mqtt的c库怎么定时发布消息,不影响主进程其他代码执行
时间: 2024-03-05 20:48:09 浏览: 18
要实现定时发布MQTT消息,而不影响主进程执行其他代码,您可以使用多线程。一种方法是使用一个线程来处理定时任务,另一个线程来处理主进程。您需要在定时任务线程中实现代码以定期发布MQTT消息,同时确保主线程可以独立运行。
以下是一个示例代码,使用多线程实现了定时发布MQTT消息,同时不影响主进程执行其他代码:
```c
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <pthread.h>
#include <unistd.h>
#include "MQTTClient.h"
#define ADDRESS "tcp://localhost:1883"
#define CLIENTID "ExampleClientPub"
#define TOPIC "test"
#define QOS 1
#define TIMEOUT 10000L
volatile MQTTClient_deliveryToken deliveredtoken;
MQTTClient client;
void delivered(void *context, MQTTClient_deliveryToken dt) {
printf("Message with token value %d delivery confirmed\n", dt);
deliveredtoken = dt;
}
int msgarrvd(void *context, char *topicName, int topicLen, MQTTClient_message *message) {
printf("Message arrived\n");
printf(" topic: %s\n", topicName);
printf(" message: %.*s\n", message->payloadlen, (char *)message->payload);
MQTTClient_freeMessage(&message);
MQTTClient_free(topicName);
return 1;
}
void connlost(void *context, char *cause) {
printf("\nConnection lost\n");
printf(" cause: %s\n", cause);
}
void* publish_mqtt_message(void* arg) {
while (1) {
char payload[100];
sprintf(payload, "%d", rand() % 100);
MQTTClient_message pubmsg = MQTTClient_message_initializer;
pubmsg.payload = payload;
pubmsg.payloadlen = strlen(payload);
pubmsg.qos = QOS;
pubmsg.retained = 0;
deliveredtoken = 0;
MQTTClient_publishMessage(client, TOPIC, &pubmsg, &deliveredtoken);
printf("Waiting for publication of %s\n"
"on topic %s for client with ClientID: %s\n",
payload, TOPIC, CLIENTID);
MQTTClient_waitForCompletion(client, deliveredtoken, TIMEOUT);
printf("Message with delivery token %d delivered\n", deliveredtoken);
sleep(5); // 等待5秒后再次发布消息
}
return NULL;
}
int main(int argc, char* argv[]) {
pthread_t thread;
MQTTClient_connectOptions conn_opts = MQTTClient_connectOptions_initializer;
int rc;
MQTTClient_create(&client, ADDRESS, CLIENTID, MQTTCLIENT_PERSISTENCE_NONE, NULL);
conn_opts.keepAliveInterval = 20;
conn_opts.cleansession = 1;
if ((rc = MQTTClient_connect(client, &conn_opts)) != MQTTCLIENT_SUCCESS) {
printf("Failed to connect, return code %d\n", rc);
exit(EXIT_FAILURE);
}
// 创建线程,用于定时发布MQTT消息
if (pthread_create(&thread, NULL, publish_mqtt_message, NULL) != 0) {
printf("Failed to create thread\n");
exit(EXIT_FAILURE);
}
// 主线程可以执行其他代码
while (1) {
printf("Main thread is running\n");
sleep(1);
}
pthread_join(thread, NULL);
MQTTClient_disconnect(client, 10000);
MQTTClient_destroy(&client);
return rc;
}
```
在上面的示例代码中,我们使用了多线程来实现定时发布MQTT消息,同时不影响主线程执行其他代码。在`publish_mqtt_message`函数中,我们实现了代码以定期发布MQTT消息,并使用`sleep(5)`来等待5秒后再次发布。主线程可以执行其他代码,同时定时任务线程会在后台执行。
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