WaitForPinnedTasks feedback

[dougbinks]

Feedback thread for the new WaitForPinnedTasks feature.

Code on dev_WaitForPinnedTasks branch.

Feedback & questions appreciated.

Excerpt from Readme.md:

• full example in example/WaitForPinnedTasks.cpp
• C example in example/WaitForPinnedTasks_c.c

#include "TaskScheduler.h"

enki::TaskScheduler g_TS;

struct RunPinnedTaskLoopTask : enki::IPinnedTask
{
    void Execute() override
    {
        while( g_TS.GetIsRunning() )
        {
            g_TS.WaitForNewPinnedTasks(); // this thread will 'sleep' until there are new pinned tasks
            g_TS.RunPinnedTasks();
        }
    }
};

struct PretendDoFileIO : enki::IPinnedTask
{
    void Execute() override
    {
        // Do file IO
    }
};

int main(int argc, const char * argv[])
{
    enki::TaskSchedulerConfig config;

    // In this example we create more threads than the hardware can run,
    // because the IO thread will spend most of it's time idle or blocked
    // and therefore not scheduled for CPU time by the OS
    config.numTaskThreadsToCreate += 1;

    g_TS.Initialize( config );

    // in this example we place our IO threads at the end
    RunPinnedTaskLoopTask runPinnedTaskLoopTasks;
    runPinnedTaskLoopTasks.threadNum = g_TS.GetNumTaskThreads() - 1;
    g_TS.AddPinnedTask( &runPinnedTaskLoopTasks );

    // Send pretend file IO task to external thread FILE_IO
    PretendDoFileIO pretendDoFileIO;
    pretendDoFileIO.threadNum = runPinnedTaskLoopTasks.threadNum;
    g_TS.AddPinnedTask( &pretendDoFileIO );

    // ensure runPinnedTaskLoopTasks complete by explicitly calling shutdown
    g_TS.WaitforAllAndShutdown();

    return 0;
}