'\" te
.\" Copyright (c) 2008, Sun Microsystems, Inc.  All Rights Reserved.
.\" The contents of this file are subject to the terms of the Common Development and Distribution License (the "License").  You may not use this file except in compliance with the License.
.\" You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE or http://www.opensolaris.org/os/licensing.  See the License for the specific language governing permissions and limitations under the License.
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.TH AIO_WAITN 3C "Dec 18, 2008"
.SH NAME
aio_waitn \- wait for completion of asynchronous I/O operations
.SH SYNOPSIS
.LP
.nf
#include <aio.h>

\fBint\fR \fBaio_waitn\fR(\fBstruct aiocb *\fR\fIlist\fR[], \fBuint_t\fR \fInent\fR,
     \fBuint_t *\fR\fInwait\fR, \fBconst struct timespec *\fR\fItimeout\fR);
.fi

.SH DESCRIPTION
.sp
.LP
The \fBaio_waitn()\fR function suspends the calling thread until at least the
number of requests specified by \fInwait\fR have completed, until a signal
interrupts the function, or if \fItimeout\fR is not \fINULL\fR, until the time
interval specified by \fItimeout\fR has passed.
.sp
.LP
To effect a poll, the \fItimeout\fR argument should be non-zero, pointing to a
zero-valued \fBtimespec\fR structure.
.sp
.LP
The \fIlist\fR argument is an array of uninitialized I/O completion block
pointers to be filled in by the system before \fBaio_waitn()\fR returns. The
\fInent\fR argument indicates the maximum number of elements that can be placed
in \fIlist\fR[] and is limited to \fB_AIO_LISTIO_MAX\fR = 4096.
.sp
.LP
The \fInwait\fR argument points to the minimum number of requests
\fBaio_waitn()\fR should wait for. Upon returning, the content of \fInwait\fR
is set to the actual number of requests in the \fBaiocb\fR list, which can be
greater than the initial value specified in \fInwait\fR. The \fBaio_waitn()\fR
function attempts to return as many requests as possible, up to the number of
outstanding asynchronous I/Os but less than or equal to the maximum specified
by the \fInent\fR argument. As soon as the number of outstanding asynchronous
I/O requests becomes 0, \fBaio_waitn()\fR returns with the current list of
completed requests.
.sp
.LP
The \fBaiocb\fR structures returned will have been used in initiating an
asynchronous I/O request from any thread in the process with
\fBaio_read\fR(3C), \fBaio_write\fR(3C), or \fBlio_listio\fR(3C).
.sp
.LP
If the time interval expires before the expected number of I/O operations
specified by \fInwait\fR are completed, \fBaio_waitn()\fR returns the number of
completed requests and the content of the \fInwait\fR pointer is updated with
that number.
.sp
.LP
If \fBaio_waitn()\fR is interrupted by a signal, \fInwait\fR is set to the
number of completed requests.
.sp
.LP
The application can determine the status of the completed asynchronous I/O by
checking the associated error and return status using \fBaio_error\fR(3C) and
\fBaio_return\fR(3C), respectively.
.SH RETURN VALUES
.sp
.LP
Upon successful completion, \fBaio_waitn()\fR returns 0. Otherwise, it returns
-1 and sets \fBerrno\fR to indicate the error.
.SH ERRORS
.sp
.LP
The \fBaio_waitn()\fR function will fail if:
.sp
.ne 2
.na
\fB\fBEAGAIN\fR\fR
.ad
.RS 10n
There are no outstanding asynchronous I/O requests.
.RE

.sp
.ne 2
.na
\fB\fBEFAULT\fR\fR
.ad
.RS 10n
The \fIlist\fR[], \fInwait\fR, or \fItimeout\fR argument points to an address
outside the address space of the process. The \fBerrno\fR variable is set to
\fBEFAULT\fR only if this condition is detected by the application process.
.RE

.sp
.ne 2
.na
\fB\fBEINTR\fR\fR
.ad
.RS 10n
The execution of \fBaio_waitn()\fR was interrupted by a signal.
.RE

.sp
.ne 2
.na
\fB\fBEINVAL\fR\fR
.ad
.RS 10n
The \fItimeout\fR element \fItv_sec\fR or \fItv_nsec\fR is < 0, \fInent\fR is
set to 0 or > \fB_AIO_LISTIO_MAX\fR, or \fInwait\fR is either set to 0 or is >
\fInent\fR.
.RE

.sp
.ne 2
.na
\fB\fBENOMEM\fR\fR
.ad
.RS 10n
There is currently not enough available memory. The application can try again
later.
.RE

.sp
.ne 2
.na
\fB\fBETIME\fR\fR
.ad
.RS 10n
The time interval expired before \fInwait\fR outstanding requests have
completed.
.RE

.SH USAGE
.sp
.LP
The \fBaio_waitn()\fR function has a transitional interface for 64-bit file
offsets.  See \fBlf64\fR(5).
.SH ATTRIBUTES
.sp
.LP
See \fBattributes\fR(5) for descriptions of the following attributes:
.sp

.sp
.TS
box;
c | c
l | l .
ATTRIBUTE TYPE	ATTRIBUTE VALUE
_
Interface Stability	Committed
_
MT-Level	Safe
.TE

.SH SEE ALSO
.sp
.LP
\fBaio.h\fR(3HEAD), \fBaio_error\fR(3C), \fBaio_read\fR(3C),
\fBaio_write\fR(3C), \fBlio_listio\fR(3C), \fBaio_return\fR(3C),
\fBattributes\fR(5), \fBlf64\fR(5)