c语言编程之消息队列
//msg.c
#include
#include
#include
#include
#include
#define MSGKEY 1000
struct msgStru
{
long msgType;
char msgText[4096];
};
main()
{
int iMsgId;
struct msgStru slQMsg,slRcvMsg;
int ilRc;
iMsgId = msgget(MSGKEY,IPC_EXCL);/*检查消息队列是否存在*/
if ( iMsgId < 0 ){
iMsgId = msgget(MSGKEY,IPC_CREAT|0666);/*创建消息队列*/
if ( iMsgId < 0 ){
printf("create msgQ error! errno=%d[%s]\n",errno,strerror(errno));
exit(-1);
}
}
slQMsg.msgType = 100;
strcpy(slQMsg.msgText,"Hello mcfeng.");
ilRc = msgsnd(iMsgId, &slQMsg, sizeof(struct msgStru),IPC_NOWAIT);
if( ilRc < 0 ) {
printf("msgsnd()写消息队列失败,errno=%d[%s]\n",errno,strerror(errno));
exit(-1);
}
ilRc = msgrcv(iMsgId,&slRcvMsg,sizeof(struct msgStru),0,0);/*接收消息队列*/
printf("text=[%s]\n",slRcvMsg.msgText);
msgctl(iMsgId,IPC_RMID,0); /* 删除消息队列 */
exit(0);
}
//receive.c
#include
#include
#include
#include
#include
#define MSGKEY 1024
struct msgstru
{
long msgtype;
char msgtext[2048];
};
main()
{
int imsgID;
struct msgstru slQMsg,slRcvMsg;
int ilrc;
char str[1024];
imsgID=msgget(MSGKEY,IPC_EXCL );//检查消息队列是否存在
if(imsgID < 0){
printf("消息不存在! errno=%d [%s]\n",errno,strerror(errno));
exit(-1);
}
ilrc = msgrcv(imsgID,&slRcvMsg,sizeof(struct msgstru),0,0);/*接收消息队列*/
printf("text=[%s]\n",slRcvMsg.msgtext);
msgctl(imsgID,IPC_RMID,0); //删除消息队列
exit(0);
}
//send.c
#include
#include
#include
#include
#include
#define MSGKEY 1024
struct msgstru
{
long msgtype;
char msgtext[2048];
};
main()
{
int imsgID;
struct msgstru slQMsg,slRcvMsg;
int ilrc;
char str[2048];
printf("请输入字符串:");
scanf ("%s",str);
imsgID=msgget(MSGKEY,IPC_EXCL ); //检查消息队列是否存在
if(imsgID < 0){
imsgID=msgget(MSGKEY,IPC_CREAT|0666);//创建消息队列
if(imsgID <0 ){
printf("创建消息失败! errno=%d [%s]\n",errno,strerror(errno));
exit(-1);
}
}
slQMsg.msgtype = 100;
strcpy(slQMsg.msgtext, str);
ilrc = msgsnd(imsgID,&slQMsg,sizeof(struct msgstru),IPC_NOWAIT); //发送消息队列
if ( ilrc < 0 ) {
printf("msgsnd()写消息队列失败,errno=%d[%s]\n",errno,strerror(errno));
exit(-1);
}
exit(0);
}
本程序实例介绍linux环境下利用消息队列进行进程间通信，主要介绍ftok函数，msgget创建消息队列和获取已存在消息队列，
msgctl获取消息队列结构信息，msgsnd发送消息到消息队列，msgrcv从消息队列中获取消息。
本程序由两个.c文件组成，msgQueueRecv.c和msgQueueSend.c，msgQueueRecv.c里面创建消息队列并阻塞式从消息队列接收消息，
最后删除消息队列(消息队列在内核创建)；msgQueueSend.c获取以创建的消息队列，向消息队列发送消息。
请参考《unix环境高级编程》辅助学习。
//msgQueueRecv.c
#include
#include
#include
#include
#include
#include
#define BUFF_LEN 1024
#define RET_ERROR 1
#define RET_OK 0
int main()
{
char *pcPathName = "/"; /* pathname for ftok */
int iProjectId = 5; /* id for ftok */
key_t kId; /* key id */
struct msqid_ds stMsgInfo; /* msg queue info structure */
struct msgRecvStructure
{
long lMsgType; /* msg type */
char acMsgRecvBuff[BUFF_LEN]; /* send msg buffer */
}stMsgRecv;
int iRet;
int iMsgId; /* msg queue id */
int iFlag = IPC_CREAT | IPC_EXCL | 0666; /* msg queue creating flag */
/* build key using ftok function */
kId = ftok(pcPathName, iProjectId);
if ( kId == -1 )
{
printf("building key error, ftok() error!\n");
return RET_ERROR;
}
/* create msg queue */
iMsgId = msgget(kId, iFlag);
if ( iMsgId == -1 )
{
printf("create msg queue error, msgget() error!\n");
return RET_ERROR;
}
/* recv msg from msg queue */
iRet = msgrcv(iMsgId, &stMsgRecv, BUFF_LEN, 1, 0);
if ( iRet == -1 )
{
printf("msg recv error, msgrcv() error!\n");
msgctl(iMsgId, IPC_RMID, &stMsgInfo); /* delete msg queue from kernel */
return RET_ERROR;
}
else
{
printf("msg recv content: %s\n", stMsgRecv.acMsgRecvBuff);
}
msgctl(iMsgId, IPC_RMID, &stMsgInfo); /* delete msg queue from kernel */
return RET_OK;
}
msgQueueSend.c
#include
#include
#include
#include
#include
#include
#define BUFF_LEN 1024
#define RET_ERROR 1
#define RET_OK 0
int main()
{
char *pcPathName = "/"; /* pathname for ftok */
int iProjectId = 5; /* id for ftok */
key_t kId; /* key id */
struct msqid_ds stMsgInfo; /* msg queue info structure */
struct msgSendStructure
{
long lMsgType; /* msg type */
char acMsgSendBuff[BUFF_LEN]; /* send msg buffer */
}stMsgSend;
int iRet;
int iMsgId; /* msg queue id */
int iFlag = 0666; /* msg queue creating flag */
/* build key using ftok function */
kId = ftok(pcPathName, iProjectId);
if ( kId == -1 )
{
printf("building key error, ftok() error!\n");
return RET_ERROR;
}
/* get existing msg queue */
iMsgId = msgget(kId, iFlag);
if ( iMsgId == -1 )
{
printf("get msg queue error, msgget() error!\n");
return RET_ERROR;
}
/* send msg to msg queue */
stMsgSend.lMsgType = 1;
strcpy(stMsgSend.acMsgSendBuff, "hello,world");
iRet = msgsnd(iMsgId, &stMsgSend, strlen("hello,world")+1, IPC_NOWAIT);
if ( iRet == -1 )
{
printf("msg send error, msgsnd() error!\n");
return RET_ERROR;
}
return RET_OK;
}