.. _program_listing_file__tmp_ws_src_rmf_utils_rmf_utils_include_rmf_utils_AssignID.hpp:

Program Listing for File AssignID.hpp
=====================================

|exhale_lsh| :ref:`Return to documentation for file <file__tmp_ws_src_rmf_utils_rmf_utils_include_rmf_utils_AssignID.hpp>` (``/tmp/ws/src/rmf_utils/rmf_utils/include/rmf_utils/AssignID.hpp``)

.. |exhale_lsh| unicode:: U+021B0 .. UPWARDS ARROW WITH TIP LEFTWARDS

.. code-block:: cpp

   /*
    * Copyright (C) 2022 Open Source Robotics Foundation
    *
    * Licensed under the Apache License, Version 2.0 (the "License");
    * you may not use this file except in compliance with the License.
    * You may obtain a copy of the License at
    *
    *     http://www.apache.org/licenses/LICENSE-2.0
    *
    * Unless required by applicable law or agreed to in writing, software
    * distributed under the License is distributed on an "AS IS" BASIS,
    * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    * See the License for the specific language governing permissions and
    * limitations under the License.
    *
   */
   
   #ifndef RMF_UTILS__ASSIGNID_HPP
   #define RMF_UTILS__ASSIGNID_HPP
   
   #include <atomic>
   
   namespace rmf_utils {
   
   //==============================================================================
   template<typename T>
   class AssignID
   {
   public:
   
     AssignID(T initial_value = 0)
     : _value(std::move(initial_value))
     {
       // Do nothing
     }
   
     T assign() const
     {
       return _value.fetch_add(1);
     }
   
     void fast_forward_to(const T desired_value) const
     {
       // TODO(MXG): We could give more consideration to what memory models we are
       // using in these atomic operations.
       auto current_value = _value.load();
       while (current_value < desired_value)
       {
         const bool success =
           _value.compare_exchange_weak(current_value, desired_value);
   
         if (success)
           return;
   
         current_value = _value.load();
       }
     }
   
   private:
     mutable std::atomic<T> _value;
   };
   
   } // namespace rmf_utils
   
   #endif // RMF_UTILS__ASSIGNID_HPP