FR: sort commits by template-aliases.commit_timestamp

[avamsi]

I tried the new commit_timestamp knob and I think I like author timestamp better -- but the log graph still uses committer timestamp to sort commits. It would be nice to somehow use commit_timestamp directly or at least provide another knob to sort by author timestamp.

I think @yuja's #2078 (that adds CommitByCommitterTimestamp) would be a good reference for a potential implementation.

[yuja]

Do you mean the order of graph nodes? It's basically creation order in non-linear part (with some tweaks to group nodes topologically.)

We could add an option to sort non-graph log, but implementation-wise, there would be no relation to templater.

[avamsi]

Yes, I mean the order of sibling graph nodes.

Consider this example:

$ jj new xo -m 1
$ jj new xo -m 2
$ jj new xo

These result in the following state:

@  p avamsi07 27 seconds ago e7b2447
│  (empty) (no description set)
│ ○  y avamsi07 32 seconds ago 05cc689
├─╯  (empty) 2
│ ○  xs avamsi07 45 seconds ago dd2786d
├─╯  (empty) 1
◆  xo avamsi07 1 week ago main git_head() 2a24fd2
│  initial commit
~

Now if we run jj desc xs -m 11:

@  p avamsi07 3 minutes ago e7b2447
│  (empty) (no description set)
│ ○  xs avamsi07 3 minutes ago fa5fec9
├─╯  (empty) 11
│ ○  y avamsi07 3 minutes ago 05cc689
├─╯  (empty) 2
◆  xo avamsi07 1 week ago main git_head() 2a24fd2
│  initial commit
~

xs and y are swapped, presumably because they're being sorted by committer timestamp -- I want to sort them by author timestamp instead. Does that make sense?

[yuja]

Ok, relevant code is here:

jj/cli/src/commands/log.rs

Lines 187 to 194 in 6c14ccd

	let mut forward_iter = TopoGroupedGraphIterator::new(revset.iter_graph());
	// Emit the working-copy branch first, which is usually most
	// interesting. This also helps stabilize output order.
	if let Some(id) = workspace_command.get_wc_commit_id() {
	let has_commit = revset.containing_fn();
	if has_commit(id)? {
	forward_iter.prioritize_branch(id.clone());
	}

I have no idea how to expose the feature, but we'll probably need to

• collect heads of the graph filtered by the current revset
• sort them by some criteria
• add them to the prioritized list

It is now displayed in order of appearance (or indexed order.)