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author | jhb <jhb@FreeBSD.org> | 2016-07-25 23:37:47 +0000 |
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committer | jhb <jhb@FreeBSD.org> | 2016-07-25 23:37:47 +0000 |
commit | 580d72d572e80f537755d2949d4d0b69c4e315af (patch) | |
tree | 3f6e177225f3fd4ecd4eb28b2057e05cc5bf149e /share | |
parent | 756e5f4363706ac592c61f790be64b08694b0623 (diff) | |
download | FreeBSD-src-580d72d572e80f537755d2949d4d0b69c4e315af.zip FreeBSD-src-580d72d572e80f537755d2949d4d0b69c4e315af.tar.gz |
MFC 302899: Add documentation for the sigevent structure.
- Add a sigevent(3) manpage to give a general overview of the sigevent
structure and the available notification mechanisms.
- Document that AIO requests contain a nested sigevent structure that can
be used to request completion notification.
- Expand the sigevent details in other manuals to note details such as
the extra values stored in a queued signal's information or in a posted
kevent.
Approved by: re (gjb)
Diffstat (limited to 'share')
-rw-r--r-- | share/man/man3/Makefile | 1 | ||||
-rw-r--r-- | share/man/man3/sigevent.3 | 127 | ||||
-rw-r--r-- | share/man/man4/aio.4 | 51 |
3 files changed, 178 insertions, 1 deletions
diff --git a/share/man/man3/Makefile b/share/man/man3/Makefile index 72e4c54..b63ab81 100644 --- a/share/man/man3/Makefile +++ b/share/man/man3/Makefile @@ -15,6 +15,7 @@ MAN= assert.3 \ offsetof.3 \ ${PTHREAD_MAN} \ queue.3 \ + sigevent.3 \ siginfo.3 \ stdarg.3 \ sysexits.3 \ diff --git a/share/man/man3/sigevent.3 b/share/man/man3/sigevent.3 new file mode 100644 index 0000000..493691e --- /dev/null +++ b/share/man/man3/sigevent.3 @@ -0,0 +1,127 @@ +.\" -*- nroff -*- +.\" +.\" Copyright (c) 2016 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. +.\" +.\" $FreeBSD$ +.\" +.Dd July 15, 2016 +.Dt SIGEVENT 3 +.Os +.Sh NAME +.Nm sigevent +.Nd "asynchronous event notification" +.Sh SYNOPSIS +.In signal.h +.Sh DESCRIPTION +Some operations permit threads to request asychronous notification of events +via a +.Vt struct sigevent +structure. +This structure contains several fields that describe the requested notification: +.Bl -column ".Vt void (*)(union sigval)" ".Va sigev_notify_kevent_flags" +.It Sy Type Ta Sy Member Ta Sy Description +.It Vt int Ta sigev_notify Ta notification method +.It Vt int Ta sigev_signo Ta signal number +.It Vt union sigval Ta sigev_value Ta signal value +.It Vt int Ta sigev_notify_kqueue Ta +.Xr kqueue 2 +file descriptor +.It Vt unsigned short Ta sigev_notify_kevent_flags Ta kevent flags +.It Vt lwpid_t Ta sigev_notify_thread_id Ta LWP ID +.It Vt void (*)(union sigval) Ta sigev_notify_function Ta +callback function pointer +.It Vt pthread_attr_t * Ta sigev_notify_attributes Ta +callback thread attributes +.El +.Pp +The +.Va sigev_notify +field specifies the notification method used when the event triggers: +.Bl -tag -width ".Dv SIGEV_THREAD_ID" +.It Dv SIGEV_NONE +No notification is sent. +.It Dv SIGEV_SIGNAL +The signal +.Va sigev_signo +is queued as a real-time signal to the calling process. +The value stored in +.Va sigev_value +will be present in the +.Va si_value +of the +.Vt siginfo_t +structure of the queued signal. +.It Dv SIGEV_THREAD +The notification function in +.Va sigev_notify_function +is called in a separate thread context. +The thread is created with the attributes specified in +.Va *sigev_notify_attributes . +The value stored in +.Va sigev_value +is passed as the sole argument to +.Va sigev_notify_function . +If +.Va sigev_notify_attributes +is +.Dv NULL , +the thread is created with default attributes. +.It Dv SIGEV_KEVENT +A new kevent is posted to the kqueue +.Va sigev_notify_kqueue . +The +.Va udata +member of the kevent structure contains the value stored in +.Va sigev_value . +The meaning of other fields in the kevent are specific to the type of triggered +event. +.It Dv SIGEV_THREAD_ID +The signal +.Va sigev_signo +is queued to the thread whose LWP ID is +.Va sigev_notify_thread_id . +The value stored in +.Va sigev_value +will be present in the +.Va si_value +of the +.Vt siginfo_t +structure of the queued signal. +.El +.Sh NOTES +Note that programs wishing to use +.Dv SIGEV_THREAD +notifications must link against the +.Lb librt . +.Sh SEE ALSO +.Xr aio_read 2 , +.Xr mq_notify 2 , +.Xr timer_create 2 , +.Xr siginfo 3 +.Sh STANDARDS +The +.Vt struct sigevent +type conforms to +.St -p1003.1-2004 . diff --git a/share/man/man4/aio.4 b/share/man/man4/aio.4 index f973639..460b3c8 100644 --- a/share/man/man4/aio.4 +++ b/share/man/man4/aio.4 @@ -27,7 +27,7 @@ .\" .\" $FreeBSD$ .\" -.Dd March 1, 2016 +.Dd July 15, 2016 .Dt AIO 4 .Os .Sh NAME @@ -137,6 +137,54 @@ The number of outstanding asynchronous I/O requests system-wide. The maximum number of outstanding asynchronous I/O requests permitted system-wide. .El +.Pp +Asynchronous I/O control buffers should be zeroed before initializing +individual fields. +This ensures all fields are initialized. +.Pp +All asynchronous I/O control buffers contain a +.Vt sigevent +structure in the +.Va aio_sigevent +field which can be used to request notification when an operation completes. +.Pp +For +.Dv SIGEV_KEVENT +notifications, +the posted kevent will contain: +.Bl -column ".Va filter" +.It Sy Member Ta Sy Value +.It Va ident Ta asynchronous I/O control buffer pointer +.It Va filter Ta Dv EVFILT_AIO +.It Va udata Ta +value stored in +.Va aio_sigevent.sigev_value +.El +.Pp +For +.Dv SIGEV_SIGNO +and +.Dv SIGEV_THREAD_ID +notifications, +the information for the queued signal will include +.Dv SI_ASYNCIO +in the +.Va si_code +field and the value stored in +.Va sigevent.sigev_value +in the +.Va si_value +field. +.Pp +For +.Dv SIGEV_THREAD +notifications, +the value stored in +.Va aio_sigevent.sigev_value +is passed to the +.Va aio_sigevent.sigev_notify_function +as described in +.Xr sigevent 3 . .Sh SEE ALSO .Xr aio_cancel 2 , .Xr aio_error 2 , @@ -146,6 +194,7 @@ system-wide. .Xr aio_waitcomplete 2 , .Xr aio_write 2 , .Xr lio_listio 2 , +.Xr sigevent 3 , .Xr sysctl 8 .Sh HISTORY The |