http://blog.csdn.net/ljianhui/article/details/10287879
#include <sys/type.h>
#include <sys/ipc.h>
#include <sys/msg.h>
int msgget(key_t key, int flag);
int msgsnd(int msqid, const void *ptr, size_t nbytes, int flag);
int msgrcv(int msqid, void *ptr, size_t nbytes, long type, int flag);
int msgctl(int msqid, int cmd, struct mspid_ds *buf);
int msgget(key_t key, int flag);
msgflg是一个权限标志，表示消息队列的访问权限，它与文件的访问权限一样。msgflg可以与IPC_CREAT做或操作，表示当key所命名的消息队列不存在时创建一个消息队列，如果key所命名的消息队列存在时，IPC_CREAT标志会被忽略，而只返回一个标识符。它返回一个以key命名的消息队列的标识符（非零整数），失败时返回-1.
int msgsnd(int msqid, const void *ptr, size_t nbytes, int flag);
int msgrcv(int msqid, void *ptr, size_t nbytes, long msgtype, int flag);
msgtype可以实现一种简单的接收优先级。如果msgtype为0，就获取队列中的第一个消息。如果它的值大于零，将获取具有相同消息类型的第一个信息。如果它小于零，就获取类型等于或小于msgtype的绝对值的第一个消息。
flag取值包括0（阻塞）和IPC_NOWAIT（如果消息队列为空，则返回一个ENOMSG）
int msgctl(int msqid, int cmd, struct mspid_ds *buf);
cmd是将要采取的动作，它可以取3个值，
IPC_STAT：把msgid_ds结构中的数据设置为消息队列的当前关联值，即用消息队列的当前关联值覆盖msgid_ds的值。
IPC_SET：如果进程有足够的权限，就把消息列队的当前关联值设置为msgid_ds结构中给出的值
IPC_RMID：删除消息队列
#include <sys/types.h> #include <sys/ipc.h> #include <sys/msg.h> #include <stdio.h> #include <stdlib.h> #include <string.h> #include <pthread.h> #include <pthread.h> #include <sys/syscall.h> #include <unistd.h> /* #include <sys/type.h> #include <sys/ipc.h> #include <sys/msg.h> int msgget(key_t key, int flag); int msgsnd(int msqid, const void *ptr, size_t nbytes, int flag); int msgrcv(int msqid, void *ptr, size_t nbytes, long type, int flag); int msgctl(int msqid, int cmd, struct mspid_ds *buf); */ #ifndef T_DESC #define T_DESC(x, y) (y) #endif #if T_DESC("TU1", 1) int msg_qid; typedef struct msgbuf { long msgtype; char msgtext[128]; } PRIV_MSG_INFO; int send_task(void) { PRIV_MSG_INFO sndmsg; for(;;) { sndmsg.msgtype++; sprintf(sndmsg.msgtext, "type %ld", sndmsg.msgtype); if(msgsnd(msg_qid, (PRIV_MSG_INFO *)&sndmsg, sizeof(PRIV_MSG_INFO), 0)==-1) { printf("msgsnd error\n"); exit(254); } sleep(3); } } int recv_task(void) { PRIV_MSG_INFO rcvmsg; for(;;) { if(msgrcv(msg_qid, (PRIV_MSG_INFO *)&rcvmsg, sizeof(PRIV_MSG_INFO), 0, 0) == -1) { printf("msgsnd error\n"); exit(254); } printf("recv msg: %s\n", rcvmsg.msgtext); } } int tu1_proc(void) { pthread_t id_1,id_2; int i,ret; msg_qid = msgget(IPC_PRIVATE, 0666); if(msg_qid == -1) { printf("msgget error\n"); exit(254); } ret = pthread_create(&id_1, NULL, (void *)send_task, NULL); if(ret != 0) { printf("Create pthread error!\n"); return -1; } ret = pthread_create(&id_2, NULL, (void *)recv_task, NULL); if(ret != 0) { printf("Create pthread error!\n"); return -1; } /*µÈ´ýÏ߳̽áÊø*/ pthread_join(id_1, NULL); pthread_join(id_2, NULL); msgctl(msg_qid, IPC_RMID, 0); return 0; } #endif #if T_DESC("TU2", 1) int send_task2(void) { PRIV_MSG_INFO sndmsg; msg_qid = msgget((key_t)1234, 0666 | IPC_CREAT); if(msg_qid == -1) { printf("msgget error\n"); exit(254); } for(;;) { sndmsg.msgtype=10; sprintf(sndmsg.msgtext, "type %ld", sndmsg.msgtype); if(msgsnd(msg_qid, (PRIV_MSG_INFO *)&sndmsg, sizeof(PRIV_MSG_INFO), 0)==-1) { printf("msgsnd error\n"); exit(254); } sndmsg.msgtype=20; sprintf(sndmsg.msgtext, "type %ld", sndmsg.msgtype); if(msgsnd(msg_qid, (PRIV_MSG_INFO *)&sndmsg, sizeof(PRIV_MSG_INFO), 0)==-1) { printf("msgsnd error\n"); exit(254); } sleep(3); } } int recv_task2(void) { PRIV_MSG_INFO rcvmsg; msg_qid = msgget((key_t)1234, 0666 | IPC_CREAT); if(msg_qid == -1) { printf("msgget error\n"); exit(254); } for(;;) { if(msgrcv(msg_qid, (PRIV_MSG_INFO *)&rcvmsg, sizeof(PRIV_MSG_INFO), 10, 0) == -1) { printf("msgsnd error\n"); exit(254); } printf("recv msg: %s\n", rcvmsg.msgtext); } } int tu2_proc(int argc, char **argv) { pthread_t id_1,id_2; int i,ret; int param; if (argc < 2) return 1; param = atoi(argv[1]); if (!param) { ret = pthread_create(&id_1, NULL, (void *)send_task2, NULL); } else { ret = pthread_create(&id_2, NULL, (void *)recv_task2, NULL); } if(ret != 0) { printf("Create pthread error!\n"); return -1; } /*µÈ´ýÏ߳̽áÊø*/ if (!param) { pthread_join(id_1, NULL); } else { pthread_join(id_2, NULL); } return 0; } #endif #if T_DESC("global", 1) void usage() { printf("\n Usage: <cmd> <tu> <p1> <...>"); printf("\n 1 -- msgQ between thread"); printf("\n 2 -- msgQ between process"); printf("\n => P1: 0 - create pid 0; 1 - create pid 1"); printf("\n"); } int main(int argc, char **argv) { int ret; if(argc < 2) { usage(); return 0; } int tu = atoi(argv[1]); if (tu == 1) ret = tu1_proc(); if (tu == 2) ret = tu2_proc(argc - 1, &argv[1]); return ret; } #endif
