Fundamental Vector Reduction/Transformation Operator (RTOp) Interfaces  Version of the Day
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RTOpPack::RTOpT< Scalar > Class Template Referenceabstract

Templated interface to vector reduction/transformation operators {abstract}. More...

#include <RTOpPack_RTOpT_decl.hpp>

Inheritance diagram for RTOpPack::RTOpT< Scalar >:
Inheritance graph
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public types

typedef PrimitiveTypeTraits
< Scalar, Scalar >
::primitiveType 
primitive_value_type
 

Reduction object functions (NVI)

void get_reduct_type_num_entries (const Ptr< int > &num_values, const Ptr< int > &num_indexes, const Ptr< int > &num_chars) const
 Get the number of entries of each basic data type in the externalized state for a reduction object for this operator. More...
 
Teuchos::RCP< ReductTargetreduct_obj_create () const
 Creates a new reduction target object initialized and ready to be used in a reduction. More...
 
void reduce_reduct_objs (const ReductTarget &in_reduct_obj, const Ptr< ReductTarget > &inout_reduct_obj) const
 Reduce intermediate reduction target objects. More...
 
void reduct_obj_reinit (const Ptr< ReductTarget > &reduct_obj) const
 Reinitialize an already created reduction object. More...
 
void extract_reduct_obj_state (const ReductTarget &reduct_obj, const ArrayView< primitive_value_type > &value_data, const ArrayView< index_type > &index_data, const ArrayView< char_type > &char_data) const
 Extract the state of an already created reduction object. More...
 
void load_reduct_obj_state (const ArrayView< const primitive_value_type > &value_data, const ArrayView< const index_type > &index_data, const ArrayView< const char_type > &char_data, const Ptr< ReductTarget > &reduct_obj) const
 Load the state of an already created reduction object given arrays of primitive objects. More...
 

Operator functions (NIV)

std::string op_name () const
 Return the name (as a null-terminated C-style string) of the operator. More...
 
bool coord_invariant () const
 Returns true if this operator is coordinate invariant. More...
 
Range1D range () const
 Returns the continuous range of elements that this operator is defined over. More...
 
void apply_op (const ArrayView< const ConstSubVectorView< Scalar > > &sub_vecs, const ArrayView< const SubVectorView< Scalar > > &targ_sub_vecs, const Ptr< ReductTarget > &reduct_obj) const
 Apply the reduction/transformation operator to a set of sub-vectors. More...
 

Protected virtual functions to be overridden by subclasses.

virtual void get_reduct_type_num_entries_impl (const Ptr< int > &num_values, const Ptr< int > &num_indexes, const Ptr< int > &num_chars) const
 
virtual Teuchos::RCP
< ReductTarget
reduct_obj_create_impl () const
 
virtual void reduce_reduct_objs_impl (const ReductTarget &in_reduct_obj, const Ptr< ReductTarget > &inout_reduct_obj) const
 
virtual void reduct_obj_reinit_impl (const Ptr< ReductTarget > &reduct_obj) const
 
virtual void extract_reduct_obj_state_impl (const ReductTarget &reduct_obj, const ArrayView< primitive_value_type > &value_data, const ArrayView< index_type > &index_data, const ArrayView< char_type > &char_data) const
 
virtual void load_reduct_obj_state_impl (const ArrayView< const primitive_value_type > &value_data, const ArrayView< const index_type > &index_data, const ArrayView< const char_type > &char_data, const Ptr< ReductTarget > &reduct_obj) const
 
virtual std::string op_name_impl () const
 
virtual bool coord_invariant_impl () const
 
virtual Range1D range_impl () const
 
virtual void apply_op_impl (const ArrayView< const ConstSubVectorView< Scalar > > &sub_vecs, const ArrayView< const SubVectorView< Scalar > > &targ_sub_vecs, const Ptr< ReductTarget > &reduct_obj) const =0
 

Nonvirtual protected functions.

 RTOpT (const std::string &op_name_base="")
 Constructor that creates an operator name appended with the type. More...
 
void setOpNameBase (const std::string &op_name_base)
 Just set the operator name. More...
 

Detailed Description

template<class Scalar>
class RTOpPack::RTOpT< Scalar >

Templated interface to vector reduction/transformation operators {abstract}.

The purpose of this base class is to allow users to specify arbitrary reduction/transformation operations on vectors without requiring the vectors to reveal their implementation details. The design is motivated partly by the "Visitor" patter (Gamma, 1995).

This interface is designed to allow implementation of a distributed parallel abstract numerical algorithm without the explicit knowledge of the algorithm.

