TimeStepBase Class Reference

#include <deal.II/numerics/time_dependent.h>

Inheritance diagram for TimeStepBase:

Public Types
enum	SolutionState { primal_problem = 0x0 , dual_problem = 0x1 , postprocess = 0x2 }

Public Member Functions
	TimeStepBase (const double time)
virtual	~TimeStepBase () override=default
	TimeStepBase (const TimeStepBase &)=delete
TimeStepBase &	operator= (const TimeStepBase &)=delete
virtual void	wake_up (const unsigned int)
virtual void	sleep (const unsigned int)
virtual void	start_sweep ()
virtual void	end_sweep ()
virtual void	init_for_primal_problem ()
virtual void	init_for_dual_problem ()
virtual void	init_for_postprocessing ()
virtual void	solve_primal_problem ()=0
virtual void	solve_dual_problem ()
virtual void	postprocess_timestep ()
double	get_time () const
unsigned int	get_timestep_no () const
double	get_backward_timestep () const
double	get_forward_timestep () const
virtual std::size_t	memory_consumption () const
template<class Archive >
void	serialize (Archive &ar, const unsigned int version)
EnableObserverPointer functionality
Classes derived from EnableObserverPointer provide a facility to subscribe to this object. This is mostly used by the ObserverPointer class.
void	subscribe (std::atomic< bool > *const validity, const std::string &identifier="") const
void	unsubscribe (std::atomic< bool > *const validity, const std::string &identifier="") const
unsigned int	n_subscriptions () const
template<typename StreamType >
void	list_subscribers (StreamType &stream) const
void	list_subscribers () const

Static Public Member Functions
static ::ExceptionBase &	ExcInUse (int arg1, std::string arg2, std::string arg3)
static ::ExceptionBase &	ExcNoSubscriber (std::string arg1, std::string arg2)

Protected Attributes
const TimeStepBase *	previous_timestep
const TimeStepBase *	next_timestep
unsigned int	sweep_no
unsigned int	timestep_no
const double	time
unsigned int	next_action

Private Types
using	map_value_type = decltype(counter_map)::value_type
using	map_iterator = decltype(counter_map)::iterator

Private Member Functions
void	set_previous_timestep (const TimeStepBase *previous)
void	set_next_timestep (const TimeStepBase *next)
void	set_timestep_no (const unsigned int step_no)
void	set_sweep_no (const unsigned int sweep_no)
void	check_no_subscribers () const noexcept

Private Attributes
std::atomic< unsigned int >	counter
std::map< std::string, unsigned int >	counter_map
std::vector< std::atomic< bool > * >	validity_pointers
const std::type_info *	object_info

Static Private Attributes
static std::mutex	mutex

Friends
class	TimeDependent

Detailed Description

Base class for a time step in time dependent problems. This class provides barely more than the basic framework, defining the necessary virtual functions (namely sleep and wake_up), the interface to previous and following grids, and some functions to be called before a new loop over all time steps is started.

Definition at line 663 of file time_dependent.h.

Member Typedef Documentation

map_value_type

using EnableObserverPointer::map_value_type = decltype(counter_map)::value_type

privateinherited

The data type used in counter_map.

Definition at line 238 of file enable_observer_pointer.h.

map_iterator

using EnableObserverPointer::map_iterator = decltype(counter_map)::iterator

privateinherited

The iterator type used in counter_map.

Definition at line 243 of file enable_observer_pointer.h.

Member Enumeration Documentation

SolutionState

enum TimeStepBase::SolutionState

Enum denoting the type of problem which will have to be solved next.

Enumerator
primal_problem	Solve the primal problem next.
dual_problem	Solve the dual problem next.
postprocess	Perform postprocessing next.

Definition at line 669 of file time_dependent.h.

Constructor & Destructor Documentation

TimeStepBase() [1/2]

TimeStepBase::TimeStepBase

(

const double

time

)

Constructor. Does nothing here apart from setting the time.

Definition at line 268 of file time_dependent.cc.

~TimeStepBase()

virtual TimeStepBase::~TimeStepBase ( )

overridevirtualdefault

Destructor. At present, this does nothing.

