rrq_task_create_expr: Create a task based on an expression

In mrc-ide/rrq: Simple Redis Queue

Create a task based on an expression

Description

Create a task based on an expression. The expression passed as expr will typically be a function call (e.g., f(x)). We will analyse the expression and find all variables that you reference (in the case of f(x) this is x) and combine this with the function name to run on the worker. If x cannot be found in your calling environment we will error.

Usage

rrq_task_create_expr(
  expr,
  queue = NULL,
  separate_process = FALSE,
  timeout_task_run = NULL,
  depends_on = NULL,
  controller = NULL
)

Arguments

expr	The expression, does not need quoting. See Details.
queue	The queue to add the task to; if not specified the "default" queue (which all workers listen to) will be used. If you have configured workers to listen to more than one queue you can specify that here. Be warned that if you push jobs onto a queue with no worker, it will queue forever.
separate_process	Logical, indicating if the task should be run in a separate process on the worker. If TRUE, then the worker runs the task in a separate process using the callr package. This means that the worker environment is completely clean, subsequent runs are not affected by preceding ones. The downside of this approach is a considerable overhead in starting the external process and transferring data back.
timeout_task_run	Optionally, a maximum allowed running time, in seconds. This parameter only has an effect if separate_process is TRUE. If given, then if the task takes longer than this time it will be stopped and the task status set to TIMEOUT.
depends_on	Vector or list of IDs of tasks which must have completed before this job can be run. Once all dependent tasks have been successfully run, this task will get added to the queue. If the dependent task fails then this task will be removed from the queue.
controller	The controller to use. If not given (or NULL) we'll use the controller registered with rrq_default_controller_set().

Details

Alternatively you may provide a multiline statement by using {} to surround multiple lines, such as:

task_create_expr({
  x <- runif(1)
  f(x)
}, ...)

in this case, we apply a simple heuristic to work out that x is locally assigned and should not be saved with the expression.

mrc-ide/rrq documentation built on April 25, 2024, 11:59 p.m.