The DevServer TCP-based data server

[Dkt01]

One possible issue I see is that you never seem to lock data during reads/writes. If you're managing (potentially) high-volume accesses of data, asynchronous reads and writes of un-locked data could lead to race conditions and/or data corruption. I haven't closely inspected your code, but it appears you are using threading for save_file_fs_async(). Consider the case where that data is being read during an asynchronous save. Implementing even a simple lock system would prevent undesired behavior.

Unrelated: some commenting of your code would go a long way. In its current state, your code makes it difficult to quickly understand what is going on. Consider commenting a description of what each function does and what its parameters are.

Good work so far!