enkiTS

enki Task Scheduler

A permissively licensed C and C++ Task Scheduler for creating parallel programs.

• C API via src/TaskScheduler_c.h
• C++ API via src/TaskScheduler.h
• C++ 11 version on Branch C++11
• User thread version on Branch UserThread for running enkiTS on other tasking / threading systems, so it can be used as in other engines as well as standalone for example.
• C++ 11 version of user threads on Branch UserThread_C++11

Note - this is a work in progress conversion from my code for enkisoftware's Avoyd codebase, with RuntimeCompiledC++ removed along with the removal of profiling code.

As this was originally written before widespread decent C++11 support for atomics and threads, these are implemented here per-platform supporting Windows, Linux and OSX on Intel x86 / x64 (also works on ARM iOS and Android but not as well tested). A separate C++11 branch exists for those who would like to use it, but this currently has slightly slower performance under very high task throughput when there is low work per task.

The example code requires C++ 11 for chrono (and for C++ 11 features in the C++11 branch C++11 )

For further examples, see https://github.com/dougbinks/enkiTSExamples

Building

Building enkiTS is simple, just add the files in enkiTS/src to your build system (_c.* files can be ignored if you only need C++ interface), and add enkiTS/src to your include path. Unix / Linux builds will require the pthreads library.

For cmake, on Windows / Mac OS X / Linux with cmake installed, open a prompt in the enkiTS directory and:

1. mkdir build
2. cmake ..
3. either run make or open enkiTS.sln

Project Features

1. Lightweight - enkiTS is designed to be lean so you can use it anywhere easily, and understand it.
2. Fast, then scalable - enkiTS is designed for consumer devices first, so performance on a low number of threads is important, followed by scalability.
3. Braided parallelism - enkiTS can issue tasks from another task as well as from the thread which created the Task System.
4. Up-front Allocation friendly - enkiTS is designed for zero allocations during scheduling.
5. NEW - Can pin tasks to a given thread - enkiTS can schedule a task which will only be run on the specified thread.

Usage

C usage:

#include "TaskScheduler_c.h"

enkiTaskScheduler*	g_pTS;

void ParalleTaskSetFunc( uint32_t start_, uint32_t end, uint32_t threadnum_, void* pArgs_ ) {
   /* Do something here, can issue tasks with g_pTS */
}

int main(int argc, const char * argv[]) {
   enkiTaskSet* pTask;
   g_pTS = enkiNewTaskScheduler();
   enkiInitTaskScheduler( g_pTS );
	
   // create a task, can re-use this to get allocation occurring on startup
   pTask	= enkiCreateTaskSet( g_pTS, ParalleTaskSetFunc );

   enkiAddTaskSetToPipe( g_pTS, pTask, NULL, 1); // NULL args, setsize of 1

   // wait for task set (running tasks if they exist) - since we've just added it and it has no range we'll likely run it.
   enkiWaitForTaskSet( g_pTS, pTask );
   
   enkiDeleteTaskSet( pTask );
   
   enkiDeleteTaskScheduler( g_pTS );
   
   return 0;
}

C++ usage:

#include "TaskScheduler.h"

enki::TaskScheduler g_TS;

// define a task set, can ignore range if we only do one thing
struct ParallelTaskSet : enki::ITaskSet {
   virtual void    ExecuteRange(  enki::TaskSetPartition range, uint32_t threadnum ) {
      // do something here, can issue tasks with g_TS
   }
};

int main(int argc, const char * argv[]) {
   g_TS.Initialize();
   ParallelTaskSet task; // default constructor has a set size of 1
   g_TS.AddTaskSetToPipe( &task );

   // wait for task set (running tasks if they exist) - since we've just added it and it has no range we'll likely run it.
   g_TS.WaitforTask( &task );
   return 0;
}

C++ 11 usage (currently requires C++11 branch, or define own lambda wrapper taskset interface.

#include "TaskScheduler.h"

enki::TaskScheduler g_TS;

int main(int argc, const char * argv[]) {
   g_TS.Initialize();

   enki::TaskSet task( 1, []( enki::TaskSetPartition range, uint32_t threadnum  ) {
         // do something here
      }  );

   g_TS.AddTaskSetToPipe( &task );
   g_TS.WaitforTask( &task );
   return 0;
}

Pinned Tasks usage in C++ (see example/PinnedTask_c.c for C example).

#include "TaskScheduler.h"

enki::TaskScheduler g_TS;

// define a task set, can ignore range if we only do one thing
struct PinnedTask : enki::IPinnedTask {
    virtual void    Execute() {
      // do something here, can issue tasks with g_TS
   }
};

int main(int argc, const char * argv[]) {
   g_TS.Initialize();
   PinnedTask task; //default constructor sets thread for pinned task to 0 (main thread)
   g_TS.AddPinnedTask( &task );
   
   // RunPinnedTasks must be called on main thread to run any pinned tasks for that thread.
   // Tasking threads automatically do this in their task loop.
   g_TS.RunPinnedTasks();
   // wait for task set (running tasks if they exist) - since we've just added it and it has no range we'll likely run it.
   g_TS.WaitforTask( &task );
   return 0;
}

License (zlib)

Copyright (c) 2013 Doug Binks

This software is provided 'as-is', without any express or implied warranty. In no event will the authors be held liable for any damages arising from the use of this software.

Permission is granted to anyone to use this software for any purpose, including commercial applications, and to alter it and redistribute it freely, subject to the following restrictions:

1. The origin of this software must not be misrepresented; you must not claim that you wrote the original software. If you use this software in a product, an acknowledgement in the product documentation would be appreciated but is not required.
2. Altered source versions must be plainly marked as such, and must not be misrepresented as being the original software.
3. This notice may not be removed or altered from any source distribution.