include/Gaudi/AsynchronousAlgorithm.h

0001 /***********************************************************************************\
0002 * (c) Copyright 2023-2024 CERN for the benefit of the LHCb and ATLAS collaborations *
0003 *                                                                                   *
0004 * This software is distributed under the terms of the Apache version 2 licence,     *
0005 * copied verbatim in the file "LICENSE".                                            *
0006 *                                                                                   *
0007 * In applying this licence, CERN does not waive the privileges and immunities       *
0008 * granted to it by virtue of its status as an Intergovernmental Organization        *
0009 * or submit itself to any jurisdiction.                                             *
0010 \***********************************************************************************/
0011 #pragma once
0012 // ============================================================================
0013 // Include files
0014 // ============================================================================
0015 // Gaudi
0016 #include <Gaudi/Algorithm.h>
0017 #include <GaudiKernel/IHiveWhiteBoard.h>
0018
0019 // Others
0020 #include <boost/fiber/all.hpp>
0021 #include <chrono>
0022
0023 namespace Gaudi {
0024   /** Base class for asynchronous algorithms.
0025    *
0026    *  Augments Gaudi::Algorithm by saving and restoring current slot whenever
0027    *  fiber is suspended and resumed. This requires using the member functions for
0028    *  suspending instead of the boost::fiber functions directly.
0029    *
0030    *  @author Beojan Stanislaus
0031    *  @date 2023
0032    */
0033
0034   class GAUDI_API AsynchronousAlgorithm : public Gaudi::Algorithm {
0035   public:
0036     using Gaudi::Algorithm::Algorithm;
0037     StatusCode sysInitialize() override;
0038     StatusCode sysExecute( const EventContext& ctx ) override;
0039
0040     /// Restore after suspend
0041     virtual StatusCode restoreAfterSuspend() const;
0042
0043     /// Forwards to boost::this_fiber::yield
0044     StatusCode yield() const;
0045
0046     /// Forwards to boost::this_fiber::sleep_until
0047     template <typename Clock, typename Duration>
0048     StatusCode sleep_until( std::chrono::time_point<Clock, Duration> const& sleep_time ) const {
0049       boost::this_fiber::sleep_until( sleep_time );
0050       return restoreAfterSuspend();
0051     }
0052
0053     /// Forwards to boost::this_fiber::sleep_for
0054     template <typename Rep, typename Period>
0055     StatusCode sleep_for( std::chrono::duration<Rep, Period> const& dur ) const {
0056       boost::this_fiber::sleep_for( dur );
0057       return restoreAfterSuspend();
0058     }
0059
0060   private:
0061     /// Contains current slot
0062     boost::fibers::fiber_specific_ptr<std::size_t> s_currentSlot{};
0063   };
0064 } // namespace Gaudi