On Apr 17, 2021, at 1:00 PM, Albrecht Schlosser <AlbrechtS.fltk@online.de> wrote:

On 4/17/21 2:25 PM Michael Sweet wrote:

Another crazy option: just have Fl::lock() be a no-op if the run loop is not active and then have Fl::run() call Fl::lock() unconditionally. When threading is enabled (which should be all the time now) the right thing happens without any special initialization, and Fl::lock()/unlock() can continue to be used for synchronization as before.

Mike, IIRC there's still the "side effect" that the first call into Fl::lock() enables the locking and unlocking feature. Hence, if you never call it, locking and unlocking will not be done by the FLTK thread (event loop), which is probably one of "fast and light" design aspects of FLTK.

#include <stdio.h>

#include <time.h>

#include <sys/time.h>

#include <pthread.h>

int main(void)

{

  struct timeval start, end;

  int i;

  pthread_mutex_t mutex = PTHREAD_MUTEX_INITIALIZER;

  double secs;

  gettimeofday(&start, NULL);

  for (i = 0; i < 1000000000; i ++)

  {

    pthread_mutex_lock(&mutex);

    pthread_mutex_unlock(&mutex);

  }

  gettimeofday(&end, NULL);

  secs = end.tv_sec - start.tv_sec + 0.000001 * (end.tv_usec - start.tv_usec);

  printf("%.3f seconds\n", secs);

  return (0);

}