BluFedora Job System Library

This is a C++17 library for handling of Tasks / Jobs in a multi-threaded environment.

Examples

Minimal Example

#include "concurrent/job_api.hpp"
 
#include <cassert>
#include <iostream>
 
static constexpr int k_DataSize = 100000;
 
static int s_ExampleData[k_DataSize] = {};
 
// Print the first 20 items for brevity
static void printFirst20Items()
{
  for (int i = 0; i < 20; ++i)
  {
    std::printf("data[%i] = %i\n", i, s_ExampleData[i]);
  }
}
 
int main()
{
   Job::Initialize(Job::MemRequirementsForConfig({}));
 
  // Initialize Dummy Data
  for (int i = 0; i < k_DataSize; ++i)
  {
    s_ExampleData[i] = i;
  }
 
  std::printf("Before:\n");
  printFirst20Items();
 
  auto* t = Job::ParallelFor(
   s_ExampleData, 
   k_DataSize, 
   Job::CountSplitter{6}, 
   [](int* data, std::size_t data_size) {
     for (std::size_t i = 0; i < data_size; ++i)
     {
       data[i] = data[i] * 5;
     }
   });
 
  Job::TaskSubmit(t);
 
  Job::WaitOnTask(t);
 
  std::printf("After:\n");
  printFirst20Items();
 
  // Check that the jobs finished working on all items.
  for (int i = 0; i < k_DataSize; ++i)
  {
    assert(s_ExampleData[i] == i * 5);
  }
 
  Job::Shutdown();
 
  return 0;
}

Architecture

Task

A Task is a single unit of work that can be scheduled by the Job System. Each Task has a total sizeof of 128bytes (2 * hardware interference size) with some of the bytes taken by essential bookkeeping date then the rest used for user storage.

A Tasks can be added as a child of another task, this means that when you wait on the parent Task then it will wait for all child Tasks as well.

Queues

A Queue hold a list of Tasks waiting to be executed. There are four different types of queues.

• MAIN This queue has a guarantee that the task will be run on the main thread.
• NORMAL Slightly lower priority than 'QueueType::HIGH'.
• WORKER This queue has a guarantee that the task will never be run on the main thread.

Dependencies

• C++ Standard Library (C++17 or above)
• PCG Random