In the following discussion, v[k], x, y and z are some abstract vector objects of dimension n. Users can define operators to perform reduction and/or transformation operations. Reduction operations applied over all of the elements of a vector require communication between nodes in a parallel environment but do not change any of the vectors involved. Transformation operations don't require communication between nodes in a parallel environment. The targets of a transformation operation is a set of one or more vectors which are changed in some way.

The idea is that the user may want to perform reduction operations of the form:

op(v[0]...v[*],z[0]...z[*]) -> reduct_obj

where reduct_obj is a single object based on a reduction over all the elements of the vector arguments, or transformation operations of the form:

op(v[0](i)...v[*](i),z[0](i)...z[*](i)) -> z[0](i)...z[*](i), for i = 0...n-1

Operators can also be defined that perform reduction and transformation operations on the same vectors that that should only be done for efficiency reasons.

The tricky part though, is that the reduct_obj object of the reduction operation may be more complex than a single scalar value. For instance, it could be a double and an int pair such as in the reduction operation:

min{ |x(i)|, i = 0...n-1 } -> [ x(j_min), j_min ]

or it could perform several reductions at once and store several scalar values such as in:

min_max_sum{ x(i), i = 0...n-1 } -> [ x(j_min), j_min, x(j_max), j_max, x_sum ]

Transformation operations are much simpler to think about and to deal with. Some off-the-wall examples of transformation operations that this design will support are:

max{ |x(i)|, |y(i)| } + |z(i)| -> z(i), for i = 0...n-1

alpha * |z(i)| / x(i) -> z(i), for i = 0...n-1

alpha * x(i) * y(i) + beta * z(i) -> z(i), for i = 0...n-1

Reduction operations present the more difficult technical challenge since they require information gathered from all of the elements to arrive at the final result. This design allows operator classes to be defined that can simultaneously perform reduction and transformation operations:

  op(v[0](i)...v[*](i),z[0](i)...z[*](i)) -> z[0](i)...z[*](i),reduct_obj,
     for i = 0...n-1

This design is based on a few assumptions about the reduction and transformation operations and vector implementations themselves. First, we will assume that vectors are stored and manipulated as chunks of sub-vectors (of dimension subDim) where each sub-vector is sufficiently large to overcome the inherent overhead of this design. This design supports dense strided sub-vectors (see ConstSubVectorView and SubVectorView) but is relatively flexible.

It is strictly the responsibility of the vector implementations to determine how these operators are applied. For instance, if we are performing a transformation operation of the form:

op( x(i), y(i), z(i) ) -> z(i), for i = 0...n-1

where x, y, and z are distributed parallel vectors, then we would assume that the elements would be partitioned onto the various processors with the same local elements stored on each processor so as not to require any communication between processors.

Definition at line 137 of file RTOpPack_RTOpT_decl.hpp.

Member Typedef Documentation

template<class Scalar >
typedef PrimitiveTypeTraits<Scalar,Scalar>::primitiveType RTOpPack::RTOpT< Scalar >::primitive_value_type

Definition at line 145 of file RTOpPack_RTOpT_decl.hpp.

Constructor & Destructor Documentation

template<class Scalar >
RTOpPack::RTOpT< Scalar >::RTOpT ( const std::string &  op_name_base = "")
protected

Constructor that creates an operator name appended with the type.

Definition at line 113 of file RTOpPack_RTOpT_def.hpp.

Member Function Documentation

template<class Scalar >
void RTOpPack::RTOpT< Scalar >::get_reduct_type_num_entries ( const Ptr< int > &  num_values,
const Ptr< int > &  num_indexes,
const Ptr< int > &  num_chars 
) const
inline

Get the number of entries of each basic data type in the externalized state for a reduction object for this operator.

Note that a specific reduction object is not passed in as an argument. This is because the structure of a reduction object is completely determined by its associated operator object and this structure can not change as a result of a reduction operation (this is needed to simplify global communication code when used * with MPI).

The default implementation returns zeros for *num_values, *num_indexes and *num_chars (i.e. by default there is no reduction operation performed).

Definition at line 167 of file RTOpPack_RTOpT_decl.hpp.

template<class Scalar >
Teuchos::RCP<ReductTarget> RTOpPack::RTOpT< Scalar >::reduct_obj_create ( ) const
inline

Creates a new reduction target object initialized and ready to be used in a reduction.

The default implementation returns returnVal.get()==NULL (i.e. by default there is no reduction operation performed).

