On Fri, 30 Jun 2006, Luben Tuikov wrote:
>
> I took a comparative look with and without "--full-history",
> and FWIW, enabling full history just clobbers the output with a lot
> of unnecessary information. I.e. it shows merges which do not have
> direct consequence or change to the files in the path spec specified
> after the "--".
Oh, you're right - "--full-history" right now is literally geared solely
towards the graphical kind, which needs all the merges (regardless of
whether they change a file or not) to make sense of the history.
> I.e. no new, relevant information is being shown when "--full-history"
> is enabled. In fact the default git-rev-list case, simplify_history=1,
> still shows a merge here and there which doesn't have any direct
> changes into what is being sought, but the difference is
> about 48% less clobber.
Well, with history simplification, we still show merges that are required
to make the history _complete_, ie say that you had
a
|
b
/ \
c d
| |
and neither "a" nor "b" actually changed the file, but both "c" and "d"
did: in this case we have to leave "b" around just because otherwise there
would be no way to show the _relationship_, even if "b" itself doesn't
actually change the tree in any way what-so-ever.
> Can you consider the default case to be simplify_history=1,
> which is currently the default behaviour of git-rev-list.
Actually, for your case, you don't want _any_ merges, unless those merges
literally changed the tree from all of the parents.
I think it would make sense to make that further simplification if the
"--parents" flag wasn't present.
Hmm. Maybe something like this..
BTW! Junio, I think this patch actually fixes a real bug.
Without this patch, the "--parents --full-history" combination (which
you'd get if you do something like
gitk --full-history Makefile
or similar) will actually _drop_ merges where all children are identical.
That's wrong in the --full-history case, because it measn that the graph
ends up missing lots of entries.
In the process, this also should make
git-rev-list --full-history Makefile
give just the _true_ list of all commits that changed Makefile (and
properly ignore merges that were identical in one parent), because now
we're not asking for "--parent", so we don't need the unnecessary merge
commits to keep the history together.
Luben, does this fix the problem for you?
Linus
----
diff --git a/revision.c b/revision.c
index b963f2a..1cf6276 100644
--- a/revision.c
+++ b/revision.c
@@ -280,7 +280,7 @@ int rev_same_tree_as_empty(struct rev_in
static void try_to_simplify_commit(struct rev_info *revs, struct commit *commit)
{
struct commit_list **pp, *parent;
- int tree_changed = 0;
+ int tree_changed = 0, tree_same = 0;
if (!commit->tree)
return;
@@ -298,6 +298,7 @@ static void try_to_simplify_commit(struc
parse_commit(p);
switch (rev_compare_tree(revs, p->tree, commit->tree)) {
case REV_TREE_SAME:
+ tree_same = 1;
if (!revs->simplify_history || (p->object.flags & UNINTERESTING)) {
/* Even if a merge with an uninteresting
* side branch brought the entire change
@@ -334,7 +335,7 @@ static void try_to_simplify_commit(struc
}
die("bad tree compare for commit %s", sha1_to_hex(commit->object.sha1));
}
- if (tree_changed)
+ if (tree_changed && !tree_same)
commit->object.flags |= TREECHANGE;
}
@@ -896,6 +897,8 @@ static int rewrite_one(struct rev_info *
struct commit *p = *pp;
if (!revs->limited)
add_parents_to_list(revs, p, &revs->commits);
+ if (p->parents && p->parents->next)
+ return 0;
if (p->object.flags & (TREECHANGE | UNINTERESTING))
return 0;
if (!p->parents)
@@ -988,8 +991,15 @@ struct commit *get_revision(struct rev_i
commit->parents && commit->parents->next)
continue;
if (revs->prune_fn && revs->dense) {
- if (!(commit->object.flags & TREECHANGE))
- continue;
+ /* Commit without changes? */
+ if (!(commit->object.flags & TREECHANGE)) {
+ /* drop merges unless we want parenthood */
+ if (!revs->parents)
+ continue;
+ /* non-merge - always ignore it */
+ if (commit->parents && !commit->parents->next)
+ continue;
+ }
if (revs->parents)
rewrite_parents(revs, commit);
}
-
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