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. Reviewed by: kib MFC after: 3 days Differential Revision: https://reviews.freebsd.org/D7122
This commit is contained in:
John Baldwin
parent
bcc238eaed
commit
463970da7b
Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=302899
@ -24,7 +24,7 @@
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.\"
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.\" $FreeBSD$
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.\"
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.Dd December 27, 2013
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.Dd July 15, 2016
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.Dt AIO_FSYNC 2
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.Os
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.Sh NAME
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@ -71,6 +71,29 @@ while it is in progress.
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.Pp
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If the request could not be enqueued (generally due to invalid arguments),
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the call returns without having enqueued the request.
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.Pp
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The
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.Fa iocb->aio_sigevent
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structure can be used to request notification of the request's
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completion as described in
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.Xr aio 4 .
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.Sh RESTRICTIONS
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The asynchronous I/O Control Block structure pointed to by
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.Fa iocb
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must remain valid until the
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operation has completed.
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For this reason, use of auto (stack) variables
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for these objects is discouraged.
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.Pp
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The asynchronous I/O control buffer
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.Fa iocb
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should be zeroed before the
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.Fn aio_fsync
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call to avoid passing bogus context information to the kernel.
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.Pp
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Modifications of the Asynchronous I/O Control Block structure or the
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buffer contents after the request has been enqueued, but before the
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request has completed, are not allowed.
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.Sh RETURN VALUES
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.Rv -std aio_fsync
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.Sh ERRORS
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@ -80,6 +103,10 @@ system call will fail if:
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.Bl -tag -width Er
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.It Bq Er EAGAIN
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The request was not queued because of system resource limitations.
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.It Bq Er EINVAL
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The asynchronous notification method in
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.Fa iocb->aio_sigevent.sigev_notify
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is invalid or not supported.
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.It Bq Er ENOSYS
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The
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.Fn aio_fsync
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@ -138,6 +165,7 @@ system calls.
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.Xr aio_waitcomplete 2 ,
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.Xr aio_write 2 ,
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.Xr fsync 2 ,
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.Xr sigevent 3 ,
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.Xr siginfo 3 ,
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.Xr aio 4
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.Sh STANDARDS
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@ -24,7 +24,7 @@
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.\"
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.\" $FreeBSD$
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.\"
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.Dd June 3, 2013
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.Dd July 15, 2016
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.Dt AIO_MLOCK 2
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.Os
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.Sh NAME
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@ -64,6 +64,12 @@ If the request could not be enqueued (generally due to
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.Xr aio 4
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limits),
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then the call returns without having enqueued the request.
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.Pp
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The
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.Fa iocb->aio_sigevent
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structure can be used to request notification of the request's
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completion as described in
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.Xr aio 4 .
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.Sh RESTRICTIONS
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The Asynchronous I/O Control Block structure pointed to by
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.Fa iocb
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@ -92,6 +98,10 @@ system call will fail if:
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.Bl -tag -width Er
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.It Bq Er EAGAIN
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The request was not queued because of system resource limitations.
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.It Bq Er EINVAL
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The asynchronous notification method in
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.Fa iocb->aio_sigevent.sigev_notify
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is invalid or not supported.
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.It Bq Er ENOSYS
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The
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.Fn aio_mlock
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@ -116,6 +126,7 @@ if the request was explicitly cancelled via a call to
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.Xr aio_error 2 ,
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.Xr aio_return 2 ,
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.Xr mlock 2 ,
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.Xr sigevent 3 ,
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.Xr aio 4
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.Sh PORTABILITY
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The
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@ -24,7 +24,7 @@
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.\"
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.\" $FreeBSD$
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.\"
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.Dd November 17, 1998
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.Dd July 15, 2016
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.Dt AIO_READ 2
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.Os
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.Sh NAME
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@ -79,6 +79,12 @@ If the request is successfully enqueued, the value of
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.Fa iocb->aio_offset
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can be modified during the request as context, so this value must
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not be referenced after the request is enqueued.
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.Pp
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The
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.Fa iocb->aio_sigevent
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structure can be used to request notification of the request's
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completion as described in
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.Xr aio 4 .
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.Sh RESTRICTIONS
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The Asynchronous I/O Control Block structure pointed to by
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.Fa iocb
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@ -115,6 +121,10 @@ system call will fail if:
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.Bl -tag -width Er
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.It Bq Er EAGAIN
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The request was not queued because of system resource limitations.
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.It Bq Er EINVAL
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The asynchronous notification method in
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.Fa iocb->aio_sigevent.sigev_notify
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is invalid or not supported.
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.It Bq Er ENOSYS
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The
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.Fn aio_read
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@ -191,6 +201,7 @@ would be invalid.
