[PATCH v3 06/12] get_short_oid: sort ambiguous objects by type, then SHA-1
Change the output emitted when an ambiguous object is encountered so that we show tags first, then commits, followed by trees, and finally blobs. Within each type we show objects in hashcmp() order. Before this change the objects were only ordered by hashcmp().
The reason for doing this is that the output looks better as a result, e.g. the v2.17.0 tag before this change on "git show e8f2" would display:
hint: The candidates are:
hint: e8f2093055 tree
hint: e8f21caf94 commit 2013-06-24 - bash prompt: print unique detached HEAD abbreviated object name
hint: e8f21d02f7 blob
hint: e8f21d577c blob
hint: e8f25a3a50 tree
hint: e8f26250fa commit 2017-02-03 - Merge pull request #996 from jeffhostetler/jeffhostetler/register_rename_src
hint: e8f2650052 tag v2.17.0
hint: e8f2867228 blob
hint: e8f28d537c tree
hint: e8f2a35526 blob
hint: e8f2bc0c06 commit 2015-05-10 - Documentation: note behavior for multiple remote.url entries
hint: e8f2cf6ec0 treeNow we'll instead show:
hint: e8f2650052 tag v2.17.0
hint: e8f21caf94 commit 2013-06-24 - bash prompt: print unique detached HEAD abbreviated object name
hint: e8f26250fa commit 2017-02-03 - Merge pull request #996 from jeffhostetler/jeffhostetler/register_rename_src
hint: e8f2bc0c06 commit 2015-05-10 - Documentation: note behavior for multiple remote.url entries
hint: e8f2093055 tree
hint: e8f25a3a50 tree
hint: e8f28d537c tree
hint: e8f2cf6ec0 tree
hint: e8f21d02f7 blob
hint: e8f21d577c blob
hint: e8f2867228 blob
hint: e8f2a35526 blobSince we show the commit data in the output that's nicely aligned once we sort by object type. The decision to show tags before commits is pretty arbitrary. I don't want to order by object_type since there tags come last after blobs, which doesn't make sense if we want to show the most important things first.
I could display them after commits, but it's much less likely that we'll display a tag, so if there is one it makes sense to show it prominently at the top.
A note on the implementation: Derrick rightly pointed out[1] that we're bending over backwards here in get_short_oid() to first de-duplicate the list, and then emit it, but could simply do it in one step.
The reason for that is that oid_array_for_each_unique() doesn't actually require that the array be sorted by oid_array_sort(), it just needs to be sorted in some order that guarantees that all objects with the same ID are adjacent to one another, which (barring a hash collision, which'll be someone else's problem) the sort_ambiguous() function does.
I agree that would be simpler for this code, and had forgotten why I initially wrote it like this[2]. But on further reflection I think it's better to do more work here just so we're not underhandedly using the oid-array API where we lie about the list being sorted. That would break any subsequent use of oid_array_lookup() in subtle ways.
I could get around that by hacking the API itself to support this use-case and documenting it, which I did as a WIP patch in [3], but I think it's too much code smell just for this one call site. It's simpler for the API to just introduce a oid_array_for_each() function to eagerly spew out the list without sorting or de-duplication, and then do the de-duplication and sorting in two passes.
1. https://public-inbox.org/git/20180501130318.58251-1-dstolee@microsoft.com/
2. https://public-inbox.org/git/876047ze9v.fsf@evledraar.gmail.com/
3. https://public-inbox.org/git/874ljrzctc.fsf@evledraar.gmail.com/
Helped-by: Derrick Stolee <dstolee@microsoft.com>
Signed-off-by: Ævar Arnfjörð Bjarmason <avarab@gmail.com>
---
Documentation/technical/api-oid-array.txt | 17 +++++++----
sha1-array.c | 17 +++++++++++
sha1-array.h | 3 ++
sha1-name.c | 37 ++++++++++++++++++++++-
t/t1512-rev-parse-disambiguation.sh | 21 +++++++++++++
5 files changed, 88 insertions(+), 7 deletions(-)
Show changes to 5 files +88 −7
Documentation/technical/api-oid-array.txt, sha1-array.c, sha1-array.h, sha1-name.c, t/t1512-rev-parse-disambiguation.sh
diff --git a/Documentation/technical/api-oid-array.txt b/Documentation/technical/api-oid-array.txt
index b0c11f868d..94b529722c 100644
--- a/Documentation/technical/api-oid-array.txt
+++ b/Documentation/technical/api-oid-array.txt
@@ -35,13 +35,18 @@ Functions
Free all memory associated with the array and return it to the
initial, empty state.
+`oid_array_for_each`::
+ Iterate over each element of the list, executing the callback
+ function for each one. Does not sort the list, so any custom
+ hash order is retained. If the callback returns a non-zero
+ value, the iteration ends immediately and the callback's
+ return is propagated; otherwise, 0 is returned.
+
`oid_array_for_each_unique`::
- Efficiently iterate over each unique element of the list,
- executing the callback function for each one. If the array is
- not sorted, this function has the side effect of sorting it. If
- the callback returns a non-zero value, the iteration ends
- immediately and the callback's return is propagated; otherwise,
- 0 is returned.
