消息队列，这个可是鼎鼎大名，经常在某些地方看见大家那个膜拜，那个，嗯，那个。。。
那就给个完整的例子，大家欣赏就行，我一直认为不用那个，嗯@
这个队列的最大作用就是进程间通信，你要非搞个持久化，那也行，随你高兴喽！
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// 进程间通信，通过消息队列
//msgqueue-server.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <sys/msg.h>
#include <signal.h>
#define MSG_FILE "/etc/passwd"
struct msg_form
{
long mtype;
char mtext[256];
};
static sig_atomic_t run =1;
void sigint(int signum)
{
if (SIGINT==signum)
{
run = 0;
}
}
int main()
{
signal(SIGINT, sigint);
int msqid;
key_t key;
struct msg_form msg;
int len;
if (0>(key=ftok(MSG_FILE, 'z')))
{
perror("ftok error!\n");
exit(1);
}
printf("MSG -server key is %0x\n", key);
if (-1==(msqid=msgget(key, IPC_CREAT|0777)))
{
perror("msgget error!\n");
exit(1);
}
printf("msqid is %0x\n", msqid);
printf("pid is %0x\n", getpid());
while (run)
{
len = msgrcv(msqid, &msg, 256, 888, IPC_NOWAIT);
if (0<len)
{
printf("MSG -server receive msg type is %0x\n", (unsigned int)msg.mtype);
printf("MSG -server receive msg is %s\n", msg.mtext);
msg.mtype = 999;
sprintf(msg.mtext, "Hello, I'm server %0x\n", getpid());
msgsnd(msqid, &msg, sizeof(msg.mtext), 0);
}
}
printf("MSG -server quit!\n");
if (-1==msgctl(msqid, IPC_RMID, 0))
{
printf("msqid %0x is rmed with error %d %s\n", msqid, errno, strerror(errno));
exit(1);
}
return 0;
}
// msgqueue-client.c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <unistd.h>
#include <sys/msg.h>
#include <signal.h>
#define MSG_FILE "/etc/passwd"
struct msg_form
{
long mtype;
char mtext[256];
};
int main()
{
int msqid;
key_t key;
struct msg_form msg;
int isnd, len;
if (0>(key=ftok(MSG_FILE, 'z')))
{
perror("ftok error!");
exit(1);
}
printf("MSG -client key is %0x\n", key);
if (-1==(msqid=msgget(key, 0777)))
{
perror("msgget error");
exit(1);
}
printf("msqid is %0x\n", msqid);
printf("pid is %0x\n", getpid());
msg.mtype = 888;
sprintf(msg.mtext, "Hello, I'm client %0x\n", getpid());
isnd = msgsnd(msqid, &msg, sizeof(msg.mtext), IPC_NOWAIT);
if (0==isnd)
{
len = msgrcv(msqid, &msg, 256, 999, 0);
if (0<len)
{
printf("MSG -client receive msg type is %0x\n", (unsigned int)msg.mtype);
printf("MSG -client receive msg is %s\n", msg.mtext);
}
}
return 0;
}
// result
# ./msgqueue-server &
[1] 2588
MSG -server key is 7a011886
msqid is 28000
pid is a1c
# ./msgqueue-client &
[2] 2592
MSG -client key is 7a011886
msqid is 28000
pid is a20
MSG -server receive msg type is 378
MSG -server receive msg is Hello, I'm client a20
MSG -client receive msg type is 3e7
MSG -client receive msg is Hello, I'm server a1c
[2]+ Done ./msgqueue-client
e# jobs
[1]- Running ./msgqueue-server &
# fg 1
./msgqueue-server
^CMSG -server quit!
Finally:
用好了，还是挺强大的啊