io_getevents - read asynchronous I/O events from the completion queue
#include <linux/aio_abi.h> /* Defines needed types */
#include <linux/time.h> /* Defines 'struct timespec' */
int io_getevents(aio_context_t ctx_id, long min_nr, long nr,
struct io_event *events, struct timespec *timeout);
Note
: There is no glibc wrapper for this system call; see
NOTES.
Note
: this page describes the raw Linux system call
interface. The wrapper function provided by libaio
uses a
different type for the ctx_id
argument. See NOTES.
The io_getevents() system call attempts to read at
least min_nr
events and up to nr
events from the
completion queue of the AIO context specified by ctx_id
.
The timeout
argument specifies the amount of time to wait
for events, and is specified as a relative timeout in a structure of the
following form:
struct timespec {
time_t tv_sec; /* seconds */
long tv_nsec; /* nanoseconds [0 .. 999999999] */
};
The specified time will be rounded up to the system clock granularity and is guaranteed not to expire early.
Specifying timeout
as NULL means block indefinitely until at
least min_nr
events have been obtained.
On success, io_getevents() returns the number of
events read. This may be 0, or a value less than min_nr
, if the
timeout
expired. It may also be a nonzero value less than
min_nr
, if the call was interrupted by a signal handler.
For the failure return, see NOTES.
Either events
or timeout
is an invalid pointer.
Interrupted by a signal handler; see signal(7).
ctx_id
is invalid. min_nr
is out of range or
nr
is out of range.
io_getevents() is not implemented on this architecture.
The asynchronous I/O system calls first appeared in Linux 2.5.
io_getevents() is Linux-specific and should not be used in programs that are intended to be portable.
Glibc does not provide a wrapper function for this system call. You
could invoke it using syscall(2). But instead, you
probably want to use the io_getevents() wrapper
function provided by libaio
.
Note that the libaio
wrapper function uses a different type
(io_context_t
) for the ctx_id
argument. Note also that
the libaio
wrapper does not follow the usual C library
conventions for indicating errors: on error it returns a negated error
number (the negative of one of the values listed in ERRORS). If the
system call is invoked via syscall(2), then the return
value follows the usual conventions for indicating an error: -1, with
errno
set to a (positive) value that indicates the error.
An invalid ctx_id
may cause a segmentation fault instead of
generating the error EINVAL.
This page is part of release 5.10 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/.