cosmopolitan/libc/thread/pthread_timedjoin_np.c
Jōshin 6e6fc38935
Apply clang-format update to repo (#1154)
Commit bc6c183 introduced a bunch of discrepancies between what files
look like in the repo and what clang-format says they should look like.
However, there were already a few discrepancies prior to that. Most of
these discrepancies seemed to be unintentional, but a few of them were
load-bearing (e.g., a #include that violated header ordering needing
something to have been #defined by a 'later' #include.)

I opted to take what I hope is a relatively smooth-brained approach: I
reverted the .clang-format change, ran clang-format on the whole repo,
reapplied the .clang-format change, reran clang-format again, and then
reverted the commit that contained the first run. Thus the full effect
of this PR should only be to apply the changed formatting rules to the
repo, and from skimming the results, this seems to be the case.

My work can be checked by applying the short, manual commits, and then
rerunning the command listed in the autogenerated commits (those whose
messages I have prefixed auto:) and seeing if your results agree.

It might be that the other diffs should be fixed at some point but I'm
leaving that aside for now.

fd '\.c(c|pp)?$' --print0| xargs -0 clang-format -i
2024-04-25 10:38:00 -07:00

129 lines
5.8 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│ vi: set et ft=c ts=2 sts=2 sw=2 fenc=utf-8 :vi │
╞══════════════════════════════════════════════════════════════════════════════╡
│ Copyright 2022 Justine Alexandra Roberts Tunney │
│ │
│ Permission to use, copy, modify, and/or distribute this software for │
│ any purpose with or without fee is hereby granted, provided that the │
│ above copyright notice and this permission notice appear in all copies. │
│ │
│ THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL │
│ WARRANTIES WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED │
│ WARRANTIES OF MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE │
│ AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL │
│ DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR │
│ PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR OTHER │
│ TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR │
│ PERFORMANCE OF THIS SOFTWARE. │
╚─────────────────────────────────────────────────────────────────────────────*/
#include "libc/assert.h"
#include "libc/calls/cp.internal.h"
#include "libc/calls/struct/timespec.h"
#include "libc/calls/struct/timespec.internal.h"
#include "libc/errno.h"
#include "libc/fmt/itoa.h"
#include "libc/intrin/atomic.h"
#include "libc/intrin/describeflags.internal.h"
#include "libc/intrin/dll.h"
#include "libc/intrin/strace.internal.h"
#include "libc/thread/posixthread.internal.h"
#include "libc/thread/thread2.h"
#include "libc/thread/tls.h"
#include "third_party/nsync/futex.internal.h"
static const char *DescribeReturnValue(char buf[30], int err, void **value) {
char *p = buf;
if (!value)
return "NULL";
if (err)
return "[n/a]";
*p++ = '[';
p = FormatHex64(p, (uintptr_t)*value, 1);
*p++ = ']';
*p = 0;
return buf;
}
/**
* Blocks until memory location becomes zero.
*
* 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, FreeBSD, OpenBSD, and Windows. On other
* platforms this uses polling with exponential backoff.
*
* @return 0 on success, or errno on error
* @raise ECANCELED if calling thread was cancelled in masked mode
* @raise EBUSY if `abstime` was specified and deadline expired
* @cancelationpoint
*/
static errno_t _pthread_wait(atomic_int *ctid, struct timespec *abstime) {
int x, e, rc = 0;
unassert(ctid != &__get_tls()->tib_tid);
// "If the thread calling pthread_join() is canceled, then the target
// thread shall not be detached." ──Quoth POSIX.1-2017
if (!(rc = pthread_testcancel_np())) {
BEGIN_CANCELATION_POINT;
while ((x = atomic_load_explicit(ctid, memory_order_acquire))) {
e = nsync_futex_wait_(ctid, x, !IsWindows() && !IsXnu(), abstime);
if (e == -ECANCELED) {
rc = ECANCELED;
break;
} else if (e == -ETIMEDOUT) {
rc = EBUSY;
break;
}
}
END_CANCELATION_POINT;
}
return rc;
}
/**
* Waits for thread to terminate.
*
* Multiple threads joining the same thread is undefined behavior. If a
* deferred or masked cancelation happens to the calling thread either
* before or during the waiting process then the target thread will not
* be joined. Calling pthread_join() on a non-joinable thread, e.g. one
* that's been detached, is undefined behavior. If a thread attempts to
* join itself, then the behavior is undefined.
*
* @param value_ptr if non-null will receive pthread_exit() argument
* if the thread called pthread_exit(), or `PTHREAD_CANCELED` if
* pthread_cancel() destroyed the thread instead
* @param abstime specifies an absolute deadline or the timestamp of
* when we'll stop waiting; if this is null we will wait forever
* @return 0 on success, or errno on error
* @raise ECANCELED if calling thread was cancelled in masked mode
* @raise EBUSY if `abstime` deadline elapsed
* @cancelationpoint
* @returnserrno
*/
errno_t pthread_timedjoin_np(pthread_t thread, void **value_ptr,
struct timespec *abstime) {
errno_t err;
struct PosixThread *pt;
enum PosixThreadStatus status;
pt = (struct PosixThread *)thread;
status = atomic_load_explicit(&pt->pt_status, memory_order_acquire);
// "The behavior is undefined if the value specified by the thread
// argument to pthread_join() does not refer to a joinable thread."
// ──Quoth POSIX.1-2017
unassert(status == kPosixThreadJoinable || status == kPosixThreadTerminated);
if (!(err = _pthread_wait(&pt->tib->tib_tid, abstime))) {
_pthread_lock();
dll_remove(&_pthread_list, &pt->list);
_pthread_unlock();
if (value_ptr) {
*value_ptr = pt->pt_rc;
}
_pthread_unref(pt);
}
STRACE("pthread_timedjoin_np(%d, %s, %s) → %s", _pthread_tid(pt),
DescribeReturnValue(alloca(30), err, value_ptr),
DescribeTimespec(err ? -1 : 0, abstime), DescribeErrno(err));
return err;
}