Linux消息队列

常用函数

//创建/获取消息队列 
int msgget (key_t key, int msgflg);
/*
key : 为键值,ftok();
msgflg:IPC_CREAT - 创建，不存在即创建，已存在即获取，除非… IPC_EXCL - 排斥，已存在即失败。
*/// 向消息队列发送消息 
int msgsnd (int msqid, const void* msgp,size_t msgsz, int msgflg);
/*
msqid : msgget()返回
msgp : 包含消息类型和消息数据的内存块.前4个字节必须是一个大于0的整数，代表消息类型，其后消息数据
msgsz:不包括消息类型的，只算消息数据的内存大小
msgflg :IPC_NOWAIT内核中的消息队列缓冲区没有足够的空闲空间时，此函数不会阻塞，而是返回-1
*///从消息队列接收消息
ssize_t msgrcv (int msqid, void* msgp, size_t msgsz,long msgtyp, int msgflg);
/*
msqid : msgget()返回
msgp : 包含消息类型和消息数据的内存块
smgsz:接收的内存大小，如果接收到的内存＞smgsz，则只会截取内存大小部分
msgtyp:=0 - 返回消息队列中的第一条消息。 >0 - 若msgflg参数不包含MSG_EXCEPT位，则返回消息队列中第一个类型为msgtyp的消息，若msgflg参数包含MSG_EXCEPT位，则返回消息队列中第一个类型不为msgtyp的消息。 <0 - 返回消息队列中类型小于等于msgtyp的绝对值的消息，若有多个，则取类型最小者。
*///销毁/控制消息队列 
int msgctl (int msqid, int cmd, struct msqid_ds* buf); 
/*
IPC_STAT 
获取消息队列的属性
IPC_SET 
设置消息队列的属性
IPC_RMID - 立即删除消息队列。 此时所有阻塞在对该消息队列的，msgsnd和msgrcv函数调用，都会立即返回失败，errno为EIDRM。*/

例子

为了展示例程，部分代码删减，且多个文件合并了，开发过程中，请不要模仿，这样不规范。

server

#include "server.h"
#include "server_function.h"
#include "fileoper.h"
#include "slinklist.h"
#include <stdbool.h>
#include <signal.h>
#include <assert.h>
#include "client.h"/*typedef struct Msg{int type;char msg[1024];
}Msg;typedef struct Back{int type;char msg[1024];
}Back;*/
#define PATH "/home/zhizhen/项目/本地银行"
#define SERVER 100
#define CLIENT 101int id1 ,id2;
Slink list = NULL;
Slink node = NULL;
void myexit(int sig){file_write(list);slink_destory(list);des_msg(id1);des_msg(id2);printf("退出成功\n");exit(0);
}
int server_run(){list = slink_create();assert(list != NULL);file_read(list);int id1 = create_msg(PATH,SERVER);int id2 = create_msg(PATH,CLIENT);assert(id1 != -1 && id2 != -1);while(1){	signal(SIGINT,myexit);Msg msg = {};//后面定义的，接收的消息的结构体Back back = {};int ret = 0;size_t msgsz = 0;//接收消息ssize_t sz = recv_msg(id1,(void *)&msg,sizeof(msg.msg));assert(sz != -1);if(sz == 0){printf("该用户退出了\n");	node = NULL;}int opt = msg.type;switch(opt){case R:msgsz = recv_Reg(&msg,&back,list);break;case E:node = recv_Ent(&msg,&back,list);msgsz = sizeof(B_Ent);break;case G:msgsz = recv_GetM(&msg,&back,list,node);break;case S:msgsz = recv_SaveM(&msg,&back,list,node);break;case T:msgsz = recv_TranM(&msg,&back,list,node);break;case C:msgsz = recv_ChgP(&msg,&back,list,node);break;case D:msgsz = recv_Des(&msg,&back,list,node);break;}Slink next1 = list->next;int i = 1;while(next1 != NULL){Client *p = (Client *)(next1->elem);printf("-------------------\n");printf("*******%d*******\n",i);i++;printf("id:%s\n",p->id);printf("name:%s\n",p->name);printf("password:%s\n",p->password);printf("tel:%s\n",p->tel);printf("money:%d\n",p->money);printf("------------------\n");next1 = next1->next;}ret = send_msg(id2,(const void *)&back,msgsz);//发送反馈assert(ret != -1);}
}

client

#include "client.h"
#include <stdbool.h>
#include <assert.h>static void menu(){printf("--------%d.注册\n",R);printf("--------%d.登录\n",E);printf("--------非%d和%d即:退出\n",R,E);printf(">>>>\n");
}static void menu_Ent(){printf("******%d.取钱\n",G);printf("******%d.充值\n",S);printf("******%d.转账\n",T);printf("******%d.修改密码\n",C);printf("******%d.销户\n",D);printf("*******0.退出\n");printf(">>>>>\n");
}/*typedef struct Msg{int type;char msg[1024];
}Msg;typedef struct Back{int type;char msg[1024];
}Back;*/int create_msg(char *s,int id){key_t key = ftok(s,id);assert(key != -1);return msgget(key,IPC_CREAT|0644);
}
int send_msg(int msqid,const void *msg,size_t msgsz){return msgsnd(msqid,msg,msgsz,0);
}
int recv_msg(int msqid,void *msg,size_t msgsz){return msgrcv(msqid,msg,msgsz,0,0);
}
int des_msg(int msqid){return msgctl(msqid,IPC_RMID,NULL);
}
int client_run(){int id1 = create_msg(PATH,SERVER);int id2 = create_msg(PATH,CLIENT);assert(id1 != -1 && id2 != -1);
Beg:while(1){Msg msg = {};size_t msgsz = 0;Back back = {};int ret = 0;menu();int opt = 0;scanf("%d",&opt);switch(opt){case R:msgsz = send_Reg(&msg);break;case E:msgsz = send_Ent(&msg);break;default:printf("退出成功\n");exit(0);break;}ret = send_msg(id1,(const void *)&msg,msgsz);assert(ret != -1);ret = recv_msg(id2,(void *)&back,sizeof(back.msg));assert(ret != -1);opt = back.type;switch(opt){case R:back_Reg(&back);break;case E:{if(back_Ent(&back) == 1){while(1){menu_Ent();int opt = 0;Msg msg = {};Back back = {};size_t msgsz = 0;scanf("%d",&opt);switch(opt){case G:msgsz = send_GetM(&msg);break;case S:msgsz = send_SaveM(&msg);break;case T:msgsz = send_TranM(&msg);break;case C:msgsz = send_ChgP(&msg);break;case D:msgsz = send_Des(&msg);break;default:goto Beg;printf("退出成功!\n");break;}ret = send_msg(id1,(const void *)&msg,msgsz);assert(ret != -1);ret = recv_msg(id2,&back,sizeof(back.msg));assert(ret != -1);opt = back.type;switch(opt){case G:back_GetM(&back);break;case S:back_SaveM(&back);break;case T:back_TranM(&back);break;case C:back_ChgP(&back);break;case D:back_Des(&back);break;}}}else{printf("登录失败!\n");}break;}}}
}