Modify SearchShards API and TransportSearchAction for CPS when MRT=false

server/src/main/java/org/elasticsearch/action/search/SearchRequest.java

@@ -163,6 +163,11 @@ public boolean allowsRemoteIndices() {
         return true;
     }
 
+    @Override
+    public boolean allowsCrossProject() {
+        return true;
+    }
+
     /**
      * Creates a new sub-search request starting from the original search request that is provided.
      * For internal use only, allows to fork a search request into multiple search requests that will be executed independently.

server/src/main/java/org/elasticsearch/action/search/SearchResponse.java

@@ -609,13 +609,18 @@ public Clusters(StreamInput in) throws IOException {
         }
 
         public Clusters(Map<String, Cluster> clusterInfoMap) {
+            this(clusterInfoMap, true);
+        }
+
+        public Clusters(Map<String, Cluster> clusterInfoMap, boolean ccsMinimizeRoundtrips) {
             assert clusterInfoMap.size() > 0 : "this constructor should not be called with an empty Cluster info map";
             this.total = clusterInfoMap.size();
-            this.clusterInfo = clusterInfoMap;
+            this.clusterInfo = ConcurrentCollections.newConcurrentMap();
+            this.clusterInfo.putAll(clusterInfoMap);
             this.successful = getClusterStateCount(Cluster.Status.SUCCESSFUL);
             this.skipped = getClusterStateCount(Cluster.Status.SKIPPED);
             // should only be called if "details" section of fromXContent is present (for ccsMinimizeRoundtrips)
-            this.ccsMinimizeRoundtrips = true;
+            this.ccsMinimizeRoundtrips = ccsMinimizeRoundtrips;
         }
 
         @Override

server/src/main/java/org/elasticsearch/action/search/SearchShardsRequest.java

@@ -12,6 +12,7 @@
 import org.elasticsearch.action.ActionRequestValidationException;
 import org.elasticsearch.action.IndicesRequest;
 import org.elasticsearch.action.LegacyActionRequest;
+import org.elasticsearch.action.ResolvedIndexExpressions;
 import org.elasticsearch.action.support.IndicesOptions;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
@@ -43,6 +44,8 @@ public final class SearchShardsRequest extends LegacyActionRequest implements In
 
     private final String clusterAlias;
 
+    private ResolvedIndexExpressions resolvedIndexExpressions;
+
     public SearchShardsRequest(
         String[] indices,
         IndicesOptions indicesOptions,
@@ -179,4 +182,14 @@ public int hashCode() {
         result = 31 * result + Arrays.hashCode(indices);
         return result;
     }
+
+    @Override
+    public void setResolvedIndexExpressions(ResolvedIndexExpressions expressions) {
+        this.resolvedIndexExpressions = expressions;
+    }
+
+    @Override
+    public ResolvedIndexExpressions getResolvedIndexExpressions() {
+        return resolvedIndexExpressions;
+    }
 }

server/src/main/java/org/elasticsearch/action/search/SearchShardsResponse.java

@@ -9,13 +9,16 @@
 
 package org.elasticsearch.action.search;
 
+import org.elasticsearch.TransportVersion;
 import org.elasticsearch.action.ActionResponse;
+import org.elasticsearch.action.ResolvedIndexExpressions;
 import org.elasticsearch.action.admin.cluster.shards.ClusterSearchShardsGroup;
 import org.elasticsearch.action.admin.cluster.shards.ClusterSearchShardsResponse;
 import org.elasticsearch.cluster.node.DiscoveryNode;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.util.Maps;
+import org.elasticsearch.core.Nullable;
 import org.elasticsearch.index.Index;
 import org.elasticsearch.index.shard.ShardId;
 import org.elasticsearch.search.internal.AliasFilter;
@@ -35,28 +38,50 @@ public final class SearchShardsResponse extends ActionResponse {
     private final Collection<SearchShardsGroup> groups;
     private final Collection<DiscoveryNode> nodes;
     private final Map<String, AliasFilter> aliasFilters;
+    private final ResolvedIndexExpressions resolvedIndexExpressions;
+    public static final TransportVersion SEARCH_SHARDS_RESOLVED_INDEX_EXPRESSIONS = TransportVersion.fromName(
+        "search_shards_resolved_index_expressions"
+    );
 
     public SearchShardsResponse(
         Collection<SearchShardsGroup> groups,
         Collection<DiscoveryNode> nodes,
-        Map<String, AliasFilter> aliasFilters
+        Map<String, AliasFilter> aliasFilters,
+        @Nullable ResolvedIndexExpressions resolvedIndexExpressions
     ) {
         this.groups = groups;
         this.nodes = nodes;
         this.aliasFilters = aliasFilters;
+        this.resolvedIndexExpressions = resolvedIndexExpressions;
+    }
+
+    public SearchShardsResponse(
+        Collection<SearchShardsGroup> groups,
+        Collection<DiscoveryNode> nodes,
+        Map<String, AliasFilter> aliasFilters
+    ) {
+        this(groups, nodes, aliasFilters, null);
     }
 
     public SearchShardsResponse(StreamInput in) throws IOException {
         this.groups = in.readCollectionAsList(SearchShardsGroup::new);
         this.nodes = in.readCollectionAsList(DiscoveryNode::new);
         this.aliasFilters = in.readMap(AliasFilter::readFrom);
+        if (in.getTransportVersion().supports(SEARCH_SHARDS_RESOLVED_INDEX_EXPRESSIONS)) {
+            this.resolvedIndexExpressions = in.readOptionalWriteable(ResolvedIndexExpressions::new);
+        } else {
+            this.resolvedIndexExpressions = null;
+        }
     }
 
     @Override
     public void writeTo(StreamOutput out) throws IOException {
         out.writeCollection(groups);
         out.writeCollection(nodes);
         out.writeMap(aliasFilters, StreamOutput::writeWriteable);
+        if (out.getTransportVersion().supports(SEARCH_SHARDS_RESOLVED_INDEX_EXPRESSIONS)) {
+            out.writeOptionalWriteable(resolvedIndexExpressions);
+        }
     }
 
     /**
@@ -114,4 +139,9 @@ static SearchShardsResponse fromLegacyResponse(ClusterSearchShardsResponse oldRe
     public String toString() {
         return "SearchShardsResponse{" + "groups=" + groups + ", nodes=" + nodes + ", aliasFilters=" + aliasFilters + '}';
     }
+
+    @Nullable
+    public ResolvedIndexExpressions getResolvedIndexExpressions() {
+        return resolvedIndexExpressions;
+    }
 }