TimeStepBase() [2/2]

TimeStepBase::TimeStepBase ( const TimeStepBase &  )

delete

The copy constructor is deleted to avoid shallow copies with unexpected behavior.

Member Function Documentation

operator=()

TimeStepBase & TimeStepBase::operator= ( const TimeStepBase &  )

delete

The copy assignment operator is deleted to avoid shallow copies with unexpected behavior.

wake_up()

void TimeStepBase::wake_up ( const unsigned int  )

virtual

Reconstruct all the data that is needed for this time level to work. This function serves to reget all the variables and data structures to work again after they have been send to sleep some time before, or at the first time we visit this time level. In particular, it is used to reconstruct the triangulation, degree of freedom handlers, to reload data vectors in case they have been stored to disk, etc.

The actual implementation of this function does nothing.

Since this is an important task, you should call this function from your own function, should you choose to overload it in your own class (which likely is the case), preferably at the beginning so that your function can take effect of the triangulation already existing.

Reimplemented in TimeStepBase_Tria< dim >.

Definition at line 280 of file time_dependent.cc.

sleep()

void TimeStepBase::sleep ( const unsigned int  )

virtual

This is the opposite function to wake_up. It is used to delete data or save it to disk after they are no more needed for the present sweep. Typical kinds of data for this are data vectors, degree of freedom handlers, triangulation objects, etc. which occupy large amounts of memory and may therefore be externalized.

By default, this function does nothing.

Reimplemented in TimeStepBase_Tria< dim >.

Definition at line 286 of file time_dependent.cc.

start_sweep()

void TimeStepBase::start_sweep ( )

virtual

This function is called each time before a new sweep is started. You may want to set up some fields needed in the course of the computations, and so on. You should take good care, however, not to install large objects, which should be deferred until the wake_up function is called.

A typical action of this function would be sorting out names of temporary files needed in the process of solving, etc.

At the time this function is called, the values of timestep_no, sweep_no and the pointer to the previous and next time step object already have their correct value.

The default implementation of this function does nothing.

Definition at line 292 of file time_dependent.cc.

end_sweep()

void TimeStepBase::end_sweep ( )

virtual

This is the analogous to the above function, but it is called at the end of a sweep. You will usually want to do clean-ups in this function, such as deleting temporary files and the like.

Definition at line 298 of file time_dependent.cc.

init_for_primal_problem()

void TimeStepBase::init_for_primal_problem ( )

virtual

Before the primal problem is solved on each time level, this function is called (i.e. before the solution takes place on the first time level). By default, this function sets the next_action variable of this class. You may overload this function, but you should call this function within your own one.

Definition at line 304 of file time_dependent.cc.

init_for_dual_problem()

void TimeStepBase::init_for_dual_problem ( )

virtual

Same as above, but called before a round of dual problem solves.

Definition at line 312 of file time_dependent.cc.

init_for_postprocessing()

void TimeStepBase::init_for_postprocessing ( )

virtual

Same as above, but called before a round of postprocessing steps.

Definition at line 320 of file time_dependent.cc.

solve_primal_problem()

virtual void TimeStepBase::solve_primal_problem ( )

pure virtual

This function is called by the manager object when solving the primal problem on this time level is needed. It is called after the wake_up function was called and before the sleep function will be called. There is no default implementation for obvious reasons, so you have to overload this function.

solve_dual_problem()

void TimeStepBase::solve_dual_problem ( )

virtual

This function is called by the manager object when solving the dual problem on this time level is needed. It is called after the wake_up function was called and before the sleep function will be called. There is a default implementation doing plain nothing since some problems may not need solving a dual problem. However, it will abort the program when being called anyway, since then you should really overload the function.

Definition at line 328 of file time_dependent.cc.

postprocess_timestep()

void TimeStepBase::postprocess_timestep ( )

virtual

This function is called by the manager object when postprocessing this time level is needed. It is called after the wake_up function was called and before the sleep function will be called. There is a default implementation doing plain nothing since some problems may not need doing a postprocess step, e.g. if everything was already done when solving the primal problem. However, it will abort the program when being called anyway, since then you should really overload the function.

Definition at line 336 of file time_dependent.cc.

get_time()

double TimeStepBase::get_time

(

)

const

Return the time value of this time step.

