AIO_WAITN(3C) Standard C Library Functions AIO_WAITN(3C)


aio_waitn - wait for completion of asynchronous I/O operations


#include <aio.h>

int aio_waitn(struct aiocb *list[], uint_t nent,
uint_t *nwait, const struct timespec *timeout);


The aio_waitn() function suspends the calling thread until at least the
number of requests specified by nwait have completed, until a signal
interrupts the function, or if timeout is not NULL, until the time
interval specified by timeout has passed.

To effect a poll, the timeout argument should be non-zero, pointing to a
zero-valued timespec structure.

The list argument is an array of uninitialized I/O completion block
pointers to be filled in by the system before aio_waitn() returns. The
nent argument indicates the maximum number of elements that can be placed
in list[] and is limited to _AIO_LISTIO_MAX = 4096.

The nwait argument points to the minimum number of requests aio_waitn()
should wait for. Upon returning, the content of nwait is set to the
actual number of requests in the aiocb list, which can be greater than
the initial value specified in nwait. The aio_waitn() 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
nent argument. As soon as the number of outstanding asynchronous I/O
requests becomes 0, aio_waitn() returns with the current list of
completed requests.

The aiocb structures returned will have been used in initiating an
asynchronous I/O request from any thread in the process with
aio_read(3C), aio_write(3C), or lio_listio(3C).

If the time interval expires before the expected number of I/O operations
specified by nwait are completed, aio_waitn() returns the number of
completed requests and the content of the nwait pointer is updated with
that number.

If aio_waitn() is interrupted by a signal, nwait is set to the number of
completed requests.

The application can determine the status of the completed asynchronous
I/O by checking the associated error and return status using
aio_error(3C) and aio_return(3C), respectively.


Upon successful completion, aio_waitn() returns 0. Otherwise, it returns
-1 and sets errno to indicate the error.


The aio_waitn() function will fail if:

There are no outstanding asynchronous I/O requests.

The list[], nwait, or timeout argument points to an address
outside the address space of the process. The errno variable is
set to EFAULT only if this condition is detected by the
application process.

The execution of aio_waitn() was interrupted by a signal.

The timeout element tv_sec or tv_nsec is < 0, nent is set to 0
or > _AIO_LISTIO_MAX, or nwait is either set to 0 or is > nent.

There is currently not enough available memory. The application
can try again later.

The time interval expired before nwait outstanding requests
have completed.


The aio_waitn() function has a transitional interface for 64-bit file
offsets. See lf64(7).


See attributes(7) for descriptions of the following attributes:

|Interface Stability | Committed |
|MT-Level | Safe |


aio_error(3C), aio_read(3C), aio_return(3C), aio_write(3C),
lio_listio(3C), aio.h(3HEAD), attributes(7), lf64(7)

December 18, 2008 AIO_WAITN(3C)