Re: DEVEL: Help with feature implementation

On 1/18/21 1:58 PM, Derrick Stolee wrote:

On 1/18/2021 2:31 PM, Aiyee Bee wrote:

quoted

Hi Antonio and Derrick!

quoted

I think what you really want is --full-history --simplify-merges [1]. This
will show the merges that "fork" the history into parallel tracks where
at least two of them contain interesting commits.

It doesn't look like the implementation of --simplify-merges helps much
here. That makes its decision on basis of the parents of the commit, which is
simple to do as it's information attached freely to each commit. I think the
problem here would be figuring out, given any commit, how many of its children
are "relevant" commits.

You should definitely give this a try instead of assuming things about the
implementation. The algorithm uses a lot of "simplifying" that makes it look
like the decision is a local one. However, I assure you that is not the case.

As a side note, would this list be willing to look at patches that remove
the need to use revs->limited?  Adding new features would be much easier if
we could restrict git to use streaming algorithms for these simplifications.

Please assemble a test case that demonstrates the behavior you want and how
that is different from what is present in --simplify-merges.

I can't figure out how to get the behavior from --simplify-merges, which is
described as

	Additional option to --full-history to remove some needless
	merges from  the resulting history, as there are no selected
	commits contributing to this merge.

It seems that the desired behavior is to include commits which are parents to
multiple branches.  Here is an example:

test_commit() {
 echo >> file
 git add file
 git commit "$@"
}

git init
test_commit -m a
test_commit -m b
test_commit -m c
git checkout -b fork
test_commit -m y
test_commit -m z
git switch master
test_commit -m d
test_commit -m e
test_commit -m f

git log --graph --oneline master fork

* 08029fd f
* 55b09fe e
* 83b7801 d
| * efc204e z
| * 316219e y
|/  
* 3594039 c
* 4321987 b
* bd44220 a

git log --graph --oneline --full-history --simplify-merges master fork

* 08029fd f
* 55b09fe e
* 83b7801 d
| * efc204e z
| * 316219e y
|/  
* 3594039 c
* 4321987 b
* bd44220 a

git log --graph --oneline --simplify-by-decoration --full-history --simplify-merges master fork

* 08029fd f
| * efc204e z
|/  
* bd44220 a

git log --graph --oneline --full-history --simplify-merges master fork

* 08029fd f
* 55b09fe e
* 83b7801 d
| * efc204e z
| * 316219e y
|/  
* 3594039 c
* 4321987 b
* bd44220 a

git --version
git version 2.30.0

I can't seem to get commit c, the crucial fork, to show up with simplifications with this mechanism.
Am I missing something here?

-Stolee

Antonio