如何将this指针传递给类内的任务?

Question

我正在创建一个库来管理许多ESP32设备上的wifi网络连接。

在我的库中，我有一个任务，它正在循环1秒暂停，在我的.begin()函数中开始使用xTaskCreate。问题是，我不能启动任务，如果我没有使它在我的。h文件静态。因此，一旦任务被声明为静态，我就不能访问this->此任务中的指针。我可以把这个寄过去吗?>指针在我的任务中，比如在参数中或者类似的地方?

下面是一些代码:

class EraWiFi{
public:
EraWiFi();
/*!
* @brief Initialize WiFi
* @return Returns true if successful
*/
bool begin(fs::FS &fs);
/*!
* @brief Start EraWiFi service
* @return Returns true if successful
*/
void downloadWiFi();
private:
static void wifiTask(void * parameter);
};

bool EraWiFi::begin(fs::FS &fs){
File file = fs.open("/WiFi.json", FILE_READ);
if(file){
DynamicJsonDocument wifi(2048);
DeserializationError error = deserializeJson(wifi, file);
file.close();
if (!error){
Serial.println("We have a VALID WiFi.json configurations file!");
Serial.println("Adding wifi networks:");
for (JsonArray arr : wifi.as<JsonArray>()){
Serial.print("SSID: ");
Serial.print(arr[0].as<char*>());
Serial.print(", KEY: ");
Serial.println(arr[1].as<char*>());
wifiMulti.addAP(arr[0].as<char*>(), arr[1].as<char*>());
}
}else{
Serial.println("We don't have a VALID WiFi.json configurations file!");
}
}else{
Serial.println("There is no WiFi.json configurations file!");
}
wifiMulti.addAP("Testing", "1234");
xTaskCreate(
this->wifiTask,    // Function that should be called
"WiFiTask",   // Name of the task (for debugging)
10000,            // Stack size (bytes)
(void*)&this,            // Parameter to pass
1,               // Task priority
NULL   // Task handle
);
return true;
}

void EraWiFi::downloadWiFi(){
Serial.println("Downloading WiFi.json from ErabliTEK Server.");
HTTPClient http;
// Send request
http.useHTTP10(true);
String url = "https://testing.testing.com/wifis/getWiFi/";
http.begin(url);
int httpResponseCode =  http.GET();
if(httpResponseCode == HTTP_CODE_OK){
// Parse response
DynamicJsonDocument doc(2048);
DeserializationError error = deserializeJson(doc, http.getStream());
// Disconnect
http.end();
if (!error){
File file = fs.open("/WiFi.json", FILE_WRITE);
if(file){
// Serialize JSON to file
if (serializeJson(doc, file) == 0) {
Serial.println("Error saving WiFi.json!");
Serial.println(http.getString());
}else{
Serial.println("Succesfully saved WiFi.json!");
}
}
// Close the file
file.close();
}else{
Serial.println("Error downloading WiFi.json");
}
}else{
Serial.println("Problem connecting to " + url + " with http code: " + String(httpResponseCode));
}
}

void EraWiFi::wifiTask(void * parameters){
bool wifiConnected = false;
for(;;){
uint8_t wifiStatus = wifiMulti.run();
if((wifiStatus != WL_CONNECTED) and wifiConnected) {
wifiConnected = false;
Serial.println("WiFi not connected!");
}else if((wifiStatus == WL_CONNECTED) and !wifiConnected){
wifiConnected = true;
Serial.println("WiFi Connected.");
Serial.print("SSID: ");
Serial.println(WiFi.SSID());
Serial.print("KEY: ");
Serial.println(WiFi.psk());
Serial.print("IP Address: ");
Serial.println(WiFi.localIP());
EraWiFi::downloadWiFi();
}
vTaskDelay(1000 / portTICK_PERIOD_MS);
}
}

Answer 1

你已经这么做了，只是你没有意识到。看看FreeRTOS关于xTaskCreate()的文档，它解释了第四个参数pvParameters是一个空指针，它被传递给新任务作为它的(唯一的)输入参数。

这里的注释行意味着您正在获取EraWiFi对象的地址并将其传递给任务:

xTaskCreate(
this->wifiTask,
"WiFiTask",
10000,
(void*)&this,  //< Pointer gets forwarded to the task
1,
NULL
);

要在任务中使用指针，只需要从void*中强制转换它:

void EraWiFi::wifiTask(void * parameters){
EraWifi* p = static_cast<EraWifi*>(parameters); //< That's the same pointer
p->someMethod();
...

p。还要注意(在你从不同的线程戳同一个对象之前，可能会导致难以发现的bug)， FreeRTOS提供了优秀的线程间通信设施——队列和任务通知通常是最有用的。查看他们的教程/书以获得解释。