deal.II version GIT relicensing-1982-gbb401394a0 2024-10-13 08:40:01+00:00
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Public Member Functions | Static Public Member Functions | Private Types | Private Member Functions | Private Attributes | Static Private Attributes | List of all members
MGSmootherBase< VectorType > Class Template Referenceabstract

#include <deal.II/multigrid/mg_base.h>

Inheritance diagram for MGSmootherBase< VectorType >:
Inheritance graph
[legend]

Public Member Functions

virtual ~MGSmootherBase () override=default
 
virtual void clear ()=0
 
virtual void smooth (const unsigned int level, VectorType &u, const VectorType &rhs) const =0
 
virtual void apply (const unsigned int level, VectorType &u, const VectorType &rhs) 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 ::ExceptionBaseExcInUse (int arg1, std::string arg2, std::string arg3)
 
static ::ExceptionBaseExcNoSubscriber (std::string arg1, std::string arg2)
 

Private Types

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

Private Member Functions

void check_no_subscribers () const noexcept
 

Private Attributes

std::atomic< unsigned intcounter
 
std::map< std::string, unsigned intcounter_map
 
std::vector< std::atomic< bool > * > validity_pointers
 
const std::type_info * object_info
 

Static Private Attributes

static std::mutex mutex
 

Detailed Description

template<typename VectorType>
class MGSmootherBase< VectorType >

Base class for multigrid smoothers. Does nothing but defining the interface used by multigrid methods.

The smoother interface provides two methods, a smooth() method and an apply() method. The multigrid preconditioner interfaces distinguish between the two for efficiency reasons: Upon entry to the preconditioner operations, the vector u needs to be set to zero and smoothing starts by a simple application of the smoother on the rhs vector. This method is provided by the apply() method of this class. It is the same as first setting u to zero and then calling smooth(), but for many classes the separate apply() interface is more efficient because it can skip one matrix-vector product.

In the multigrid preconditioner interfaces, the apply() method is used for the pre-smoothing operation because the previous content in the solution vector needs to be overwritten for a new incoming residual. On the other hand, all subsequent operations need to smooth the content already present in the vector u given the right hand side, which is done by smooth().

Definition at line 251 of file mg_base.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 231 of file enable_ref_counting_by_observer_pointer.h.

◆ map_iterator

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

The iterator type used in counter_map.

Definition at line 236 of file enable_ref_counting_by_observer_pointer.h.

Constructor & Destructor Documentation

◆ ~MGSmootherBase()

template<typename VectorType >
virtual MGSmootherBase< VectorType >::~MGSmootherBase ( )
overridevirtualdefault

Virtual destructor.

Member Function Documentation

◆ clear()

template<typename VectorType >
virtual void MGSmootherBase< VectorType >::clear ( )
pure virtual

◆ smooth()

template<typename VectorType >
virtual void MGSmootherBase< VectorType >::smooth ( const unsigned int  level,
VectorType &  u,
const VectorType &  rhs 
) const
pure virtual

Smoothing function that smooths the content in u given the right hand side vector rhs. This is the function used in multigrid methods.

Implemented in MGSmootherIdentity< VectorType >, MGSmootherRelaxation< MatrixType, RelaxationType, VectorType >, mg::SmootherRelaxation< RelaxationType, VectorType >, and MGSmootherPrecondition< MatrixType, PreconditionerType, VectorType >.

◆ apply()

template<typename VectorType >
void MGSmootherBase< VectorType >::apply ( const unsigned int  level,
VectorType &  u,
const VectorType &  rhs 
) const
virtual

As opposed to the smooth() function, this function applies the action of the smoothing, overwriting the previous content in the vector u. This function must be equivalent to the following code

u = 0;
smooth(level, u, rhs);
virtual void smooth(const unsigned int level, VectorType &u, const VectorType &rhs) const =0
unsigned int level
Definition grid_out.cc:4626

but can usually be implemented more efficiently than the former. If a particular smoother does not override the apply() method, the default implementation as described here is used.

In the multigrid preconditioner interfaces, the apply() method is used for the pre-smoothing operation because the previous content in the solution vector needs to be overwritten for a new incoming residual. On the other hand, all subsequent operations need to smooth the content already present in the vector u given the right hand side, which is done by smooth().

Reimplemented in MGSmootherRelaxation< MatrixType, RelaxationType, VectorType >, mg::SmootherRelaxation< RelaxationType, VectorType >, and MGSmootherPrecondition< MatrixType, PreconditionerType, VectorType >.

Definition at line 33 of file mg_base.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_ref_counting_by_observer.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_ref_counting_by_observer.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 315 of file enable_ref_counting_by_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 332 of file enable_ref_counting_by_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_ref_counting_by_observer.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 324 of file enable_ref_counting_by_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_ref_counting_by_observer.cc.

Member Data Documentation

◆ 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 220 of file enable_ref_counting_by_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 226 of file enable_ref_counting_by_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 242 of file enable_ref_counting_by_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 250 of file enable_ref_counting_by_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 273 of file enable_ref_counting_by_observer_pointer.h.


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