A correct barriers implementation blocks in uv_barrier_destroy() until
the last thread returns from uv_barrier_wait() so make the test more
rigorous by destroying the barrier straight away instead of first
joining the worker thread.
Signed-off-by: Fedor Indutny <fedor@indutny.com>
Make uv_barrier_wait() return a boolean value indicating whether this
thread was the "serializer".
From `man pthread_barrier_wait`:
Upon successful completion, the pthread_barrier_wait() function
shall return PTHREAD_BARRIER_SERIAL_THREAD for a single (arbitrary)
thread synchronized at the barrier and zero for each of the other
threads.
Exposing that information from libuv is useful because it can make
cleanup significantly easier:
if (uv_barrier_wait(&barrier) > 0)
uv_barrier_destroy(&barrier);
Signed-off-by: Fedor Indutny <fedor@indutny.com>
