freebsd-dev/lib/libc_r/man/pthread_once.3
Julian Elischer 0f7d684755 Submitted by: John Birrell <cimaxp1!jb@werple.net.au>
Here are the diffs for libc_r to get it one step closer to P1003.1c
These make most of the thread/mutex/condvar structures opaque to the
user. There are three functions which have been renamed with _np
suffixes because they are extensions to P1003.1c (I did them for JAVA,
which needs to suspend/resume threads and also start threads suspended).

I've created a new header (pthread_np.h) for the non-POSIX stuff.

The egrep tags stuff in /usr/src/lib/libc_r/Makefile that I uncommented
doesn't work. I think its best to delete it. I don't think libc_r needs
tags anyway, 'cause most of the source is in libc which does have tags.

also:

Here's the first batch of man pages for the thread functions.
The diff to /usr/src/lib/libc_r/Makefile removes some stuff that was
inherited from /usr/src/lib/libc/Makefile that should only be done with
libc.

also:

I should have sent this diff with the pthread(3) man page.
It allows people to type

make -DWANT_LIBC_R world

to get libc_r built with the rest of the world. I put this in the
pthread(3) man page.  The default is still not to build libc_r.


also:
The diff attached adds a pthread(3) man page to /usr/src/share/man/man3.
The idea is that without libc_r installed, this man page will give people
enough info to know that they have to build libc_r.
1996-08-20 08:22:01 +00:00

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3.2 KiB
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.\" Copyright (c) 1996 John Birrell <jb@cimlogic.com.au>.
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.Dd April 4, 1996
.Dt PTHREAD_ONCE 3
.Os BSD 4
.Sh NAME
.Nm pthread_once
.Nd dynamic package initialization
.Sh SYNOPSIS
.Fd #include <pthread.h>
.Pp
pthread_once
.Fa once_control
= PTHREAD_ONCE_INIT;
.Ft int
.Fn pthread_once "pthread_once_t *once_control" "void *(*init_routine)(void)"
.Sh DESCRIPTION
The first call to
.Fn pthread_once
by any thread in a process, with a given
.Fa once_control ,
will call the
.Fn init_routine
with no arguments. Subsequent calls to
.Fn pthread_once
with the same
.Fa once_control
will not call the
.Fn init_routine .
On return from
.Fn pthread_once ,
it is guaranteed that
.Fn init_routine
has completed. The
.Fa once_control
parameter is used to determine whether the associated initialization
routine has been called.
.Pp
The function
.Fn pthread_once
is not a cancellation point. However, if
.Fn init_routine
is a cancellation point and is cancelled, the effect on
.Fa once_control is as if
.Fn pthread_once
was never called.
.Pp
The constant
.Fa PTHREAD_ONCE_INIT
is defined by header
.Aq Pa pthread.h .
.Pp
The behavior of
.Fn pthread_once
is undefined if
.Fa once_control
has automatic storage duration or is not initialized by
.Fa PTHREAD_ONCE_INIT .
.Pp
.Sh RETURN VALUES
If successful, the
.Fn pthread_once
function will return zero. Otherwise an error number will be returned to
indicate the error.
.Sh ERRORS
None.
.Pp
.Sh STANDARDS
.Fn pthread_once
is expected to conform to IEEE
.Pq Dq Tn POSIX
Std 1003.1c when it is published.