[Feature Request] return mirai objects from everywhere()

[dgkf]

I've finally landed on a good project for experimenting with mirai and I've been super impressed.

All was going well until I started getting errors in some code I was calling with everywhere(). Not any issue with mirai directly - it turns out a web request I needed to make from each node was starting to error due to some server downtime. To debug the issues in everywhere(), I had to re-write it as single mirai() call to inspect the result.

It would be helpful if everywhere() returned a list of mirai objects similar to mirai_map. This would allow me to build some checks into my scripts for situations where successful execution relies on external factors.

daemons(2)
ms <- everywhere({ 
  do_flaky_web_request()
  "success"
})

ms[]
ms[[1]]$data
#> [1] "success"

ms[[2]]$data
#> 'miraiError' chr Error in do_flaky_web_request: server timeout

[dgkf]

For the time being, I did something really hacky to return the vector of mirai connections already stored in everywhere():

https://github.com/shikokuchuo/mirai/blob/92afc179be94781973e1a709cf24b0694c1018b6/R/mirai.R#L268

-   invisible()
+   invisible(vec)

# modify `everywhere()` to return `vec`
everywhere <- mirai::everywhere
body(everywhere) <- bquote({ .(body(everywhere)); invisible(vec) })

ms <- mirai::collect_mirai(everywhere({
  do_flaky_web_request()
  "success"
}))

if (any(is_error <- vapply(ms, mirai::is_mirai_error, logical(1L)))) {
  stop("issues encountered during daemon setup")
}

This let me terminate early when anything goes wrong. In practice, I can also expose things like individual node error messages and stack traces stored in the mirai error objects.

Although modifying a function body is a last resort, I was impressed by how simple the change was.

[shikokuchuo]

Thanks Doug. I'm persuaded of the benefits of your request.

Leave this with me - it may take some time as I might be updating the underlying implementation (currently comprised of mirai calls) - and I don't want to be changing the API too often.

[shikokuchuo]

This has been incorporated now in mirai 1.3.1.9022 (what will be mirai v2). everywhere() now returns a list of mirai.