ask_Y {templr}

ask&tell component function to 'ask' objective function evaluation.

Description

ask&tell component function to 'ask' objective function evaluation.

Usage

ask_Y(
  x,
  id = 0,
  X.tmp = "X.todo",
  Y.tmp = "Y.done",
  tmp_path = file.path(tempdir(), "..", "asktell.tmp"),
  sleep_step = 0.1,
  sleep_init = 0,
  timeout = 360000,
  trace = function(...) cat(paste0(..., "\n")),
  clean = TRUE,
  force_cleanup = FALSE
)

Arguments

x

input values of objective function to compute

id

unique identifier for this asktell loop (default: "0")

X.tmp

temporary "X" values file (default: "X.todo")

Y.tmp

temporary "Y" values file (default: "Y.done")

tmp_path

temporary directory to store X.tmp & Y.tmp (default: 'tempdir()/../asktell.tmp')

sleep_step

delay between checking X.tmp and Y.tmp (default: 0.1 sec.)

sleep_init

initial delay before checking X.tmp and Y.tmp (default: 0 sec.)

timeout

maximum delay before breaking loop if X.tmp or Y.tmp doesn't appear (default: 36000 sec. = 10 min.) .

trace

function to display asktell loop status (default : 'cat')

clean

should we cleanup temporary files after reading ? (default: TRUE)

force_cleanup

should we cleanup temporary files before writing (possible conflicting asktell calls) ? (default: FALSE)

Details

'ask&tell' injection loop to call an external objective function within an inline algorithm (like optim(...)) Main idea: pass 'ask_Y' as objectve function argument of algorithm, which will wait until you call 'tell_Y' in another R process. In this secondary process, you can read what X is called using 'ask_X', and when you know what values returns from the external objective, just call 'tell_Y' to give it.

Value

output value of objective function, as given by tell_Y() call in parallel session

Author(s)

Y. Richet, discussions with D. Sinoquet. Async IO principle was defined by G. Pujol.

Examples

## Not run:  ### Assumes you can use two independent R sessions
## In main R session
  ask_Y(x=123)
## In another R session
  ask_X() # returns 123
  tell_Y(y=456)
## Then ask_Y in main R session returns with value '456'

## End(Not run)