A distributed object (Charm++ Chare) that executes a series of Actions and is capable of sending and receiving data. Acts as an interface to Charm++. More...

#include <DistributedObject.hpp>

Public Types
using	all_actions_list = tmpl::flatten< tmpl::list< typename PhaseDepActionListsPack::action_list... > >
	List of Actions in the order that generates the DataBox types.

using	metavariables = typename ParallelComponent::metavariables
	The metavariables class passed to the Algorithm.

using	inbox_tags_list = Parallel::get_inbox_tags< all_actions_list >
	List off all the Tags that can be received into the Inbox.

using	array_index = typename get_array_index< typename ParallelComponent::chare_type >::template f< ParallelComponent >
	The type of the object used to uniquely identify the element of the array, group, or nodegroup. The default depends on the component, see ParallelComponentHelpers.

using	parallel_component = ParallelComponent

using	chare_type = typename parallel_component::chare_type
	The type of the Chare.

using	cproxy_type = typename chare_type::template cproxy< parallel_component, array_index >
	The Charm++ proxy object type.

using	cbase_type = typename chare_type::template cbase< parallel_component, array_index >
	The Charm++ base object type.

using	phase_dependent_action_lists = tmpl::list< PhaseDepActionListsPack... >

using	inbox_type = tuples::tagged_tuple_from_typelist< inbox_tags_list >

using	all_cache_tags = get_const_global_cache_tags< metavariables >

using	distributed_object_tags = typename Tags::distributed_object_tags< metavariables, array_index >

using	databox_type = db::compute_databox_type< tmpl::flatten< tmpl::list< distributed_object_tags, typename parallel_component::simple_tags_from_options, Tags::GlobalCacheImplCompute< metavariables >, Tags::ResourceInfoReference< metavariables >, db::wrap_tags_in< Tags::FromGlobalCache, all_cache_tags >, Algorithm_detail::action_list_simple_tags< parallel_component >, Algorithm_detail::action_list_compute_tags< parallel_component > > > >

Public Member Functions
template<class... InitializationTags>
	DistributedObject (const Parallel::CProxy_GlobalCache< metavariables > &global_cache_proxy, tuples::TaggedTuple< InitializationTags... > initialization_items)
	Constructor used by Main to initialize the algorithm.

	DistributedObject (const Parallel::CProxy_GlobalCache< metavariables > &global_cache_proxy, Parallel::Phase current_phase, std::unordered_map< Parallel::Phase, size_t > phase_bookmarks, const std::unique_ptr< Parallel::Callback > &callback)
	Constructor used to dynamically add a new element of an array The `callback` is executed after the element is created.

	DistributedObject (CkMigrateMessage *)
	Charm++ migration constructor, used after a chare is migrated.

std::string	print_types () const
	Print the expanded type aliases.

std::string	print_state () const
	Print the current state of the algorithm.

std::string	print_inbox () const
	Print the current contents of the inboxes.

std::string	print_databox () const
	Print the current contents of the DataBox.

const auto &	get_inboxes () const
	Get read access to all the inboxes.

void	pup (PUP::er &p) override

template<typename Action , typename Arg >
void	reduction_action (Arg arg)
	Calls the `apply` function `Action` after a reduction has been completed. More...

template<typename Action , typename... Args>
void	simple_action (std::tuple< Args... > args)
	Explicitly call the action `Action`.

template<typename Action >
void	simple_action ()

template<typename Action , typename... Args>
Action::return_type	local_synchronous_action (Args &&... args)
	Call the `Action` sychronously, returning a result without any parallelization. The action is called immediately and control flow returns to the caller immediately upon completion. More...

template<typename ReceiveTag , typename ReceiveDataType >
void	receive_data (typename ReceiveTag::temporal_id instance, ReceiveDataType &&t, bool enable_if_disabled=false)
	Receive data and store it in the Inbox, and try to continue executing the algorithm. More...

template<typename ReceiveTag , typename MessageType >
void	receive_data (MessageType *message)

void	start_phase (const Parallel::Phase next_phase)
	Start execution of the phase-dependent action list in `next_phase`. If `next_phase` has already been visited, execution will resume at the point where the previous execution of the same phase left off.

