The Job object encapsulates an expression and its evaluation parameters. It also provides a way to check for and retrieve the result.
exprR expression that will be run by this Job.
varsGet or set - List of variables that will be placed into the expression's environment before evaluation.
reformatGet or set - function (job) for defining <Job>$result.
signalGet or set - Conditions to signal.
cpusGet or set - Number of CPUs to reserve for evaluating expr.
timeoutGet or set - Time limits to apply to this Job.
proxyGet or set - Job to proxy in place of running expr.
stateGet or set - The Job's state: 'created', 'submitted', 'queued',
'dispatched', 'starting', 'running', or 'done'.
Assigning to <Job>$state will trigger callback hooks.
outputGet or set - Job's raw output.
Assigning to <Job>$output will change the Job's state to 'done'.
resultResult of expr. Will block until Job is finished.
hooksCurrently registered callback hooks as a named list of functions.
Set new hooks with <Job>$on().
is_doneTRUE or FALSE depending on if the Job's result is ready.
uidA short string, e.g. 'J16', that uniquely identifies this Job.
new()Creates a Job object defining how to run an expression on a background worker process.
Typically you won't need to call Job$new(). Instead, create a Queue and use
<Queue>$run() to generate Job objects.
Job$new(
expr,
vars = NULL,
timeout = NULL,
hooks = NULL,
reformat = NULL,
signal = FALSE,
cpus = 1L,
...
)exprA call or R expression wrapped in curly braces to evaluate on a
worker. Will have access to any variables defined by vars, as well
as the Worker's globals, packages, and init configuration.
See vignette('eval').
varsA named list of variables to make available to expr during
evaluation. Alternatively, an object that can be coerced to a named
list with as.list(), e.g. named vector, data.frame, or environment.
Or a function (job) that returns such an object.
timeoutA named numeric vector indicating the maximum number of
seconds allowed for each state the job passes through, or 'total' to
apply a single timeout from 'submitted' to 'done'. Or a
function (job) that returns the same. Example:
timeout = c(total = 2.5, running = 1). See vignette('stops').
hooksA named list of functions to run when the Job state changes,
of the form hooks = list(created = function (worker) {...}). Or a
function (job) that returns the same. Names of worker hooks are
typically 'created', 'submitted', 'queued', 'dispatched',
'starting', 'running', 'done', or '*' (duplicates okay).
See vignette('hooks').
reformatSet reformat = function (job) to define what
<Job>$result should return. The default, reformat = NULL passes
<Job>$output to <Job>$result unchanged.
See vignette('results').
signalShould calling <Job>$result signal on condition objects?
When FALSE, <Job>$result will return the object without
taking additional action. Setting to TRUE or a character vector of
condition classes, e.g. c('interrupt', 'error', 'warning'), will
cause the equivalent of stop(<condition>) to be called when those
conditions are produced. Alternatively, a function (job) that
returns TRUE or FALSE. See vignette('results').
cpusHow many CPU cores to reserve for this Job. Or a
function (job) that returns the same. Used to limit the number of
Jobs running simultaneously to respect <Queue>$max_cpus. Does not
prevent a Job from using more CPUs than reserved.
...Arbitrary named values to add to the returned Job object.
A Job object.
...Arguments are not used currently.
This Job, invisibly.
on()Attach a callback function to execute when the Job enters state.
Job$on(state, func)stateThe name of a Job state. Typically one of:
'*' - Every time the state changes.
'.next' - Only one time, the next time the state changes.
'created' - After Job$new() initialization.
'submitted' - After <Job>$queue is assigned.
'queued' - After stop_id and copy_id are resolved.
'dispatched' - After <Job>$worker is assigned.
'starting' - Before evaluation begins.
'running' - After evaluation begins.
'done' - After <Job>$output is assigned.
Custom states can also be specified.
funcA function that accepts a Job object as input. You can call
<Job>$stop() or edit <Job>$ values and the changes will be
persisted (since Jobs are reference class objects). You can also
edit/stop other queued jobs by modifying the Jobs in
<Job>$queue$jobs. Return value is ignored.
A function that when called removes this callback from the Job.
wait()Blocks until the Job enters the given state.
Job$wait(state = "done", timeout = NULL)stateThe name of a Job state. Typically one of:
'*' - Every time the state changes.
'.next' - Only one time, the next time the state changes.
'created' - After Job$new() initialization.
'submitted' - After <Job>$queue is assigned.
'queued' - After stop_id and copy_id are resolved.
'dispatched' - After <Job>$worker is assigned.
'starting' - Before evaluation begins.
'running' - After evaluation begins.
'done' - After <Job>$output is assigned.
Custom states can also be specified.
timeoutStop the Job if it takes longer than this number of seconds, or NULL.
This Job, invisibly.
stop()Stop this Job. If the Job is running, its Worker will be restarted.
Job$stop(reason = "job stopped by user", cls = NULL)reasonA message to include in the 'interrupt' condition object that will be returned as the Job's result. Or a condition object.
clsCharacter vector of additional classes to prepend to
c('interrupt', 'condition').
This Job, invisibly.