diff options
author | jhb <jhb@FreeBSD.org> | 2009-11-20 19:19:51 +0000 |
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committer | jhb <jhb@FreeBSD.org> | 2009-11-20 19:19:51 +0000 |
commit | b850b4760dddafa38d7850f86e99ce47326a2676 (patch) | |
tree | 9dcf60a4d7bd680a0877e1a8aa449c9766bdcc8f /lib/libc/gen/_once_stub.c | |
parent | be8a54e0c3db12d3fecac288bf6ddfd350731d11 (diff) | |
download | FreeBSD-src-b850b4760dddafa38d7850f86e99ce47326a2676.zip FreeBSD-src-b850b4760dddafa38d7850f86e99ce47326a2676.tar.gz |
Add an internal _once() method. This works identical to pthread_once(3)
with the additional property that it is safe for routines in libc to use
in both single-threaded and multi-threaded processes. Multi-threaded
processes use the pthread_once() implementation from the threading library
while single-threaded processes use a simplified "stub" version internal
to libc. The libc stub-version of pthread_once() now also uses the
simplified "stub" version as well instead of being a nop.
Reviewed by: deischen, Matthew Fleming @ Isilon
Suggested by: alc
MFC after: 1 week
Diffstat (limited to 'lib/libc/gen/_once_stub.c')
-rw-r--r-- | lib/libc/gen/_once_stub.c | 67 |
1 files changed, 67 insertions, 0 deletions
diff --git a/lib/libc/gen/_once_stub.c b/lib/libc/gen/_once_stub.c new file mode 100644 index 0000000..0d20c01 --- /dev/null +++ b/lib/libc/gen/_once_stub.c @@ -0,0 +1,67 @@ +/*- + * Copyright (c) 2009 Advanced Computing Technologies LLC + * Written by: John H. Baldwin <jhb@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, 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 AND CONTRIBUTORS ``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 OR CONTRIBUTORS 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. + */ + +#include <sys/cdefs.h> +__FBSDID("$FreeBSD$"); + +#include "namespace.h" +#include <pthread.h> +#include "un-namespace.h" +#include "libc_private.h" + +/* + * This implements pthread_once() for the single-threaded case. It is + * non-static so that it can be used by _pthread_stubs.c. + */ +int +_libc_once(pthread_once_t *once_control, void (*init_routine)(void)) +{ + + if (once_control->state == PTHREAD_DONE_INIT) + return (0); + init_routine(); + once_control->state = PTHREAD_DONE_INIT; + return (0); +} + +/* + * This is the internal interface provided to libc. It will use + * pthread_once() from the threading library in a multi-threaded + * process and _libc_once() for a single-threaded library. Because + * _libc_once() uses the same ABI for the values in the pthread_once_t + * structure as the threading library, it is safe for a process to + * switch from _libc_once() to pthread_once() when threading is + * enabled. + */ +int +_once(pthread_once_t *once_control, void (*init_routine)(void)) +{ + + if (__isthreaded) + return (_pthread_once(once_control, init_routine)); + return (_libc_once(once_control, init_routine)); +} |