Statistics about a delta and the search that produced it.

• literal_bytes, literal_commands - data carried in the delta itself.
• copy_bytes, copy_commands - data taken from the basis.
• weak_hits - windows whose weak checksum appeared in the signature; each costs one strong hash.
• false_weak_hits - weak hits whose strong hash matched no block.

literal_bytes + copy_bytes is the size of the rebuilt data. The search counters are nil when the statistics are computed from a delta alone (Rexd.Delta.stats/1), since the search is not known then.

A high false_weak_hits relative to the input size points to data crafted against the signature (see the notes on untrusted input) or to a very short strong_sum_len being unnecessary: false hits cost time, not correctness.