collect_mirai waits for the ‘mirai’ to resolve if still in
progress, and returns its value directly. It is a more efifcient version
of and equivalent to call_mirai(x)$data.
Value
An object (the return value of the ‘mirai’), or a list of such objects (the same length as ‘x’, preserving names).
Details
This function will wait for the asynchronous operation(s) to complete if still in progress (blocking), and is not interruptible.
x[] may be used to wait for and return the value of a mirai
x, and is the user-interruptible counterpart to
collect_mirai(x).
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’
(the stack trace is available at $stack.trace on the error
object). is_mirai_error may be used to test for this.
If a daemon crashes or terminates unexpectedly during evaluation, an
‘errorValue’ 19 (Connection reset) is returned (when not using
dispatcher or using dispatcher with retry = FALSE). Otherwise,
using dispatcher with retry = TRUE, the mirai will remain
unresolved and is automatically re-tried on the next daemon to connect to
the particular instance. To cancel the task instead, use
saisei(force = TRUE) (see saisei).
is_error_value tests for all error conditions including
‘mirai’ errors, interrupts, and timeouts.
Examples
if (interactive()) {
# Only run examples in interactive R sessions
# 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[]
}