glusterfs

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#include <stdio.h>
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#include <string.h>
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#include <unistd.h>
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#include <fcntl.h>
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#include <pthread.h>
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pthread_t th[5] = {0};
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void
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flock_init(struct flock *f, short int type, off_t start, off_t len)
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{
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    f->l_type = type;
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    f->l_start = start;
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    f->l_len = len;
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}
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int
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flock_range_in_steps(int fd, int is_set, short l_type, int start, int end,
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                     int step)
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{
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    int ret = 0;
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    int i = 0;
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    struct flock f = {
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        0,
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    };
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    for (i = start; i + step < end; i += step) {
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        flock_init(&f, l_type, i, step);
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        ret = fcntl(fd, (is_set) ? F_SETLKW : F_GETLK, &f);
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        if (ret) {
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            perror("fcntl");
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            goto out;
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        }
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    }
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out:
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    return ret;
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}
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void *
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random_locker(void *arg)
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{
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    int fd = *(int *)arg;
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    int i = 0;
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    int is_set = 0;
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    /* use thread id to choose GETLK or SETLK operation*/
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    is_set = pthread_self() % 2;
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    (void)flock_range_in_steps(fd, is_set, F_WRLCK, 0, 400, 1);
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    return NULL;
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}
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int
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main(int argc, char **argv)
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{
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    int fd = -1;
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    int ret = 1;
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    int i = 0;
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    char *fname = NULL;
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    if (argc < 2)
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        goto out;
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    fname = argv[1];
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    fd = open(fname, O_RDWR);
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    if (fd == -1) {
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        perror("open");
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        goto out;
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    }
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    ret = flock_range_in_steps(fd, 1, F_WRLCK, 0, 2000, 2);
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    for (i = 0; i < 5; i++) {
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        pthread_create(&th[i], NULL, random_locker, (void *)&fd);
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    }
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    ret = flock_range_in_steps(fd, 1, F_WRLCK, 0, 2000, 2);
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    for (i = 0; i < 5; i++) {
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        pthread_join(th[i], NULL);
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    }
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out:
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    if (fd != -1)
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        close(fd);
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    return ret;
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}
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