Query.java

// Method that overrides the gRPC 

@Override
  public void search(
      SearchRequest request,
      StreamObserver<SearchResult> responseObserver) {

    doSearch(request)
        .whenCompleteAsync(
            (result, t) -> {
              if (t != null) {
                LOG.error("Error completing the future", t);
                responseObserver.onError(t);
              } else {
                responseObserver.onNext(result);
                responseObserver.onCompleted();
              }
            });
  }
  
  public CompletableFuture<SearchResult> doSearch(SearchRequest request) {

    List<CompletableFuture<KaldbSearch.SearchResult>> queryServers = new ArrayList<>(servers.size());
    for (String server : servers) {
      // get stub
      queryServers.add(ListenableFuturesExtra.toCompletableFuture(stub.search(request)));
    }
    
    // query all servers
    CompletableFuture<List<SearchResult>> searchResults = CompletableFutures.successfulAsList(queryServers, t -> emptyResult);
    // aggregate
    // convert to proto
    return SearchResultUtils.toSearchResultProto(aggregatedResult);
  }