typedef struct {
    perl_mutex          mutex;
    PerlInterpreter    *owner;
    I32                 locks;
    perl_cond           cond;
} recursive_lock_t;

void
recursive_lock_acquire(pTHX_ recursive_lock_t *lock, char *file, int line)
{
    assert(aTHX);
    MUTEX_LOCK(&lock->mutex);
    if (lock->owner == aTHX) {
        lock->locks++;
    } else {
        while (lock->owner) {
          COND_WAIT(&lock->cond,&lock->mutex);
        }
        lock->locks = 1;
        lock->owner = aTHX;
    }
    MUTEX_UNLOCK(&lock->mutex);
    SAVEDESTRUCTOR_X(recursive_lock_release,lock);
}