plumber2 (version 0.2.0)

register_async: Register an async evaluator

Description

plumber supports async request handling in two ways. Either manual by returning a promise from the handler, or automatic through the @async tag / async argument in the handler functions. The default evaluator is controlled by the plumber2.async option or the PLUMBER2_ASYNC environment variable.

Usage

register_async(name, fun, dependency = NULL)
show_registered_async()
get_async(name = NULL, ...)

Arguments

name

The name of the evaluator

fun

A function that, upon calling it returns an evaluator taking an expr and envir argument. See the async evaluator functions for examples

dependency

Package dependencies for the evaluator.

...

Arguments passed on to the async function creator

Examples

# Register an async evaluator based on future (the provided mirai backend is
# superior in every way so this is for illustrative purpose)
future_async <- function(...) {
  function(expr, envir) {
    promises::future_promise(
      expr = expr,
      envir = envir,
      substitute = FALSE,
      ...
    )
  }
}
register_async("future", future_async, c("promises", "future"))