Error in os_workgroup_join

OSAudioWorkgroupProblem.cpp

#include <mach/mach_time.h>
#import <AudioToolbox/AudioToolbox.h>

#include <thread>
#include <chrono>

// This workgroup attribute isn't currently used. Set it to NULL.
os_workgroup_attr_t _Nullable attr = nullptr;


// One nanosecond in seconds.
constexpr static double kOneNanosecond = 1.0e9;


// The I/O interval time in seconds.
constexpr static double kIOIntervalTime = 0.020;


// The clock identifier that specifies interval timestamps.
os_clockid_t clockId = OS_CLOCK_MACH_ABSOLUTE_TIME;


// Create a workgroup interval.
os_workgroup_interval_t _Nullable workgroup =
    AudioWorkIntervalCreate("My Work Interval", clockId, attr);

bool joinThisThreadToWorkgroup(os_workgroup_t workgroup);


void realtimeThreadFunction() {


    // Join this thread to the workgroup.
    if (not joinThisThreadToWorkgroup(workgroup))
    {
        // Early return, unable to add this thread to the workgroup
        return;
    }


    // Get the mach time info.
    struct mach_timebase_info timeBaseInfo;
    mach_timebase_info(&timeBaseInfo);


    // The frequency of the clock is: (timeBaseInfo.denom / timeBaseInfo.numer) * kOneNanosecond
    const auto nanoSecFrequency = static_cast<double>(timeBaseInfo.denom) / static_cast<double>(timeBaseInfo.numer);
    const auto frequency = nanoSecFrequency * kOneNanosecond;


    // Convert the interval time in seconds to mach time length.
    const auto intervalMachLength = static_cast<int64_t>(kIOIntervalTime * frequency);
    while (true) {
        // Get the current host time.
        const auto currentTime = mach_absolute_time();
        const auto deadline = currentTime + intervalMachLength;


        // Call os_workgroup_interval_start each time the thread begins a work cycle
        int result = os_workgroup_interval_start(workgroup, currentTime, deadline, nullptr);


        if (result != 0) {
            // Something went wrong.
        }


        // Perform some custom DSP processing.
        std::this_thread::sleep_for(std::chrono::milliseconds(10));
        //customAudioDSP();


        // Call os_workgroup_interval_finish on completion of each a work cycle.
        result = os_workgroup_interval_finish(workgroup, nullptr);
    }
}

// Return true if the method joined the thread to the workgroup.
bool joinThisThreadToWorkgroup(os_workgroup_t aWorkgroup) {
    // Join this thread to the workgroup.
    os_workgroup_join_token_t joinToken{};
    const int result = os_workgroup_join(aWorkgroup, joinToken);
    if (result == 0) {
        return true;
    } else if (result == EALREADY) {
        // The thread is already part of a workgroup that can't be
        // nested in the the specified workgroup.
        assert(false);
        return false;
    } else if (result == EINVAL) {
        // The workgroup has been canceled.
        assert(false);
        return false;
    }
    else
    {
        assert(false);
    }
}

int main()
{
    realtimeThreadFunction();
}