1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
|
// See ../getdents/getdents.go for some info on why
// this exists.
#define _GNU_SOURCE
#include <fcntl.h>
#include <stdio.h>
#include <unistd.h>
#include <stdlib.h>
#include <stdint.h>
#include <sys/stat.h>
#include <sys/syscall.h>
#include <errno.h>
#include <pthread.h>
static pthread_mutex_t mutex;
static int sum;
struct up {
pthread_mutex_t *my_mutex;
pthread_mutex_t *other_mutex;
int fd;
};
void *reader(void *arg) {
struct up* up = (struct up*)arg;
int fd = up->fd;
char tmp[10000];
while(1) {
pthread_mutex_lock(up->my_mutex);
int n = syscall(SYS_getdents64, fd, tmp, sizeof(tmp));
if (n > 0) {
printf("t%ld: n=%d\n", gettid(), n);
} else {
printf("t%ld: n=0 errno=%d total %d bytes\n", gettid(), errno, sum);
if (n < 0) {
exit(1);
}
pthread_mutex_unlock(up->other_mutex);
break;
}
sum += n;
pthread_mutex_unlock(up->other_mutex);
}
}
int main(int argc, char *argv[])
{
if(argc != 2) {
printf("Usage: %s PATH\n", argv[0]);
printf("Run getdents(2) on PATH in a 100ms loop\n");
exit(1);
}
const char *path = argv[1];
for (int i = 1 ; ; i ++ ) {
sum = 0;
int fd = open(path, O_RDONLY);
if (fd == -1) {
perror("open");
exit(1);
}
pthread_t reader1_thread, reader2_thread;
pthread_mutex_t m1 = PTHREAD_MUTEX_INITIALIZER, m2 = PTHREAD_MUTEX_INITIALIZER;
pthread_mutex_lock(&m2);
struct up up1, up2;
up1.fd = fd;
up1.my_mutex = &m1;
up1.other_mutex = &m2;
up2.fd = fd;
up2.my_mutex = &m2;
up2.other_mutex = &m1;
pthread_create(&reader1_thread, NULL, reader, &up1);
pthread_create(&reader2_thread, NULL, reader, &up2);
pthread_join(reader1_thread, NULL);
pthread_join(reader2_thread, NULL);
close(fd);
printf("---\n");
usleep(100000);
}
}
|
