Collect logged events in memory

Registers a sink that keeps every event in a buffer instead of writing it anywhere, so a run's logging can be asserted on rather than eyeballed. Read the buffer back with logtree_sink_memory_events(). This is the answer to "did my pipeline log what it should have?" – previously that meant capturing console output and pattern-matching the rendered tree.

Usage

logtree_sink_memory(max = 1000, threshold = NULL)

Arguments

max

Maximum number of events to keep. Once the buffer is full the oldest events are dropped, so what you read back is always the most recent max. Default 1000.

threshold

Minimum leaf level to collect, as in logtree_sink(). NULL (the default) follows the global logtree_threshold(); pass "debug" to collect everything a run logged regardless of what the console was set to show.

Value

The sink's id, invisibly – pass it to logtree_sink_memory_events() to read the buffer, and to logtree_sink_remove() to stop collecting.

Details

The buffer is dropped when the sink is removed with logtree_sink_remove(), and it is capped: a long-running process cannot grow it without bound.

See also

logtree_sink_memory_events(), logtree_sink()

Examples

logtree_reset()
h <- logtree_sink_memory()

f <- function() {
  log_step("Load data")
  log_warn("coerced 3 rows")
}
invisible(f())
#> ▶ Load data
#> ├─ ⚠ coerced 3 rows
#> └─ ⚠ Done  0.01s

events <- logtree_sink_memory_events(h)
events[, c("level", "label", "status")]
#>   level          label  status
#> 1  open      Load data    step
#> 2  leaf coerced 3 rows warning
#> 3 close      Load data warning

logtree_sink_remove(h)