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.Xr aio_suspend 2 ,
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.Xr aio_waitcomplete 2 ,
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.Xr aio_write 2 ,
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.Xr sigevent 3 ,
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.Xr siginfo 3 ,
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.Xr aio 4
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.Sh STANDARDS
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@ -24,7 +24,7 @@
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.\"
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.\" $FreeBSD$
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.\"
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.Dd June 2, 1999
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.Dd July 15, 2016
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.Dt AIO_WRITE 2
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.Os
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.Sh NAME
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@ -85,6 +85,12 @@ If the request is successfully enqueued, the value of
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.Fa iocb->aio_offset
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can be modified during the request as context, so this value must not
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be referenced after the request is enqueued.
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.Pp
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The
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.Fa iocb->aio_sigevent
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structure can be used to request notification of the request's
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completion as described in
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.Xr aio 4 .
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.Sh RESTRICTIONS
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The Asynchronous I/O Control Block structure pointed to by
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.Fa iocb
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@ -119,6 +125,10 @@ system call will fail if:
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.Bl -tag -width Er
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.It Bq Er EAGAIN
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The request was not queued because of system resource limitations.
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.It Bq Er EINVAL
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The asynchronous notification method in
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.Fa iocb->aio_sigevent.sigev_notify
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is invalid or not supported.
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.It Bq Er ENOSYS
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The
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.Fn aio_write
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@ -186,6 +196,7 @@ would be invalid.
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.Xr aio_return 2 ,
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.Xr aio_suspend 2 ,
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.Xr aio_waitcomplete 2 ,
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.Xr sigevent 3 ,
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.Xr siginfo 3 ,
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.Xr aio 4
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.Sh STANDARDS
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@ -24,7 +24,7 @@
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.\"
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.\" $FreeBSD$
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.\"
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.Dd January 12, 2003
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.Dd July 15, 2016
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.Dt LIO_LISTIO 2
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.Os
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.Sh NAME
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@ -83,14 +83,52 @@ If
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.Fa mode
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is
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.Dv LIO_NOWAIT ,
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the requests are processed asynchronously, and the signal specified by
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.Fa sig
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is sent when all operations have completed.
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can be used to request asynchronous notification when all operations have
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completed.
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If
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.Fa sig
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is
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.Dv NULL ,
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the calling process is not notified of I/O completion.
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no notification is sent.
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.Pp
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For
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.Dv SIGEV_KEVENT
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notifications,
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the posted kevent will contain:
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.Bl -column ".Va filter"
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.It Sy Member Ta Sy Value
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.It Va ident Ta Fa list
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.It Va filter Ta Dv EVFILT_LIO
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.It Va udata Ta
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value stored in
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.Fa sig->sigev_value
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.El
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.Pp
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For
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.Dv SIGEV_SIGNO
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and
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.Dv SIGEV_THREAD_ID
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notifications,
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the information for the queued signal will include
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.Dv SI_ASYNCIO
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in the
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.Va si_code
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field and the value stored in
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.Fa sig->sigev_value
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in the
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.Va si_value
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field.
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.Pp
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For
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.Dv SIGEV_THREAD
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notifications,
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the value stored in
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.Fa sig->sigev_value
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is passed to the
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.Fa sig->sigev_notify_function
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as described in
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.Xr sigevent 3 .
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.Pp
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The order in which the requests are carried out is not specified;
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in particular, there is no guarantee that they will be executed in
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@ -136,6 +174,10 @@ or
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.Fa nent
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is greater than
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.Dv AIO_LISTIO_MAX .
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.It Bq Er EINVAL
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The asynchronous notification method in
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.Fa sig->sigev_notify
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is invalid or not supported.
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.It Bq Er EINTR
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A signal interrupted the system call before it could be completed.
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.It Bq Er EIO
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@ -166,6 +208,7 @@ structure individually by calling
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.Xr aio_write 2 ,
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.Xr read 2 ,
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.Xr write 2 ,
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.Xr sigevent 3 ,
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.Xr siginfo 3 ,
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.Xr aio 4
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.Sh STANDARDS
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@ -37,7 +37,7 @@
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.\"
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.\" $FreeBSD$
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.\"
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.Dd November 29, 2005
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.Dd July 15, 2016
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.Dt MQ_NOTIFY 2
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.Os
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.Sh NAME
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@ -77,18 +77,27 @@ is
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.Dv SIGEV_NONE ,
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then no signal will be posted, but the error status and the return status
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for the operation will be set appropriately.
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If
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.Fa notification->sigev_notify
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is
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.Dv SIGEV_SIGNAL ,
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then the signal specified in
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For
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.Dv SIGEV_SIGNO
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and
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.Dv SIGEV_THREAD_ID
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notifications,
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the signal specified in
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.Fa notification->sigev_signo
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will be sent to the process.
