TaskJob R6 Class

Run a cs9 task in a background R process with live output streaming back to the current R console via later::later() polling. Equivalent in spirit to run_task_sequentially_as_rstudio_job_using_load_all() but does not depend on RStudio's job API (which Positron does not implement).

Methods: $start() spawn background process and begin polling $wait(t) block this session, draining the event loop, until done $is_alive() TRUE while the background process is running $status() summary $tail(n) last n lines of the log file (snapshot, not live) $kill() terminate the background process

Public fields

task_name

Character string. Name of the task being run.

ss_prefix

Character string. R expression used to access the surveillance system in the child process.

script_path

Character string. Path to the temporary R script that is sourced in the background process.

log_path

Character string. Path to the log file where background process output is written.

started_at

POSIXct. Time at which $start() was called.

finished_at

POSIXct. Time at which the background process exited.

Methods

Public methods

• TaskJob$new()

• TaskJob$start()

• TaskJob$is_alive()

• TaskJob$status()

• TaskJob$wait()

• TaskJob$kill()

• TaskJob$tail()

• TaskJob$clone()

---

TaskJob$new()

Create a new TaskJob.

Usage

TaskJob$new(
  task_name,
  ss_prefix = "global$ss",
  log_dir = tempdir(check = TRUE)
)

Arguments

task_name

Character string. Name of the task to run, as registered in the surveillance system (e.g. ss$tasks[["my_task"]]).

ss_prefix

Character string. R expression that evaluates to the surveillance system object in the child process. Defaults to "global$ss".

log_dir

Character string. Directory where the temporary script and log file are written. Defaults to tempdir().

Returns

A new TaskJob object. Call $start() to launch the background process.

---

TaskJob$start()

Spawn the background process and begin polling its output.

Usage

TaskJob$start()

Returns

Invisibly returns the TaskJob object.

---

TaskJob$is_alive()

Check whether the background process is still running.

Usage

TaskJob$is_alive()

Returns

Logical. TRUE while the background process is alive.

---

TaskJob$status()

Print a brief status summary (task name, start time, alive status, log path).

Usage

TaskJob$status()

Returns

Invisibly returns the TaskJob object.

---

TaskJob$wait()

Block the current session until the background task finishes or the timeout expires, draining the later event loop while waiting.

Usage

TaskJob$wait(timeout_s = 600)

Arguments

timeout_s

Numeric. Maximum number of seconds to wait. Defaults to 600 (10 minutes).

Returns

Invisibly returns the TaskJob object.

---

TaskJob$kill()

Terminate the background process.

Usage

TaskJob$kill()

Returns

Invisibly returns the TaskJob object.

---

TaskJob$tail()

Print the last n lines of the task log file (snapshot, not live).

Usage

TaskJob$tail(n = 20)

Arguments

n

Integer. Number of trailing lines to show. Defaults to 20.

Returns

Invisibly returns the TaskJob object.

---

TaskJob$clone()

The objects of this class are cloneable with this method.

Usage

TaskJob$clone(deep = FALSE)

Arguments

deep

Whether to make a deep clone.

Examples

if (FALSE) { # \dontrun{
job <- TaskJob$new("my_task")
job$start()
job$status()
job$wait(timeout_s = 120)
job$tail(n = 30)
} # }