Phase	phase () const
	Get the current phase.

const std::unordered_map< Parallel::Phase, size_t > &	phase_bookmarks () const
	Get the phase bookmarks. More...

constexpr void	set_terminate (const bool t)
	Tell the Algorithm it should no longer execute the algorithm. This does not mean that the execution of the program is terminated, but only that the algorithm has terminated. An algorithm can be restarted by passing `true` as the second argument to the `receive_data` method or by calling perform_algorithm(true).

constexpr bool	get_terminate () const
	Check if an algorithm should continue being evaluated.

template<typename ThisAction , typename PhaseIndex , typename DataBoxIndex >
bool	invoke_iterable_action ()

void	contribute_termination_status_to_main ()
	Does a reduction over the component of the reduction status sending the result to Main's did_all_elements_terminate member function.

const std::string &	deadlock_analysis_next_iterable_action () const
	Returns the name of the last "next iterable action" to be run before a deadlock occurred.


template<typename Action , typename... Args, Requires<((void) sizeof...(Args), std::is_same_v< Parallel::Algorithms::Nodegroup, chare_type >)> = nullptr>
void	threaded_action (std::tuple< Args... > args)
	Call an Action on a local nodegroup requiring the Action to handle thread safety. More...

template<typename Action >
void	threaded_action ()
	Call an Action on a local nodegroup requiring the Action to handle thread safety. More...


void	perform_algorithm ()
	Start evaluating the algorithm until it is stopped by an action.

void	perform_algorithm (const bool restart_if_terminated)
	Start evaluating the algorithm until it is stopped by an action.


int	number_of_procs () const
	Wrappers for charm++ informational functions. More...

int	my_proc () const
	Index of my processing element.

int	number_of_nodes () const
	Number of nodes.

int	my_node () const
	Index of my node.

int	procs_on_node (const int node_index) const
	Number of processing elements on the given node.

int	my_local_rank () const
	The local index of my processing element on my node. This is in the interval 0, ..., procs_on_node(my_node()) - 1.

int	first_proc_on_node (const int node_index) const
	Index of first processing element on the given node.

int	node_of (const int proc_index) const
	Index of the node for the given processing element.

int	local_rank_of (const int proc_index) const
	The local index for the given processing element on its node.

Detailed Description

template<typename ParallelComponent, typename... PhaseDepActionListsPack>
class DistributedObject< ParallelComponent, tmpl::list< PhaseDepActionListsPack... > >

A distributed object (Charm++ Chare) that executes a series of Actions and is capable of sending and receiving data. Acts as an interface to Charm++.

Different Types of Algorithms

Charm++ chares can be one of four types, which is specified by the type alias chare_type inside the ParallelComponent. The four available types of Algorithms are:

A Parallel::Algorithms::Singleton where there is only one in the entire execution of the program.
A Parallel::Algorithms::Array which holds zero or more elements each of which is a distributed object on some core. An array can grow and shrink in size dynamically if need be and can also be bound to another array. That is, the bound array has the same number of elements as the array it is bound to, and elements with the same ID are on the same core.
A Parallel::Algorithms::Group, which is an array but there is one element per core and they are not able to be moved around between cores. These are typically useful for gathering data from array elements on their core, and then processing or reducing it.
A Parallel::Algorithms::Nodegroup, which is similar to a group except that there is one element per node. For Charm++ SMP (shared memory parallelism) builds a node corresponds to the usual definition of a node on a supercomputer. However, for non-SMP builds nodes and cores are equivalent. An important difference between groups and nodegroups is that entry methods (remote calls to functions) are not threadsafe on nodegroups. It is up to the person writing the Actions that will be executed on the Nodegroup Algorithm to ensure they are threadsafe.

What is an Algorithm?

An Algorithm is a distributed object, a Charm++ chare, that repeatedly executes a series of Actions. An Action is a struct that has a static apply function with signature:

template <typename... DbTags, typename... InboxTags, typename Metavariables,
typename ArrayIndex,  typename ActionList>
static auto  apply(db::DataBox<tmpl::list<DbTags...>>& box,
                   tuples::TaggedTuple<InboxTags...>& inboxes,
                   const GlobalCache<Metavariables>& cache,
                   const ArrayIndex& array_index,
                   const TemporalId& temporal_id, const ActionList meta);

Note that any of the arguments can be const or non-const references except array_index, which must be a const&.

Explicit instantiations of entry methods

The code in src/Parallel/CharmMain.tpp registers all entry methods, and if one is not properly registered then a static_assert explains how to have it be registered. If there is a bug in the implementation and an entry method isn't being registered or hitting a static_assert then Charm++ will give an error of the following form:

* registration happened after init Entry point: simple_action(), addr:
* 0x555a3d0e2090
* ------------- Processor 0 Exiting: Called CmiAbort ------------
* Reason: Did you forget to instantiate a templated entry method in a .ci file?
*

If you encounter this issue please file a bug report supplying everything necessary to reproduce the issue.

