#include "internal.h"
#if USE_MACH_SEM
#define DISPATCH_SEMAPHORE_VERIFY_KR(x) do { \
if (slowpath(x)) { \
DISPATCH_CRASH("flawed group/semaphore logic"); \
} \
} while (0)
#elif USE_POSIX_SEM
#define DISPATCH_SEMAPHORE_VERIFY_RET(x) do { \
if (slowpath((x) == -1)) { \
DISPATCH_CRASH("flawed group/semaphore logic"); \
} \
} while (0)
#endif
DISPATCH_WEAK long _dispatch_semaphore_signal_slow(dispatch_semaphore_t dsema);
static void _dispatch_semaphore_dispose(dispatch_semaphore_t dsema);
static size_t _dispatch_semaphore_debug(dispatch_semaphore_t dsema, char *buf,
size_t bufsiz);
static long _dispatch_group_wake(dispatch_semaphore_t dsema);
#pragma mark -
#pragma mark dispatch_semaphore_t
struct dispatch_semaphore_vtable_s {
DISPATCH_VTABLE_HEADER(dispatch_semaphore_s);
};
const struct dispatch_semaphore_vtable_s _dispatch_semaphore_vtable = {
.do_type = DISPATCH_SEMAPHORE_TYPE,
.do_kind = "semaphore",
.do_dispose = _dispatch_semaphore_dispose,
.do_debug = _dispatch_semaphore_debug,
};
dispatch_semaphore_t
dispatch_semaphore_create(long value)
{
dispatch_semaphore_t dsema;
if (value < 0) {
return NULL;
}
dsema = calloc(1, sizeof(struct dispatch_semaphore_s));
if (fastpath(dsema)) {
dsema->do_vtable = &_dispatch_semaphore_vtable;
dsema->do_next = DISPATCH_OBJECT_LISTLESS;
dsema->do_ref_cnt = 1;
dsema->do_xref_cnt = 1;
dsema->do_targetq = dispatch_get_global_queue(
DISPATCH_QUEUE_PRIORITY_DEFAULT, 0);
dsema->dsema_value = value;
dsema->dsema_orig = value;
#if USE_POSIX_SEM
int ret = sem_init(&dsema->dsema_sem, 0, 0);
DISPATCH_SEMAPHORE_VERIFY_RET(ret);
#endif
}
return dsema;
}
#if USE_MACH_SEM
static void
_dispatch_semaphore_create_port(semaphore_t *s4)
{
kern_return_t kr;
semaphore_t tmp;
if (*s4) {
return;
}
while ((kr = semaphore_create(mach_task_self(), &tmp,
SYNC_POLICY_FIFO, 0))) {
DISPATCH_VERIFY_MIG(kr);
sleep(1);
}
if (!dispatch_atomic_cmpxchg(s4, 0, tmp)) {
kr = semaphore_destroy(mach_task_self(), tmp);
DISPATCH_SEMAPHORE_VERIFY_KR(kr);
}
_dispatch_safe_fork = false;
}
#endif
static void
_dispatch_semaphore_dispose(dispatch_semaphore_t dsema)
{
if (dsema->dsema_value < dsema->dsema_orig) {
DISPATCH_CLIENT_CRASH(
"Semaphore/group object deallocated while in use");
}
#if USE_MACH_SEM
kern_return_t kr;
if (dsema->dsema_port) {
kr = semaphore_destroy(mach_task_self(), dsema->dsema_port);
DISPATCH_SEMAPHORE_VERIFY_KR(kr);
}
if (dsema->dsema_waiter_port) {
kr = semaphore_destroy(mach_task_self(), dsema->dsema_waiter_port);
DISPATCH_SEMAPHORE_VERIFY_KR(kr);
}
#elif USE_POSIX_SEM
int ret = sem_destroy(&dsema->dsema_sem);
DISPATCH_SEMAPHORE_VERIFY_RET(ret);
#endif
_dispatch_dispose(dsema);
