nest::SparseNodeArray Class Reference

Sparse representation of local nodes. More...

#include <sparse_node_array.h>

Collaboration diagram for nest::SparseNodeArray:

Classes
class	NodeEntry
	Entry representing individual node. More...

Public Types
typedef BlockVector< SparseNodeArray::NodeEntry >::const_iterator	const_iterator
	Iterator inherited from BlockVector.

Public Member Functions
	SparseNodeArray ()
	Create empty sparse node array.
size_t	size () const
	Return size of container.
void	clear ()
	Clear the array.
void	add_local_node (Node &)
	Add single local node.
void	set_max_node_id (size_t)
	Set max node ID to maximum in network.
size_t	get_max_node_id () const
	Globally largest node ID.
Node *	get_node_by_node_id (size_t) const
	Return pointer to node or nullptr if node is not local.
Node *	get_node_by_index (size_t) const
	Lookup node based on index into container.
const_iterator	begin () const
	Constant iterators for safe iteration of SparseNodeArray.
const_iterator	end () const

Private Member Functions
bool	is_consistent_ () const

Private Attributes
BlockVector< NodeEntry >	nodes_
	stores local node information
size_t	global_max_node_id_
	globally largest node ID
size_t	local_min_node_id_
	smallest local node ID
size_t	local_max_node_id_
	largest local node ID
double	left_scale_
	scale factor for left side of array
double	right_scale_
	scale factor for right side of array
size_t	split_node_id_
	Globally smallest node ID in right side of array.
size_t	split_idx_
	Array index of first element in right side of array.
bool	have_split_
	Mark whether split has happened during network construction.
bool	left_side_has_proxies_
	Proxy status of nodes on left side of array.

Detailed Description

Sparse representation of local nodes.

SparseNodeArray maps node IDs of thread-local nodes to Node*. It provides a const iterator interface for iteration over all local nodes, lookup by node ID and lookup by numeric index into local nodes. The latter is provided to support HPC synapses using TargetIdentifierIndex representation.

For efficient lookup, all normal nodes (with proxies) need to be created together and all devices need to be created together. It does not matter which are created first. If nodes and devices are created alternatingly, lookup performance may suffer significantly if many devices are present. This mainly affects network connection.

As nodes are added to an initially empty SparseNodeArray, the array tracks whether nodes have proxies or not. Array lookup is split at the point of the first proxy/no-proxy (or no-proxy/proxy) transition between nodes. In the no-proxy region, where all nodes are represented locally, Node IDs are mapped directly to array indices. In the proxy region, they are scaled by 1/n_vp.

To reliably reject requests for node IDs beyond the globally maximal node ID, the latter must be set explicitly. A SparseNodeArray is said to be in consistent state if the global maximal node ID has been set. Once add_local_node() is called, the array is not in consistent state until the global maximal node ID is set again. This is indicated by setting the max_node_id_ == 0. Looking up nodes while the array is not in a consistent state triggers an assertion.

To also support cases in which users alternate creation of nodes with and without proxies or use nodes with special behavior (e.g., MUSIC nodes), we perform a linear search from the estimated location of the node in the array.

The following invariants hold when the array is in consistent state:

1. Entries are sorted by strictly increasing node ID (nid).
2. All entries with index i < split_idx_ belong to the left part of the array, all remaining entries to the right part.
3. All entries with node ID nid < split_node_id_ belong to the left part of the array, all remaining entries to the right part.
4. nodes_[0].get_node()->has_proxies() == nodes_[i].get_node()->has_proxies() for 0 <= i < lookup_split_idx_

Note

• The last invariant simply means that all nodes in the left part of the array have the same value of has_proxies().

Member Typedef Documentation

const_iterator

typedef BlockVector<SparseNodeArray::NodeEntry>::const_iterator nest::SparseNodeArray::const_iterator

Iterator inherited from BlockVector.

Constructor & Destructor Documentation

SparseNodeArray()

nest::SparseNodeArray::SparseNodeArray

(

)

Create empty sparse node array.

Member Function Documentation

add_local_node()

void nest::SparseNodeArray::add_local_node

(

Node &

node

)

Add single local node.

References nest::Node::get_node_id(), nest::VPManager::get_num_virtual_processes(), global_max_node_id_, nest::Node::has_proxies(), have_split_, nest::kernel(), left_scale_, left_side_has_proxies_, local_max_node_id_, local_min_node_id_, nodes_, right_scale_, split_idx_, and nest::KernelManager::vp_manager.

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begin()

SparseNodeArray::const_iterator nest::SparseNodeArray::begin ( ) const

inline

Constant iterators for safe iteration of SparseNodeArray.

References nodes_.

