所谓消息队列就是指一个消息链表。
int msgget(key_t, int flag)：创建和打开队列
int msgsnd(int msqid, struct msgbuf *msgp, size_t msgsz, int flag):发送消息，msgid是消息队列的id，msgp是消息内容所在的缓冲区，msgsz是消息的大小，msgflg是标志。
int msgget(key_t, int flag)：创建和打开队列
int msgsnd(int msqid, struct msgbuf *msgp, size_t msgsz, int flag):发送消息，msgid是消息队列的id，msgp是消息内容所在的缓冲区，msgsz是消息的大小，msgflg是标志。
int msgrcv(int msqid, struct msgbuf *msgp, size_t msgsz, long msgtyp, int flag):接受消息，msgtyp是期望接收的消息类型。
msgqueue.c文件内容如下；
#include<sys/types.h>
#include<sys/ipc.h>
#include<stdio.h>
#include<stdlib.h>
#include<unistd.h>
#include<string.h>
#include<pthread.h> // 增加线程支持
#define BUFSZ 512
struct message{
long msg_type;
char msg_text[BUFSZ];
};
#define MSG_SIZE sizeof(struct message)
char app_exit = 0;
void *thread_funtion(void *parg);
int main()
{
int qid;
key_t key;
int len;
int res;
pthread_t a_thread;
struct message msg;
if((key = ftok(".",'a')) == -1){ // ftok 获得一个key
perror("ftok");
exit(1);
}
if((qid = msgget(key,IPC_CREAT|0666)) == -1){ // 创建一个消息队列
perror("msgget");
exit(1);
}
printf("opened queue %d\n",qid);
puts("Please enter the message to queue:");
if((fgets(msg.msg_text,BUFSZ,stdin)) == NULL){ // 从标准输入获得buffer
puts("no message");
exit(1);
}
msg.msg_type = getpid();
len = strlen(msg.msg_text) + sizeof(msg.msg_type);
if((msgsnd(qid,&msg,len,0)) < 0){ // 发送消息
perror("message posted");
exit(1);
}
/*
memset(&msg,0,sizeof(msg)); // 清除内存为0
if(msgrcv(qid,&msg,len,0) < 0){ // 接收消息
perror("message recv");
exit(1);
}
printf("message is:%s\n",(&msg)->msg_text);
if((msgctl(qid,IPC_RMID,NULL))<0){
perror("msgctl");
exit(1);
}
*/
res = pthread_create(&a_thread,NULL,thread_funtion,(void *)&qid);
printf("The msgrcv thread is create sucess!\n");
while((app_exit = getchar()) != 'e'){sleep(50);}
printf("exit main funtion!\n");
exit(0);
}
void *thread_funtion(void *parg)
{
struct message msg;
int qid;
qid = *((int *)parg);
memset(&msg,0,MSG_SIZE);
while(app_exit != 'e'){
if(msgrcv(qid,&msg,MSG_SIZE) < 0){
sleep(50);
continue;
}
printf("message is:%s\n",(&msg)->msg_text);
if(msgctl(qid,IPC_RMID,NULL) < 0){
perror("msgctl");
}
sleep(50);
}
}
Makefile文件类型如下；
all:msgqueue
# which compiler
CC = gcc
# Where are include file kept
INCLUDE = .
# Where to install
INSTDIR = /usr/local/bin
# Options for development
CFLAGS = -g -Wall -ansi
msgqueue:msgqueue.o
$(CC) -D_REENTRANT -o msgqueue msgqueue.o -lpthread
msgqueue.o:msgqueue.c
# $(CC) -I$(INCLUDE) $(CFLAGS) -c msgqueue.c
# $(CC) -D_REENTRANT -c msgqueue.c -lpthread
$(CC) -c msgqueue.c
clean:
-rm msgqueue.o msgqueue
install:msgqueue
@if [-d $(INSTDIR) ];\
then \
cp msgqueue $(INSTDIR);\
chmod a+x $(INSTDIR)/msgqueue;\
chmod og-w $(INSTDIR)/msgqueue;\
echo "Install in $(INSTDIR)";\
else \
echo "Sorry,$(INSTDIR) does not exist";\
fi
