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分类: LINUX

2013-03-24 12:47:00

消息队列是消息的链接表,存放在内核中并由消息队列标示符标识。
1. 创建或打开一个队列
    int msgget(key_t key, int flag);
    key: 键 由ftok()生成
        key_t ftok(const char* path, int id);
    flag: IPC_CREAT 或 IPC_EXCL 
2. 发送消息
    int msgsnd(int msgid, const void* ptr, size_t nbyte, int flag);
    msgid: 消息队列标识
    ptr: 发送的消息,一般格式为:
        struct _msg{
            long mtype;
            char _msg[512];
            . . . 
        };
    nbyte:消息大小,一般为sizeof(struct _msg)-sizeof(long)
    flag: 0                     默认阻塞方式
            IPC_NOWAIT  非阻塞
3. 接收消息
    int msgrcv(int msgid, void* ptr, size_t nbyte, long mtype, int flag);

msgQueue.h
#ifndef _MSGQUEUE_H_
#define _MSGQUEUE_H_

#include
#include
#include
#include
#include

using namespace std;

#define KEYPATH "/tmp/count"
#define KEYPROJ 'a'
#define NAMESIZE 16
#define MTYPE 2

typedef struct {
long mtype;
char name[NAMESIZE];
int iChiScore;
int iEngScore;
int iMathScore;
} S_SCORE_ST;
#endif

send.c

#include "msgQueue.h"

int main()
{
int iRet = 0;
key_t key;
int msgid;
S_SCORE_ST score_st;
do {
key = ftok(KEYPATH, KEYPROJ);
if (key < 0) {
iRet = -1;
cout << "ftok() error : " << key <<  endl;
break;
}

msgid = msgget(key, IPC_CREAT);
if (msgid < 0) {
iRet = -1;
cout << "msgget() error : " << msgid << endl;
break;
}
strcpy(score_st.name, "leex");
score_st.iChiScore = 100;
score_st.iEngScore = 100;
score_st.iMathScore = 100;
score_st.mtype = MTYPE;

iRet = msgsnd(msgid, &score_st, sizeof(score_st)-sizeof(long),  0);
if (iRet < 0) {
cout << "msgsnd() error : " << iRet << endl;
break;
}

} while(false);
return iRet;
}

recv.c
        
#include "msgQueue.h"

int main()
{
int iRet = 0;
key_t key;
int msgid;
S_SCORE_ST score_st;
do {
key = ftok(KEYPATH, KEYPROJ);
if (key < 0) {
iRet = -1;
cout << "ftok() error : " << key <<  endl;
break;
}

msgid = msgget(key, IPC_CREAT);
if (msgid < 0) {
iRet = -1;
cout << "msgget() error : " << msgid << endl;
break;
}

while (1) {
iRet = msgrcv(msgid, &score_st, sizeof(score_st)-sizeof(long), MTYPE, 0);
if (iRet < 0) {
cout << "msgrcv() error : " << iRet << endl;
break;
}
cout << "name:\t" << score_st.name << endl;
cout << "chinese score:\t" << score_st.iChiScore << endl;
cout << "english score:\t" << score_st.iEngScore << endl;
cout << "math score:\t" << score_st.iMathScore << endl;
}
} while(false);
return iRet;
}

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