Package: libaio-dev
Version: 0.3.107-3
Severity: normal
Hi,
attached is a example source that shows how to use libaio to read,
write and how to use eventfd to poll for events.
MfG
Goswin
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Versions of packages libaio-dev depends on:
ii libaio1 0.3.107-3 Linux kernel AIO access library -
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/*
* eventfd-aio-test by Davide Libenzi (test app for eventfd hooked into KAIO)
* Copyright (C) 2007 Davide Libenzi
* Modified to use libaio by Goswin von Brederlow <[email protected]>
*
* This program is free software; you can redistribute it and/or modify
* it under the terms of the GNU General Public License as published by
* the Free Software Foundation; either version 2 of the License, or
* (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software
* Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
*
* Davide Libenzi <[email protected]>
*
*/
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
#include <sys/eventfd.h>
#include <poll.h>
#include <libaio.h>
#define TESTFILE_SIZE (4096 * 5120)
#define IORTX_SIZE (1024 * 4)
#define NUM_EVENTS 128
static long waitasync(int afd, int timeo) {
struct pollfd pfd;
pfd.fd = afd;
pfd.events = POLLIN;
pfd.revents = 0;
if (poll(&pfd, 1, timeo) < 0) {
perror("poll");
return -1;
}
if ((pfd.revents & POLLIN) == 0) {
fprintf(stderr, "no results completed\n");
return 0;
}
return 1;
}
static long test_read(io_context_t ctx, int fd, long range, int afd) {
long i, n, r, j;
u_int64_t eval;
struct iocb **piocb;
struct iocb *iocb;
struct timespec tmo;
static struct io_event events[NUM_EVENTS];
static char buf[IORTX_SIZE];
n = range / IORTX_SIZE;
iocb = malloc(n * sizeof(struct iocb));
piocb = malloc(n * sizeof(struct iocb *));
if (!iocb || !piocb) {
perror("iocb alloc");
return -1;
}
for (i = 0; i < n; i++) {
piocb[i] = &iocb[i];
io_prep_pread(&iocb[i], fd, buf, sizeof(buf),
(n - i - 1) * IORTX_SIZE);
io_set_eventfd(&iocb[i], afd);
io_set_callback(&iocb[i], (io_callback_t)(i + 1));
}
fprintf(stdout, "submitting read request ...\n");
if (io_submit(ctx, n, piocb) <= 0) {
perror("io_submit");
return -1;
}
for (i = 0; i < n;) {
fprintf(stdout, "waiting ... ");
waitasync(afd, -1);
eval = 0;
if (read(afd, &eval, sizeof(eval)) != sizeof(eval))
perror("read");
fprintf(stdout, "done! %llu\n", (unsigned long long) eval);
while (eval > 0) {
tmo.tv_sec = 0;
tmo.tv_nsec = 0;
r = io_getevents(ctx, 1, eval > NUM_EVENTS ? NUM_EVENTS: (long) eval,
events, &tmo);
if (r > 0) {
for (j = 0; j < r; j++) {
}
i += r;
eval -= r;
fprintf(stdout, "test_write got %ld/%ld results so far\n",
i, n);
}
}
}
free(iocb);
free(piocb);
return n;
}
static long test_write(io_context_t ctx, int fd, long range, int afd) {
long i, n, r, j;
u_int64_t eval;
struct iocb **piocb;
struct iocb *iocb;
struct timespec tmo;
static struct io_event events[NUM_EVENTS];
static char buf[IORTX_SIZE];
for (i = 0; i < IORTX_SIZE; i++)
buf[i] = i & 0xff;
n = range / IORTX_SIZE;
iocb = malloc(n * sizeof(struct iocb));
piocb = malloc(n * sizeof(struct iocb *));
if (!iocb || !piocb) {
perror("iocb alloc");
return -1;
}
for (i = 0; i < n; i++) {
piocb[i] = &iocb[i];
io_prep_pwrite(&iocb[i], fd, buf, sizeof(buf),
(n - i - 1) * IORTX_SIZE);
io_set_eventfd(&iocb[i], afd);
io_set_callback(&iocb[i], (io_callback_t)(i + 1));
}
fprintf(stdout, "submitting write request ...\n");
if (io_submit(ctx, n, piocb) <= 0) {
perror("io_submit");
return -1;
}
for (i = 0; i < n;) {
fprintf(stdout, "waiting ... ");
waitasync(afd, -1);
eval = 0;
if (read(afd, &eval, sizeof(eval)) != sizeof(eval))
perror("read");
fprintf(stdout, "done! %llu\n", (unsigned long long) eval);
while (eval > 0) {
tmo.tv_sec = 0;
tmo.tv_nsec = 0;
r = io_getevents(ctx, 1, eval > NUM_EVENTS ? NUM_EVENTS: (long) eval,
events, &tmo);
if (r > 0) {
for (j = 0; j < r; j++) {
}
i += r;
eval -= r;
fprintf(stdout, "test_write got %ld/%ld results so far\n",
i, n);
}
}
}
free(iocb);
free(piocb);
return n;
}
int main(int argc, char **argv) {
int afd, fd;
io_context_t ctx;
char const *testfn = "/tmp/eventfd-aio-test.data";
(void)argc;
(void)argv;
fprintf(stdout, "creating an eventfd ...\n");
if ((afd = eventfd(0, EFD_NONBLOCK | EFD_CLOEXEC)) == -1) {
perror("eventfd");
return 2;
}
fprintf(stdout, "done! eventfd = %d\n", afd);
if (io_queue_init(TESTFILE_SIZE / IORTX_SIZE + 256, &ctx)) {
perror("io_queue_init");
return 3;
}
if ((fd = open(testfn, O_RDWR | O_CREAT, 0644)) == -1) {
perror(testfn);
return 4;
}
ftruncate(fd, TESTFILE_SIZE);
test_write(ctx, fd, TESTFILE_SIZE, afd);
test_read(ctx, fd, TESTFILE_SIZE, afd);
io_queue_release(ctx);
close(fd);
close(afd);
remove(testfn);
return 0;
}
