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Make more improvements to threading support

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- fix rare thread exit race condition on openbsd
- pthread_getattr_np() now supplies detached status
- child threads may now pthread_join() the main thread
- introduce sigandset(), sigorset(), and sigisemptyset()
- introduce pthread_cleanup_push() and pthread_cleanup_pop()
This commit is contained in:
Justine Tunney 2022-10-08 23:54:05 -07:00
parent 38df0a4186
commit 4a6fd3d910
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GPG key ID: BE714B4575D6E328
52 changed files with 586 additions and 241 deletions
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79
libc/thread/wait0.c
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@ -16,71 +16,10 @@
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/atomic.h"
#include "libc/calls/calls.h"
#include "libc/calls/struct/timespec.h"
#include "libc/calls/struct/timespec.internal.h"
#include "libc/dce.h"
#include "libc/errno.h"
#include "libc/intrin/atomic.h"
#include "libc/intrin/describeflags.internal.h"
#include "libc/intrin/kprintf.h"
#include "libc/intrin/strace.internal.h"
#include "libc/nt/runtime.h"
#include "libc/nt/synchronization.h"
#include "libc/sysv/consts/futex.h"
#include "libc/thread/freebsd.internal.h"
#include "libc/thread/wait0.internal.h"
int _futex(atomic_int *, int, int, const struct timespec *);
static int _wait0_sleep(struct timespec *ts) {
int rc, e = errno;
if ((rc = nanosleep(ts, 0))) {
_npassert(errno == EINTR);
errno = e;
}
return rc;
}
static void _wait0_poll(struct timespec *ts) {
if (ts->tv_nsec < 1000) {
// prefer sched_yield() for small time intervals because nanosleep()
// will ceiling round to 1ms on the new technology.
sched_yield();
ts->tv_nsec <<= 1;
} else if (!_wait0_sleep(ts)) {
if (ts->tv_nsec < 100 * 1000 * 1000) {
ts->tv_nsec <<= 1;
}
}
}
static void _wait0_futex(const atomic_int *a, int e) {
int rc, op;
op = FUTEX_WAIT; // we need a shared mutex
if (IsWindows()) {
if (WaitOnAddress(a, &e, sizeof(*a), -1)) {
rc = 0;
} else {
rc = -GetLastError();
}
} else if (IsFreebsd()) {
rc = sys_umtx_op(a, UMTX_OP_WAIT_UINT, e, 0, 0);
} else {
rc = _futex(a, op, e, 0);
if (IsOpenbsd() && rc > 0) {
rc = -rc;
}
}
STRACE("futex(%t, %s, %d, %s) → %s", a, DescribeFutexOp(op), e, "NULL",
DescribeErrnoResult(rc));
_npassert(rc == 0 || //
rc == -EINTR || //
rc == -ETIMEDOUT || //
rc == -EWOULDBLOCK);
}
#include "third_party/nsync/futex.internal.h"
/**
* Blocks until memory location becomes zero.
@ -88,20 +27,12 @@ static void _wait0_futex(const atomic_int *a, int e) {
* This is intended to be used on the child thread id, which is updated
* by the clone() system call when a thread terminates. We need this in
* order to know when it's safe to free a thread's stack. This function
* uses futexes on Linux, OpenBSD, and Windows. On other platforms this
* uses polling with exponential backoff.
* uses futexes on Linux, FreeBSD, OpenBSD, and Windows. On other
* platforms this uses polling with exponential backoff.
*/
void _wait0(const atomic_int *ctid) {
int x;
struct timespec ts = {0, 1};
while ((x = atomic_load_explicit(ctid, memory_order_acquire))) {
if (IsLinux() || IsOpenbsd() || IsWindows()) {
_wait0_futex(ctid, x);
} else {
_wait0_poll(&ts);
}
}
if (IsOpenbsd()) {
sched_yield(); // TODO(jart): whhhy?
while ((x = atomic_load_explicit(ctid, memory_order_relaxed))) {
nsync_futex_wait_((int *)ctid, x, !IsWindows(), 0);
}
}