#include <particle_halo_topology.hpp>

Classes
struct	FlatTopo

Public Member Functions
void	init (const ParticleMigrator< Dim > &mig)
	Bind to a migrator (provides the decomposition, domain map, rank and comm).

void	build (const std::vector< Vec< Dim > > &pos, double rcut, bool includePeriodicSelf=false, bool allImages=false)
	(Re)establish the owner<->ghost correspondence: every owned particle within `rcut` of another rank's block becomes a ghost there.

std::size_t	numOwned () const

std::size_t	numGhost () const

const std::vector< Vec< Dim > > &	ghostPositions () const

void	forwardPositions (const Vec< Dim > owned, Vec< Dim > ghost)
	owned[N] -> ghost[G], with the periodic image shift added (use for positions).

template<typename T >
void	forward (const T owned, T ghost)
	owned[N] -> ghost[G], verbatim (translation-invariant fields: velocity, id, radius, ...).

template<typename T >
void	reverse (const T ghost, T owned)
	ghost[G] -> owned[N], accumulated (T must have operator+=).

MPI_Comm	comm () const

FlatTopo	flatten () const

Detailed Description

template<int Dim>
class peclet::core::halo::ParticleHaloTopology< Dim >

Definition at line 37 of file particle_halo_topology.hpp.

Member Function Documentation

◆ init()

template<int Dim>

void peclet::core::halo::ParticleHaloTopology< Dim >::init ( const ParticleMigrator< Dim > & mig )

inline

Bind to a migrator (provides the decomposition, domain map, rank and comm).

Definition at line 40 of file particle_halo_topology.hpp.

◆ build()

template<int Dim>

void peclet::core::halo::ParticleHaloTopology< Dim >::build	(	const std::vector< Vec< Dim > > &	pos,
		double	rcut,
		bool	includePeriodicSelf = `false`,
		bool	allImages = `false`
	)

inline

(Re)establish the owner<->ghost correspondence: every owned particle within rcut of another rank's block becomes a ghost there.

Call after migration / on neighbour-list rebuild.

includePeriodicSelf additionally emits LOCAL periodic self-ghosts: copies of an owned particle at its own periodic image(s) that fall within rcut of THIS rank's own block. They are needed when a rank borders itself across a periodic face — i.e. an undecomposed periodic axis (a "×1" ORB axis, e.g. the z of a 2×2×1 layout) or np=1 — where the periodic neighbour is owned by the same rank and so is never produced by the cross-rank exchange. Off by default => byte-identical to the cross-rank-only behaviour (no self-ghosts, no MPI self-messages). Self-ghosts occupy the ghost slots AFTER the received ones ([numReceived, numGhost)) and are filled locally (no MPI).

allImages changes what the CROSS-RANK exchange sends. Off (the default), each owned particle goes to each other rank at most once, at the single periodic image nearest that rank's block (withinRcutOfBlock). On a periodic axis the ORB leaves undecomposed, that nearest image is always the unshifted one (its gap on the axis is 0), so a wrapped image inside rcut is never sent. On, EVERY periodic image of the particle within rcut of rank r's block is sent (imagesWithinRcutOfBlock with the identity allowed), one send entry per image: the same owned index may then appear several times in one rank's send list, each with its own shift, and a receiver identifies a ghost by (owner id, shift). Every exchange works per entry, so forwardPositions places each image, and reverse sums every image's contribution onto the owner. The shift of an allImages entry is exactly 0 or +-L per axis. Off => byte-identical to the one-image behaviour.

Definition at line 65 of file particle_halo_topology.hpp.

References peclet::core::halo::ParticleHaloTopology< Dim >::forwardPositions(), and MPI_Comm_size().

◆ numOwned()

template<int Dim>

std::size_t peclet::core::halo::ParticleHaloTopology< Dim >::numOwned ( ) const

inline

Definition at line 183 of file particle_halo_topology.hpp.

◆ numGhost()

template<int Dim>

std::size_t peclet::core::halo::ParticleHaloTopology< Dim >::numGhost ( ) const

inline

Definition at line 184 of file particle_halo_topology.hpp.

Referenced by peclet::core::halo::ParticleHalo< Dim >::init().

◆ ghostPositions()

template<int Dim>

const std::vector< Vec< Dim > > & peclet::core::halo::ParticleHaloTopology< Dim >::ghostPositions ( ) const

inline

Definition at line 185 of file particle_halo_topology.hpp.

◆ forwardPositions()

template<int Dim>

void peclet::core::halo::ParticleHaloTopology< Dim >::forwardPositions	(	const Vec< Dim > *	owned,
		Vec< Dim > *	ghost
	)

inline

owned[N] -> ghost[G], with the periodic image shift added (use for positions).

Direct point-to-point over the topology fixed by build() (no NBX consensus) – this is the per-iteration hot path, so it must not pay the dynamic-discovery cost every call.

Definition at line 190 of file particle_halo_topology.hpp.

Referenced by peclet::core::halo::ParticleHaloTopology< Dim >::build().