Introduce IndexReshardingMetadata

server/src/main/java/org/elasticsearch/cluster/metadata/IndexMetadata.java

@@ -561,6 +561,8 @@ public Iterator<Setting<?>> settings() {
 
     public static final String KEY_INFERENCE_FIELDS = "field_inference";
 
+    public static final String KEY_RESHARDING = "resharding";
+
     public static final String INDEX_STATE_FILE_PREFIX = "state-";
 
     static final TransportVersion STATS_AND_FORECAST_ADDED = TransportVersions.V_8_6_0;
@@ -654,6 +656,8 @@ public Iterator<Setting<?>> settings() {
     private final Double writeLoadForecast;
     @Nullable
     private final Long shardSizeInBytesForecast;
+    @Nullable
+    private final IndexReshardingMetadata reshardingMetadata;
 
     private IndexMetadata(
         final Index index,
@@ -702,7 +706,8 @@ private IndexMetadata(
         final IndexVersion indexCompatibilityVersion,
         @Nullable final IndexMetadataStats stats,
         @Nullable final Double writeLoadForecast,
-        @Nullable Long shardSizeInBytesForecast
+        @Nullable Long shardSizeInBytesForecast,
+        @Nullable IndexReshardingMetadata reshardingMetadata
     ) {
         this.index = index;
         this.version = version;
@@ -761,6 +766,7 @@ private IndexMetadata(
         this.writeLoadForecast = writeLoadForecast;
         this.shardSizeInBytesForecast = shardSizeInBytesForecast;
         assert numberOfShards * routingFactor == routingNumShards : routingNumShards + " must be a multiple of " + numberOfShards;
+        this.reshardingMetadata = reshardingMetadata;
     }
 
     IndexMetadata withMappingMetadata(MappingMetadata mapping) {
@@ -814,7 +820,8 @@ IndexMetadata withMappingMetadata(MappingMetadata mapping) {
             this.indexCompatibilityVersion,
             this.stats,
             this.writeLoadForecast,
-            this.shardSizeInBytesForecast
+            this.shardSizeInBytesForecast,
+            this.reshardingMetadata
         );
     }
 
@@ -875,7 +882,8 @@ public IndexMetadata withInSyncAllocationIds(int shardId, Set<String> inSyncSet)
             this.indexCompatibilityVersion,
             this.stats,
             this.writeLoadForecast,
-            this.shardSizeInBytesForecast
+            this.shardSizeInBytesForecast,
+            this.reshardingMetadata
         );
     }
 
@@ -934,7 +942,8 @@ public IndexMetadata withIncrementedPrimaryTerm(int shardId) {
             this.indexCompatibilityVersion,
             this.stats,
             this.writeLoadForecast,
-            this.shardSizeInBytesForecast
+            this.shardSizeInBytesForecast,
+            this.reshardingMetadata
         );
     }
 
@@ -994,7 +1003,8 @@ public IndexMetadata withTimestampRanges(IndexLongFieldRange timestampRange, Ind
             this.indexCompatibilityVersion,
             this.stats,
             this.writeLoadForecast,
-            this.shardSizeInBytesForecast
+            this.shardSizeInBytesForecast,
+            this.reshardingMetadata
         );
     }
 
@@ -1049,7 +1059,8 @@ public IndexMetadata withIncrementedVersion() {
             this.indexCompatibilityVersion,
             this.stats,
             this.writeLoadForecast,
-            this.shardSizeInBytesForecast
+            this.shardSizeInBytesForecast,
+            this.reshardingMetadata
         );
     }
 
@@ -1905,6 +1916,7 @@ public static class Builder {
         private IndexMetadataStats stats = null;
         private Double indexWriteLoadForecast = null;
         private Long shardSizeInBytesForecast = null;
+        private IndexReshardingMetadata reshardingMetadata = null;
 
         public Builder(String index) {
             this.index = index;
@@ -1940,6 +1952,7 @@ public Builder(IndexMetadata indexMetadata) {
             this.stats = indexMetadata.stats;
             this.indexWriteLoadForecast = indexMetadata.writeLoadForecast;
             this.shardSizeInBytesForecast = indexMetadata.shardSizeInBytesForecast;
+            this.reshardingMetadata = indexMetadata.reshardingMetadata;
         }
 
         public Builder index(String index) {
@@ -2190,6 +2203,11 @@ public Builder putInferenceFields(Map<String, InferenceFieldMetadata> values) {
             return this;
         }
 
+        public Builder reshardingMetadata(IndexReshardingMetadata reshardingMetadata) {
+            this.reshardingMetadata = reshardingMetadata;
+            return this;
+        }
+
         public IndexMetadata build() {
             return build(false);
         }
@@ -2389,7 +2407,8 @@ IndexMetadata build(boolean repair) {
                 SETTING_INDEX_VERSION_COMPATIBILITY.get(settings),
                 stats,
                 indexWriteLoadForecast,
-                shardSizeInBytesForecast
+                shardSizeInBytesForecast,
+                reshardingMetadata
             );
         }
 
@@ -2529,6 +2548,12 @@ public static void toXContent(IndexMetadata indexMetadata, XContentBuilder build
                 builder.endObject();
             }
 
+            if (indexMetadata.reshardingMetadata != null) {
+                builder.startObject(KEY_RESHARDING);
+                indexMetadata.reshardingMetadata.toXContent(builder, params);
+                builder.endObject();
+            }
+
             builder.endObject();
         }
 
@@ -2615,6 +2640,9 @@ public static IndexMetadata fromXContent(XContentParser parser, Map<String, Mapp
                                 builder.putInferenceField(InferenceFieldMetadata.fromXContent(parser));
                             }
                             break;
+                        case KEY_RESHARDING:
+                            builder.reshardingMetadata(IndexReshardingMetadata.fromXContent(parser));
+                            break;
                         default:
                             // assume it's custom index metadata
                             builder.putCustom(currentFieldName, parser.mapStrings());