API综合使用

//父进程发送消息,子进程接收消息
struct msgBuf
{
    long mtype;       /* message type, must be > 0 */
    char mtext[104];    /* message data */
};
const int MSGNUMBER = 10;

int main()
{
    //获取一个键
    key_t msgKey = ftok("/tmp/mySeedFile",‘f‘);
    //获取一个消息队列
    int msgid = msgget(msgKey,IPC_CREAT|0666);
    if (msgid == -1)
    {
        err_exit("msgget error");
    }

    struct msgBuf myBuffer;

    pid_t pid = fork();
    if (pid == -1)
    {
        err_exit("fork error");
    }
    //父进程,发送数据
    if (pid > 0)
    {
        myBuffer.mtype = getpid();
        //向消息队列中发送消息,如果队列full,则该进程一直阻塞
        for (int i = 0; i < MSGNUMBER; ++i)
        {
            sprintf(myBuffer.mtext,"Hello, My Number is %d",i);
            msgsnd(msgid,&myBuffer,strlen(myBuffer.mtext),0);
        }

　　//等待子进程结束
        wait(NULL);
    }
    else if (pid == 0)  //子进程
　　{
　　//睡眠1秒,等待父进程发送结束
        sleep(1);
        memset(&myBuffer,0,sizeof(myBuffer));
        //从队首不断的取数据
        for (int i = 0; i < MSGNUMBER; ++i)
        {
            int recvBytes = 0;
            if ((recvBytes = msgrcv(msgid,&myBuffer,sizeof(myBuffer.mtext),
                                    getppid(),IPC_NOWAIT)) == -1)
            {
                err_exit("msgrcv error");
            }
            else
            {
                cout << "recvBytes = " << recvBytes << endl;
                cout << "myBuffer.mtype = " << myBuffer.mtype << endl;
                cout << "\t" << myBuffer.mtext << endl;
            }
        }
        cout << "strlen(myBuffer.mtext) = " << strlen(myBuffer.mtext) << endl;
    }
    return 0;
}

消息队列项目开发案例

消息队列实现回射客户/服务器

/**一个简化实现->程序说明:
　　1.客户端发送数据格式:
　　类型为:客户端pid
　　内容为键盘输入的内容
2.客户端接收格式
　　类型为自己的pid
　　内容为服务器发送过来的内容

　　3.服务器接收的数据
　　类型为客户端pid
　　内容为各个客户端的消息内容
　　4.服务器发送的数据
　　类型为客户端id
　　内容为客户端消息内容
*/

//server.cpp
#include "commen.h"

void echo_server(int msgid)
{
    struct msgBuf myMsgBuf;

    while (true)
    {
        memset(&myMsgBuf,0,sizeof(myMsgBuf));
        int recvBytes = msgrcv(msgid,&myMsgBuf,MAXMSGSIZE,0,0);
        if (recvBytes == -1)
        {
            err_exit("msgrcv error");
        }

        fputs(myMsgBuf.mtext,stdout);
        if (msgsnd(msgid,&myMsgBuf,strlen(myMsgBuf.mtext),0) < 0)
        {
            err_exit("msgsnd error");
        }
    }
}

int main()
{
    key_t key = ftok(FILESEED,‘f‘);
    int msgid = msgget(key,0666|IPC_CREAT);
    if (msgid == -1)
    {
        err_exit("msgget error");
    }

    echo_server(msgid);

    return 0;
}

//client.cpp
#include "commen.h"

void echo_client(int msgid)
{
    struct msgBuf myMsgBuf,recvMsgBuf;
    myMsgBuf.mtype = getpid();

    while (fgets(myMsgBuf.mtext,MAXMSGSIZE,stdin) != NULL)
    {
        if (msgsnd(msgid,&myMsgBuf,strlen(myMsgBuf.mtext),0) == -1)
        {
            err_exit("msgsnd error");
        }

        memset(&recvMsgBuf,0,sizeof(recvMsgBuf));
        if (msgrcv(msgid,&recvMsgBuf,sizeof(recvMsgBuf),getpid(),0) == -1)
        {
            err_exit("msgrcv error");
        }

        fputs(recvMsgBuf.mtext,stdout);

        memset(&myMsgBuf+4,0,sizeof(myMsgBuf)-4);
    }
}

int main()
{
    key_t key = ftok(FILESEED,‘f‘);
    int msgid = msgget(key,0666);
    if (msgid == -1)
    {
        err_exit("msgget error");
    }

    echo_client(msgid);

    return 0;
}

//commen.h
#ifndef COMMEN_H_INCLUDED
#define COMMEN_H_INCLUDED

#include <string>
#include <string.h>
#include <errno.h>
#include <stdlib.h>
#include <stdio.h>

const char FILESEED[] = "/tmp/mySeedFile";
const int MAXMSGSIZE = 1024;

struct msgBuf
{
    long mtype;             //Message Type: Client PID
    char mtext[MAXMSGSIZE]; //message data
};

void err_exit(std::string str)
{
    perror(str.c_str());
    exit(EXIT_FAILURE);
}

#endif // COMMEN_H_INCLUDED

开拓眼界

附-Makefile

CC = g++ 
CPPFLAGS = -Wall -g

BIN = client server 
SOURCES = $(BIN.=.cpp)

.PHONY: clean all 

all: $(BIN)

$(BIN): $(SOURCES)

clean:
    -rm -rf $(BIN) bin/ obj/ core

Linux消息队列实践(3)