Definition at line 344 of file time_dependent.cc.

get_timestep_no()

unsigned int TimeStepBase::get_timestep_no

(

)

const

Return the number of this time step. Note that this number may vary between different sweeps, if timesteps are added or deleted.

Definition at line 352 of file time_dependent.cc.

get_backward_timestep()

double TimeStepBase::get_backward_timestep

(

)

const

Compute the time difference to the last time step. If this timestep is the first one, this function will result in an exception. Though this behavior seems a bit drastic, it is appropriate in most cases since if there is no previous time step you will need special treatment anyway and this way no invalid value is returned which could lead to wrong but unnoticed results of your computation. (The only sensible value to return in that case would not be zero, since valid computation can be done with that, but would be a denormalized value such as NaN. However, there is not much difference in finding that the results of a computation are all denormalized values or in getting an exception; in the latter case you at least get the exact place where your problem lies.)

Definition at line 360 of file time_dependent.cc.

get_forward_timestep()

double TimeStepBase::get_forward_timestep

(

)

const

Return the time difference to the next time step. With regard to the case that there is no next time step, the same applies as for the function above.

Definition at line 371 of file time_dependent.cc.

memory_consumption()

std::size_t TimeStepBase::memory_consumption ( ) const

virtual

Determine an estimate for the memory consumption (in bytes) of this object.

You will want to overload this function in derived classes to compute the amount memory used by the derived class, and add the result of this function to your result.

Reimplemented in TimeStepBase_Tria< dim >.

Definition at line 414 of file time_dependent.cc.

set_previous_timestep()

void TimeStepBase::set_previous_timestep ( const TimeStepBase *  previous )

private

Reset the pointer to the previous time step; shall only be called by the time level manager object.

This function is called at the set-up of the manager object and whenever a timestep is inserted or deleted.

Definition at line 382 of file time_dependent.cc.

set_next_timestep()

void TimeStepBase::set_next_timestep ( const TimeStepBase *  next )

private

Reset the pointer to the next time step; shall only be called by the time level manager object.

This function is called at the set-up of the manager object and whenever a timestep is inserted or deleted.

Definition at line 390 of file time_dependent.cc.

set_timestep_no()

void TimeStepBase::set_timestep_no ( const unsigned int  step_no )

private

Set the number this time step has in the list of timesteps. This function is called by the time step management object at the beginning of each sweep, to update information which may have changed due to addition or deletion of time levels.

Definition at line 398 of file time_dependent.cc.

set_sweep_no()

void TimeStepBase::set_sweep_no ( const unsigned int  sweep_no )

private

Set the number of the sweep we are presently in. This function is called by the time level management object at start-up time of each sweep.

Definition at line 406 of file time_dependent.cc.

subscribe()

void EnableObserverPointer::subscribe ( std::atomic< bool > *const  validity, const std::string &  identifier = ""  ) const

inherited

Subscribes a user of the object by storing the pointer validity. The subscriber may be identified by text supplied as identifier.

Definition at line 131 of file enable_observer_pointer.cc.

unsubscribe()

void EnableObserverPointer::unsubscribe ( std::atomic< bool > *const  validity, const std::string &  identifier = ""  ) const

inherited

Unsubscribes a user from the object.

Note

The identifier and the validity pointer must be the same as the one supplied to subscribe().

Definition at line 151 of file enable_observer_pointer.cc.

n_subscriptions()

unsigned int EnableObserverPointer::n_subscriptions ( ) const

inlineinherited

Return the present number of subscriptions to this object. This allows to use this class for reference counted lifetime determination where the last one to unsubscribe also deletes the object.

Definition at line 322 of file enable_observer_pointer.h.

list_subscribers() [1/2]

template<typename StreamType >

void EnableObserverPointer::list_subscribers ( StreamType &  stream ) const

inlineinherited

List the subscribers to the input stream.

Definition at line 339 of file enable_observer_pointer.h.

list_subscribers() [2/2]

void EnableObserverPointer::list_subscribers ( ) const

inherited

List the subscribers to deallog.

Definition at line 199 of file enable_observer_pointer.cc.

serialize()

template<class Archive >

void EnableObserverPointer::serialize ( Archive &  ar, const unsigned int  version  )

inlineinherited

Read or write the data of this object to or from a stream for the purpose of serialization using the BOOST serialization library.