Member Function Documentation

◆ local_synchronous_action()

template<typename ParallelComponent , typename... PhaseDepActionListsPack>

template<typename Action , typename... Args>

Action::return_type DistributedObject< ParallelComponent, tmpl::list< PhaseDepActionListsPack... > >::local_synchronous_action ( Args &&... args )

Call the Action sychronously, returning a result without any parallelization. The action is called immediately and control flow returns to the caller immediately upon completion.

Note: Action must have a type alias return_type specifying its return type. This constraint is to simplify the variant visitation logic for the DataBox.

◆ number_of_procs()

template<typename ParallelComponent , typename... PhaseDepActionListsPack>

int DistributedObject< ParallelComponent, tmpl::list< PhaseDepActionListsPack... > >::number_of_procs ( ) const

inline

Wrappers for charm++ informational functions.

Number of processing elements

◆ phase_bookmarks()

template<typename ParallelComponent , typename... PhaseDepActionListsPack>

const std::unordered_map< Parallel::Phase, size_t > & DistributedObject< ParallelComponent, tmpl::list< PhaseDepActionListsPack... > >::phase_bookmarks ( ) const

inline

Get the phase bookmarks.

Details

These are used to allow a phase to be resumed at a specific step in its iterable action list after PhaseControl is used to temporarily switch to other phases.

◆ receive_data()

template<typename ParallelComponent , typename... PhaseDepActionListsPack>

template<typename ReceiveTag , typename ReceiveDataType >

void DistributedObject< ParallelComponent, tmpl::list< PhaseDepActionListsPack... > >::receive_data	(	typename ReceiveTag::temporal_id	instance,
		ReceiveDataType &&	t,
		bool	enable_if_disabled = `false`
	)

Receive data and store it in the Inbox, and try to continue executing the algorithm.

When an algorithm has terminated it can be restarted by passing enable_if_disabled = true. This allows long-term disabling and re-enabling of algorithms

◆ reduction_action()

template<typename ParallelComponent , typename... PhaseDepActionListsPack>

template<typename Action , typename Arg >

void DistributedObject< ParallelComponent, tmpl::list< PhaseDepActionListsPack... > >::reduction_action ( Arg arg )

Calls the apply function Action after a reduction has been completed.

The apply function must take arg as its last argument.

◆ threaded_action() [1/2]

template<typename ParallelComponent , typename... PhaseDepActionListsPack>

template<typename Action >

void DistributedObject< ParallelComponent, tmpl::list< PhaseDepActionListsPack... > >::threaded_action ( )

Call an Action on a local nodegroup requiring the Action to handle thread safety.

The Parallel::NodeLock of the nodegroup is passed to the Action instead of the action_list as a const gsl::not_null<Parallel::NodeLock*>&. The node lock can be locked with the Parallel::NodeLock::lock() function, and unlocked with Parallel::unlock(). Parallel::NodeLock::try_lock() is also provided in case something useful can be done if the lock couldn't be acquired.

◆ threaded_action() [2/2]

template<typename ParallelComponent , typename... PhaseDepActionListsPack>

template<typename Action , typename... Args, Requires<((void) sizeof...(Args), std::is_same_v< Parallel::Algorithms::Nodegroup, chare_type >)> = nullptr>

void DistributedObject< ParallelComponent, tmpl::list< PhaseDepActionListsPack... > >::threaded_action ( std::tuple< Args... > args )

inline

Call an Action on a local nodegroup requiring the Action to handle thread safety.

The Parallel::NodeLock of the nodegroup is passed to the Action instead of the action_list as a const gsl::not_null<Parallel::NodeLock*>&. The node lock can be locked with the Parallel::NodeLock::lock() function, and unlocked with Parallel::unlock(). Parallel::NodeLock::try_lock() is also provided in case something useful can be done if the lock couldn't be acquired.

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

src/Parallel/DistributedObject.hpp

Public Types

Public Member Functions

Detailed Description

Different Types of Algorithms

What is an Algorithm?

Explicit instantiations of entry methods

Member Function Documentation

◆ local_synchronous_action()

◆ number_of_procs()

◆ phase_bookmarks()

Details

◆ receive_data()

◆ reduction_action()

◆ threaded_action() [1/2]

◆ threaded_action() [2/2]