SIGEVENT
Section: Linux Programmer's Manual (7)
Updated: 2010-09-19
NAME
struct sigevent - structure for notification from asynchronous routines
SYNOPSIS
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 only employ 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'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 the
siginfo_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 with
sigev_value
as its sole argument.
If
sigev_notify_attributes
is not NULL, it should point to a
pthread_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).
CONFORMING TO
POSIX.1-2001.
SEE ALSO
timer_create(2),
aio_fsync(3),
mq_notify(3),
pthreads(7)
COLOPHON
This page is part of release 3.27 of the Linux
man-pages
project.
A description of the project,
and information about reporting bugs,
can be found at
http://www.kernel.org/doc/man-pages/.
Index
- NAME
-
- SYNOPSIS
-
- DESCRIPTION
-
- CONFORMING TO
-
- SEE ALSO
-
- COLOPHON
-
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Time: 07:34:51 GMT, March 26, 2013