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The signal will be queued to the process and the value specified in
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will be sent to the calling process
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.Pq Dv SIGEV_SIGNO
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or to the thread whose LWP ID is
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.Fa notification->sigev_notify_thread_id
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.Pq Dv SIGEV_THREAD_ID .
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The information for the queued signal will include:
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.Bl -column ".Va si_value"
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.It Sy Member Ta Sy Value
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.It Va si_code Ta Dv SI_MESGQ
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.It Va si_value Ta
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the value stored in
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.Fa notification->sigev_value
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will be the
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.Va si_value
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component of the generated signal.
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.It Va si_mqd Ta Fa mqdes
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.El
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.Pp
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If
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.Fa notification
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@ -123,11 +132,16 @@ The
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argument is not a valid message queue descriptor.
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.It Bq Er EBUSY
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Process is already registered for notification by the message queue.
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.It Bq Er EINVAL
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The asynchronous notification method in
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.Fa notification->sigev_notify
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is invalid or not supported.
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.El
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.Sh SEE ALSO
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.Xr mq_open 2 ,
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.Xr mq_send 2 ,
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.Xr mq_timedsend 2 ,
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.Xr sigevent 3 ,
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.Xr siginfo 3
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.Sh STANDARDS
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The
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@ -27,7 +27,7 @@
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.\"
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.\" $FreeBSD$
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.\"
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.Dd January 12, 2009
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.Dd July 15, 2016
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.Dt TIMER_CREATE 2
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.Os
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.Sh NAME
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@ -74,6 +74,36 @@ structure.
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This structure,
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allocated by the application, defines the asynchronous notification to occur
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when the timer expires.
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.Pp
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If
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.Fa evp->sigev_notify
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is
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.Dv SIGEV_SIGNO
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or
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.Dv SIGEV_THREAD_ID ,
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the signal specified in
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.Fa evp->sigev_signo
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will be sent to the calling process
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.Pq Dv SIGEV_SIGNO
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or to the thread whose LWP ID is
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.Fa evp->sigev_notify_thread_id
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.Pq Dv SIGEV_THREAD_ID .
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The information for the queued signal will include:
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.Bl -column ".Va si_value"
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.It Sy Member Ta Sy Value
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.It Va si_code Ta Dv SI_TIMER
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.It Va si_value Ta
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the value stored in
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.Fa evp->sigev_value
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.It Va si_timerid Ta timer ID
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.It Va si_overrun Ta timer overrun count
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.It Va si_errno Ta
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If timer overrun is
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.Brq Dv DELAYTIMER_MAX ,
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an error code defined in
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.In errno.h
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.El
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.Pp
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If the
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.Fa evp
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argument is
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@ -88,12 +118,14 @@ member having the value
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.Dv SIGEV_SIGNAL ,
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the
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.Va sigev_signo
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having a default signal number, and the
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having a default signal number
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.Pq Dv SIGALRM ,
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and the
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.Va sigev_value
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member having
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the value of the timer ID.
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.Pp
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The implementations supports a
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This implementation supports a
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.Fa clock_id
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of
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.Dv CLOCK_REALTIME
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@ -144,6 +176,8 @@ The calling process has already created all of the timers it is allowed by
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this implementation.
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.It Bq Er EINVAL
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The specified clock ID is not supported.
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.It Bq Er EINVAL
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The specified asynchronous notification method is not supported.
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.It Bq Er EFAULT
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Any arguments point outside the allocated address space or there is a
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memory protection fault.
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@ -152,6 +186,7 @@ memory protection fault.
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.Xr clock_getres 2 ,
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.Xr timer_delete 2 ,
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.Xr timer_getoverrun 2 ,
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.Xr sigevent 3 ,
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.Xr siginfo 3
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.Sh STANDARDS
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The
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@ -15,6 +15,7 @@ MAN= assert.3 \
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offsetof.3 \
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${PTHREAD_MAN} \
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queue.3 \
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sigevent.3 \
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siginfo.3 \
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stdarg.3 \
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sysexits.3 \
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127
share/man/man3/sigevent.3
Normal file
127
share/man/man3/sigevent.3
Normal file
@ -0,0 +1,127 @@
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.\" -*- nroff -*-
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.\"
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.\" Copyright (c) 2016 John H. Baldwin <jhb@FreeBSD.org>
|
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.\" All rights reserved.
|
||||
.\"
|
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.\" 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
|
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.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 .
|
||||
@ -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
|
||||
|
||||
Loading…
Reference in New Issue
Block a user