Recipe for non clobbering atomic persist?

[Ravencentric]

NamedTempFile has two methods for persisting, persist() and persist_noclobber(). The former is atomic while the latter is not as stated by the documentation.

Now I'm no expert here, which is why I'm grateful for this crate so thank you for your work, but I was wondering how would I go about achieving non clobbering atomic persist? A naive implementation would look like the following pseudocode:

if !overwrite && path.exists() { /* error */ };
tempfile.persist()

But I'm guessing that the above is susceptible to race conditions.

If the answer is that persist_noclobber is already the best that's possible, then that's okay too. Feel free to close this issue in that case.

[Stebalien]

It's "atomic" on modern Linux (assuming a modern filesystem, etc.) and on Windows, but not on macos or the various BSDs (or anything else).

By "not atomic", I mean that the old name for the temporary file might persist in the filesystem (the rename isn't atomic). Any files at the target path will never be overwritten.

Does #334 help clarify this?

[Ravencentric]

Yep! That clarifies it. Thank you.