Any reason posthog_rs::client is async?

[danechitoaie]

Any reason this is async? https://github.com/PostHog/posthog-rs/blob/main/src/client/async_client.rs#L16

[oliverb123]

Hey @danechitoaie,
The SDK actually supports both blocking and async usage, it's just async by default - we actually use it in blocking mode internally in our own CLI. We support both modes because we use both modes - async projects want an async SDK, blocking ones want a blocking one.

[danechitoaie]

Yes, but the client function doesn't need to be async no? Only the capture and capture_batch should be async.
My usecase was that that I was creating the posthog_rs client in my main function (that is not async) and then I was starting the async "part" and passing the client instance to be used. So since posthog_rs::client() needs the be awaited I can't create it outside the async scope while the posthog_rs::client() doesn't do any awaiting in it so it shouldn't need to be async.

At least that's my understanding.

[oliverb123]

Ah, sorry, I understand the question now - the client constructor is deliberately async to prevent needing a breaking change in the future. We have a lot of server-side SDK functionality, for things like our feature flags offering, that require some network requests to be made during client initialisation. If/when we add them to this SDK, we'd need to then make that async, which would require a major version bump.

For your use, you could pass the future the posthog_rs::client call returns in to the async function and then await and use it there? I know it's not pretty but it might do the job for you.

Something like:

fn my_main() {
    let client_fut = client("");
    let res = tokio::runtime::Handle::current().block_on(my_async_fn(client_fut));
}

async fn my_async_fn(client_fut: impl Future<Output = Client>) -> usize {
    let client = client_fut.await;
    // Do some work here
    0
}

[rafaeelaudibert]

I know the original question wasn't about the sync/async difference, but here's a PR to document that behaviour anyway: PostHog/posthog.com#13264

[danechitoaie]

I'm using Pingora and only the functions that execute every request are async, so not sure how to do that. Calling await for the client on each request might not be ok, and I'm not aware yet of another way. Pingora constructor is also not async, only the on_... handlers are.

For now I just ended up using reqwests crate directly to send the analytics events (since creating the reqwests client is not async only sending the requests is) but looking for another way todo the required async stuff outside of of the constructor might be something you should consider as there might be more cases like mine in the future.