Section (7) sigevent
Name
sigevent — structure for notification from asynchronous routines
Synopsis
#include <signal.h>
|
||||
union | sigval { |
/* Data passed with notification */
|
||
int | sival_int ; |
/* Integer value */
|
||
void | * | sival_ptr ; |
/* Pointer value */
|
|
}; | ||||
struct | sigevent { | |||
int | sigev_notify ; |
/* Notification method */
|
||
int | sigev_signo ; |
/* Notification signal */
|
||
union sigval | sigev_value ; |
/* Data passed with
notification */ |
||
void | (* | sigev_notify_function )(union sigval); |
/* Function used for thread
notification (SIGEV_THREAD) */ |
|
void | * | sigev_notify_attributes ; |
/* Attributes for notification thread
(SIGEV_THREAD) */ |
|
pid_t | sigev_notify_thread_id ; |
/* ID of thread to signal (SIGEV_THREAD_ID) */
|
||
}; |
DESCRIPTION
The sigevent
structure is
used by various APIs to describe the way a process is to be
notified about an event (e.g., completion of an asynchronous
request, expiration of a timer, or the arrival of a
message).
The definition shown in the SYNOPSIS is approximate: some
of the fields in the sigevent
structure may be defined as part of a union. Programs should
employ only those fields relevant to the value specified in
sigev_notify
.
The sigev_notify
field specifies how notification is to be performed. This
field can have one of the following values:
SIGEV_NONE
-
A null notification: don_zsingle_quotesz_t do anything when the event occurs.
SIGEV_SIGNAL
-
Notify the process by sending the signal specified in
sigev_signo
.If the signal is caught with a signal handler that was registered using the sigaction(2)
SA_SIGINFO
flag, then the following fields are set in thesiginfo_t
structure that is passed as the second argument of the handler:si_code
-
This field is set to a value that depends on the API delivering the notification.
si_signo
-
This field is set to the signal number (i.e., the same value as in
sigev_signo
). si_value
-
This field is set to the value specified in
sigev_value
.
Depending on the API, other fields may also be set in the
siginfo_t
structure.The same information is also available if the signal is accepted using sigwaitinfo(2).
SIGEV_THREAD
-
Notify the process by invoking
sigev_notify_function
as if it were the start function of a new thread. (Among the implementation possibilities here are that each timer notification could result in the creation of a new thread, or that a single thread is created to receive all notifications.) The function is invoked withsigev_value
as its sole argument. Ifsigev_notify_attributes
is not NULL, it should point to apthread_attr_t
structure that defines attributes for the new thread (see pthread_attr_init(3)). SIGEV_THREAD_ID
(Linux-specific)-
Currently used only by POSIX timers; see timer_create(2).
SEE ALSO
timer_create(2), aio_fsync(3), aio_read(3), aio_write(3), getaddrinfo_a(3), lio_listio(3), mq_notify(3), aio(7), pthreads(7)
COLOPHON
This page is part of release 4.16 of the Linux man-pages
project. A
description of the project, information about reporting bugs,
and the latest version of this page, can be found at
https://www.kernel.org/doc/man−pages/.
Copyright (C) 2006, 2010 Michael Kerrisk <mtk.manpagesgmail.com> Copyright (C) 2009 Petr Baudis <paskysuse.cz> %%%LICENSE_START(VERBATIM) Permission is granted to make and distribute verbatim copies of this manual provided the copyright notice and this permission notice are preserved on all copies. Permission is granted to copy and distribute modified versions of this manual under the conditions for verbatim copying, provided that the entire resulting derived work is distributed under the terms of a permission notice identical to this one. Since the Linux kernel and libraries are constantly changing, this manual page may be incorrect or out-of-date. The author(s) assume no responsibility for errors or omissions, or for damages resulting from the use of the information contained herein. The author(s) may not have taken the same level of care in the production of this manual, which is licensed free of charge, as they might when working professionally. Formatted or processed versions of this manual, if unaccompanied by the source, must acknowledge the copyright and authors of this work. %%%LICENSE_END |