text: /**
   *    Copyright (C) 2015 MongoDB Inc.
   *
   *    This program is free software: you can redistribute it and/or  modify
   *    it under the terms of the GNU Affero General Public License, version 3,
   *    as published by the Free Software Foundation.
   *
   *    This program is distributed in the hope that it will be useful,
   *    but WITHOUT ANY WARRANTY; without even the implied warranty of
   *    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
   *    GNU Affero General Public License for more details.
   *
   *    You should have received a copy of the GNU Affero General Public License
   *    along with this program.  If not, see <http://www.gnu.org/licenses/>.
   *
   *    As a special exception, the copyright holders give permission to link the
   *    code of portions of this program with the OpenSSL library under certain
   *    conditions as described in each individual source file and distribute
   *    linked combinations including the program with the OpenSSL library. You
   *    must comply with the GNU Affero General Public License in all respects for
   *    all of the code used other than as permitted herein. If you modify file(s)
   *    with this exception, you may extend this exception to your version of the
   *    file(s), but you are not obligated to do so. If you do not wish to do so,
   *    delete this exception statement from your version. If you delete this
   *    exception statement from all source files in the program, then also delete
   *    it in the license file.
   */
  
  #pragma once
  
  #include <string>
  #include <vector>
  
  #include "mongo/base/status.h"
  #include "mongo/bson/bsonobj.h"
  #include "mongo/s/commands/strategy.h"
  #include "mongo/stdx/memory.h"
  
  namespace mongo {
  
  class BSONObj;
  
  class AScopedConnection;
  class ClusterCursorManager;
  class DBClientBase;
  class DBClientCursor;
  
  namespace executor {
  class TaskExecutor;
  }  // namespace executor
  
  /**
   * DEPRECATED - do not use in any new code. All new code must use the TaskExecutor interface
   * instead.
   */
  class Future {
  public:
      class CommandResult {
      public:
          std::string getServer() const {
              return _server;
          }
  
          bool isDone() const {
              return _done;
          }
  
          bool ok() const {
              verify(_done);
              return _ok;
          }
  
          BSONObj result() const {
              verify(_done);
              return _res;
          }
  
          /**
             blocks until command is done
             returns ok()
           */
          bool join(OperationContext* txn, int maxRetries = 1);
  
      private:
          CommandResult(const std::string& server,
                        const std::string& db,
                        const BSONObj& cmd,
                        int options,
                        DBClientBase* conn,
                        bool useShardedConn);
          void init();
  
          std::string _server;
          std::string _db;
          int _options;
          BSONObj _cmd;
          DBClientBase* _conn;
          std::unique_ptr<AScopedConnection> _connHolder;  // used if not provided a connection
          bool _useShardConn;
  
          std::unique_ptr<DBClientCursor> _cursor;
  
          BSONObj _res;
          bool _ok;
          bool _done;
  
          friend class Future;
      };
  
  
      /**
       * @param server server name
       * @param db db name
       * @param cmd cmd to exec
       * @param conn optional connection to use.  will use standard pooled if non-specified
       * @param useShardConn use ShardConnection
       */
      static std::shared_ptr<CommandResult> spawnCommand(const std::string& server,
                                                         const std::string& db,
                                                         const BSONObj& cmd,
                                                         int options,
                                                         DBClientBase* conn = 0,
                                                         bool useShardConn = false);
  };
  
  /**
   * Utility function to compute a single error code from a vector of command results.
   *
   * @return If there is an error code common to all of the error results, returns that error
   *          code; otherwise, returns 0.
   */
  int getUniqueCodeFromCommandResults(const std::vector<Strategy::CommandResult>& results);
  
  /**
   * Utility function to return an empty result set from a command.
   */
  bool appendEmptyResultSet(BSONObjBuilder& result, Status status, const std::string& ns);
  
  }  // namespace mongo
  