ah_parallel_example.cc File Reference

Parallel functional programming utilities (ah-parallel.H): map/filter/fold/predicates/zip/sort. More...

#include <ah-parallel.H>
#include <iostream>
#include <iomanip>
#include <vector>
#include <cmath>
#include <chrono>
#include <numeric>
#include <random>
#include <string>

Include dependency graph for ah_parallel_example.cc:

Go to the source code of this file.

Functions
void	print_header (const std::string &title)
void	example_parallel_map ()
void	example_parallel_filter ()
void	example_parallel_fold ()
void	example_parallel_predicates ()
void	example_parallel_find ()
void	example_parallel_aggregations ()
void	example_parallel_sort ()
void	example_parallel_zip ()
void	example_variadic_zip ()
void	example_parallel_enumerate ()
void	example_performance_comparison ()
int	main ()

Detailed Description

Parallel functional programming utilities (ah-parallel.H): map/filter/fold/predicates/zip/sort.

Overview

This example demonstrates Aleph-w's parallel functional programming helpers from ah-parallel.H. The API provides ML-style operations (map, filter, fold, predicates, etc.) that execute in parallel using an Aleph::ThreadPool.

The file is structured as a series of demos covering:

• parallel map/filter/fold
• parallel predicates and find
• aggregations (sum/product/min/max)
• parallel sort
• parallel zip / enumerate
• a simple parallel vs sequential performance comparison

Data model used by this example

• Primary containers: std::vector<int>, std::vector<double>, std::vector<std::string>
• Execution engine: ThreadPool pool(std::thread::hardware_concurrency())

Usage

./ah_parallel_example

This example has no command-line options; it runs all demos.

Algorithms and Aleph-w API

Common signature pattern:

• the first parameter is always a ThreadPool&
• the remaining parameters are similar to the sequential counterparts

Core operations demonstrated:

• pmaps(pool, container, f)
• pfilter(pool, container, pred)
• pfoldl(pool, container, init, op)
• pall / pexists / pnone / pcount_if
• pfind / pfind_value
• psum / pproduct / pmin / pmax
• psort
• pzip_*, penumerate_*

Complexity

Asymptotically, most operations have the same work complexity as the sequential version (e.g. O(n) for map/filter), but with wall-clock time reduced by parallelization.

Actual speedups depend on:

• task granularity and chunking
• CPU core count
• memory bandwidth
• overhead of scheduling

Pitfalls and edge cases

• For pfoldl, the binary operator should be associative to ensure that parallel reduction is well-defined.
• Short-circuit operations (pall, pexists, pfind) may stop early.
• Parallel overhead can dominate for small inputs; measure before assuming gains.

References / see also

• ah-parallel.H
• thread_pool_example.cc (ThreadPool usage)

Definition in file ah_parallel_example.cc.

Function Documentation

example_parallel_aggregations()

void example_parallel_aggregations

(

)

Definition at line 358 of file ah_parallel_example.cc.

References Aleph::maps(), Aleph::mean(), Aleph::pmax(), Aleph::pmin(), Aleph::pminmax(), print_header(), Aleph::psum(), rng, and Aleph::sum().

Referenced by main().

example_parallel_enumerate()

void example_parallel_enumerate

(

)

Definition at line 584 of file ah_parallel_example.cc.

References Aleph::maps(), Aleph::penumerate_for_each(), Aleph::penumerate_maps(), and print_header().

Referenced by main().

example_parallel_filter()

void example_parallel_filter

(

)

Definition at line 163 of file ah_parallel_example.cc.

References StlAlephIterator< SetName >::begin(), StlAlephIterator< SetName >::end(), is_prime(), Aleph::maps(), Aleph::pfilter(), primes, print_header(), and Aleph::HTList::size().

Referenced by main().

example_parallel_find()

void example_parallel_find

(

)

Definition at line 314 of file ah_parallel_example.cc.

References Aleph::maps(), Aleph::pfind(), Aleph::pfind_value(), print_header(), and rng.

Referenced by main().

example_parallel_fold()

void example_parallel_fold

(

)

Definition at line 222 of file ah_parallel_example.cc.

References Aleph::maps(), Aleph::pfoldl(), print_header(), Aleph::psum(), and Aleph::sum().

Referenced by main().

example_parallel_map()

void example_parallel_map

(

)

Definition at line 113 of file ah_parallel_example.cc.

References StlAlephIterator< SetName >::begin(), StlAlephIterator< SetName >::end(), Aleph::maps(), Aleph::ThreadPool::num_threads(), Aleph::pmaps(), print_header(), and Aleph::HTList::size().

Referenced by main().

example_parallel_predicates()

void example_parallel_predicates

(

)

Definition at line 268 of file ah_parallel_example.cc.

References Aleph::maps(), Aleph::pall(), Aleph::pcount_if(), Aleph::pexists(), Aleph::pnone(), and print_header().

Referenced by main().

example_parallel_sort()

void example_parallel_sort

(

)

Definition at line 404 of file ah_parallel_example.cc.

References Aleph::is_sorted(), Aleph::maps(), print_header(), Aleph::psort(), and rng.

Referenced by main().

example_parallel_zip()

void example_parallel_zip

(

)

Definition at line 458 of file ah_parallel_example.cc.

References Aleph::maps(), print_header(), Aleph::pzip_foldl(), Aleph::pzip_for_each(), Aleph::pzip_maps(), Aleph::sum(), and y.

Referenced by main().

example_performance_comparison()

void example_performance_comparison

(

)

Definition at line 625 of file ah_parallel_example.cc.

References StlAlephIterator< SetName >::begin(), StlAlephIterator< SetName >::end(), Aleph::maps(), Aleph::ThreadPool::num_threads(), Aleph::pmaps(), and print_header().

Referenced by main().

example_variadic_zip()

void example_variadic_zip

(

)

Definition at line 516 of file ah_parallel_example.cc.

References Aleph::count(), Aleph::maps(), print_header(), Aleph::pzip_all_n(), Aleph::pzip_count_if_n(), Aleph::pzip_maps_n(), and y.

Referenced by main().

main()

int main

(

)

Definition at line 690 of file ah_parallel_example.cc.

References example_parallel_aggregations(), example_parallel_enumerate(), example_parallel_filter(), example_parallel_find(), example_parallel_fold(), example_parallel_map(), example_parallel_predicates(), example_parallel_sort(), example_parallel_zip(), example_performance_comparison(), and example_variadic_zip().

print_header()

void print_header

(

const std::string &

title

)

Definition at line 93 of file ah_parallel_example.cc.

References Aleph::maps().