Function measure_memory_with 

pub fn measure_memory_with(
    runner: &mut dyn Runner,
    codec: &'static str,
    level: Option<i32>,
    plan: &Plan,
    input_files: &[Snapshot],
) -> Memory

One row’s memory under plan: a compress child and a decompress child per stream (plan.mode: one stream over every file, or one per file), reporting each side’s largest peak. Per stream the parent creates an armed temp file, the compress child writes the compressed stream into it, and the decompress child reads it back; it is removed before the next stream begins. Strictly after the row’s timed runs.

A side whose child fails for any stream is None, and the first failure’s text, prefixed by its side, is error. A failed decompress child leaves the compress side standing; a failed compress child (or a temp file that cannot be made) leaves no copy, so both sides are None. Never an error of its own.