linux c++進(jìn)程通信之消息隊(duì)列
消息隊(duì)列是一個(gè)存放在內(nèi)核中的消息鏈表，每個(gè)消息隊(duì)列由隊(duì)列標(biāo)識(shí)符標(biāo)識(shí)，與管道不同的是消息隊(duì)列是放在內(nèi)核當(dāng)中，只有在內(nèi)核重啟，或者顯式的刪除一個(gè)消息隊(duì)列，該消息隊(duì)列才會(huì)被真正的刪除，以下會(huì)有幾個(gè)操作，
1.創(chuàng)建消息隊(duì)列
#include
#include
key_t ftok(const char* pathname,int proj_id);
根據(jù)傳入的參數(shù)的唯一性，創(chuàng)建一個(gè)消息隊(duì)列
int? msgget(key_t key,int msgflag);
該參數(shù)ley是即為ftok函數(shù)的返回值，mshflag是一個(gè)標(biāo)識(shí)參數(shù)
IPC_CREATE：如果內(nèi)核中不存在于key相等的消息隊(duì)列，則新建一個(gè)消息隊(duì)列
IPC_EXCL和IPC_CREATE一起使用，如果對(duì)應(yīng)鍵值的消息對(duì)流已經(jīng)存在，則出錯(cuò)，返回-1
2.寫(xiě)消息隊(duì)列
int msgsnd(int msgid,struct msgbuf* msgp,size_t msgz,int msgflag)
msgid是消息隊(duì)列的標(biāo)識(shí)
msgp是發(fā)送的消息
msgz要發(fā)送的消息的大小
msgflag操作標(biāo)識(shí)，當(dāng)他是0的時(shí)候，當(dāng)消息隊(duì)列已曼則，msgsnd則會(huì)阻塞，直到可以寫(xiě)入，如果msgflag是
IPC_NOWAIT的時(shí)候，如果消息隊(duì)列已滿(mǎn)則，立即返回
3.讀消息隊(duì)列
int msgrcv(int msgid,struct msgbuf* msgp,size_t msglen,long msgtyp,int msgflag);
現(xiàn)在源代碼如下
msg_server.c
/*
?*?main.cpp
?*
?*??Created?on:?Jul?18,?2014
?*??????Author:?john
?*/
#include#include#include#include#include#include#include#include#include#include#include#define?BUF_SIZE?256
#define?PROJ_ID??32
#define?PATH_NAME?"/tmp"
#define?SERVER_MSG??1
#define?CLIENT_MSG?2
using?namespace?std;
int?main()
{
???struct?mymsg
???{
?????long?msgtype;
?????char?content[256];
???}msgbuf;
???
??//?var?define
???int?qid;//消息隊(duì)列標(biāo)識(shí)
????int?msglen;//消息長(zhǎng)度
???key_t?msgkey;
?
??//獲取鍵值
??msgkey=ftok(PATH_NAME,PROJ_ID);
??if(msgkey==-1)
???{
?????cout<<"sorry?key?create?failed:?"<<strerror(errno)<<endl;
?????exit(0);???
??}
??//獲取消息隊(duì)列
??cout<<"創(chuàng)建鍵值成功n";
??
??qid=msgget(msgkey,IPC_CREAT|0666);
??if(qid==-1)
???{
??????cout<<"get?msg?quen?failed?"<<strerror(errno)<<endl;
??????exit(0);
???}
??cout<<"獲取消息隊(duì)列成功"<<qid<<"n";
??//開(kāi)始讀取和寫(xiě)入消息
??while(1)
??{
?????cout<>msgbuf.content;
?????if(strncmp(msgbuf.content,"exit",4)==0)
?????{
???? ?//獲取消息屬性，IPC——RMID從內(nèi)核中刪除qid的消息隊(duì)列
?????????msgctl(qid,IPC_RMID,NULL);
?????????exit(0);
?????}
?????msgbuf.msgtype=SERVER_MSG;
??????if(?msgsnd(qid,&msgbuf,strlen(msgbuf.content)+1,0)==-1)
?????{
??????????cout<<"msg?send?failed"<<endl;
??????????exit(1);
?????}
??????cout<<"正在接收客戶(hù)端的消息n";
?????if(msgrcv(qid,&msgbuf,BUF_SIZE,CLIENT_MSG,0)==-1)
?????{
?????????cout<<"msg?rcv?failed"<<endl;
?????????exit(0);
?????}
?????cout<<"Client:?"<<msgbuf.content<<endl;
?????
??}
}msg_client.c文件如下：
/*
?*?main.cpp
?*
?*??Created?on:?Jul?18,?2014
?*??????Author:?john
?*/
#include#include#include#include#include#include#include#include#include#include#include#define?BUF_SIZE?256
#define?PROJ_ID??32
#define?PATH_NAME?"/tmp"
#define?SERVER_MSG??1
#define?CLIENT_MSG?2
using?namespace?std;
int?main()
{
???struct?mymsg
???{
?????long?msgtype;
?????char?content[256];
???}msgbuf;
??//?var?define
???int?qid;//消息隊(duì)列標(biāo)識(shí)
????int?msglen;//消息長(zhǎng)度
???key_t?msgkey;
??//獲取鍵值
??msgkey=ftok(PATH_NAME,PROJ_ID);
??if(msgkey==-1)
???{
?????cout<<"sorry?key?create?failed:?"<<strerror(errno)<<endl;
?????exit(0);
??}
??cout<<"獲取鍵值成功n";
??//獲取消息隊(duì)列
??qid=msgget(msgkey,IPC_CREAT|0666);
??if(qid==-1)
???{
??????cout<<"get?msg?quen?failed?"<<strerror(errno)<<endl;
??????exit(0);
???}
??cout<<"獲取消息隊(duì)列成功"<<qid<<"n";
??//開(kāi)始讀取和寫(xiě)入消息
??while(1)
??{
??cout<<"正在接收服務(wù)器給客戶(hù)段的消息n";
??if(msgrcv(qid,&msgbuf,BUF_SIZE,SERVER_MSG,0)==-1)
??????{
??????????cout<<"msg?rcv?failed"<<endl;
??????????exit(0);
??????}
??????cout<<"Server:?"<<msgbuf.content<<endl;
?????cout<>msgbuf.content;
?????if(strncmp(msgbuf.content,"exit",4)==0)
?????{
???? ?//獲取消息屬性，IPC——RMID從內(nèi)核中刪除qid的消息隊(duì)列
?????????msgctl(qid,IPC_RMID,NULL);
?????????exit(0);
?????}
?????msgbuf.msgtype=CLIENT_MSG;
??????if(?msgsnd(qid,&msgbuf,strlen(msgbuf.content)+1,0)==-1)
?????{
??????????cout<<"msg?send?failed"<<endl;
??????????exit(1);
?????}
??}
}唯一需要注意的是，在msgrcv的參數(shù)中要寫(xiě)入需要接收的消息的類(lèi)型。
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