/* 如sem[index]为负且不超时，则阻塞，超时则返回EAGAIN，否则将信号量减1，返回0*/
int TryLockSemaphore(int semid, int index, int milliseconds)
{
int ret;
struct sembuf operation;
operation.sem_num = index;
operation.sem_op = -1;
if(milliseconds<1)
{
operation.sem_flg = IPC_NOWAIT;
ret= semop (semid, &operation, 1);
}
else
{
operation.sem_flg = SEM_UNDO;
struct timespec timeout;
timeout.tv_sec = (milliseconds / 1000);
timeout.tv_nsec = (milliseconds - timeout.tv_sec*1000L)*1000000L;
ret= semtimedop(semid, &operation, 1, &timeout);
}
if(ret == -1)
{
if(errno == EAGAIN) return EAGAIN;
}
return (ret == -1)? WhenError("Wait(semop)", errno):ret;
}
int SetSemaphoreValues(int semid, unsigned short * values)
{
union semun argument;
argument.array=values;
int ret;
ret= semctl(semid,0,SETALL,argument);
return (ret == -1)? WhenError("Set Values(semctl)", errno):ret;
}
/* Set a semaphore to a value。*/
int SetSemaphoreValue(int semid, int index, int value)
{
union semun argument;
argument.val = value;
int ret;
ret= semctl(semid,index,SETVAL,argument);
return (ret == -1)? WhenError("Set Value(semctl)", errno):ret;
}
/* 将sem[index]值加一。 这个操作会立即返回，应配合LockSemaphore一起使用。*/
int UnlockSemaphore(int semid, int index)
{
struct sembuf operation;
operation.sem_num = index;
operation.sem_op = 1; /* 加一 */
operation.sem_flg = SEM_UNDO; /* 允许撤销操作 */
int ret;
ret= semop(semid, &operation, 1);
return (ret == -1)? WhenError("Post(semctl)", errno):ret;
}
/* 如果sem[index]为负，则阻塞，直到信号量值为正，然后将其减1*/
int LockSemaphore(int semid, int index)
{
struct sembuf operation;
operation.sem_num = index;
operation.sem_op = -1; /* 减一。 */
operation.sem_flg = SEM_UNDO; /* 允许撤销操作 */
int ret;
ret= semop (semid, &operation, 1);
return (ret == -1)? WhenError("Wait(semop)", errno):ret;
}
/* 获取一个count元信号量的标识符。如果需要则创建这个信号量 */
int CreateSemaphore(int count)
{
// key_t key;
// key = ftok("/var/httcsec",IPC_ID);
// printf("key:%d\n", (int)key);
int semid;
semid = semget ((key_t)12345, count, 0666|IPC_CREAT);
if(EEXIST == semid) printf("exist semid\n");
return (semid == -1)? WhenError("create sem(semget)", errno):semid;
}
void Lex::ThrowError(const char *e)
{
WhenError(e);
throw Parser::Error();
}
int GetSemaphoreValue(int semid, int index)
{
int ret = semctl(semid,index,GETVAL,0);
return (ret == -1)? WhenError("Get Value(semctl)", errno):ret;
}