Register an async evaluator — register

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

if (FALSE) {
# 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"))
}