Worker.h

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#ifndef art_Framework_Principal_Worker_h
#define art_Framework_Principal_Worker_h
// vim: set sw=2 expandtab :

// ======================================================================
// Worker: this is a basic scheduling unit - an abstract base class to
// something that is really a producer or filter.
//
// A worker will not actually call through to the module unless it is
// in a Ready state.  After a module is actually run, the state will
// not be Ready.  The Ready state can only be reestablished by doing a
// reset().
//
// Pre/post module signals are posted only in the Ready state.
//
// Execution statistics are kept here.
//
// If a module has thrown an exception during execution, that
// exception will be rethrown if the worker is entered again and the
// state is not Ready.  In other words, execution results (status) are
// cached and reused until the worker is reset().
// ======================================================================

#include "art/Framework/Principal/fwd.h"
#include "art/Persistency/Provenance/ModuleDescription.h"
#include "art/Utilities/ScheduleID.h"
#include "art/Utilities/Transition.h"
#include "hep_concurrency/WaitingTaskList.h"

#include <atomic>
#include <exception>
#include <string>
#include <vector>

namespace hep::concurrency {
  class SerialTaskQueueChain;
}

namespace art {
  class ActivityRegistry;
  class ModuleContext;
  class FileBlock;
  class RunPrincipal;
  class SubRunPrincipal;
  class EventPrincipal;
  namespace detail {
    class SharedResources;
  }

  class Worker {
    friend class RunWorkerFunctor;

  public:
    enum State { Ready, Pass, Fail, Working, ExceptionThrown };

    virtual ~Worker() = default;
    Worker(ModuleDescription const&, WorkerParams const&);

    void beginJob(detail::SharedResources const&);
    void endJob();
    void respondToOpenInputFile(FileBlock const& fb);
    void respondToCloseInputFile(FileBlock const& fb);
    void respondToOpenOutputFiles(FileBlock const& fb);
    void respondToCloseOutputFiles(FileBlock const& fb);
    bool doWork(Transition, Principal&, ModuleContext const&);

    void doWork_event(hep::concurrency::WaitingTaskPtr workerInPathDoneTask,
                      EventPrincipal&,
                      ModuleContext const&);

    // This is used only to do trigger results insertion.
    void doWork_event(EventPrincipal&, ModuleContext const&);

    ScheduleID
    scheduleID() const
    {
      return scheduleID_;
    }
    ModuleDescription const& description() const;
    std::string const& label() const;

    // Used only by WorkerInPath.
    bool returnCode() const;

    hep::concurrency::SerialTaskQueueChain* serialTaskQueueChain() const;

    // Used by EventProcessor
    // Used by Schedule
    // Used by EndPathExecutor
    void reset();

    // Used only by writeSummary
    std::size_t timesVisited() const;
    std::size_t timesRun() const;
    std::size_t timesPassed() const;
    std::size_t timesFailed() const;
    std::size_t timesExcept() const;

    void runWorker(EventPrincipal&, ModuleContext const&);

  protected:
    virtual std::string workerType() const = 0;
    virtual hep::concurrency::SerialTaskQueueChain* implSerialTaskQueueChain()
      const = 0;
    virtual void implBeginJob(detail::SharedResources const& resources) = 0;
    virtual void implEndJob() = 0;
    virtual bool implDoBegin(RunPrincipal& rp, ModuleContext const& mc) = 0;
    virtual bool implDoEnd(RunPrincipal& rp, ModuleContext const& mc) = 0;
    virtual bool implDoBegin(SubRunPrincipal& srp, ModuleContext const& mc) = 0;
    virtual bool implDoEnd(SubRunPrincipal& srp, ModuleContext const& mc) = 0;
    virtual bool implDoProcess(EventPrincipal&, ModuleContext const&) = 0;

  private:
    // API implementation classes must use to provide their API to us
    virtual void implRespondToOpenInputFile(FileBlock const& fb) = 0;
    virtual void implRespondToCloseInputFile(FileBlock const& fb) = 0;
    virtual void implRespondToOpenOutputFiles(FileBlock const& fb) = 0;
    virtual void implRespondToCloseOutputFiles(FileBlock const& fb) = 0;

    ScheduleID const scheduleID_;
    ModuleDescription const md_;
    ActionTable const& actions_;
    ActivityRegistry const& actReg_;
    std::atomic<int> state_{Ready};

    // if state is 'exception'
    // Note: threading: There is no accessor for this data, the only
    // way it is ever used is from the doWork* functions.  Right now
    // event processing only sets it, but run and subrun processing
    // reads it.  It is not clear that event processing needs this
    // anymore, and if we go to multiple runs and subruns in flight,
    // they may not need it anymore as well.  For now, leave this, is
    // not thread safe.
    std::exception_ptr cached_exception_{};

    std::atomic<bool> workStarted_{false};
    std::atomic<bool> returnCode_{false};

    // Holds the waiting workerInPathDone tasks.  Note: For shared
    // modules the workers are shared.  For replicated modules each
    // schedule has its own private worker copies (the whole reason
    // schedules exist!).
    hep::concurrency::WaitingTaskList waitingTasks_;

  protected:
    std::atomic<std::size_t> counts_visited_{};
    std::atomic<std::size_t> counts_run_{};
    std::atomic<std::size_t> counts_passed_{};
    std::atomic<std::size_t> counts_failed_{};
    std::atomic<std::size_t> counts_thrown_{};
  };

} // namespace art

#endif /* art_Framework_Principal_Worker_h */

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