Wait for group of tasks — rrq_task

Wait for a task, or set of tasks, to complete. If you have used rrq prior to version 0.8.0, you might expect this function to return the result, but we now return a logical value which indicates success or not. You can fetch the task result with rrq_task_result.

Usage

rrq_task_wait(
  task_id,
  timeout = NULL,
  time_poll = 1,
  progress = NULL,
  follow = NULL,
  controller = NULL
)

Arguments

task_id: A vector of task ids to poll for (can be one task or many)
timeout: Optional timeout, in seconds, after which an error will be thrown if the task has not completed. If not given, falls back on the controller's timeout_task_wait (see rrq_controller)
time_poll: Optional time with which to "poll" for completion. By default this will be 1 second; this is the time that each request for a completed task may block for (however, if the task is finished before this, the actual time waited for will be less). Increasing this will reduce the responsiveness of your R session to interrupting, but will cause slightly less network load. Values less than 1s are only supported with Redis server version 6.0.0 or greater (released September 2020).
progress: Optional logical indicating if a progress bar should be displayed. If NULL we fall back on the value of the global option rrq.progress, and if that is unset display a progress bar if in an interactive session.
follow: Optional logical, indicating if we should follow any redirects set up by doing rrq_task_retry. If not given, falls back on the value passed into the controller, the global option rrq.follow, and finally TRUE. Set to FALSE if you want to return information about the original task, even if it has been subsequently retried.
controller: The controller to use. If not given (or NULL) we'll use the controller registered with rrq_default_controller_set().

Value

A scalar logical value; TRUE if all tasks complete successfully and FALSE otherwise

Examples

obj <- rrq_controller("rrq:example")
t1 <- rrq_task_create_expr(Sys.sleep(1), controller = obj)
rrq_task_wait(t1, controller = obj)
#> [1] TRUE

# The return value of wait gives a summary of successfullness
# of the task
t2 <- rrq_task_create_expr(stop("Some error"), controller = obj)
rrq_task_wait(t2, controller = obj)
#> [1] FALSE

# If you wait on many tasks, the return value is effectively
# reduced with "all" (so the result is TRUE if all tasks were
# successful)
rrq_task_wait(c(t1, t2), controller = obj)
#> [1] FALSE