tf::RandomPartitioner< C > Class Template Reference

class to construct a random partitioner for scheduling parallel algorithms More...

#include <taskflow/algorithm/partitioner.hpp>

Inheritance diagram for tf::RandomPartitioner< C >:

Collaboration diagram for tf::RandomPartitioner< C >:

Public Member Functions
	RandomPartitioner ()=default
	default constructor
	RandomPartitioner (size_t sz)
	construct a dynamic partitioner with the given chunk size
	RandomPartitioner (size_t sz, C &&closure)
	construct a random partitioner with the given chunk size and the closure
	RandomPartitioner (float alpha, float beta)
	constructs a random partitioner with the given parameters
	RandomPartitioner (float alpha, float beta, C &&closure)
	constructs a random partitioner with the given parameters and the closure
float	alpha () const
	queries the alpha value
float	beta () const
	queries the beta value
std::pair< size_t, size_t >	chunk_size_range (size_t N, size_t W) const
	queries the range of chunk size
Public Member Functions inherited from tf::PartitionerBase< DefaultClosureWrapper >
	PartitionerBase ()=default
	default constructor
	PartitionerBase (size_t chunk_size)
	construct a partitioner with the given chunk size
	PartitionerBase (size_t chunk_size, DefaultClosureWrapper &&closure_wrapper)
	construct a partitioner with the given chunk size and closure wrapper
size_t	chunk_size () const
	query the chunk size of this partitioner
void	chunk_size (size_t cz)
	update the chunk size of this partitioner
const DefaultClosureWrapper &	closure_wrapper () const
	acquire an immutable access to the closure wrapper object
DefaultClosureWrapper &	closure_wrapper ()
	acquire a mutable access to the closure wrapper object
void	closure_wrapper (F &&fn)
	modify the closure wrapper object
decltype(auto)	operator() (F &&callable)
	wraps the given callable with the associated closure wrapper

Static Public Member Functions
static constexpr PartitionerType	type ()
	queries the partition type (dynamic)

Additional Inherited Members
Public Types inherited from tf::PartitionerBase< DefaultClosureWrapper >
using	closure_wrapper_type
	the closure type
Static Public Attributes inherited from tf::PartitionerBase< DefaultClosureWrapper >
static constexpr bool	is_default_wrapper_v
	indicating if the given closure wrapper is a default wrapper (i.e., empty)

Detailed Description

template<typename C = DefaultClosureWrapper>
class tf::RandomPartitioner< C >

class to construct a random partitioner for scheduling parallel algorithms

Template Parameters

C	closure wrapper type (default tf::DefaultClosureWrapper)

Similar to tf::DynamicPartitioner, the partitioner splits iterations into many partitions but each with a random chunk size in the range, c = [alpha * N * W, beta * N * W]. By default, alpha is 0.01 and beta is 0.5, respectively.

In addition to partition size, the application can specify a closure wrapper for a random partitioner. A closure wrapper allows the application to wrap a partitioned task (i.e., closure) with a custom function object that performs additional tasks. For example:

std::atomic<int> count = 0;
tf::Taskflow taskflow;
taskflow.for_each_index(0, 100, 1, 
  [](){                 
    printf("%d\n", i); 
  },
  tf::RandomPartitioner(0, [](auto&& closure){
    // do something before invoking the partitioned task
    // ...
    
    // invoke the partitioned task
    closure();
 
    // do something else after invoking the partitioned task
    // ...
  }
);
executor.run(taskflow).wait();

Member Function Documentation

chunk_size_range()

template<typename C>

std::pair< size_t, size_t > tf::RandomPartitioner< C >::chunk_size_range	(	size_t	N,
		size_t	W ) const

queries the range of chunk size

Parameters

N	number of iterations
W	number of workers

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

• taskflow/algorithm/partitioner.hpp