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.
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.
- EFAULT
- Either events or timeout is an invalid pointer.
- EINTR
- Interrupted by a signal handler; see signal(7).
- EINVAL
- ctx_id is invalid. min_nr is out of range or nr is
out of range.
- ENOSYS
- 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.
io_cancel(2),
io_destroy(2),
io_setup(2),
io_submit(2),
aio(7),
time(7)