MueLu_MutuallyExclusiveTime.hpp

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#ifndef MUELU_MUTUALLYEXCLUSIVETIME_HPP
#define MUELU_MUTUALLYEXCLUSIVETIME_HPP

#include <string>
#include <stack>
#include <map>
#include <iostream>                     // for basic_ostream, etc
#include <utility>                      // for pair
#include "Teuchos_FancyOStream.hpp"     // for basic_FancyOStream, etc
#include "Teuchos_RCP.hpp"              // for RCP::operator->, etc
#include "Teuchos_RCPDecl.hpp"          // for RCP
#include "Teuchos_TestForException.hpp"  // for TEUCHOS_TEST_FOR_EXCEPTION
#include "Teuchos_Time.hpp"
#include "Teuchos_TimeMonitor.hpp"
#include "MueLu_ConfigDefs.hpp"
#include "MueLu_Exceptions.hpp"
#include "MueLu_BaseClass.hpp"
#include "MueLu_VerbosityLevel.hpp"     // for MsgType::Debug, etc

namespace MueLu {

  // Map that record parent/child relations for post-processing.
  extern std::map<std::string,std::string> myParent_;

  template<class TagName>
  class MutuallyExclusiveTime : public BaseClass {

  public:


    MutuallyExclusiveTime(const std::string &name, bool startFlag=false)
      : name_(name),
        timer_(rcp(new Teuchos::Time(name, false))),  // second argument is false in any case, because if start==true,
                                                      // timer has to be started by MutuallyExclusiveTime::start() instead of Teuchos::Time::start().
        isPaused_(false)
    {
      if (startFlag == true) timer_->start();
    }

    ~MutuallyExclusiveTime() {
      // This timer can only be destroyed if it is not in the stack
      if (isPaused()) {
        // error message because cannot throw an exception in destructor
        GetOStream(Errors) << "MutuallyExclusiveTime::~MutuallyExclusiveTime(): Error: destructor called on a paused timer." << std::endl;
        //TODO: Even if timing results will be wrong, the timer can be removed from the stack to avoid a segmentation fault.
      }

      stop(); // if isRunning(), remove from the stack, resume previous timer
    }

    void start(bool reset=false) {
      TEUCHOS_TEST_FOR_EXCEPTION(isPaused(), Exceptions::RuntimeError, "MueLu::MutuallyExclusiveTime::start(): timer is paused. Use resume().");

      if (isRunning()) { return; } // If timer is already running, do not pause/push-in-the-stack/start the timer.
                                   // Otherwise, something bad will happen when this.stop() will be called

      // pause currently running timer
      if (!timerStack_.empty()) {
        GetOStream(Debug) << "pausing parent timer " << timerStack_.top()->name_ << std::endl;
        timerStack_.top()->pause();
        GetOStream(Debug) << "starting child timer " << this->name_ << std::endl;
        myParent_[this->name_] = timerStack_.top()->name_;
      } else {
        GetOStream(Debug) << "starting orphan timer " << this->name_ << std::endl;
        myParent_[this->name_] = "no parent";
      }

      // start this timer
      timer_->start(reset);
      timerStack_.push(this);
    }



    double stop() {
      if(isPaused())
        GetOStream(Errors) << "MueLu::MutuallyExclusiveTime::stop(): timer is paused. Use resume()" << std::endl;

      if (!isRunning()) { return timer_->stop(); } // stop() can be called on stopped timer

      // Here, timer is running, so it is the head of the stack
      TopOfTheStack();

      timerStack_.pop();
      double r = timer_->stop();

      if (!timerStack_.empty()) {
            GetOStream(Debug) << "resuming timer " << timerStack_.top()->name_ << std::endl;
            timerStack_.top()->resume();
      }

      return r;
    }

    void pause() {
      if (isPaused()) // calling twice pause() is allowed
        return;

      TopOfTheStack();

      timer_->stop();
      isPaused_ = true;
    }


    void resume() {
      TopOfTheStack();

      // no 'shortcut' test necessary:
      // - if timer is stop, it is in pause (cannot be stop and not in pause because this timer is the head of the stack).
      // - if timer is running, nothing is changed by this function.

      timer_->start(false);
      isPaused_ = false;
    }





    bool isRunning() {
      if (timer_->isRunning()) {
               // TEUCHOS_TEST_FOR_EXCEPTION(timerStack_.top() != this, Exceptions::RuntimeError,
               //            "MueLu::MutuallyExclusiveTime::isRunning(): this timer is active so it is supposed to be the head of the stack");
      }
      return timer_->isRunning();
    }

    bool isPaused() {
      TEUCHOS_TEST_FOR_EXCEPTION(isPaused_ && timer_->isRunning(), Exceptions::RuntimeError, "");
      return isPaused_;
    }


    // Note: this function is provided by the timer class, not by a monitor (!= Teuchos)
    static RCP<MutuallyExclusiveTime<TagName> > getNewTimer(const std::string& name) {
      RCP<MutuallyExclusiveTime<TagName> > timer = rcp(new MutuallyExclusiveTime<TagName>(Teuchos::TimeMonitor::getNewTimer(name)));
      timer->name_ = name;
      return timer;
    }

    void incrementNumCalls() { timer_->incrementNumCalls(); }

    std::string name_;

    static void PrintParentChildPairs() {
      //key is child, value is parent
      RCP<Teuchos::FancyOStream> fos = Teuchos::fancyOStream(Teuchos::rcpFromRef(std::cout)); fos->setOutputToRootOnly(0);
      *fos << "Parent Child Map" << std::endl;
      std::map<std::string, std::string >::const_iterator iter;
      for (iter = ::MueLu::myParent_.begin(); iter != ::MueLu::myParent_.end(); ++iter) {
        *fos << "Key: " << iter->first << "  Value: " << iter->second << std::endl;
      }
    }

  private:

    MutuallyExclusiveTime(RCP<Teuchos::Time> timer)
      : timer_(timer), isPaused_(false)
    { }

    // MutuallyExclusiveTime() { }

    RCP<Teuchos::Time> timer_;
    bool isPaused_;

    // - empty when no active timer
    // - head is the active timer
    // - other timers are timers paused to enforce the mutually exclusive property of the timer set.
    static std::stack<MutuallyExclusiveTime<TagName>*> timerStack_;
    //static std::map<std::string,std::string> myParent_;

    void TopOfTheStack() {
      TEUCHOS_TEST_FOR_EXCEPTION(timerStack_.empty(), Exceptions::RuntimeError, "MueLu::MutuallyExclusiveTime::TopOfTheStack(): timer is not the head of the stack (stack is empty).");
      // TEUCHOS_TEST_FOR_EXCEPTION(timerStack_.top() != this, Exceptions::RuntimeError,  "MueLu::MutuallyExclusiveTime::TopOfTheStack(): timer is not the head of the stack.");
      TEUCHOS_TEST_FOR_EXCEPTION(!(isRunning() || isPaused()), Exceptions::RuntimeError,  "MueLu::MutuallyExclusiveTime::TopOfTheStack(): head of the stack timer is neither active nor paused.");
    }

  //TODO: test integrity of the stack:
  // Head = running or paused
  // Other timers of the stack = paused

  };

} // namespace MueLu

#endif // MUELU_MUTUALLYEXCLUSIVETIME_HPP