Definition at line 182 of file RTOpPack_RTOpT_decl.hpp.

template<class Scalar >
void RTOpPack::RTOpT< Scalar >::reduce_reduct_objs ( const ReductTarget in_reduct_obj,
const Ptr< ReductTarget > &  inout_reduct_obj 
) const
inline

Reduce intermediate reduction target objects.

The default implementation does not do anything (i.e. by default there is no reduction operation performed).

Definition at line 192 of file RTOpPack_RTOpT_decl.hpp.

template<class Scalar >
void RTOpPack::RTOpT< Scalar >::reduct_obj_reinit ( const Ptr< ReductTarget > &  reduct_obj) const
inline

Reinitialize an already created reduction object.

The default implementation does nothing (i.e. by default there is no reduction operation performed).

Parameters
reduct_obj[in/out] Reduction object is reinitialized on output.

Definition at line 206 of file RTOpPack_RTOpT_decl.hpp.

template<class Scalar >
void RTOpPack::RTOpT< Scalar >::extract_reduct_obj_state ( const ReductTarget reduct_obj,
const ArrayView< primitive_value_type > &  value_data,
const ArrayView< index_type > &  index_data,
const ArrayView< char_type > &  char_data 
) const
inline

Extract the state of an already created reduction object.

This method allows the state of a reduction target object to be externalized so that it can be passed over a heterogeneous network of computers.

The default implementation does nothing (i.e. by default there is no reduction operation performed).

Definition at line 220 of file RTOpPack_RTOpT_decl.hpp.

template<class Scalar >
void RTOpPack::RTOpT< Scalar >::load_reduct_obj_state ( const ArrayView< const primitive_value_type > &  value_data,
const ArrayView< const index_type > &  index_data,
const ArrayView< const char_type > &  char_data,
const Ptr< ReductTarget > &  reduct_obj 
) const
inline

Load the state of an already created reduction object given arrays of primitive objects.

The default implementation does nothing.

Definition at line 236 of file RTOpPack_RTOpT_decl.hpp.

template<class Scalar >
std::string RTOpPack::RTOpT< Scalar >::op_name ( ) const
inline

Return the name (as a null-terminated C-style string) of the operator.

This name is used to differentiate an operator subclass from all other operator subclasses. This is an important property needed for a client/server or master/slave runtime configuration.

The default implementation uses the value created in the constructor RTOpT().

Definition at line 260 of file RTOpPack_RTOpT_decl.hpp.

template<class Scalar >
bool RTOpPack::RTOpT< Scalar >::coord_invariant ( ) const
inline

Returns true if this operator is coordinate invariant.

The default implementation returns true as most vector operators are coordinate invariant.

Definition at line 274 of file RTOpPack_RTOpT_decl.hpp.

template<class Scalar >
Range1D RTOpPack::RTOpT< Scalar >::range ( ) const
inline

Returns the continuous range of elements that this operator is defined over.

Vector client implementations are free to ignore this but they can use this information to optimize rare operators that only interact with a subset of elements.

The default implementation return Range1D() which means all of the elements.

Definition at line 289 of file RTOpPack_RTOpT_decl.hpp.

template<class Scalar >
void RTOpPack::RTOpT< Scalar >::apply_op ( const ArrayView< const ConstSubVectorView< Scalar > > &  sub_vecs,
const ArrayView< const SubVectorView< Scalar > > &  targ_sub_vecs,
const Ptr< ReductTarget > &  reduct_obj 
) const
inline

Apply the reduction/transformation operator to a set of sub-vectors.

op(sub_vecs[], targ_sub_vecs[], reduct_obj) -> targ_sub_vecs[], reduct_obj.

This is the bread and butter of the whole design. Through this method, a vector implementation applies a reduction/transformation operator to a set of sub-vectors.

Parameters
sub_vecs[in] Array (length num_vecs) of non-mutable vectors to apply the operator over. The ordering of these sub-vectors sub_vecs[k], for k = 0...num_vecs-1, is significant to the this operator object. If num_vecs==0 then sub_vecs can be NULL.
targ_sub_vecs[in/out] Array (length num_targ_vecs) of mutable vectors to apply the operator over and be mutated. The ordering of these sub-vectors targ_sub_vecs[k], for k = 0...num_targ_vecs-1, is significant to this operator object. If num_targ_vecs==0 then targ_sub_vecs can be NULL.
reduct_obj[in/out] This reduction object must have been created by a this->reduct_obj_create() call and it may have * already passed through one or more other reduction operations (accumulating the reductions along the way). If this->get_reduct_type_num_entries() returns num_values==0, num_indexes==0 and num_chars==0, then reduct_obj should be set to NULL as no reduction will be performed.

