/*
  JobTicket  -  execution plan for render jobs

   Copyright (C)
     2012,            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.

* *****************************************************************/


/** @file job-ticket.cpp
 ** Implementation details of preparing and performing job invocations.
 ** 
 ** @todo WIP-WIP-WIP 3/2012
 ** @see Job
 **
 */


#include "steam/engine/job-ticket.hpp"
#include "vault/gear/nop-job-functor.hpp"
#include "lib/hash-combine.hpp"
#include "lib/depend.hpp"
#include "lib/util.hpp"


namespace steam {
namespace engine {
  
  using vault::gear::Job;
  using vault::gear::JobClosure;
  using lib::HashVal;
  using lib::unConst;
  using lib::time::FSecs;
  
  
  namespace { // Details...
    lib::Depend<vault::gear::NopJobFunctor> nopFunctor;
    
    /* ======== hard wired =================*/
    const FSecs JOB_MINIMUM_RUNTIME{1,1000};
    
  } // (END) Details...
  
  
  
  
  
  /** special »do nothing« JobTicket marker */
  JobTicket JobTicket::NOP{};            ////////////////////////////////////////////////////////////////////TICKET #725 : do we actually need that for the final data structure?
  
  JobTicket::JobTicket()
    : provision_{nopFunctor(), ExitNode::NIL}
  { }

  
  /**
   * Generate a render job to invoke the render network configuration
   * as defined and backing this JobTicket. The generated job descriptor record
   * will include a specific InvocationInstanceID, which factors in the nominal
   * frame time, but also the specific backing render configuration.
   * The actual implementation of the job functionality will be delegated
   * to the JobClosure, which was set up for this Segment and JobTiket
   * after the last Builder run created this part of the render network.
   */
  Job
  JobTicket::createJobFor (Time nominalTime)
  {
    if (this->empty())
      {                    //////////////////////////////////////////////////////////////////////////////////TICKET #1296 : can we get away just with a do-nothing functor?
        return Job(nopFunctor(), InvocationInstanceID(), nominalTime);
      }
    else
      {
        REQUIRE (this->isValid(), "Attempt to generate render job for incomplete or unspecified render plan.");
        JobClosure& functor = static_cast<JobClosure&> (unConst(provision_.jobFunctor));      ////////////////TICKET #1287 : fix actual interface down to JobFunctor (after removing C structs)
        InvocationInstanceID invoKey{timeHash (nominalTime, provision_.invocationSeed)};
        
        return Job(functor, invoKey, nominalTime);
      }
  }
  
  
  /**
   * Use observed runtime values of past job invocations to guess a sensible bound
   * for the calculation time to expect for next invocation.
   * @todo 6/2023 placeholder implementation with hard wired values in ExitNode
   */
  Duration
  JobTicket::getExpectedRuntime()
  {
    if (this->empty())
      return Duration{JOB_MINIMUM_RUNTIME};
    else
      {
        REQUIRE (isValid(), "Attempt to determine timings for incomplete or unspecified render plan.");
        return provision_.exitNode.getUpperBoundRuntime();
      }
  }
  
  
  /**
   * Tag the precomputed invocation ID with the nominal frame time
   */
  InvocationInstanceID
  JobTicket::timeHash (Time nominalTime, InvocationInstanceID const& seed)
  {
    InvocationInstanceID res{seed};
    HashVal timeMark = res.part.t;
    lib::hash::combine (timeMark, hash_value (nominalTime));
    res.part.t = timeMark;
    return res;
  }
  
  
  /**
   * Helper for tests: verify the given invocation parameters match this JobTicket.
   */
  bool
  JobTicket::verifyInstance (JobFunctor& functor, InvocationInstanceID const& invoKey, Time nominalTime)  const
  {
    return util::isSameObject (provision_.jobFunctor, functor)
       and invoKey == timeHash (nominalTime, provision_.invocationSeed);
  }

  
  
  
}} // namespace steam::engine