C实现
#include <stdio.h>
#include <time.h>
#include <unistd.h>
#include <sys/ipc.h>
#include <sys/shm.h>
#include <sys/sem.h>
#define NEED_P 2
#define NEED_C 3
#define WORKS_P 6
#define WORKS_C 4
#define BUF_LENGTH (sizeof(struct mybuffer))
#define LETTER_NUM 3
#define SHM_MODE 0600
#define SEM_ALL_KEY 1234
#define SEM_EMPTY 0
#define SEM_FULL 1
//缓冲区结构（循环队列）
struct mybuffer
{
char letter[LETTER_NUM];
int head;
int tail;
int is_empty;
};
//得到5以内的一个随机数
int get_random()
{
int t;
srand((unsigned)(getpid() + time(NULL)));
t = rand() % 5;
return t;
}
//得到A~Z的一个随机字母
char get_letter()
{
char a;
srand((unsigned)(getpid() + time(NULL)));
a = (char)((char)(rand() % 26) + 'A');
return a;
}
//P操作
void p(int sem_id, int sem_num)
{
struct sembuf xx;
xx.sem_num = sem_num;
xx.sem_op = - 1;
xx.sem_flg = 0;
semop(sem_id, & xx, 1);
}
//V操作
void v(int sem_id, int sem_num)
{
struct sembuf xx;
xx.sem_num = sem_num;
xx.sem_op = 1;
xx.sem_flg = 0;
semop(sem_id, & xx, 1);
}
//主函数
int main(int argc, char *argv[])
{
int i, j;
int shm_id, sem_id;
int num_p = 0, num_c = 0;
struct mybuffer *shmptr;
char lt;
time_t now;
pid_t pid_p, pid_c;
sem_id = semget(SEM_ALL_KEY, 2, IPC_CREAT | 0660);
if (sem_id >= 0)
{
printf("主进程开始，信号量创建完毕\n");
}
semctl(sem_id, SEM_EMPTY, SETVAL, LETTER_NUM);
semctl(sem_id, SEM_FULL, SETVAL, 0);
if ((shm_id = shmget(IPC_PRIVATE, BUF_LENGTH, SHM_MODE)) < 0)
{
printf("Error on shmget.\n");
exit(1);
}
if ((shmptr = shmat(shm_id, 0, 0)) == (void *)-1)
{
printf("Error on shmat.\n");
exit(1);
}
shmptr->head = 0;
shmptr->tail = 0;
shmptr->is_empty = 1;
while ((num_p++) < NEED_P)
{
if ((pid_p = fork()) < 0)
{
printf("Error on fork.\n");
exit(1);
}
//如果是子进程，开始创建生产者
if (pid_p == 0)
{
if ((shmptr = shmat(shm_id, 0, 0)) == (void *)-1)
{
printf("Error on shmat.\n");
exit(1);
}
for (i = 0; i < WORKS_P; i++)
{
p(sem_id, SEM_EMPTY);
sleep(get_random());
shmptr->letter[shmptr->tail] = lt = get_letter();
shmptr->tail = (shmptr->tail + 1) % LETTER_NUM;
shmptr->is_empty = 0;
now = time(NULL);
printf("当前时间 %02d:%02d:%02d\t", localtime(&now)->tm_hour, localtime(&now)->tm_min, localtime(&now)->tm_sec);
printf("生产者 %d 放入 '%c'\t当前缓冲区：", num_p, lt);
for (j = (shmptr->tail - 1 >= shmptr->head) ? (shmptr->tail - 1) : (shmptr->tail - 1 + LETTER_NUM); !(shmptr->is_empty) && j >= shmptr->head; j--)
{
printf("%c", shmptr->letter[j % LETTER_NUM]);
}
printf("\n");
fflush(stdout);
v(sem_id, SEM_FULL);
}
shmdt(shmptr);
exit(0);
}
}
while (num_c++ < NEED_C)
{
if ((pid_c = fork()) < 0)
{
printf("Error on fork.\n");
exit(1);
}
//如果是子进程，开始创建消费者
if (pid_c == 0)
{
if ((shmptr = shmat(shm_id, 0, 0)) == (void *)-1)
{
printf("Error on shmat.\n");
exit(1);
}
for (i = 0; i < WORKS_C; i++)
{
p(sem_id, SEM_FULL);
sleep(get_random());
lt = shmptr->letter[shmptr->head];
shmptr->head = (shmptr->head + 1) % LETTER_NUM;
shmptr->is_empty = (shmptr->head == shmptr->tail);
now = time(NULL);
printf("当前时间 %02d:%02d:%02d\t", localtime(&now)->tm_hour, localtime(&now)->tm_min, localtime(&now)->tm_sec);
printf("消费者 %d 拿走 '%c'\t当前缓冲区：", num_c, lt);
for (j = (shmptr->tail - 1 >= shmptr->head) ? (shmptr->tail - 1) : (shmptr->tail - 1 + LETTER_NUM); !(shmptr->is_empty) && j >= shmptr->head; j--)
{
printf("%c", shmptr->letter[j % LETTER_NUM]);
}
printf("\n");
fflush(stdout);
v(sem_id, SEM_EMPTY);
}
shmdt(shmptr);
exit(0);
}
}
//主控程序最后退出
while (wait(0) != - 1);
shmdt(shmptr);
shmctl(shm_id, IPC_RMID, 0);
semctl(sem_id, IPC_RMID, 0);
printf("主程序完成\n");
fflush(stdout);
exit(0);
}
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