}
static size_t
_dispatch_semaphore_debug(dispatch_semaphore_t dsema, char *buf, size_t bufsiz)
{
size_t offset = 0;
offset += snprintf(&buf[offset], bufsiz - offset, "%s[%p] = { ",
dx_kind(dsema), dsema);
offset += _dispatch_object_debug_attr(dsema, &buf[offset], bufsiz - offset);
#if USE_MACH_SEM
offset += snprintf(&buf[offset], bufsiz - offset, "port = 0x%u, ",
dsema->dsema_port);
#endif
offset += snprintf(&buf[offset], bufsiz - offset,
"value = %ld, orig = %ld }", dsema->dsema_value, dsema->dsema_orig);
return offset;
}
DISPATCH_NOINLINE
long
_dispatch_semaphore_signal_slow(dispatch_semaphore_t dsema)
{
_dispatch_retain(dsema);
(void)dispatch_atomic_inc2o(dsema, dsema_sent_ksignals);
#if USE_MACH_SEM
_dispatch_semaphore_create_port(&dsema->dsema_port);
kern_return_t kr = semaphore_signal(dsema->dsema_port);
DISPATCH_SEMAPHORE_VERIFY_KR(kr);
#elif USE_POSIX_SEM
int ret = sem_post(&dsema->dsema_sem);
DISPATCH_SEMAPHORE_VERIFY_RET(ret);
#endif
_dispatch_release(dsema);
return 1;
}
long
dispatch_semaphore_signal(dispatch_semaphore_t dsema)
{
dispatch_atomic_release_barrier();
long value = dispatch_atomic_inc2o(dsema, dsema_value);
if (fastpath(value > 0)) {
return 0;
}
if (slowpath(value == LONG_MIN)) {
DISPATCH_CLIENT_CRASH("Unbalanced call to dispatch_group_leave() or "
"dispatch_semaphore_signal()");
}
return _dispatch_semaphore_signal_slow(dsema);
}
DISPATCH_NOINLINE
static long
_dispatch_semaphore_wait_slow(dispatch_semaphore_t dsema,
dispatch_time_t timeout)
{
long orig;
again:
while ((orig = dsema->dsema_sent_ksignals)) {
if (dispatch_atomic_cmpxchg2o(dsema, dsema_sent_ksignals, orig,
orig - 1)) {
return 0;
}
}
#if USE_MACH_SEM
mach_timespec_t _timeout;
kern_return_t kr;
_dispatch_semaphore_create_port(&dsema->dsema_port);
switch (timeout) {
default:
do {
uint64_t nsec = _dispatch_timeout(timeout);
_timeout.tv_sec = (typeof(_timeout.tv_sec))(nsec / NSEC_PER_SEC);
_timeout.tv_nsec = (typeof(_timeout.tv_nsec))(nsec % NSEC_PER_SEC);
kr = slowpath(semaphore_timedwait(dsema->dsema_port, _timeout));
} while (kr == KERN_ABORTED);
if (kr != KERN_OPERATION_TIMED_OUT) {
DISPATCH_SEMAPHORE_VERIFY_KR(kr);
break;
}
case DISPATCH_TIME_NOW:
while ((orig = dsema->dsema_value) < 0) {
if (dispatch_atomic_cmpxchg2o(dsema, dsema_value, orig, orig + 1)) {
return KERN_OPERATION_TIMED_OUT;
}
}
case DISPATCH_TIME_FOREVER:
do {
kr = semaphore_wait(dsema->dsema_port);
} while (kr == KERN_ABORTED);
DISPATCH_SEMAPHORE_VERIFY_KR(kr);
break;
}
#elif USE_POSIX_SEM
struct timespec _timeout;
int ret;
switch (timeout) {
default:
do {
uint64_t nsec = _dispatch_timeout(timeout);
