scheduler-invocation.hpp

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/*
  SCHEDULER-INVOCATION.hpp  -  invocation layer of the render engine scheduler

   Copyright (C)
     2023,            Hermann Vosseler <Ichthyostega@web.de>

  **Lumiera** is free software; you can redistribute it and/or modify it
  under the terms of the GNU General Public License as published by the
  Free Software Foundation; either version 2 of the License, or (at your
  option) any later version. See the file COPYING for further details.

*/


#ifndef SRC_VAULT_GEAR_SCHEDULER_INVOCATION_H_
#define SRC_VAULT_GEAR_SCHEDULER_INVOCATION_H_


#include "vault/common.hpp"
#include "lib/nocopy.hpp"
#include "vault/gear/activity.hpp"
#include "lib/time/timevalue.hpp"
#include "lib/util.hpp"

#include <queue>
#include <boost/lockfree/queue.hpp>
#include <unordered_set>
#include <utility>

namespace vault{
namespace gear {
  
  using lib::time::Time;
  using std::move;
  
  namespace error = lumiera::error;
  
  namespace {// Internal defaults
    const size_t INITIAL_CAPACITY = 128;
  }
  
  struct ActivationEvent
    {
      Activity* activity;
      int64_t   starting;
      int64_t   deadline;
      
      uint32_t  manifestation :32;
      bool      isCompulsory  :1;
      
      ActivationEvent()
        : activity{nullptr}
        , starting{_raw(Time::ANYTIME)}
        , deadline{_raw(Time::NEVER)}
        , manifestation{0}
        , isCompulsory{false}
        { }

      ActivationEvent(Activity& act, Time when
                                   , Time dead =Time::NEVER
                                   , ManifestationID manID =ManifestationID()
                                   , bool compulsory =false)
        : activity{&act}
        , starting{_raw(act.constrainedStart(when))}
        , deadline{_raw(act.constrainedDeath(dead))}
        , manifestation{manID}
        , isCompulsory{compulsory}
        { }
       // default copy operations acceptable
      
      bool
      operator< (ActivationEvent const& o)  const
        {
          return starting > o.starting;
        }
      
      operator bool()      const { return bool{activity}; }
      operator Activity*() const { return activity; }
      
      Time startTime()     const { return Time{TimeValue{starting}};}
      Time deathTime()     const { return Time{TimeValue{deadline}};}
      
      void
      refineTo (Activity* chain, Time when, Time dead)
        {
          activity = chain;
          starting = _raw(activity->constrainedStart (when.isRegular()? when:startTime()));
          deadline = _raw(activity->constrainedDeath (dead.isRegular()? dead:deathTime()));
        }
    };
  
  
  
  
  /***************************************************/
  class SchedulerInvocation
    : util::NonCopyable
    {
      using InstructQueue = boost::lockfree::queue<ActivationEvent>;
      using PriorityQueue = std::priority_queue<ActivationEvent>;
      using ActivationSet = std::unordered_set<ManifestationID>;
      
      InstructQueue instruct_;
      PriorityQueue priority_;
      
      ActivationSet allowed_;
      
    public:
      SchedulerInvocation()
        : instruct_{INITIAL_CAPACITY}
        , priority_{}
        , allowed_{}
        { }
      
      
      void
      discardSchedule()
        {
          instruct_.consume_all([](auto&){/*obliterate*/});
          priority_ = PriorityQueue();
        }
      
      
      void
      instruct (ActivationEvent actEvent)
        {
          bool success = instruct_.push (move (actEvent));
          if (not success)
            throw error::Fatal{"Scheduler entrance: memory allocation failed"};
        }
      
      
      void
      feedPrioritisation()
        {
          ActivationEvent actEvent;
          while (instruct_.pop (actEvent))
            priority_.push (move (actEvent));
        }
      
      
      void
      feedPrioritisation (ActivationEvent actEvent)
        {
          priority_.push (move (actEvent));
        }
      
      
      ActivationEvent
      peekHead()
        {
          return priority_.empty()? ActivationEvent()
                                  : priority_.top();
        }
      
      ActivationEvent
      pullHead()
        {
          ActivationEvent head = peekHead();
          if (head)
            priority_.pop();
          return head;
        }
      
      void
      activate (ManifestationID manID)
        {
          if (manID)
            allowed_.insert (manID);
        }
      
      void
      drop (ManifestationID manID)
        {
          allowed_.erase (manID);
        }
      
      
      /* ===== query functions ===== */
      
      bool
      isDue (Time now)  const
        {
          return not priority_.empty()
             and priority_.top().starting <= waterLevel(now);
        }

      bool
      isMissed (Time now)  const
        {
          return not priority_.empty()
             and waterLevel(now) > priority_.top().deadline;
        }
      
      bool
      isActivated (ManifestationID manID)  const
        {
          return manID == ManifestationID()
              or util::contains (allowed_, manID);
        }
      
      bool
      isOutdated (Time now)  const
        {
          return isMissed (now)
              or (not priority_.empty()
                  and not isActivated (priority_.top().manifestation));
        }
      
      bool
      isOutOfTime (Time now)  const
        {
          return isMissed (now)
             and (not priority_.empty()
                  and priority_.top().isCompulsory
                  and isActivated (priority_.top().manifestation));
        }
      
      bool
      hasPendingInput()  const
        {
          return not instruct_.empty();
        }
      
      bool
      empty()  const
        {
          return instruct_.empty()
             and priority_.empty();
        }
      
      Time
      headTime()  const
        {
          return priority_.empty()? Time::NEVER
                                  : Time{TimeValue{priority_.top().starting}};
        }                              //Note: 64-bit waterLevel corresponds to µ-Ticks
      
    private:
      static int64_t
      waterLevel (Time time)
        {
          return _raw(time);
        }
    };
  
  
  
}} // namespace vault::gear
#endif /*SRC_VAULT_GEAR_SCHEDULER_INVOCATION_H_*/