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Using DUT in a Multi-threaded Execution Environment

As originally written, DUT was completely unaware of concurrency, which is not to say that you couldn't use it to test code that was going to run concurrently. You could detect even race conditions with code like:

#include "dut.h"
#include <pthead.h>

#define NITER 100000
int count = 0;

void* plus(void *a){
  int i, local;
  for (i=0; i<NITER; i++){
    local = count;
    local++;
    count+=local;
  };
};

void* minus(void *a){
  int i, local;
  for (i=0; i<NITER; i++){
    local = count;
    local--;
    count+=local;
  };
};

int main(int argc, char** argv){
  DUT_TEST_FILE_HEADER;

  pthread_t th1, th2;
  pthread_create(&th1,NULL,&plus,NULL);
  pthread_create(&th2,NULL,&minus,NULL);
  pthread_join(th1,NULL);
  pthread_join(th2,NULL);
  DUT_TESTEQ_WARN("Race condition",count,0,%i,DUT_INT);

  DUT_TEST_FILE_FOOTER;
};

But is was not safe to run tests concurrently. DUT uses global storage to keep track of the description of the current test, how many test have been completed, how many tests have generated warnings, and so on. A race condition between tests could result in erroneous reporting of what failure occurred where...

For version 0.8.3 a simple (and optional) locking mechanism based on POSIX semaphores was installed. There is no fundamental reason other kinds of semaphores could not be used.

You activate the locking mechanism by #defineing _DUT_THREAD_SAFE_, which simply brackets all the test macros with a (un)locking calls on the semaphore DUT_UPDATE_SEM. This renders it safe to use DUT test macros in multi-threaded code as long as your test code (CVAL and TVAL) does not block on other semaphore controlled resources, which could result in deadlocks.

Since you're writing concurrent code, I assume that you are familiar with the risks and the standard solutions. Good luck.