_timeout.tv_sec = (typeof(_timeout.tv_sec))(nsec / NSEC_PER_SEC);
_timeout.tv_nsec = (typeof(_timeout.tv_nsec))(nsec % NSEC_PER_SEC);
ret = slowpath(sem_timedwait(&dsema->dsema_sem, &_timeout));
} while (ret == -1 && errno == EINTR);
if (ret == -1 && errno != ETIMEDOUT) {
DISPATCH_SEMAPHORE_VERIFY_RET(ret);
break;
}
case DISPATCH_TIME_NOW:
while ((orig = dsema->dsema_value) < 0) {
if (dispatch_atomic_cmpxchg2o(dsema, dsema_value, orig, orig + 1)) {
errno = ETIMEDOUT;
return -1;
}
}
case DISPATCH_TIME_FOREVER:
do {
ret = sem_wait(&dsema->dsema_sem);
} while (ret != 0);
DISPATCH_SEMAPHORE_VERIFY_RET(ret);
break;
}
#endif
goto again;
}
long
dispatch_semaphore_wait(dispatch_semaphore_t dsema, dispatch_time_t timeout)
{
long value = dispatch_atomic_dec2o(dsema, dsema_value);
dispatch_atomic_acquire_barrier();
if (fastpath(value >= 0)) {
return 0;
}
return _dispatch_semaphore_wait_slow(dsema, timeout);
}
#pragma mark -
#pragma mark dispatch_group_t
dispatch_group_t
dispatch_group_create(void)
{
return (dispatch_group_t)dispatch_semaphore_create(LONG_MAX);
}
void
dispatch_group_enter(dispatch_group_t dg)
{
dispatch_semaphore_t dsema = (dispatch_semaphore_t)dg;
(void)dispatch_semaphore_wait(dsema, DISPATCH_TIME_FOREVER);
}
DISPATCH_NOINLINE
static long
_dispatch_group_wake(dispatch_semaphore_t dsema)
{
struct dispatch_sema_notify_s *next, *head, *tail = NULL;
long rval;
head = dispatch_atomic_xchg2o(dsema, dsema_notify_head, NULL);
if (head) {
tail = dispatch_atomic_xchg2o(dsema, dsema_notify_tail, NULL);
}
rval = dispatch_atomic_xchg2o(dsema, dsema_group_waiters, 0);
if (rval) {
#if USE_MACH_SEM
_dispatch_semaphore_create_port(&dsema->dsema_waiter_port);
do {
kern_return_t kr = semaphore_signal(dsema->dsema_waiter_port);
DISPATCH_SEMAPHORE_VERIFY_KR(kr);
} while (--rval);
#elif USE_POSIX_SEM
do {
int ret = sem_post(&dsema->dsema_sem);
DISPATCH_SEMAPHORE_VERIFY_RET(ret);
} while (--rval);
#endif
}
if (head) {
do {
dispatch_async_f(head->dsn_queue, head->dsn_ctxt, head->dsn_func);
_dispatch_release(head->dsn_queue);
next = fastpath(head->dsn_next);
if (!next && head != tail) {
while (!(next = fastpath(head->dsn_next))) {
_dispatch_hardware_pause();
}
}
free(head);
} while ((head = next));
_dispatch_release(dsema);
}
return 0;
}
void
dispatch_group_leave(dispatch_group_t dg)
{
dispatch_semaphore_t dsema = (dispatch_semaphore_t)dg;
dispatch_semaphore_signal(dsema);
if (dsema->dsema_value == dsema->dsema_orig) {
(void)_dispatch_group_wake(dsema);
}
}
DISPATCH_NOINLINE
static long
_dispatch_group_wait_slow(dispatch_semaphore_t dsema, dispatch_time_t timeout)
{
long orig;
again:
if (dsema->dsema_value == dsema->dsema_orig) {