+ Iterate over each unique element of the list in sort order ,
+ but otherwise behaves like `oid_array_for_each`. If the array
+ is not sorted, this function has the side effect of sorting
+ it.
Examples
--------
diff --git a/sha1-array.c b/sha1-array.c
index 466a926aa3..265941fbf4 100644
--- a/sha1-array.c
+++ b/sha1-array.c
@@ -41,6 +41,23 @@ void oid_array_clear(struct oid_array *array)
array->sorted = 0;
}
+
+int oid_array_for_each(struct oid_array *array,
+ for_each_oid_fn fn,
+ void *data)
+{
+ int i;
+
+ /* No oid_array_sort() here! See the api-oid-array.txt docs! */
+
+ for (i = 0; i < array->nr; i++) {
+ int ret = fn(array->oid + i, data);
+ if (ret)
+ return ret;
+ }
+ return 0;
+}
+
int oid_array_for_each_unique(struct oid_array *array,
for_each_oid_fn fn,
void *data)
diff --git a/sha1-array.h b/sha1-array.h
index 1e1d24b009..232bf95017 100644
--- a/sha1-array.h
+++ b/sha1-array.h
@@ -16,6 +16,9 @@ void oid_array_clear(struct oid_array *array);
typedef int (*for_each_oid_fn)(const struct object_id *oid,
void *data);
+int oid_array_for_each(struct oid_array *array,
+ for_each_oid_fn fn,
+ void *data);
int oid_array_for_each_unique(struct oid_array *array,
for_each_oid_fn fn,
void *data);
diff --git a/sha1-name.c b/sha1-name.c
index 9d7bbd3e96..46d8b1afa6 100644
--- a/sha1-name.c
+++ b/sha1-name.c
@@ -378,6 +378,34 @@ static int collect_ambiguous(const struct object_id *oid, void *data)
return 0;
}
+static int sort_ambiguous(const void *a, const void *b)
+{
+ int a_type = oid_object_info(a, NULL);
+ int b_type = oid_object_info(b, NULL);
+ int a_type_sort;
+ int b_type_sort;
+
+ /*
+ * Sorts by hash within the same object type, just as
+ * oid_array_for_each_unique() would do.
+ */
+ if (a_type == b_type)
+ return oidcmp(a, b);
+
+ /*
+ * Between object types show tags, then commits, and finally
+ * trees and blobs.
+ *
+ * The object_type enum is commit, tree, blob, tag, but we
+ * want tag, commit, tree blob. Cleverly (perhaps too
+ * cleverly) do that with modulus, since the enum assigns 1 to
+ * commit, so tag becomes 0.
+ */
+ a_type_sort = a_type % 4;
+ b_type_sort = b_type % 4;
+ return a_type_sort > b_type_sort ? 1 : -1;
+}
+
static int get_short_oid(const char *name, int len, struct object_id *oid,
unsigned flags)
{
@@ -409,6 +437,8 @@ static int get_short_oid(const char *name, int len, struct object_id *oid,
status = finish_object_disambiguation(&ds, oid);
if (!quietly && (status == SHORT_NAME_AMBIGUOUS)) {
+ struct oid_array collect = OID_ARRAY_INIT;
+
error(_("short SHA1 %s is ambiguous"), ds.hex_pfx);
/*
@@ -421,7 +451,12 @@ static int get_short_oid(const char *name, int len, struct object_id *oid,
ds.fn = NULL;
advise(_("The candidates are:"));
- for_each_abbrev(ds.hex_pfx, show_ambiguous_object, &ds);
+ for_each_abbrev(ds.hex_pfx, collect_ambiguous, &collect);
+ QSORT(collect.oid, collect.nr, sort_ambiguous);
+
+ if (oid_array_for_each(&collect, show_ambiguous_object, &ds))
+ BUG("show_ambiguous_object shouldn't return non-zero");
+ oid_array_clear(&collect);
}
return status;
diff --git a/t/t1512-rev-parse-disambiguation.sh b/t/t1512-rev-parse-disambiguation.sh
index 711704ba5a..2701462041 100755
--- a/t/t1512-rev-parse-disambiguation.sh
+++ b/t/t1512-rev-parse-disambiguation.sh
@@ -361,4 +361,25 @@ test_expect_success 'core.disambiguate does not override context' '
git -c core.disambiguate=committish rev-parse $sha1^{tree}
'
+test_expect_success C_LOCALE_OUTPUT 'ambiguous commits are printed by type first, then hash order' '
+ test_must_fail git rev-parse 0000 2>stderr &&
+ grep ^hint: stderr >hints &&
+ grep 0000 hints >objects &&
+ cat >expected <<-\EOF &&
+ tag
+ commit
+ tree
+ blob
+ EOF
+ awk "{print \$3}" <objects >objects.types &&
+ uniq <objects.types >objects.types.uniq &&
+ test_cmp expected objects.types.uniq &&
+ for type in tag commit tree blob
+ do
+ grep $type objects >$type.objects &&
+ sort $type.objects >$type.objects.sorted &&
+ test_cmp $type.objects.sorted $type.objects
+ done
+'
+
test_done
--
2.17.0.290.gded63e768a
Ævar Arnfjörð Bjarmason
