RE: [PATCH 1/2] revision: Denote root commits with '#'

["Jason Pyeron" <jpyeron@pdinc.us>]

> -----Original Message-----
> From: Junio C Hamano <gitster@pobox.com>
> Sent: Saturday, January 23, 2021 1:07 PM
> 
> "Jason Pyeron" writes:
> 
> > Summary: --graph used with --oneline sometimes produces ambiguous
> > output when more than one commit has no parents and are not yet
> > merged
> > ...
> >> "(branch name)" in the output, instead of painting the commit in the
> >> graph by replacing the '*' node with something else.
> >>
> >> And how often do you really need to see commits near the root, say
> >> the earliest 100 commits, in the 35k+ commit history?  Is it really
> >> necessary to tell which among these 100 is the root?
> >
> > Yes, and the assumption that they are at the beginning is flawed too.
> >
> > $ git log --oneline --graph --all | cat -n | egrep $(git rev-list --max-parents=0 --all | cut -c 1-8
> | tr '\n' '|' | head -c -1)
> >     87  | | * be2c70b7 bug 2252 test case (e.g. for tomcat 9 with unpackWARs=false)
> >   2161  | | * 8ef73128 Add migrate-from-blackfat.sql
> >   2164  | | * 5505e019 initial
> >   2235  | | | | | | | | | | | | | * 83337c67 intial
> >   2921  | | | | * ca14dc49 Initial commit
> >   2931  | | | * cbdce824 initial commit
> >   2963  | | * 8f1828c1 Base applet
> >   2971  | * 658af21f parrent pom
> >   3026  * 8356af31 Initial commit from Create React App
> >
> > git log --oneline --graph produces 3026 lines in this example.
> 
> Hmph.  Are you saying that you have 3000+ root commits in the 35k+
> history?
> 

I think you misread the specific example of 9 roots in 3026 commits, distributed throughout history.

> Whether we add '[root]' decoration to the true roots (like
> '(branchname)' decoration we add to branch tips), or painted '*' in
> a different color (like '#'), you do not have to look for 'initial',
> so having that many roots will not be a problem per-se with respect
> to the "log" output, but there must be something strange going on.
> 
> I am not going to ask you why you need so many roots, because I
> suspect that I will regret asking ;-).
> 
> By the way, I sense that your problem description is flip-flopping
> again and I can no longer keep track of.  The way I read the message
> I got from Kyle was, even when a graph has two commits that have no
> parents in the visible part of the history, either Kyle wanted (or
> Kyle got an impression after talking to you that you wanted) to see
> these differently if one of them is a root and the other is non-root
> (but happens to have none of its parents shown due to A..B range).
> And that is why I started asking how meaningful to special case only
> "root".
> 

I may be having trouble with my writing, apologies.

Here is the issue (bug):

1. I never want to see a commit implied to be the parent of an unrelated commit.
2. I never want to see a commit implied to be the child of an unrelated commit.

--graph --oneline is broken with regards to the man page and my desire to not be confused by the implication of relationship for inappropriately connected nodes on the graph.

| | * 1234567 commit child of 2345678
| | * 2345678 the first commit, having no parent
| | * 9876543 an unrelated commit and child of 8765432
| | * 8765432 ...

> Now the message from you I am responding to in the "Sumary" above
> says that it is not "root" but is about the placement of graph
> nodes.
> 

One and the same issue. Placing an * directly above another * is the issue.

Solution #1

| | * 1234567 commit child of 2345678
| | # 2345678 the first commit, having no parent
| | * 9876543 an unrelated commit and child of 8765432
| | * 8765432 ...

Or

Solution #2

| | * 1234567 commit child of 2345678
| | * 2345678 the first commit, having no parent
| |
| | * 9876543 an unrelated commit and child of 8765432
| | * 8765432 ...

Or

Solution #3

| | * 1234567 commit child of 2345678
| | \
| |  * 2345678 the first commit, having no parent
| | * 9876543 an unrelated commit and child of 8765432
| | * 8765432 ...

All of these solutions will solve the bug. #1 seems to be the easiest and becomes searchable. You have indicated that #3 others have failed to do so. #2 is very much aligned to the --graph without --oneline

> So, I dunno, with changing the description of the goalpost.  Now it
> is that "root" is so not special at all and we only care about that
> the a commit, none of whose parents are in the part of the shown
> history, is shown in such a way that the user can tell that any
> unrelated commits shown in the graph near it are not parents of such
> a commit?  Or do you still want to show such a commit in two ways,
> one for root and one for the ones above the boundary?

A commit without a parent is special - it has no parent. This means it has no history beyond that point. Something special happened at that time - the birth of new source code in source control.

Hopefully, I have cleared up the ambiguous wording.