Tpetra parallel linear algebra  Version of the Day
 All Classes Namespaces Files Functions Variables Typedefs Enumerations Enumerator Macros Pages
Classes | Public Member Functions | List of all members
Tpetra::Details::TieBreak< LocalOrdinal, GlobalOrdinal > Class Template Referenceabstract

Interface for breaking ties in ownership. More...

#include <Tpetra_TieBreak.hpp>

Classes

struct  Triplet
 Representation of a global index on a process. More...
 

Public Member Functions

virtual bool mayHaveSideEffects () const
 Whether selectedIndex() may have side effects. More...
 
virtual ~TieBreak ()
 Virtual destructor (for memory safety of derived classes). More...
 
virtual std::size_t selectedIndex (GlobalOrdinal GID, const std::vector< std::pair< int, LocalOrdinal > > &pid_and_lid) const =0
 Break any ties in ownership of the given global index GID. More...
 

Detailed Description

template<typename LocalOrdinal, typename GlobalOrdinal>
class Tpetra::Details::TieBreak< LocalOrdinal, GlobalOrdinal >

Interface for breaking ties in ownership.

Template Parameters
LocalOrdinalThe type of local indices.
GlobalOrdinalThe type of global indices.

This class provides an abstract interface to a way for Directory to "break ties" in ownership of global indices. To "break a tie" for a global index GID means: Given a set of one or more (PID, LID) pairs, where each PID is a process that owns GID and LID is the corresponding local index of GID, choose exactly one (PID, LID) pair from that set. Furthermore, this choice must be a global choice, that is, the same on all participating processes.

Definition at line 68 of file Tpetra_TieBreak.hpp.

Constructor & Destructor Documentation

template<typename LocalOrdinal, typename GlobalOrdinal>
virtual Tpetra::Details::TieBreak< LocalOrdinal, GlobalOrdinal >::~TieBreak ( )
inlinevirtual

Virtual destructor (for memory safety of derived classes).

Definition at line 103 of file Tpetra_TieBreak.hpp.

Member Function Documentation

template<typename LocalOrdinal, typename GlobalOrdinal>
virtual bool Tpetra::Details::TieBreak< LocalOrdinal, GlobalOrdinal >::mayHaveSideEffects ( ) const
inlinevirtual

Whether selectedIndex() may have side effects.

If you are defining your own implementation (i.e., subclass) of this class, and if you know that your implementation of selectedIndex() does not have side effects, then you may redefine this method to return false. This may skip using the TieBreak object in certain cases, to save local work. Otherwise, we must use the TieBreak object in case the implementation has desired side effects.

Definition at line 98 of file Tpetra_TieBreak.hpp.

template<typename LocalOrdinal, typename GlobalOrdinal>
virtual std::size_t Tpetra::Details::TieBreak< LocalOrdinal, GlobalOrdinal >::selectedIndex ( GlobalOrdinal  GID,
const std::vector< std::pair< int, LocalOrdinal > > &  pid_and_lid 
) const
pure virtual

Break any ties in ownership of the given global index GID.

Given a global index GID, and a set of (PID, LID) pairs (of processes that own GID, and the local index of GID on that process), return the index of one pair in the list.

This method must always be called collectively over all the processes in the Directory's communicator. Subclasses reserve the right to use communication (either point-to-point or collective) over that communicator, but are not required to do so. However, their decisions are required to be consistent over those processes. This means that if multiple processes call this method with the same GID and the same list of pairs, all these processes must return the same index. (It would also be a good idea for subclasses not to be sensitive to the order of pairs.)

FIXME (mfh 17 Sep 2013) I'm not a fan of the name of this method. We should call it something more indicative of its function, like "arbitrateOwnership" or "breakTie".


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