zit 0.3.40

zit 0.3.40 puts line counts in the crosslink stream. A forge can show "+15 −3" on every check-in and file without running zit diff --numstat once per check-in.

No artifact, tag namespace, wire, or on-disk repository format changed. The crosslink record format is still crosslink 1.

Line counts in the crosslink stream

Each file line in zit crosslink is now followed by a line giving what the file added and removed against the primary parent:

file M src/a.zig
lines 12 3
file A src/b.zig
lines 40 0
file M logo.png
lines - -

• The counts are the ones zit diff --numstat --checkin gives for the same path. Both commands now count with one function, so they cannot disagree.
• A binary file is - -.
• A file whose mode alone changed is 0 0. --numstat leaves such a file out, because its text did not change.
• An add counts every line as added; a delete counts every line as removed.
• When the store cannot produce a file's content on either side, because the content was shunned or never fetched into a sparse store, there is no lines line for that file. Its counts appear once the content arrives.
• files unknown records carry no lines lines.

A consumer that parses only the lines it knows is unaffected: the stream has always promised that a consumer skips a line it does not know.

What it costs

Counting reads both sides of every changed file, so it is kept away from everything else:

• The counts live in a cache file of their own, .zit-cache/lines, that only crosslink reads or writes. The cache every other command builds on its first open is unchanged, and so is the time it takes.
• The first crosslink over a long history counts every change once, and takes longer than it used to. Later runs read the stored counts and count only new check-ins. A first run that is cut short keeps what it counted and resumes from there.
• A check-in's counts never change once its name is known, so growth of the repository never invalidates them; a shun discards them, since it removes content they were read from.
• --no-cache counts everything afresh and stores nothing, so its output can still be compared byte for byte with the cached run.

Compatibility

• zit diff --numstat prints exactly what it printed before.
• Existing crosslink lines are unchanged in content and order; the lines lines are the only addition.

Qualification

zig fmt --check, zig build test, e2e, smoke (19 scenarios), git-import-e2e, git-export-e2e, dst, and every fuzz target, plus the three-runner battery.