Prefix every log line with the time elapsed since the render started

`verbose = TRUE` reports how long each page took, but not when anything happened, so a phase that takes a minute between two summary lines is invisible unless the whole process is piped through a stamping filter. The handler below does that inside R: each message - which is how cli writes its output - is re-emitted with an elapsed-seconds prefix.

Usage

with_elapsed_log(expr, enabled = TRUE, start = Sys.time())

Arguments

expr

The expression to evaluate (lazily, inside the handler)

enabled

Whether to stamp at all; FALSE evaluates `expr` unchanged

start

Time the elapsed seconds are counted from

Value

The value of `expr`

Details

Forked workers inherit the calling handlers of the process they were forked from, so pages rendered in parallel are stamped as well.