futex-2.2.tar.gz_futex_futex-2.2.tar

#include <sys/time.h> #include <errno.h> #include <limits.h> #include "usersem.h" #ifndef TIMEVAL_TO_TIMESPEC # define TIMEVAL_TO_TIMESPEC(tv, ts) { \ (ts)->tv_sec = (tv)->tv_sec; \ (ts)->tv_nsec = (tv)->tv_usec * 1000; \ } #endif typedef struct futex nonpthread_mutex_t; typedef struct { int counter; } nonpthread_cond_t; typedef struct { struct futex mutex; int num_left, acks; int initial_count; } nonpthread_barrier_t; #define NONPTHREAD_MUTEX_INITIALIZER FUTEX_INITIALIZER #define NONPTHREAD_COND_INITIALIZER { 0 } int nonpthread_barrier_init(nonpthread_barrier_t *barrier, void *addr, unsigned int count) { futex_init(&barrier->mutex); barrier->num_left = barrier->initial_count = count; barrier->acks = 0; return 0; } static inline void wait_for(int *addr, int value) { int v; while ((v = *addr) != value) sys_futex(addr, FUTEX_WAIT, v, NULL); } int nonpthread_barrier_wait(nonpthread_barrier_t *barrier) { while (futex_down(&barrier->mutex) < 0) { if (errno != EINTR) return -1; } if (--barrier->num_left == 0) { /* Make sure value is nailed and wake others */ __futex_commit(); sys_futex(&barrier->num_left, FUTEX_WAKE, barrier->initial_count-1, NULL); /* Wait for them all to ack. */ wait_for(&barrier->acks, barrier->initial_count - 1); /* Reset barrier */ barrier->num_left = barrier->initial_count; barrier->acks = 0; futex_up(&barrier->mutex); return 0; /* NONPTHREAD_BARRIER_SERIAL_THREAD */ } else { futex_up(&barrier->mutex); /* Wait for decrement to zero. */ wait_for(&barrier->num_left, 0); /* Ack: last ack wakes thread. */ __atomic_inc(&barrier->acks); if (barrier->acks == barrier->initial_count - 1) sys_futex(&barrier->acks, FUTEX_WAKE, 1, NULL); return 1; } } int nonpthread_cond_signal(nonpthread_cond_t *cond) { /* Unreliable if they don't hold mutex, but that's as per spec */ cond->counter++; return sys_futex(&cond->counter, FUTEX_WAKE, 1, NULL); } int nonpthread_cond_broadcast(nonpthread_cond_t *cond) { /* Unreliable if they don't hold mutex, but that's as per spec */ cond->counter++; return sys_futex(&cond->counter, FUTEX_WAKE, INT_MAX, NULL); } int nonpthread_cond_wait(nonpthread_cond_t *cond, nonpthread_mutex_t *mutex) { int value, ret, saved_errno; value = cond->counter; futex_up(mutex); ret = sys_futex(&cond->counter, FUTEX_WAIT, value, NULL); saved_errno = errno; while (futex_down(mutex) < 0 && errno == EINTR); errno = saved_errno; return ret; } int nonpthread_cond_timedwait(nonpthread_cond_t *cond, nonpthread_mutex_t *mutex, const struct timespec *abstime) { struct timeval _now; struct timespec now, rel; int value, ret, saved_errno; value = cond->counter; futex_up(mutex); again: /* Absolute to relative */ gettimeofday(&_now, NULL); TIMEVAL_TO_TIMESPEC(&_now, &now); if (now.tv_sec > abstime->tv_sec || (now.tv_sec == abstime->tv_sec && now.tv_nsec > abstime->tv_nsec)) return ETIMEDOUT; rel.tv_sec = now.tv_sec - abstime->tv_sec; rel.tv_nsec = now.tv_nsec - abstime->tv_nsec; if (rel.tv_nsec < 0) { --rel.tv_sec; rel.tv_nsec += 1000000000; } ret = sys_futex(&cond->counter, FUTEX_WAIT, value, &rel); if (ret < 0 && errno == EINTR) goto again; saved_errno = errno; while (futex_down(mutex) < 0 && errno == EINTR); errno = saved_errno; return ret; }