Re: [take12 0/3] kevent: Generic event handling mechanism.

From: Evgeniy Polyakov
Date: Wed Aug 23 2006 - 02:52:36 EST


On Tue, Aug 22, 2006 at 04:46:19PM -0700, Ulrich Drepper (drepper@xxxxxxxxxx) wrote:
> DaveM says there are example programs for the current interfaces. I
> must admit I haven't seen those either. So if possible, point the world
> to them again. If you do that now I'll review everything and write up
> my recommendations re the interface before Monday.

Attached typical usage for inode and timer events.
Network AIO was implemented as separated syscalls.

> --
> â Ulrich Drepper â Red Hat, Inc. â 444 Castro St â Mountain View, CA â
>



--
Evgeniy Polyakov
#include <sys/types.h>
#include <sys/stat.h>
#include <sys/ioctl.h>
#include <sys/time.h>

#include <fcntl.h>
#include <stdio.h>
#include <stdlib.h>
#include <errno.h>
#include <string.h>
#include <unistd.h>

#include <linux/unistd.h>
#include <linux/types.h>
#include <linux/ukevent.h>

#define _syscall4(type,name,type1,arg1,type2,arg2,type3,arg3,type4,arg4) \
type name (type1 arg1, type2 arg2, type3 arg3, type4 arg4) \
{\
return syscall(__NR_##name, arg1, arg2, arg3, arg4);\
}

#define _syscall5(type,name,type1,arg1,type2,arg2,type3,arg3,type4,arg4, \
type5,arg5) \
type name (type1 arg1,type2 arg2,type3 arg3,type4 arg4,type5 arg5) \
{\
return syscall(__NR_##name, arg1, arg2, arg3, arg4, arg5);\
}

#define _syscall6(type,name,type1,arg1,type2,arg2,type3,arg3,type4,arg4, \
type5,arg5,type6,arg6) \
type name (type1 arg1,type2 arg2,type3 arg3,type4 arg4,type5 arg5, type6 arg6) \
{\
return syscall(__NR_##name, arg1, arg2, arg3, arg4, arg5, arg6);\
}

_syscall4(int, kevent_ctl, int, arg1, unsigned int, argv2, unsigned int, argv3, void *, argv4);
_syscall6(int, kevent_get_events, int, arg1, unsigned int, argv2, unsigned int, argv3, unsigned int, argv4, void *, argv5, unsigned, arg6);

#define ulog(f, a...) fprintf(stderr, f, ##a)
#define ulog_err(f, a...) ulog(f ": %s [%d].\n", ##a, strerror(errno), errno)

static void usage(char *p)
{
ulog("Usage: %s -t type -e event -o oneshot -p path -n wait_num -h\n", p);
}

static int get_id(int type, char *path)
{
int ret = -1;

switch (type) {
case KEVENT_TIMER:
ret = 3000;
break;
case KEVENT_INODE:
ret = open(path, O_RDONLY);
break;
}

return ret;
}

int main(int argc, char *argv[])
{
int ch, fd, err, type, event, oneshot, i, num, wait_num;
char *path;
char buf[4096];
struct ukevent *uk;
struct timeval tm1, tm2;

path = NULL;
type = event = -1;
oneshot = 0;
wait_num = 10;

while ((ch = getopt(argc, argv, "p:t:e:o:n:h")) > 0) {
switch (ch) {
case 'n':
wait_num = atoi(optarg);
break;
case 'p':
path = optarg;
break;
case 't':
type = atoi(optarg);
break;
case 'e':
event = atoi(optarg);
break;
case 'o':
oneshot = atoi(optarg);
break;
default:
usage(argv[0]);
return -1;
}
}

if (event == -1 || type == -1 || (type == KEVENT_INODE && !path)) {
ulog("You need at least -t -e parameters and -p for inode notifications.\n");
usage(argv[0]);
return -1;
}

fd = kevent_ctl(0, KEVENT_CTL_INIT, 1, NULL);
if (fd == -1) {
ulog_err("Failed create kevent control block");
return -1;
}

memset(buf, 0, sizeof(buf));

gettimeofday(&tm1, NULL);

num = 1;
for (i=0; i<num; ++i) {
uk = (struct ukevent *)buf;
uk->event = event;
uk->type = type;
if (oneshot)
uk->req_flags |= KEVENT_REQ_ONESHOT;
uk->user[0] = i;
uk->id.raw[0] = get_id(uk->type, path);

err = kevent_ctl(fd, KEVENT_CTL_ADD, 1, uk);
if (err < 0) {
ulog_err("Failed to perform control operation: type=%d, event=%d, oneshot=%d", type, event, oneshot);
close(fd);
return err;
}
ulog("%s: err: %d.\n", __func__, err);
if (err) {
ulog("%d: ret_flags: 0x%x, ret_data: %u %d.\n", i, uk->ret_flags, uk->ret_data[0], (int)uk->ret_data[1]);
}
}

gettimeofday(&tm2, NULL);

ulog("%08ld.%08ld: Load: diff=%ld usecs.\n",
tm2.tv_sec, tm2.tv_usec, ((tm2.tv_sec - tm1.tv_sec)*1000000 + (tm2.tv_usec - tm1.tv_usec))/num);

while (1) {
gettimeofday(&tm1, NULL);

err = kevent_get_events(fd, 1, wait_num, 3000, buf, 0);
if (err < 0) {
ulog_err("Failed to perform control operation: type=%d, event=%d, oneshot=%d", type, event, oneshot);
close(fd);
return err;
}

gettimeofday(&tm2, NULL);

ulog("%08ld.%08ld: Wait: num=%d, diff=%ld usec.\n",
tm2.tv_sec, tm2.tv_usec,
err,
((tm2.tv_sec - tm1.tv_sec)*1000000 + (tm2.tv_usec - tm1.tv_usec))/(err?err:1));
uk = (struct ukevent *)buf;
for (i=0; i<(signed)err; ++i) {
ulog("%08x: %08x.%08x - %08x.%08x\n",
uk[i].user[0],
uk[i].id.raw[0], uk[i].id.raw[1],
uk[i].ret_data[0], uk[i].ret_data[1]);
}
}

close(fd);
return 0;
}