Concurrency/interface/TaskBase.h

0001 #ifndef FWCore_Concurrency_TaskBase_h
0002 #define FWCore_Concurrency_TaskBase_h
0003 // -*- C++ -*-
0004 //
0005 // Package:     Concurrency
0006 // Class  :     TaskBase
0007 //
0008 /**\class TaskBase TaskBase.h FWCore/Concurrency/interface/TaskBase.h
0009
0010  Description: Base class for tasks.
0011
0012  Usage:
0013     Used as a callback to happen after a task has been completed.
0014 */
0015 //
0016 // Original Author:  Chris Jones
0017 //         Created:  Tue Jan 5 13:46:31 CST 2020
0018 // $Id$
0019 //
0020
0021 // system include files
0022 #include <atomic>
0023 #include <exception>
0024 #include <memory>
0025
0026 // user include files
0027
0028 // forward declarations
0029
0030 namespace edm {
0031   class TaskBase {
0032   public:
0033     friend class TaskSentry;
0034
0035     ///Constructor
0036     TaskBase() noexcept : m_refCount{0} {}
0037     virtual ~TaskBase() noexcept = default;
0038
0039     virtual void execute() = 0;
0040
0041     void increment_ref_count() noexcept { ++m_refCount; }
0042     unsigned int decrement_ref_count() noexcept { return --m_refCount; }
0043
0044   private:
0045     virtual void recycle() { delete this; }
0046
0047     std::atomic<unsigned int> m_refCount{0};
0048   };
0049
0050   class TaskSentry {
0051   public:
0052     TaskSentry(TaskBase* iTask) noexcept : m_task{iTask} {}
0053     ~TaskSentry() { m_task->recycle(); }
0054     TaskSentry() = delete;
0055     TaskSentry(TaskSentry const&) = delete;
0056     TaskSentry(TaskSentry&&) = delete;
0057     TaskSentry operator=(TaskSentry const&) = delete;
0058     TaskSentry operator=(TaskSentry&&) = delete;
0059
0060   private:
0061     TaskBase* m_task;
0062   };
0063 }  // namespace edm
0064
0065 #endif