lcm使用方法

lcm源码链接，可以编译生成对应的库liblcm.so：
下载地址: https://download.csdn.net/download/ding283595861/12014778

// file : userlcm.cpp
#include 
#include "userlcm_manage.h"

#define USER_LCM_LOG_ON 0
#if USER_LCM_LOG_ON
#define USERLCM_LOG(format,arg...)		printf("[%s:%s][%u]: " format,__FILE__,__FUNCTION__,__LINE__,## arg)
#else
#define USERLCM_LOG(format,arg...)
#endif


cLcmMsgManage::cLcmMsgManage()
{
    memset(&m_MsgInfo, 0, sizeof(m_MsgInfo));
}
cLcmMsgManage::~cLcmMsgManage()
{
}

void cLcmMsgManage::handleMessage(const lcm::ReceiveBuffer *rbuf, const std::string &channel)
{
    if (NULL == rbuf) {
        USERLCM_LOG("ReceiveBuffer = NULL,return!\n");
        return;
    }
    if (strcmp(channel.c_str(), m_MsgInfo.channel) == 0) {
        void *data_class = m_MsgInfo.func;
        m_MsgInfo.f(rbuf->data, rbuf->data_size, (char *)channel.c_str(), data_class);
    } else {
        USERLCM_LOG("Received messgae on channel \"%s\" and it is not channal \"%s\"\n", channel.c_str(), m_MsgInfo.channel);
    }
}
void cLcmMsgManage::Set_Msg_Info(Receive_msg_t *msg)
{
    if (msg != NULL) {
        m_MsgInfo = *msg;
    }
}

void *register_lcm_message(void *data)
{
    if (NULL == data) {
        USERLCM_LOG("f or channel is  NULL,return!\n");
        return NULL;
    }
    cLcmMsgManage *pMsgManage = new (std::nothrow)cLcmMsgManage;
    if (NULL == pMsgManage) {
        USERLCM_LOG("pMsgManage is  NULL,return!\n");
        return NULL;
    }

    // init lcm
    lcm::LCM lcm;
    if (!lcm.good()) {
        USERLCM_LOG("lcm is not good,return!\n");
        return NULL;
    }
    // store user's info
    Receive_msg_t *ptMsgInfo = (Receive_msg_t *)data;
    pMsgManage->Set_Msg_Info(ptMsgInfo);

    char channel[64] = {0};
    memcpy(channel, ptMsgInfo->channel, 64);
    USERLCM_LOG("lcm 's channel= %s\n", channel);

    lcm.subscribe(channel, &cLcmMsgManage::handleMessage, pMsgManage);

    // It seems we are safe to delete this object because it is no longer needed
    // outside.
    //ptMsgInfo receives address from "calloc",so we use "free"
    if(NULL != ptMsgInfo){
        free(ptMsgInfo);
        ptMsgInfo = NULL;
    }

    while (0 == lcm.handle());

    if (NULL != pMsgManage){
        delete pMsgManage;
        pMsgManage = NULL;
    }

    return NULL;

}

// Send Messages to LCM
int send_msg_to_lcm(userlcm_packet_t *buf, uint32_t buflen, const char *channel)
{
    if (NULL == buf || NULL == channel) {
        USERLCM_LOG("buf or channel is NULL,return!\n");
        return 0;
    }
    lcm::LCM lcm;
    if (!lcm.good()) {
        USERLCM_LOG("lcm is not good,return!\n");
        return 0;
    }
    buflen += (uint32_t)offsetof(userlcm_packet_t, msg_buf);
    int result = lcm.publish(channel, (void *)buf, buflen);
    if (0 == result) {
        return 1;
    } else {
        return 0;
    }
}

头文件:userlcm_manage.h

// file : userlcm_manage.h
// Don't include this file
#ifndef _USERLCM_MANAGE_H_
#define _USERLCM_MANAGE_H_

#include 
#include 
#include 
#include 
#include 
#include 
#include 

注册lcm回调:

static void  listen_lcm_msg_init()
{
	Receive_msg_t *pudp_lcm_recv_msg = (Receive_msg_t *)calloc(1, sizeof(Receive_msg_t));
	if (!pudp_lcm_recv_msg)
	{
		UDP_INFO("[%s]:pudp_lcm_recv_msg is null!\n", __FUNCTION__);
		return;
	}
	strncpy(pudp_lcm_recv_msg->channel, LCM_CHANNEL_TO_TEST, strlen(LCM_CHANNEL_TO_TEST));
	pudp_lcm_recv_msg->f = listen_lcm_msg;

	pthread_t listen_lcm_msg_thread;
	pthread_create(&listen_lcm_msg_thread, NULL, ®ister_lcm_message, (void *)pudp_lcm_recv_msg);
	pthread_setname_np(listen_lcm_msg_thread, "listen_lcm_msg");  //set thread name
	pthread_detach(listen_lcm_msg_thread);    //auto recover thread resource
}

回调函数对应的实现:

static void listen_lcm_msg(void *rbuf, uint32_t buflen, char *LocalChannel, void *data)
{
	UNUSED(data);

	if (rbuf == NULL || LocalChannel == NULL)
	{
		return;
	}

	//check LocalChannel
	if (strcmp(LocalChannel, LCM_CHANNEL_TO_UDP))
	{
		UDP_INFO("[%s][%d]:The LocalChannel should be \"%s\" instead of \"%s\"!\n",
		         __FUNCTION__, __LINE__, LCM_CHANNEL_TO_UDP, LocalChannel);
		return;
	}

	//copy buf to userlcm_packet
	userlcm_packet_t userlcm_packet;
	memset(&userlcm_packet, 0, sizeof(userlcm_packet_t));
	memcpy(&userlcm_packet, (userlcm_packet_t *)rbuf, buflen);
	if (!strcmp(userlcm_packet.channel, LCM_CHANNEL_FROM_RTSP))
	{
		//handle_msg_from_rtsp(&userlcm_packet);
		具体实现
		return;
	}
	else
	{
		UDP_INFO("[%s]:The unsupported source channel is %s \n", __FUNCTION__, userlcm_packet.channel);
	}

	return;
}

其它进程通过调用库接口函数 send_msg_to_lcm ，设置参数通道值LCM_CHANNEL_FROM_RTSP(通道值可以随意定,只要进程之间协商好就行)， 注册的进程 回调函数listen_lcm_msg 就能收到此消息. 然后解析相应的buf ,就能获取对应的值,做相应的事情