Mercurial: Most recent change per file - mercurial

Question

I'm looking for a way to make Mercurial output a table like this:
File Most recent revision changing the file Date of that revision
==== ====================================== =====================
foo.py 44159adb0312 2018-09-16 12:24
... ... ...
This is just like github does it on the "Code" overview page. (screenshot from torvalds/linux):
"Most recent" could refer the date or to the DAG hierarchy relative to the current changeset, or maybe to the current branch. Perhaps the latter is more useful, but in my particular use case, it doesn't make a difference.
I'd also like to be able to provide a list of files or a subdirectory for which I want the table. (I don't necessarily want it for everything)
I am aware that I could do it using a small script, looping over hg log -l 1 <file>, but I was wondering if there is a more efficient / more natural solution.

Answer 1

You won't get around looping over all files. Yet with hg manifest you get that list of files. Then template the output as needed:
for f in $(hg ma); do hg log -l1 $f -T"$f\t\t{rev}:{node|short}\t\t{date|isodate}"; done
This gives output like
.hgignore 38289:f9c426385853 2018-06-09 13:34 +0900
.hgsigs 38289:f9c426385853 2018-06-09 13:34 +0900
.hgtags 38289:f9c426385853 2018-06-09 13:34 +0900
You might want to twiddle more with the output formatting. See the mercurial wiki for a complete overview of output templating.

Answer 2

Git will follow the commit DAG, because that's all it has. In Mercurial, you have (many) more options because you have more data.
Probably the ideal option here is follow(file, .) (combined with first or last as appropriate). But as hg help revset will tell you, you have the following options (I've shrunk the list to the obvious applicable ones):
ancestors(set[, depth])
Use this with the set being . to get ancestors of the current commit, for instance, if you want to do DAG-following a la Git. Or, use ::., which is basically the same.
branch(string or set)
Use this with . to get all commits in the current branch. Combine with other restrictors (e.g., parents) to avoid looking at later commits in the current branch if you're not at the tip of the current branch.
file(pattern)
Use this with a glob pattern to find changesets that affect a given file.
filelog(pattern)
Like file but faster, trading off some accuracy for speed (see documentation for further details).
follow([file[, startrev]])
To quote the documentation:
An alias for "::." (ancestors of the working directory's first parent).
If file pattern is specified, the histories of files matching given
pattern in the revision given by startrev are followed, including
copies.
modifies(pattern)
Use this (with any pattern, not just glob) to find changesets that modify some file or directory. I think this is limited to M type modifications, not addition or removal of files, as there is also adds(pattern) and removes(pattern). Use all three, or-ed together, to find any add/modify/remove operations.
first(set, [n])
last(set, [n])
limit(set[, n[, offset]])
Use this to extract a particular entry out of the revset.
When searching forwards (the default), last(follow(file, .)) seems to work nicely to locate the correct revision. As you noted, you have to do this once per file—it will definitely go faster if you write your own Mercurial plug-in to do this without reloading the rest of the system all the time.

Answer 3

Somehow more efficient / more natural solution can be:
create template|style for desired log output (I can't predict, which way will be better for you)
create alias for hg log -l 1 --template ... or hg log -l 1 --style ...
EDIT
A lot later, more correct solution (from recent discoveries) with hg grep
hg grep "." "set:**.py" --files-with-matches -d -q -T"{files % '{file} {date|age}\n'}"
Part of output in test-repo
hggit/__init__.py 7 weeks ago
hggit/git_handler.py 7 weeks ago
hggit/gitdirstate.py 7 weeks ago
…
You have to modify fileset in order to get results only for part of your tree (for all branches) and, maybe, template in order to fulfill your needs.
I didn't have fileset for selecting "files in branch X" just now, I think, it will be something using revs() predicate
"revs(revs, pattern)"
Evaluate set in the specified revisions. If the
revset match multiple revs, this will return file matching pattern in
any of the revision.
because some not published predicates (according to examples, see # "set:revs('wdir()'..." for referencing working directory) can be used for defining revset and I can't discover/predict the correct form for branch predicate