Async Io / Tokio Support

[DrSloth]

Hi,
I am currently working on an async IoT web app and use this crate. I often have changes in templates / user defined templates
and often have to reload them. Currently, all io, such as reading and writing to disk, can only be implemented blocking from what I have seen.
Is async IO / support for Tokio planned, would you accept a PR for simple async IO if it is behind a feature flag?
Or is there a way to implement async rendering / writing that I am missing?

Thanks in advance and keep up the good work!

[sunng87]

Yes, a PR for async is welcomed. Please create it against our latest master branch because 4.0 has a new concept called TemplateSource. Let me know if you need help with the PR.

[DrSloth]

Sorry for the late answer. I am going to work on this as soon as i have time. I am going to comment here again if any questions arise.

[DrSloth]

Hello. I am sorry i forgot about this for some while and revisited it last weekend.
I couldn't find a way where async is really benficial here, as far as i can see the compiler is not really made for "streaming" parsing and compiling. Compiling a template is obviously cpu bound and for some benefit the compiler would need to handle "steams" of data rather than directly parsing a string.
The read can be made async by directly using the functions which parse from string and using something like tokio::fs::read_to_string. Maybe i am missing something but i don't know how this could be generically added while also yielding real benefit without rewriting large parts of the parser/compiler logic.

Maybe someone else has an idea where async is beneficial and they, me or we can take a look at it again.

[Diegovsky]

You would have to rewrite the parser to work with streams. Maybe using a buffer so it can go back a few bytes or forwards while parsing. I unfortunately don't have much time (and expertise) otherwise I would open a PR :(