);
@@ -439,6 +440,23 @@ public ShardSnapshotStatus status() {
         public String toString() {
             return snapshot + ", shardId [" + shardId + "], status [" + status.state() + "]";
         }
+
+        @Override
+        public boolean equals(final Object o) {
+            if (this == o) {
+                return true;
+            }
+            if (o == null || getClass() != o.getClass()) {
+                return false;
+            }
+            final UpdateIndexShardSnapshotStatusRequest that = (UpdateIndexShardSnapshotStatusRequest) o;
+            return snapshot.equals(that.snapshot) && shardId.equals(that.shardId) && status.equals(that.status);
+        }
+
+        @Override
+        public int hashCode() {
+            return Objects.hash(snapshot, shardId, status);
+        }
     }
 
     /** Notify the master node that the given shard has been successfully snapshotted **/

server/src/test/java/org/elasticsearch/snapshots/SnapshotShardsServiceTests.java

@@ -0,0 +1,53 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.elasticsearch.snapshots;
+
+import org.elasticsearch.cluster.SnapshotsInProgress;
+import org.elasticsearch.common.UUIDs;
+import org.elasticsearch.index.shard.ShardId;
+import org.elasticsearch.test.ESTestCase;
+import org.elasticsearch.test.EqualsHashCodeTestUtils;
+
+public class SnapshotShardsServiceTests extends ESTestCase {
+
+    public void testEqualsAndHashcodeUpdateIndexShardSnapshotStatusRequest() {
+        EqualsHashCodeTestUtils.checkEqualsAndHashCode(
+            new SnapshotShardsService.UpdateIndexShardSnapshotStatusRequest(
+                new Snapshot(randomAlphaOfLength(10),
+                    new SnapshotId(randomAlphaOfLength(10), UUIDs.randomBase64UUID(random()))),
+                new ShardId(randomAlphaOfLength(10), UUIDs.randomBase64UUID(random()), randomInt(5)),
+                new SnapshotsInProgress.ShardSnapshotStatus(randomAlphaOfLength(10), UUIDs.randomBase64UUID(random()))),
+            request ->
+                new SnapshotShardsService.UpdateIndexShardSnapshotStatusRequest(request.snapshot(), request.shardId(), request.status()),
+            request -> {
+                final boolean mutateSnapshot = randomBoolean();
+                final boolean mutateShardId = randomBoolean();
+                final boolean mutateStatus = (mutateSnapshot || mutateShardId) == false || randomBoolean();
+                return new SnapshotShardsService.UpdateIndexShardSnapshotStatusRequest(
+                    mutateSnapshot ? new Snapshot(randomAlphaOfLength(10),
+                        new SnapshotId(randomAlphaOfLength(10), UUIDs.randomBase64UUID(random()))) : request.snapshot(),
+                    mutateShardId ?
+                        new ShardId(randomAlphaOfLength(10), UUIDs.randomBase64UUID(random()), randomInt(5)) : request.shardId(),
+                    mutateStatus ? new SnapshotsInProgress.ShardSnapshotStatus(randomAlphaOfLength(10), UUIDs.randomBase64UUID(random()))
+                        : request.status()
+                );
+            });
+    }
+
+}