SerialWeb cannot implementation readString()

[00kenno]

I'm using WebSocket.

else if (type == WS_EVT_DATA) { // データ受信時
  AwsFrameInfo *info = (AwsFrameInfo *)arg; // フレーム情報の取得
  // Serial.printf("index: %" PRIu64 ", len: %" PRIu64 ", final: %" PRIu8 ", opcode: %" PRIu8 "\n", info->index, info->len, info->final, info->opcode); // フレーム情報の表示
  if (info->final && info->index == 0 && info->len == len) { // 完全なメッセージが1フレームで届いた場合
    if (info->opcode == WS_TEXT) { // テキストメッセージの場合
      // Serial.printf("WS Raw: %s\n", data);
      handleString((const char *)data, len);
    }        
  }
}

If the string length exceeds a certain limit, the received data will no longer be able to be correctly stored in the string array.
PLEASE HELP ME.
https://github.com/00kenno/SerialWeb/

[mathieucarbou]

Which string array ? Please provide a MRE.

[00kenno]

Thank you for your clear and direct feedback.

I sincerely apologize for my previous incomplete report. This is my first time interacting with an OSS project, and I lacked a proper understanding of what an MRE is and how to ask for help appropriately. I really appreciate you taking the time to point this out to me.

I have stripped away all the irrelevant code (such as DNS, Captive Portal, and custom JSON handling) and created a proper MRE.

(Note: I changed the file extension from .ino to .txt in order to attach it here. Please rename it back to .ino if you want to open it in the Arduino IDE.)

Issue Summary:
When receiving a string of 13 characters or more via WebSocket, the received text becomes garbled.

I would be grateful if you could take a look at the attached file when you have the time. Thank you again for your time and for maintaining this great project.

SerialWeb_MRE.txt

[mathieucarbou]

and I lacked a proper understanding of what an MRE is and how to ask for help appropriately.

MRE == ino or cpp file that we can directly flash to a MCU for testing and that can demonstrate the issue in a reproductible and non random way.

[mathieucarbou]

SerialWeb_MRE.txt

your code is incorrect: the loop is executed fast so your flag isReading is switched on and off quite frequently. At the same time, the ws callback is calling handleString(), which is doing some replacement or not depending on isReading.
Also, when handleString has the chance to execute, your loop could read partially written arrays.

[mathieucarbou]

there are many many projects using ESPAsync and WebSocket on Github: do a github search or look for libraries using ESPAsyncWebserver. Also have a look at the exemples. The library is OK, otherwise we would have known already if some important bugs like that was present.

So before anything, ask yourself if your code could be the culprit instead of the library. This library is so widely used in Arduino / ESP32 echo-system that the chances of a bug is low and usually any bug are quickly found, reported and fixed.

[00kenno]

Thank you so much for taking the time to review my code and for the quick response.

You are completely right. I now clearly understand that the issue is caused by a race condition in my code, where loop() is reading the arrays while the WebSocket callback is only partially done writing to them.

I will rethink my approach and rewrite the buffer handling properly, perhaps by using FreeRTOS queues or mutexes, and I will definitely study other projects using ESPAsyncWebServer as you suggested.

I apologize for suspecting the library before thoroughly questioning my own code. This has been a huge learning experience for me, both in terms of ESP32 concurrency and OSS communication.

Thank you again for your patience and for pointing me in the right direction.