diff options
Diffstat (limited to 'lib/libthr/thread/thr_once.c')
-rw-r--r-- | lib/libthr/thread/thr_once.c | 99 |
1 files changed, 99 insertions, 0 deletions
diff --git a/lib/libthr/thread/thr_once.c b/lib/libthr/thread/thr_once.c new file mode 100644 index 0000000..4f70374 --- /dev/null +++ b/lib/libthr/thread/thr_once.c @@ -0,0 +1,99 @@ +/* + * Copyright (c) 2005, David Xu <davidxu@freebsd.org> + * All rights reserved. + * + * Redistribution and use in source and binary forms, with or without + * modification, are permitted provided that the following conditions + * are met: + * 1. Redistributions of source code must retain the above copyright + * notice unmodified, this list of conditions, and the following + * disclaimer. + * 2. Redistributions in binary form must reproduce the above copyright + * notice, this list of conditions and the following disclaimer in the + * documentation and/or other materials provided with the distribution. + * + * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR + * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES + * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. + * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, + * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT + * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, + * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY + * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT + * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF + * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. + * + * $FreeBSD$ + * + */ + +#include "namespace.h" +#include <pthread.h> +#include "un-namespace.h" + +#include "thr_private.h" + +__weak_reference(_pthread_once, pthread_once); + +#define ONCE_NEVER_DONE PTHREAD_NEEDS_INIT +#define ONCE_DONE PTHREAD_DONE_INIT +#define ONCE_IN_PROGRESS 0x02 +#define ONCE_WAIT 0x03 + +/* + * POSIX: + * The pthread_once() function is not a cancellation point. However, + * if init_routine is a cancellation point and is canceled, the effect + * on once_control shall be as if pthread_once() was never called. + */ + +static void +once_cancel_handler(void *arg) +{ + pthread_once_t *once_control = arg; + + if (atomic_cmpset_rel_int(&once_control->state, ONCE_IN_PROGRESS, ONCE_NEVER_DONE)) + return; + atomic_store_rel_int(&once_control->state, ONCE_NEVER_DONE); + _thr_umtx_wake(&once_control->state, INT_MAX, 0); +} + +int +_pthread_once(pthread_once_t *once_control, void (*init_routine) (void)) +{ + struct pthread *curthread; + int state; + + _thr_check_init(); + + for (;;) { + state = once_control->state; + if (state == ONCE_DONE) + return (0); + if (state == ONCE_NEVER_DONE) { + if (atomic_cmpset_acq_int(&once_control->state, state, ONCE_IN_PROGRESS)) + break; + } else if (state == ONCE_IN_PROGRESS) { + if (atomic_cmpset_acq_int(&once_control->state, state, ONCE_WAIT)) + _thr_umtx_wait_uint(&once_control->state, ONCE_WAIT, NULL, 0); + } else if (state == ONCE_WAIT) { + _thr_umtx_wait_uint(&once_control->state, state, NULL, 0); + } else + return (EINVAL); + } + + curthread = _get_curthread(); + THR_CLEANUP_PUSH(curthread, once_cancel_handler, once_control); + init_routine(); + THR_CLEANUP_POP(curthread, 0); + if (atomic_cmpset_rel_int(&once_control->state, ONCE_IN_PROGRESS, ONCE_DONE)) + return (0); + atomic_store_rel_int(&once_control->state, ONCE_DONE); + _thr_umtx_wake(&once_control->state, INT_MAX, 0); + return (0); +} + +void +_thr_once_init() +{ +} |