/* include incr */
void *
incr(void *arg)
{
int i;
for (i = 0; i < nloop; i++) {
Semop(shared.semid, &waitop, 1);
shared.counter++;
Semop(shared.semid, &postop, 1);
}
return(NULL);
}
int busy()
{
int i = 0;
for(i =0; i<100; i++)
{
Semop((semid, &waitsem[0], 1));
access_shm();
Semop((semid, ¬ifysem[0], 1));
}
shmdt(shm_data);
return 0;
}
void p(int semid, int semnum) {
struct sembuf task;
task.sem_num = semnum;
task.sem_op = -1;
task.sem_flg = 0;
Semop(semid, &task, 1);
}
void my_lock(int fd)
{
int oflag, i;
union semun arg;
struct semid_ds seminfo;
if (initflag == 0) {
oflag = IPC_CREAT | IPC_EXCL | SVSEM_MODE;
if ((semid = semget(Ftok(LOCK_PATH, 0), 1, oflag)) >= 0) {
arg.val = 1;
Semctl(semid, 0, SETVAL, arg);
} else if (errno == EEXIST) {
semid = Semget(Ftok(LOCK_PATH, 0), 1, SVSEM_MODE);
arg.buf = &seminfo;
for (i = 0; i < MAX_TRIES; i++) {
Semctl(semid, 0, IPC_STAT, arg);
if (arg.buf->sem_otime != 0)
goto init;
sleep(1);
}
err_quit("semget OK, but semaphore not initalized");
} else
err_sys("semget error");
init:
initflag = 1;
postop.sem_num = 0;
postop.sem_op = 1;
postop.sem_flg = SEM_UNDO;
waitop.semnum = 0;
waitop.semop = -1;
waitop.semflg = SEM_UNDO;
}
Semop(semid, &waitop, 1);
}
int
main(int argc, char **argv)
{
int i, nthreads;
pthread_t tid[MAXNTHREADS];
union semun arg;
if (argc != 3)
err_quit("usage: incr_svsem2 <#loops> <#threads>");
nloop = atoi(argv[1]);
nthreads = min(atoi(argv[2]), MAXNTHREADS);
/* 4create semaphore and initialize to 0 */
shared.semid = Semget(IPC_PRIVATE, 1, IPC_CREAT | SVSEM_MODE);
arg.val = 0;
Semctl(shared.semid, 0, SETVAL, arg);
postop.sem_num = 0; /* and init the two semop() structures */
postop.sem_op = 1;
postop.sem_flg = SEM_UNDO;
waitop.sem_num = 0;
waitop.sem_op = -1;
waitop.sem_flg = SEM_UNDO;
/* 4create all the threads */
Set_concurrency(nthreads);
for (i = 0; i < nthreads; i++) {
Pthread_create(&tid[i], NULL, incr, NULL);
}
/* 4start the timer and release the semaphore */
Start_time();
Semop(shared.semid, &postop, 1); /* up by 1 */
/* 4wait for all the threads */
for (i = 0; i < nthreads; i++) {
Pthread_join(tid[i], NULL);
}
printf("microseconds: %.0f usec\n", Stop_time());
if (shared.counter != nloop * nthreads)
printf("error: counter = %ld\n", shared.counter);
Semctl(shared.semid, 0, IPC_RMID);
exit(0);
}
void
my_lock(int fd)
{
int oflag, i;
union semun arg;
struct semid_ds seminfo;
if (initflag == 0) {
oflag = IPC_CREAT | IPC_EXCL | SVSEM_MODE;
if ( (semid = semget(Ftok(LOCK_PATH, 0), 1, oflag)) >= 0) {
/* 4success, we're the first so initialize */
arg.val = 1;
Semctl(semid, 0, SETVAL, arg);
} else if (errno == EEXIST) {
/* 4someone else has created; make sure it's initialized */
semid = Semget(Ftok(LOCK_PATH, 0), 1, SVSEM_MODE);
arg.buf = &seminfo;
for (i = 0; i < MAX_TRIES; i++) {
Semctl(semid, 0, IPC_STAT, arg);
if (arg.buf->sem_otime != 0)
goto init;
Write(pipefd[1], "", 1); /* tell parent */
sleep(1);
}
err_quit("semget OK, but semaphore not initialized");
} else
err_sys("semget error");
init:
initflag = 1;
postop.sem_num = 0; /* and init the two semop() structures */
postop.sem_op = 1;
postop.sem_flg = SEM_UNDO;
waitop.sem_num = 0;
waitop.sem_op = -1;
waitop.sem_flg = SEM_UNDO;
}
Semop(semid, &waitop, 1); /* down by 1 */
}
int
main(int argc, char **argv)
{
int c, i, flag, semid, nops;
struct sembuf *ptr;
flag = 0;
while ( (c = Getopt(argc, argv, "nu")) != -1) {
switch (c) {
case 'n':
flag |= IPC_NOWAIT; /* for each operation */
break;
case 'u':
flag |= SEM_UNDO; /* for each operation */
break;
}
}
if (argc - optind < 2) /* argc - optind = #args remaining */
err_quit("usage: semops [ -n ] [ -u ] <id> operation ...");
semid = atol(argv[optind]);
optind++;
nops = argc - optind;
/* 4allocate memory to hold operations, store, and perform */
ptr = Calloc(nops, sizeof(struct sembuf));
for (i = 0; i < nops; i++) {
ptr[i].sem_num = i;
ptr[i].sem_op = atoi(argv[optind + i]); /* <0, 0, or >0 */
ptr[i].sem_flg = flag;
}
Semop(semid, ptr, nops);
exit(0);
}
void
my_unlock(int fd)
{
Semop(semid, &postop, 1); /* up by 1 */
}
void my_unlock(int fd)
{
Semop(semid, &postop, 1);
}
