在Linux下可以使用消息队列来实现进程间的通信
例子：
发送端：send.c
#include <iostream>
#include <thread>
#include <unistd.h>
#include <sys/msg.h>
#include <linux/mqueue.h>
//#include <mqueue.h>
#include <fcntl.h>
#include <syscall.h>
#include <sys/time.h>
#include <errno.h>
#include <string.h>
#define MY_QUE "/MuxRouter_VehicleQueue"
#define MR_MQ_MSG_NUM_MAX 30
#define MR_MQ_MSG_LEN_MAX (2176) /**< the queue size can contain whole mux frame data */
int MsgQueOpen(const char *name, int oflag, mode_t mode, struct mq_attr attr)
{
return syscall(SYS_mq_open, name + 1, oflag, mode, &attr);
}
//msgPrio 优先级
int MsgQueSend(int fd, uint8_t *data, size_t dataLen, uint32_t msgPrio, const struct timespec *abs_timeout)
{
return syscall(SYS_mq_timedsend, fd, data, dataLen, msgPrio, NULL);
}
int MsgQueReceive(int fd, uint8_t *data, size_t dataLen, uint32_t msgPrio, const struct timespec *abs_timeout)
{
return syscall(SYS_mq_timedreceive, fd, data, dataLen, msgPrio, NULL);
}
//关闭连接，但队列还存在
int MsgQueClose(int fd)
{
return syscall(SYS_close, fd);
}
//从系统移除此队列
int MsgQueUnlink(const char* queName)
{
return syscall(SYS_mq_unlink, queName);//好像是无效的
}
int main(int argc, char **argv)
{
if (MsgQueUnlink(MY_QUE) < 0)
{
printf("error: syscall unlink %s failed. %s\n", MY_QUE, strerror(errno));
//return;
}
struct mq_attr attr;
attr.mq_maxmsg = MR_MQ_MSG_NUM_MAX;
attr.mq_msgsize = MR_MQ_MSG_LEN_MAX;
int fd = MsgQueOpen(MY_QUE, O_CREAT | O_WRONLY, 0666, attr);
if (fd < 0)
{
printf("error: syscall create %s failed. %s\n", MY_QUE, strerror(errno));
return;
}
printf("create server success\n");
struct timeval curTime = {0, 0};
struct timespec waitTime = {0, 0};
time_t failedTime = 0;
char data[128] = {0};
size_t dataLen = strlen(data);
int i = 0;
while (true)
{
if (gettimeofday(&curTime, NULL) < 0)
{
curTime.tv_sec = time(NULL);
}
waitTime.tv_sec = curTime.tv_sec + 1;
waitTime.tv_nsec = curTime.tv_usec * 1000;
sprintf(data, "%d", i++);
dataLen = strlen(data);
if (MsgQueSend(fd, (uint8_t*)data, dataLen, 0, &waitTime) < 0)//不建议设置超时
{
printf("send failed, %s\n", strerror(errno));
//return;
}
printf("send:%s\n", data);
std::this_thread::sleep_for(std::chrono::milliseconds(500));
if (i == 100)
{
break;
}
}
MsgQueClose(fd);
return 0;
}
接收端：receive.c
#include <iostream>
#include <thread>
#include <unistd.h>
#include <sys/msg.h>
#include <linux/mqueue.h>
//#include <mqueue.h>
#include <fcntl.h>
#include <syscall.h>
#include <sys/time.h>
#include <errno.h>
#include <string.h>
#define MY_QUE "/MuxRouter_VehicleQueue"
#define MR_MQ_MSG_NUM_MAX 30
#define MR_MQ_MSG_LEN_MAX (2176) /**< the queue size can contain whole mux frame data */
int MsgQueOpen(const char *name, int oflag, mode_t mode, struct mq_attr attr)
{
return syscall(SYS_mq_open, name + 1, oflag, mode, &attr);
}
//msgPrio 优先级
int MsgQueSend(int fd, uint8_t *data, size_t dataLen, uint32_t msgPrio, const struct timespec *abs_timeout)
{
return syscall(SYS_mq_timedsend, fd, data, dataLen, msgPrio, NULL);
}
int MsgQueReceive(int fd, uint8_t *data, size_t dataLen, uint32_t msgPrio, const struct timespec *abs_timeout)
{
return syscall(SYS_mq_timedreceive, fd, data, dataLen, msgPrio, NULL);
}
//关闭连接，但队列还存在
int MsgQueClose(int fd)
{
return syscall(SYS_close, fd);
}
//从系统移除此队列
int MsgQueUnlink(const char* queName)
{
return syscall(SYS_mq_unlink, queName);//好像是无效的
}
int main(int argc, char **argv)
{
struct mq_attr attr;
attr.mq_maxmsg = MR_MQ_MSG_NUM_MAX;
attr.mq_msgsize = MR_MQ_MSG_LEN_MAX;
int fd = MsgQueOpen(MY_QUE, O_CREAT | O_RDONLY, 0666, attr);
if (fd < 0)
{
printf("error: syscall create %s failed. %s\n", MY_QUE, strerror(errno));
return;
}
printf("create client success\n");
struct timeval curTime = {0, 0};
struct timespec waitTime = {0, 0};
time_t failedTime = 0;
uint8_t data[4096] = {0};
size_t dataLen = sizeof(data);
printf("%d\n", dataLen);
while (true)
{
if (gettimeofday(&curTime, NULL) < 0)
{
curTime.tv_sec = time(NULL);
}
memset(data, 0, 4096);
waitTime.tv_sec = curTime.tv_sec + 1;
waitTime.tv_nsec = curTime.tv_usec * 1000;
if (MsgQueReceive(fd, data, dataLen, 0, NULL) < 0)//这里的超时不建议设置
{
printf("receive failed, %s\n", strerror(errno));
//return;
}
else
{
printf("%s\n", data);
}
std::this_thread::sleep_for(std::chrono::milliseconds(500));
}
MsgQueClose(fd);
return 0;
}
注意点：
1.创建mq失败时，检查传入的参数是否正确。
2.mq的命名规则必须为“/”开头，后面跟不含"/"的名字，如/ipc_name。
3.调用syscall的接口失败时，都可以使用 strerror(errno) 获取错误信息，根据错误信息检查问题。
4.使用 MsgQueSend 发送数据失败时，很有可能是创建的mq有问题，需要调用 MsgQueUnlink 把队列删除，重新创建。（使用syscall好像不能删除，可以使用#include<mqueue.h>头文件下的mq_unlink接口进行删除）。
5.使用 MsgQueReceive 接收消息时，data的长度必须>=创建mq时设置的 mq_msgsize。
mq_open()接口的消息队列：https://blog.csdn.net/qq_36973838/article/details/124807479