This function does not actually serialize any of the member variables of this class. The reason is that what this class stores is only who subscribes to this object, but who does so at the time of storing the contents of this object does not necessarily have anything to do with who subscribes to the object when it is restored. Consequently, we do not want to overwrite the subscribers at the time of restoring, and then there is no reason to write the subscribers out in the first place.

Definition at line 331 of file enable_observer_pointer.h.

check_no_subscribers()

void EnableObserverPointer::check_no_subscribers ( ) const

privatenoexceptinherited

Check that there are no objects subscribing to this object. If this check passes then it is safe to destroy the current object. It this check fails then this function will either abort or print an error message to deallog (by using the AssertNothrow mechanism), but will not throw an exception.

Note

Since this function is just a consistency check it does nothing in release mode.

If this function is called when there is an uncaught exception then, rather than aborting, this function prints an error message to the standard error stream and returns.

Definition at line 53 of file enable_observer_pointer.cc.

Friends And Related Symbol Documentation

TimeDependent

friend class TimeDependent

friend

Definition at line 942 of file time_dependent.h.

Member Data Documentation

previous_timestep

const TimeStepBase* TimeStepBase::previous_timestep

protected

Pointer to the previous time step object in the list.

Definition at line 872 of file time_dependent.h.

next_timestep

const TimeStepBase* TimeStepBase::next_timestep

protected

Pointer to the next time step object in the list.

Definition at line 877 of file time_dependent.h.

sweep_no

unsigned int TimeStepBase::sweep_no

protected

Number of the sweep we are presently in. This number is reset by the time level manager before a sweep is started.

Definition at line 883 of file time_dependent.h.

timestep_no

unsigned int TimeStepBase::timestep_no

protected

Number of the time step, counted from zero onwards. This number is reset at the start of each sweep by the time level manager, since some time steps may have been inserted or deleted after the previous sweep.

Definition at line 890 of file time_dependent.h.

time

const double TimeStepBase::time

protected

Discrete time this level operates on.

Definition at line 895 of file time_dependent.h.

next_action

unsigned int TimeStepBase::next_action

protected

Variable storing whether the solution of a primal or a dual problem is actual, or any of the other actions specified. This variable is set by the init_for_* functions.

Definition at line 902 of file time_dependent.h.

counter

std::atomic<unsigned int> EnableObserverPointer::counter

mutableprivateinherited

Store the number of objects which subscribed to this object. Initially, this number is zero, and upon destruction it shall be zero again (i.e. all objects which subscribed should have unsubscribed again).

The creator (and owner) of an object is counted in the map below if HE manages to supply identification.

We use the mutable keyword in order to allow subscription to constant objects also.

This counter may be read from and written to concurrently in multithreaded code: hence we use the std::atomic class template.

Definition at line 227 of file enable_observer_pointer.h.

counter_map

std::map<std::string, unsigned int> EnableObserverPointer::counter_map

mutableprivateinherited

In this map, we count subscriptions for each different identification string supplied to subscribe().

Definition at line 233 of file enable_observer_pointer.h.

validity_pointers

std::vector<std::atomic<bool> *> EnableObserverPointer::validity_pointers

mutableprivateinherited

In this vector, we store pointers to the validity bool in the ObserverPointer objects that subscribe to this class.

Definition at line 249 of file enable_observer_pointer.h.

object_info

const std::type_info* EnableObserverPointer::object_info

mutableprivateinherited

Pointer to the typeinfo object of this object, from which we can later deduce the class name. Since this information on the derived class is neither available in the destructor, nor in the constructor, we obtain it in between and store it here.

Definition at line 257 of file enable_observer_pointer.h.

mutex

std::mutex EnableObserverPointer::mutex

staticprivateinherited

A mutex used to ensure data consistency when accessing the mutable members of this class. This lock is used in the subscribe() and unsubscribe() functions, as well as in list_subscribers().

Definition at line 280 of file enable_observer_pointer.h.

---

The documentation for this class was generated from the following files:

• include/deal.II/numerics/time_dependent.h
• source/numerics/time_dependent.cc