collect_mirai: mirai (Collect Value)

In mirai: Minimalist Async Evaluation Framework for R

mirai (Collect Value)

Description

Waits for the 'mirai' to resolve if still in progress, and returns its value directly. It is a more efficient version of and equivalent to call_mirai(x)$data.

Usage

collect_mirai(x, options = NULL)

Arguments

x	a 'mirai' object, or list of 'mirai' objects.
options	(if x is a list of mirai) a character vector comprising any combination of collection options for mirai_map(), such as ".flat" or c(".progress", ".stop").

Details

This function will wait for the asynchronous operation(s) to complete if still in progress, blocking but interruptible.

x[] is an equivalent way to wait for and return the value of a mirai x.

Value

An object (the return value of the 'mirai'), or a list of such objects (the same length as x, preserving names).

Options

As an alternative to a character vector, a list where the names are the collection options is also accepted. The value for .progress is passed to the cli progress bar - if a character value as the name, and if a list as named parameters to cli::cli_progress_bar. Examples: c(.stop = TRUE, .progress = "bar name") or c(.stop = TRUE, .progress = list(name = "bar", type = "tasks"))

Alternatively

The value of a 'mirai' may be accessed at any time at ⁠$data⁠, and if yet to resolve, an 'unresolved' logical NA will be returned instead.

Using unresolved() on a 'mirai' returns TRUE only if it has yet to resolve and FALSE otherwise. This is suitable for use in control flow statements such as while or if.

Errors

If an error occurs in evaluation, the error message is returned as a character string of class 'miraiError' and 'errorValue'. is_mirai_error() may be used to test for this. The elements of the original condition are accessible via $ on the error object. A stack trace comprising a list of calls is also available at ⁠$stack.trace⁠, and the original condition classes at ⁠$condition.class⁠.

If a daemon crashes or terminates unexpectedly during evaluation, an 'errorValue' 19 (Connection reset) is returned.

is_error_value() tests for all error conditions including 'mirai' errors, interrupts, and timeouts.

Examples

# using collect_mirai()
df1 <- data.frame(a = 1, b = 2)
df2 <- data.frame(a = 3, b = 1)
m <- mirai(as.matrix(rbind(df1, df2)), df1 = df1, df2 = df2, .timeout = 1000)
collect_mirai(m)

# using x[]
m[]

# mirai_map with collection options
daemons(1, dispatcher = FALSE)
m <- mirai_map(1:3, rnorm)
collect_mirai(m, c(".flat", ".progress"))
daemons(0)

mirai documentation built on Sept. 9, 2025, 5:51 p.m.