Check whether a future is resolved or not

Check whether a future is resolved or not

Usage

# S3 method for class 'ClusterFuture'
resolved(x, run = TRUE, timeout = NULL, ...)

# S3 method for class 'MulticoreFuture'
resolved(x, run = TRUE, timeout = NULL, ...)

# S3 method for class 'Future'
resolved(x, run = TRUE, ...)

resolved(x, ...)

# Default S3 method
resolved(x, ...)

# S3 method for class 'list'
resolved(x, ...)

# S3 method for class 'environment'
resolved(x, ...)

Arguments

x

A Future, a list, or an environment (which also includes list environment).

run

(logical) If TRUE, any lazy futures is launched, otherwise not.

timeout

(numeric) The maximum time (in seconds) for polling the worker for a response. If no response is available within this time limit, FALSE is returned assuming the future is still being processed. If NULL, the value defaults to getOption("future.<type>.resolved.timeout"), then getOption("future.resolved.timeout"), and finally 0.01 (seconds), where <type> corresponds to the type of future, e.g. cluster and multicore.

...

Not used.

Value

A logical vector of the same length and dimensions as x. Each element is TRUE unless the corresponding element is a non-resolved future in case it is FALSE.

The default method always returns TRUE.

Details

resolved() attempts to launch a lazy future, if possible and unless run = FALSE.

resolved() methods must always return TRUE or FALSE values, must always launch lazy futures by default (run = TRUE), and must never block indefinitely. This is because it should always be possible to poll futures until they are resolved using resolved(), e.g. while (!all(resolved(futures))) Sys.sleep(5).

Each future backend must implement a resolved() method. It should return either TRUE or FALSE, or throw a FutureError (which indicate a significant, often unrecoverable infrastructure problem, or an interrupt).

Behavior of cluster and multisession futures

If all worker slots are occupied, resolved() for ClusterFuture and MultisessionFuture will attempt to free one up by checking whether one of the futures is resolved. If it is, then its result is collected in order to free up one worker slot.

resolved() for ClusterFuture may receive immediate condition objects, rather than a FutureResult, when polling the worker for results. In such cases, the condition object is collected and another poll it performed. Up to 100 immediate conditions may be collected this way per resolved() call, before considering the future non-resolved and FALSE being returned.

Behavior of multicore futures

resolved() for MulticoreFuture may receive immediate condition objects, rather than a FutureResult, when polling the worker for results. In such cases, all such condition objects are collected, before considering the future non-resolved and FALSE being returned.