Referenced by nest::OneToOneBuilder::connect_(), nest::AllToAllBuilder::connect_(), nest::FixedInDegreeBuilder::connect_(), nest::BernoulliBuilder::connect_(), nest::PoissonBuilder::connect_(), nest::SPManager::get_synaptic_elements(), and nest::SimulationManager::update_().

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clear()

void nest::SparseNodeArray::clear

(

)

Clear the array.

References global_max_node_id_, have_split_, left_scale_, left_side_has_proxies_, local_max_node_id_, local_min_node_id_, nodes_, right_scale_, split_idx_, and split_node_id_.

end()

SparseNodeArray::const_iterator nest::SparseNodeArray::end ( ) const

inline

References nodes_.

Referenced by nest::OneToOneBuilder::connect_(), nest::AllToAllBuilder::connect_(), nest::FixedInDegreeBuilder::connect_(), nest::BernoulliBuilder::connect_(), nest::PoissonBuilder::connect_(), nest::SPManager::get_synaptic_elements(), and nest::SimulationManager::update_().

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get_max_node_id()

size_t nest::SparseNodeArray::get_max_node_id ( ) const

inline

Globally largest node ID.

References global_max_node_id_.

get_node_by_index()

Node * nest::SparseNodeArray::get_node_by_index ( size_t  idx ) const

inline

Lookup node based on index into container.

Note

Required for target lookup by HPC synapses.

References nodes_.

get_node_by_node_id()

Node * nest::SparseNodeArray::get_node_by_node_id

(

size_t

node_id

)

const

Return pointer to node or nullptr if node is not local.

Note

The caller is responsible for providing proper proxy-node pointers for non-local nodes.

References global_max_node_id_, is_consistent_(), left_scale_, local_max_node_id_, local_min_node_id_, nodes_, right_scale_, split_idx_, and split_node_id_.

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is_consistent_()

bool nest::SparseNodeArray::is_consistent_ ( ) const

inlineprivate

References global_max_node_id_, and nodes_.

Referenced by get_node_by_node_id().

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set_max_node_id()

void nest::SparseNodeArray::set_max_node_id

(

size_t

node_id

)

Set max node ID to maximum in network.

This also sets split_node_id_ to max node ID + 1 as long as we have not split.

Note

Must be called by any method adding nodes to the network at end of each batch of nodes added.

References global_max_node_id_, have_split_, local_max_node_id_, and split_node_id_.

size()

size_t nest::SparseNodeArray::size ( ) const

inline

Return size of container.

This is the number of local nodes.

See also

get_max_node_id()

References nodes_.

Member Data Documentation

global_max_node_id_

size_t nest::SparseNodeArray::global_max_node_id_

private

globally largest node ID

Referenced by add_local_node(), clear(), get_max_node_id(), get_node_by_node_id(), is_consistent_(), and set_max_node_id().

have_split_

bool nest::SparseNodeArray::have_split_

private

Mark whether split has happened during network construction.

False as long as only one kind of neuron has been added.

Referenced by add_local_node(), clear(), and set_max_node_id().

left_scale_

double nest::SparseNodeArray::left_scale_

private

scale factor for left side of array

Referenced by add_local_node(), clear(), and get_node_by_node_id().

left_side_has_proxies_

bool nest::SparseNodeArray::left_side_has_proxies_

private

Proxy status of nodes on left side of array.

Referenced by add_local_node(), and clear().

local_max_node_id_

size_t nest::SparseNodeArray::local_max_node_id_

private

largest local node ID

Referenced by add_local_node(), clear(), get_node_by_node_id(), and set_max_node_id().

local_min_node_id_

size_t nest::SparseNodeArray::local_min_node_id_

private

smallest local node ID

Referenced by add_local_node(), clear(), and get_node_by_node_id().

nodes_

BlockVector< NodeEntry > nest::SparseNodeArray::nodes_

private

stores local node information

Referenced by add_local_node(), begin(), clear(), end(), get_node_by_index(), get_node_by_node_id(), is_consistent_(), and size().

right_scale_

double nest::SparseNodeArray::right_scale_

private

scale factor for right side of array

Referenced by add_local_node(), clear(), and get_node_by_node_id().

split_idx_

size_t nest::SparseNodeArray::split_idx_

private

Array index of first element in right side of array.

Referenced by add_local_node(), clear(), and get_node_by_node_id().

split_node_id_

size_t nest::SparseNodeArray::split_node_id_

private

Globally smallest node ID in right side of array.

• Is updated by set_max_node_id()
• Is global_max_node_id_ + 1 as long as right side is empty.

Referenced by clear(), get_node_by_node_id(), and set_max_node_id().

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

• sparse_node_array.h
• sparse_node_array.cpp