return _dispatch_group_wake(dsema);
}
(void)dispatch_atomic_inc2o(dsema, dsema_group_waiters);
if (dsema->dsema_value == dsema->dsema_orig) {
return _dispatch_group_wake(dsema);
}
#if USE_MACH_SEM
mach_timespec_t _timeout;
kern_return_t kr;
_dispatch_semaphore_create_port(&dsema->dsema_waiter_port);
switch (timeout) {
default:
do {
uint64_t nsec = _dispatch_timeout(timeout);
_timeout.tv_sec = (typeof(_timeout.tv_sec))(nsec / NSEC_PER_SEC);
_timeout.tv_nsec = (typeof(_timeout.tv_nsec))(nsec % NSEC_PER_SEC);
kr = slowpath(semaphore_timedwait(dsema->dsema_waiter_port,
_timeout));
} while (kr == KERN_ABORTED);
if (kr != KERN_OPERATION_TIMED_OUT) {
DISPATCH_SEMAPHORE_VERIFY_KR(kr);
break;
}
case DISPATCH_TIME_NOW:
while ((orig = dsema->dsema_group_waiters)) {
if (dispatch_atomic_cmpxchg2o(dsema, dsema_group_waiters, orig,
orig - 1)) {
return KERN_OPERATION_TIMED_OUT;
}
}
case DISPATCH_TIME_FOREVER:
do {
kr = semaphore_wait(dsema->dsema_waiter_port);
} while (kr == KERN_ABORTED);
DISPATCH_SEMAPHORE_VERIFY_KR(kr);
break;
}
#elif USE_POSIX_SEM
struct timespec _timeout;
int ret;
switch (timeout) {
default:
do {
uint64_t nsec = _dispatch_timeout(timeout);
_timeout.tv_sec = (typeof(_timeout.tv_sec))(nsec / NSEC_PER_SEC);
_timeout.tv_nsec = (typeof(_timeout.tv_nsec))(nsec % NSEC_PER_SEC);
ret = slowpath(sem_timedwait(&dsema->dsema_sem, &_timeout));
} while (ret == -1 && errno == EINTR);
if (!(ret == -1 && errno == ETIMEDOUT)) {
DISPATCH_SEMAPHORE_VERIFY_RET(ret);
break;
}
case DISPATCH_TIME_NOW:
while ((orig = dsema->dsema_group_waiters)) {
if (dispatch_atomic_cmpxchg2o(dsema, dsema_group_waiters, orig,
orig - 1)) {
errno = ETIMEDOUT;
return -1;
}
}
case DISPATCH_TIME_FOREVER:
do {
ret = sem_wait(&dsema->dsema_sem);
} while (ret == -1 && errno == EINTR);
DISPATCH_SEMAPHORE_VERIFY_RET(ret);
break;
}
#endif
goto again;
}
long
dispatch_group_wait(dispatch_group_t dg, dispatch_time_t timeout)
{
dispatch_semaphore_t dsema = (dispatch_semaphore_t)dg;
if (dsema->dsema_value == dsema->dsema_orig) {
return 0;
}
if (timeout == 0) {
#if USE_MACH_SEM
return KERN_OPERATION_TIMED_OUT;
#elif USE_POSIX_SEM
errno = ETIMEDOUT;
return (-1);
#endif
}
return _dispatch_group_wait_slow(dsema, timeout);
}
DISPATCH_NOINLINE
void
dispatch_group_notify_f(dispatch_group_t dg, dispatch_queue_t dq, void *ctxt,
void (*func)(void *))
{
dispatch_semaphore_t dsema = (dispatch_semaphore_t)dg;
struct dispatch_sema_notify_s *dsn, *prev;
while (!(dsn = calloc(1, sizeof(*dsn)))) {
sleep(1);
}
dsn->dsn_queue = dq;
dsn->dsn_ctxt = ctxt;
dsn->dsn_func = func;
_dispatch_retain(dq);
dispatch_atomic_store_barrier();
