进程同步（四）—— 消息队列

 1 //queuewrite.cpp
 2 #include <sys/types.h>
 3 #include <sys/msg.h>
 4 #include <unistd.h>
 5 #include <string.h>
 6 #include <iostream>
 7 
 8 using namespace std;
 9 
10 const int MSGQUEUE = 0x8769;
11 class msgQueue
12 {
13 public:
14     void initQueue();
15     int getQueueLen();
16     void addMsg(char *msgbuf);
17     int revMsg();
18     void releaseQueue();
19 private:
20     int m_queueID;
21 };
22 
23 void msgQueue::initQueue()
24 {
25     m_queueID = msgget(MSGQUEUE, 0600|IPC_CREAT);
26     if (m_queueID == -1)
27         cout<<"msgget error!";
28 }
29 int msgQueue::getQueueLen()
30 {
31     struct msqid_ds buf;
32     int ret = msgctl(m_queueID, IPC_STAT, &buf);
33     if (ret == -1)
34     {
35         cout<<"get queue len failure!";
36         return ret;
37     }
38     return buf.msg_qnum;
39 }
40 void msgQueue::addMsg(char *msgbuf)
41 {
42     struct msgbuf buf;
43     buf.mtype = 1;
44     memcpy(buf.mtext, msgbuf, sizeof(msgbuf));
45     int ret = msgsnd(m_queueID, &buf, sizeof(buf), IPC_NOWAIT);
46     if (ret != 0)
47     {
48         cout<<"send msg error!";
49         return;
50     }
51 }
52 int msgQueue::revMsg()
53 {
54     struct msgbuf buf;
55     int ret = msgrcv(m_queueID, &buf, sizeof(buf), 0, 0);
56     if (ret == -1)
57     {
58         return 0;
59     }
60     cout<<buf.mtext;
61     return 1;
62 }
63 void msgQueue::releaseQueue()
64 {
65     msgctl(m_queueID,IPC_RMID,0);
66 }
67 int main()
68 {
69     msgQueue FIFO;
70     char buf[512];
71     FIFO.initQueue();
72     while(1)
73     {
74         cin>>buf;
75         FIFO.addMsg(buf);
76     }
77     return 0;
78 }

 读消息队列只需修改main函数如下：

 1 int main()
 2 {
 3     msgQueue FIFO;
 4     FIFO.initQueue();
 5     int queLen = FIFO.getQueueLen();
 6     while(queLen--)
 7     {
 8         FIFO.revMsg();
 9     }
10     return 0;
11 }