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Name

io_getevents - read asynchronous I/O events from the completion queue

Synopsis


#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 *eventsstruct
timespec *" timeout );

Note: There is no glibc wrapper for this system call; see NOTES.

Description

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, where a NULL timeout waits until at least min_nr events have been seen. Note that timeout is relative.

Return Value

On success, io_getevents() returns the number of events read: 0 if no events are available, or less than min_nr if the timeout has elapsed. For the failure return, see NOTES.

Errors

EFAULT
Either events or timeout is an invalid pointer.
EINVAL
ctx_id is invalid. min_nr is out of range or nr is out of range.
EINTR
Interrupted by a signal handler; see signal(7) .
ENOSYS
io_getevents() is not implemented on this architecture.

Versions

The asynchronous I/O system calls first appeared in Linux 2.5.

Conforming to

io_getevents() is Linux-specific and should not be used in programs that are intended to be portable.

Notes

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.

Bugs

An invalid ctx_id may cause a segmentation fault instead of generating the error EINVAL.

See Also

io_cancel(2) , io_destroy(2) , io_setup(2) , io_submit(2) , aio(7) , time(7)

Colophon

This page is part of release 3.78 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 http://www.kernel.org/doc/man-pages/.

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