cosmopolitan/libc/thread/pthread_detach.c
Justine Tunney cee6871710
Make detached threads work better
This change adds a double linked list of threads, so that pthread_exit()
will know when it should call exit() from an orphaned child. This change
also improves ftrace and strace logging.
2022-11-09 03:58:57 -08:00

67 lines
3.3 KiB
C

/*-*- mode:c;indent-tabs-mode:nil;c-basic-offset:2;tab-width:8;coding:utf-8 -*-│
│vi: set net 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/errno.h"
#include "libc/intrin/atomic.h"
#include "libc/intrin/strace.internal.h"
#include "libc/macros.internal.h"
#include "libc/mem/mem.h"
#include "libc/thread/posixthread.internal.h"
#include "libc/thread/spawn.h"
#include "libc/thread/thread.h"
#include "third_party/nsync/dll.h"
/**
* Asks POSIX thread to free itself automatically upon termination.
*
* If this function is used, then it's important to use pthread_exit()
* rather than exit() since otherwise your program isn't guaranteed to
* gracefully terminate.
*
* Detaching a non-joinable thread is undefined behavior. For example,
* pthread_detach() can't be called twice on the same thread.
*
* @return 0 on success, or errno with error
* @returnserrno
* @threadsafe
*/
errno_t pthread_detach(pthread_t thread) {
struct PosixThread *pt;
enum PosixThreadStatus status, transition;
for (pt = (struct PosixThread *)thread;;) {
status = atomic_load_explicit(&pt->status, memory_order_acquire);
if (status == kPosixThreadJoinable) {
transition = kPosixThreadDetached;
} else if (status == kPosixThreadTerminated) {
transition = kPosixThreadZombie;
} else {
unreachable;
}
if (atomic_compare_exchange_weak_explicit(&pt->status, &status, transition,
memory_order_release,
memory_order_relaxed)) {
break;
}
}
if (transition == kPosixThreadZombie) {
_pthread_zombify(pt);
}
pthread_decimate_np();
return 0;
}