#include <deal.II/lac/vector_memory.h>

Inheritance diagram for VectorMemory< VectorType >:

Classes
class	Pointer

Public Member Functions
virtual	~VectorMemory ()

virtual VectorType *	alloc ()=0

virtual void	free (const VectorType *const)=0

Public Member Functions inherited from Subscriptor
	Subscriptor ()

	Subscriptor (const Subscriptor &)

	Subscriptor (Subscriptor &&)

virtual	~Subscriptor ()

Subscriptor &	operator= (const Subscriptor &)

Subscriptor &	operator= (Subscriptor &&)

void	subscribe (const char *identifier=0) const

void	unsubscribe (const char *identifier=0) const

unsigned int	n_subscriptions () const

void	list_subscribers () const

template<class Archive >
void	serialize (Archive &ar, const unsigned int version)

Static Public Member Functions
static ::ExceptionBase &	ExcNotAllocatedHere ()

Static Public Member Functions inherited from Subscriptor
static ::ExceptionBase &	ExcInUse (int arg1, char *arg2, std::string &arg3)

static ::ExceptionBase &	ExcNoSubscriber (char arg1, char arg2)

Detailed Description

template<typename VectorType = ::Vector<double>>
class VectorMemory< VectorType >

Memory management base class for vectors. This is an abstract base class used, among other places, by all iterative methods to allocate space for auxiliary vectors.

The purpose of this class is as follows: in iterative solvers and other places, one needs to allocate temporary storage for vectors, for example for auxiliary vectors. One could allocate and release them anew every time, but this may be expensive in some situations if it has to happen very frequently. A common case for this is when an iterative method is used to invert a matrix in each iteration an outer solver, such as when inverting a matrix block for a Schur complement solver.

In such situations, allocating and deallocating vectors anew in each call to the inner solver is expensive and leads to memory fragmentation. The present class allows to avoid this by offering an interface that other classes can use to allocate and deallocate vectors. Different derived classes then implement different strategies to provide temporary storage vectors to using classes.

For example, the PrimitiveVectorMemory class simply allocates and deallocated vectors each time it is asked for a vector. It is an appropriate implementation to use for iterative solvers that are called only once, or very infrequently.

On the other hand, the GrowingVectorMemory class never returns memory space to the operating system memory management subsystem during its lifetime; it only marks them as unused and allows them to be reused next time a vector is requested.

Yet other classes, when implemented, could provide even other strategies for memory management.

Author: Guido Kanschat, 1998-2003

Definition at line 26 of file pointer_matrix.h.

Constructor & Destructor Documentation

◆ ~VectorMemory()

template<typename VectorType = ::Vector<double>>

virtual VectorMemory< VectorType >::~VectorMemory ( )

inlinevirtual

Virtual destructor is needed as there are virtual functions in this class.

Definition at line 79 of file vector_memory.h.

Member Function Documentation

◆ alloc()

template<typename VectorType = ::Vector<double>>

virtual VectorType* VectorMemory< VectorType >::alloc ( )

pure virtual

Return a pointer to a new vector. The number of elements or their subdivision into blocks (if applicable) is unspecified and users of this function should reset vectors to their proper size. The same holds for the contents of vectors: they are unspecified.

Implemented in GrowingVectorMemory< VectorType >, GrowingVectorMemory< BlockVector< number > >, and PrimitiveVectorMemory< VectorType >.