Preconditions:

  • globalOffset==sub_vecs[k].globalOffset , for k = 0,...,sub_vecs.subDim()-1

  • globalOffset==targ_sub_vecs[k].globalOffset , for k = 0,...,targ_vecs.subDim()-1

  • subDim==sub_vecs[k].subDim() , for k = 0,...,sub_vecs.subDim()-1

  • subDim==targ_sub_vecs[k].subDim() , for k = 0,...,targ_vecs.subDim()-1

If nonnull(reduct_obj)==true then the reduction operation will be accumulated as:

op(sub_vecs[], targ_sub_vecs[], reduct_obj) -> reduct_obj

By allowing an in/out reduct_obj and an accumulation of the reduction, the maximum reuse of memory is achieved. If this->reduct_obj_create() or this->reduct_obj_reinit() (passing in reduct_obj) was called immediately before this function, then on return, reduct_obj will contain only the reduction from this function call.

If the sizes of sub_vecs and targ_sub_vecs is incompatible with the underlying operator object then InvalidNumVecs is thrown. If the sub-vectors are not compatible (i.e. globalOffset and/or subDim not the same) then IncompatibleVecs is thrown.

Definition at line 362 of file RTOpPack_RTOpT_decl.hpp.

template<class Scalar >
void RTOpPack::RTOpT< Scalar >::get_reduct_type_num_entries_impl ( const Ptr< int > &  num_values,
const Ptr< int > &  num_indexes,
const Ptr< int > &  num_chars 
) const
protectedvirtual

Definition at line 27 of file RTOpPack_RTOpT_def.hpp.

template<class Scalar >
Teuchos::RCP< ReductTarget > RTOpPack::RTOpT< Scalar >::reduct_obj_create_impl ( ) const
protectedvirtual

Definition at line 41 of file RTOpPack_RTOpT_def.hpp.

template<class Scalar >
void RTOpPack::RTOpT< Scalar >::reduce_reduct_objs_impl ( const ReductTarget in_reduct_obj,
const Ptr< ReductTarget > &  inout_reduct_obj 
) const
protectedvirtual

Definition at line 48 of file RTOpPack_RTOpT_def.hpp.

template<class Scalar >
void RTOpPack::RTOpT< Scalar >::reduct_obj_reinit_impl ( const Ptr< ReductTarget > &  reduct_obj) const
protectedvirtual

Definition at line 57 of file RTOpPack_RTOpT_def.hpp.

template<class Scalar >
void RTOpPack::RTOpT< Scalar >::extract_reduct_obj_state_impl ( const ReductTarget reduct_obj,
const ArrayView< primitive_value_type > &  value_data,
const ArrayView< index_type > &  index_data,
const ArrayView< char_type > &  char_data 
) const
protectedvirtual

Definition at line 65 of file RTOpPack_RTOpT_def.hpp.

template<class Scalar >
void RTOpPack::RTOpT< Scalar >::load_reduct_obj_state_impl ( const ArrayView< const primitive_value_type > &  value_data,
const ArrayView< const index_type > &  index_data,
const ArrayView< const char_type > &  char_data,
const Ptr< ReductTarget > &  reduct_obj 
) const
protectedvirtual

Definition at line 77 of file RTOpPack_RTOpT_def.hpp.

template<class Scalar >
std::string RTOpPack::RTOpT< Scalar >::op_name_impl ( ) const
protectedvirtual

Definition at line 89 of file RTOpPack_RTOpT_def.hpp.

template<class Scalar >
bool RTOpPack::RTOpT< Scalar >::coord_invariant_impl ( ) const
protectedvirtual

Definition at line 96 of file RTOpPack_RTOpT_def.hpp.

template<class Scalar >
Range1D RTOpPack::RTOpT< Scalar >::range_impl ( ) const
protectedvirtual

Definition at line 103 of file RTOpPack_RTOpT_def.hpp.

template<class Scalar >
virtual void RTOpPack::RTOpT< Scalar >::apply_op_impl ( const ArrayView< const ConstSubVectorView< Scalar > > &  sub_vecs,
const ArrayView< const SubVectorView< Scalar > > &  targ_sub_vecs,
const Ptr< ReductTarget > &  reduct_obj 
) const
protectedpure virtual

template<class Scalar >
void RTOpPack::RTOpT< Scalar >::setOpNameBase ( const std::string &  op_name_base)
protected

Just set the operator name.

Definition at line 120 of file RTOpPack_RTOpT_def.hpp.


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