prev = dispatch_atomic_xchg2o(dsema, dsema_notify_tail, dsn);
if (fastpath(prev)) {
prev->dsn_next = dsn;
} else {
_dispatch_retain(dg);
dsema->dsema_notify_head = dsn;
if (dsema->dsema_value == dsema->dsema_orig) {
_dispatch_group_wake(dsema);
}
}
}
#ifdef __BLOCKS__
void
dispatch_group_notify(dispatch_group_t dg, dispatch_queue_t dq,
dispatch_block_t db)
{
dispatch_group_notify_f(dg, dq, _dispatch_Block_copy(db),
_dispatch_call_block_and_release);
}
#endif
#pragma mark -
#pragma mark _dispatch_thread_semaphore_t
DISPATCH_NOINLINE
static _dispatch_thread_semaphore_t
_dispatch_thread_semaphore_create(void)
{
#if USE_MACH_SEM
semaphore_t s4;
kern_return_t kr;
while (slowpath(kr = semaphore_create(mach_task_self(), &s4,
SYNC_POLICY_FIFO, 0))) {
DISPATCH_VERIFY_MIG(kr);
sleep(1);
}
return s4;
#elif USE_POSIX_SEM
sem_t s4;
int ret = sem_init(&s4, 0, 0);
DISPATCH_SEMAPHORE_VERIFY_RET(ret);
return s4;
#endif
}
DISPATCH_NOINLINE
void
_dispatch_thread_semaphore_dispose(_dispatch_thread_semaphore_t sema)
{
#if USE_MACH_SEM
semaphore_t s4 = (semaphore_t)sema;
kern_return_t kr = semaphore_destroy(mach_task_self(), s4);
DISPATCH_SEMAPHORE_VERIFY_KR(kr);
#elif USE_POSIX_SEM
sem_t s4 = (sem_t)sema;
int ret = sem_destroy(&s4);
DISPATCH_SEMAPHORE_VERIFY_RET(ret);
#endif
}
void
_dispatch_thread_semaphore_signal(_dispatch_thread_semaphore_t sema)
{
#if USE_MACH_SEM
semaphore_t s4 = (semaphore_t)sema;
kern_return_t kr = semaphore_signal(s4);
DISPATCH_SEMAPHORE_VERIFY_KR(kr);
#elif USE_POSIX_SEM
sem_t s4 = (sem_t)sema;
int ret = sem_post(&s4);
DISPATCH_SEMAPHORE_VERIFY_RET(ret);
#endif
}
void
_dispatch_thread_semaphore_wait(_dispatch_thread_semaphore_t sema)
{
#if USE_MACH_SEM
semaphore_t s4 = (semaphore_t)sema;
kern_return_t kr;
do {
kr = semaphore_wait(s4);
} while (slowpath(kr == KERN_ABORTED));
DISPATCH_SEMAPHORE_VERIFY_KR(kr);
#elif USE_POSIX_SEM
sem_t s4 = (sem_t)sema;
int ret;
do {
ret = sem_wait(&s4);
} while (slowpath(ret != 0));
DISPATCH_SEMAPHORE_VERIFY_RET(ret);
#endif
}
_dispatch_thread_semaphore_t
_dispatch_get_thread_semaphore(void)
{
_dispatch_thread_semaphore_t sema = (_dispatch_thread_semaphore_t)
_dispatch_thread_getspecific(dispatch_sema4_key);
if (slowpath(!sema)) {
return _dispatch_thread_semaphore_create();
}
_dispatch_thread_setspecific(dispatch_sema4_key, NULL);
return sema;
}
void
_dispatch_put_thread_semaphore(_dispatch_thread_semaphore_t sema)
{
_dispatch_thread_semaphore_t old_sema = (_dispatch_thread_semaphore_t)
_dispatch_thread_getspecific(dispatch_sema4_key);
_dispatch_thread_setspecific(dispatch_sema4_key, (void*)sema);
if (slowpath(old_sema)) {
return _dispatch_thread_semaphore_dispose(old_sema);
}
}