On Sun, 6 Sep 2009, Linus Torvalds wrote:
>
> And it's not working, for some reason I'm not seeing, but I thought I'd
> send it to you just as a way to show where I'm trying to take this. Maybe
> you see what my thinko is.
Duh. My thinko was that I wasn't testing the right thing. The patch works
fine, my test failures came from the fact that I was working on a branch
with some other broken experimental features.
Now, the patch I sent out did have a buglet: when a conflict happens,
'mask' will not have the conflicting bits we just added to 'dirmask'. But
that buglet doesn't actually seem to affect any of the traverse_tree()
callers, and they are fine with 'dirmask' being separate from 'mask'.
So here's a slightly updated version, and it passes all the tests.
Again, an important note: this is _not_ meant to change semantics, it's
really only meant to re-organize the code so that we _can_ do look-ahead
in the trees for conflicts. But in its current form, the look-ahead is
limited to the next entry, the same as the old code.
So there should be no semantic changes from this patch. Just avoid using
'df_name_compare()' and create that 'find_df_conflict()' function that can
be expanded to actually look ahead more.
Linus
---
tree-walk.c | 72 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++--
1 files changed, 69 insertions(+), 3 deletions(-)
diff --git a/tree-walk.c b/tree-walk.c
index 02e2aed..fb5ca1e 100644
--- a/tree-walk.c
+++ b/tree-walk.c
@@ -62,7 +62,7 @@ void *fill_tree_descriptor(struct tree_desc *desc, const unsigned char *sha1)
static int entry_compare(struct name_entry *a, struct name_entry *b)
{
- return df_name_compare(
+ return base_name_compare(
a->path, tree_entry_len(a->path, a->sha1), a->mode,
b->path, tree_entry_len(b->path, b->sha1), b->mode);
}
@@ -138,6 +138,68 @@ char *make_traverse_path(char *path, const struct traverse_info *info, const str
return path;
}
+/*
+ * See if 'entry' may conflict with a later tree entry in 't': if so,
+ * fill in 'conflict' with the conflicting tree entry from 't'.
+ *
+ * NOTE! Right now we do _not_ create a create a private copy of the tree
+ * descriptor, so we can't actually walk it any further without losing
+ * our place. We should change it to a loop over a copy of the tree
+ * descriptor, but then we'd also have to remember the skipped entries,
+ * so this is a hacky simple case that only handles the case we used
+ * to handle historically (ie clash in the very first entry)
+ *
+ * Note that only a regular file 'entry' can conflict with a later
+ * directory, since a directory with the same name will sort later.
+ */
+static int find_df_conflict(struct tree_desc *t, struct name_entry *entry, struct name_entry *conflict)
+{
+ int len;
+
+ if (S_ISDIR(entry->mode))
+ return 0;
+ len = tree_entry_len(entry->path, entry->sha1);
+
+ while (t->size) {
+ int nlen;
+
+ entry_extract(t, conflict);
+ nlen = tree_entry_len(conflict->path, conflict->sha1);
+
+ /*
+ * We can only have a future conflict if the entry matches the
+ * beginning of the name exactly, and if the next character is
+ * smaller than '/'.
+ *
+ * Break out otherwise.
+ */
+ if (nlen < len)
+ break;
+ if (memcmp(conflict->path, entry->path, nlen))
+ break;
+
+ /*
+ * FIXME! This is the case where we'd like to mark the tree
+ * entry used in the original 't' rather than modify 't'!
+ */
+ if (nlen == len) {
+ update_tree_entry(t);
+ return 1;
+ }
+
+ if (conflict->path[len] > '/')
+ break;
+ /*
+ * FIXME! Here we'd really like to do 'update_tree_entry(©);'
+ * but that requires us to remember the conflict position specially
+ * so now we just punt and stop looking for conflicts
+ */
+ break;
+ }
+ entry_clear(conflict);
+ return 0;
+}
+
int traverse_trees(int n, struct tree_desc *t, struct traverse_info *info)
{
int ret = 0;
@@ -179,14 +241,18 @@ int traverse_trees(int n, struct tree_desc *t, struct traverse_info *info)
dirmask &= mask;
/*
- * Clear all the unused name-entries.
+ * Clear all the unused name-entries, and look for
+ * conflicts.
*/
for (i = 0; i < n; i++) {
if (mask & (1ul << i))
continue;
entry_clear(entry + i);
+ if (find_df_conflict(t+i, entry+last, entry+i))
+ dirmask |= (1ul << i);
}
- ret = info->fn(n, mask, dirmask, entry, info);
+
+ ret = info->fn(n, mask | dirmask, dirmask, entry, info);
if (ret < 0)
break;
if (ret)
--
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