Remove redundant exception object creation (elastic#81407) (elastic#88847)

Co-authored-by: GrandFisher <[email protected]>

Author: DaveCTurner

server/src/main/java/org/elasticsearch/action/support/broadcast/node/TransportBroadcastByNodeAction.java

@@ -12,7 +12,6 @@
 import org.elasticsearch.action.ActionListener;
 import org.elasticsearch.action.FailedNodeException;
 import org.elasticsearch.action.IndicesRequest;
-import org.elasticsearch.action.NoShardAvailableActionException;
 import org.elasticsearch.action.support.ActionFilters;
 import org.elasticsearch.action.support.DefaultShardOperationFailedException;
 import org.elasticsearch.action.support.HandledTransportAction;
@@ -120,7 +119,7 @@ public TransportBroadcastByNodeAction(
     private Response newResponse(
         Request request,
         AtomicReferenceArray<?> responses,
-        List<NoShardAvailableActionException> unavailableShardExceptions,
+        int unavailableShardCount,
         Map<String, List<ShardRouting>> nodes,
         ClusterState clusterState
     ) {
@@ -154,7 +153,7 @@ private Response newResponse(
                 }
             }
         }
-        totalShards += unavailableShardExceptions.size();
+        totalShards += unavailableShardCount;
         int failedShards = exceptions.size();
         return newResponse(request, totalShards, successfulShards, failedShards, broadcastByNodeResponses, exceptions, clusterState);
     }
@@ -267,7 +266,7 @@ protected class AsyncAction {
         private final Map<String, List<ShardRouting>> nodeIds;
         private final AtomicReferenceArray<Object> responses;
         private final AtomicInteger counter = new AtomicInteger();
-        private List<NoShardAvailableActionException> unavailableShardExceptions = new ArrayList<>();
+        private final int unavailableShardCount;
 
         protected AsyncAction(Task task, Request request, ActionListener<Response> listener) {
             this.task = task;
@@ -294,6 +293,7 @@ protected AsyncAction(Task task, Request request, ActionListener<Response> liste
             ShardsIterator shardIt = shards(clusterState, request, concreteIndices);
             nodeIds = new HashMap<>();
 
+            int unavailableShardCount = 0;
             for (ShardRouting shard : shardIt) {
                 // send a request to the shard only if it is assigned to a node that is in the local node's cluster state
                 // a scenario in which a shard can be assigned but to a node that is not in the local node's cluster state
@@ -308,15 +308,11 @@ protected AsyncAction(Task task, Request request, ActionListener<Response> liste
                     }
                     nodeIds.get(nodeId).add(shard);
                 } else {
-                    unavailableShardExceptions.add(
-                        new NoShardAvailableActionException(
-                            shard.shardId(),
-                            " no shards available for shard " + shard.toString() + " while executing " + actionName
-                        )
-                    );
+                    unavailableShardCount++;
                 }
-            }
 
+            }
+            this.unavailableShardCount = unavailableShardCount;
             responses = new AtomicReferenceArray<>(nodeIds.size());
         }
 
@@ -409,7 +405,7 @@ protected void onCompletion() {
 
             Response response = null;
             try {
-                response = newResponse(request, responses, unavailableShardExceptions, nodeIds, clusterState);
+                response = newResponse(request, responses, unavailableShardCount, nodeIds, clusterState);
             } catch (Exception e) {
                 logger.debug("failed to combine responses from nodes", e);
                 listener.onFailure(e);