rev-list: add commit object support in `--missing` option

The `--missing` object option in rev-list currently works only with
missing blobs/trees. For missing commits the revision walker fails with
a fatal error.

Let's extend the functionality of `--missing` option to also support
commit objects. This is done by adding a `missing_objects` field to
`rev_info`. This field is an `oidset` to which we'll add the missing
commits as we encounter them. The revision walker will now continue the
traversal and call `show_commit()` even for missing commits. In rev-list
we can then check if the commit is a missing commit and call the
existing code for parsing `--missing` objects.

A scenario where this option would be used is to find the boundary
objects between different object directories. Consider a repository with
a main object directory (GIT_OBJECT_DIRECTORY) and one or more alternate
object directories (GIT_ALTERNATE_OBJECT_DIRECTORIES). In such a
repository, using the `--missing=print` option while disabling the
alternate object directory allows us to find the boundary objects
between the main and alternate object directory.

Helped-by: Patrick Steinhardt <ps@pks.im>
Helped-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Karthik Nayak <karthik.188@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>

diff --git a/builtin/rev-list.c b/builtin/rev-list.c
index 98542e8b3ca341dd0fed2f18845ec8ec01deb3c3..181353dcf51ba8af7620b8926084a1cbea3163b2 100644 (file)
--- a/builtin/rev-list.c
+++ b/builtin/rev-list.c
@@ -149,6 +149,12 @@ static void show_commit(struct commit *commit, void *data)
 
        display_progress(progress, ++progress_counter);
 
+       if (revs->do_not_die_on_missing_objects &&
+           oidset_contains(&revs->missing_commits, &commit->object.oid)) {
+               finish_object__ma(&commit->object);
+               return;
+       }
+
        if (show_disk_usage)
                total_disk_usage += get_object_disk_usage(&commit->object);
 

diff --git a/list-objects.c b/list-objects.c
index 47296dff2f23bdde5bcb19e65a2714acb4f108d4..f4e1104b56fb64c0e9230b284350974a6900f91b 100644 (file)
--- a/list-objects.c
+++ b/list-objects.c
@@ -389,6 +389,9 @@ static void do_traverse(struct traversal_context *ctx)
                 */
                if (!ctx->revs->tree_objects)
                        ; /* do not bother loading tree */
+               else if (ctx->revs->do_not_die_on_missing_objects &&
+                        oidset_contains(&ctx->revs->missing_commits, &commit->object.oid))
+                       ;
                else if (repo_get_commit_tree(the_repository, commit)) {
                        struct tree *tree = repo_get_commit_tree(the_repository,
                                                                 commit);

diff --git a/revision.c b/revision.c
index 219dc76716fb0611ae8e7eb3dc10522d8779b213..00d5c29bfce18a1d4a5f5d701a593596ccd65783 100644 (file)
--- a/revision.c
+++ b/revision.c
@@ -6,6 +6,7 @@
 #include "object-name.h"
 #include "object-file.h"
 #include "object-store-ll.h"
+#include "oidset.h"
 #include "tag.h"
 #include "blob.h"
 #include "tree.h"
@@ -1112,6 +1113,9 @@ static int process_parents(struct rev_info *revs, struct commit *commit,
 
        if (commit->object.flags & ADDED)
                return 0;
+       if (revs->do_not_die_on_missing_objects &&
+           oidset_contains(&revs->missing_commits, &commit->object.oid))
+               return 0;
        commit->object.flags |= ADDED;
 
        if (revs->include_check &&
@@ -1168,7 +1172,8 @@ static int process_parents(struct rev_info *revs, struct commit *commit,
        for (parent = commit->parents; parent; parent = parent->next) {
                struct commit *p = parent->item;
                int gently = revs->ignore_missing_links ||
-                            revs->exclude_promisor_objects;
+                            revs->exclude_promisor_objects ||
+                            revs->do_not_die_on_missing_objects;
                if (repo_parse_commit_gently(revs->repo, p, gently) < 0) {
                        if (revs->exclude_promisor_objects &&
                            is_promisor_object(&p->object.oid)) {
@@ -1176,7 +1181,11 @@ static int process_parents(struct rev_info *revs, struct commit *commit,
                                        break;
                                continue;
                        }
-                       return -1;
+
+                       if (revs->do_not_die_on_missing_objects)
+                               oidset_insert(&revs->missing_commits, &p->object.oid);
+                       else
+                               return -1; /* corrupt repository */
                }
                if (revs->sources) {
                        char **slot = revision_sources_at(revs->sources, p);
@@ -3109,6 +3118,7 @@ void release_revisions(struct rev_info *revs)
        clear_decoration(&revs->merge_simplification, free);
        clear_decoration(&revs->treesame, free);
        line_log_free(revs);
+       oidset_clear(&revs->missing_commits);
 }
 
 static void add_child(struct rev_info *revs, struct commit *parent, struct commit *child)
@@ -3800,6 +3810,8 @@ int prepare_revision_walk(struct rev_info *revs)
                                       FOR_EACH_OBJECT_PROMISOR_ONLY);
        }
 
+       oidset_init(&revs->missing_commits, 0);
+
        if (!revs->reflog_info)
                prepare_to_use_bloom_filter(revs);
        if (!revs->unsorted_input)

diff --git a/revision.h b/revision.h
index c73c92ef40c856e24e8fb5f6c2523275f46e992f..94c43138bc3e68651accecf79cdf4c28ba98582f 100644 (file)
--- a/revision.h
+++ b/revision.h
@@ -4,6 +4,7 @@
 #include "commit.h"
 #include "grep.h"
 #include "notes.h"
+#include "oidset.h"
 #include "pretty.h"
 #include "diff.h"
 #include "commit-slab-decl.h"
@@ -373,6 +374,9 @@ struct rev_info {
 
        /* Location where temporary objects for remerge-diff are written. */
        struct tmp_objdir *remerge_objdir;
+
+       /* Missing commits to be tracked without failing traversal. */
+       struct oidset missing_commits;
 };
 
 /**

diff --git a/t/t6022-rev-list-missing.sh b/t/t6022-rev-list-missing.sh
new file mode 100755 (executable)
index 0000000..40265a4
--- /dev/null
+++ b/t/t6022-rev-list-missing.sh
@@ -0,0 +1,74 @@
+#!/bin/sh
+
+test_description='handling of missing objects in rev-list'
+
+TEST_PASSES_SANITIZE_LEAK=true
+. ./test-lib.sh
+
+# We setup the repository with two commits, this way HEAD is always
+# available and we can hide commit 1.
+test_expect_success 'create repository and alternate directory' '
+       test_commit 1 &&
+       test_commit 2 &&
+       test_commit 3
+'
+
+for obj in "HEAD~1" "HEAD~1^{tree}" "HEAD:1.t"
+do
+       test_expect_success "rev-list --missing=error fails with missing object $obj" '
+               oid="$(git rev-parse $obj)" &&
+               path=".git/objects/$(test_oid_to_path $oid)" &&
+
+               mv "$path" "$path.hidden" &&
+               test_when_finished "mv $path.hidden $path" &&
+
+               test_must_fail git rev-list --missing=error --objects \
+                       --no-object-names HEAD
+       '
+done
+
+for obj in "HEAD~1" "HEAD~1^{tree}" "HEAD:1.t"
+do
+       for action in "allow-any" "print"
+       do
+               test_expect_success "rev-list --missing=$action with missing $obj" '
+                       oid="$(git rev-parse $obj)" &&
+                       path=".git/objects/$(test_oid_to_path $oid)" &&
+
+                       # Before the object is made missing, we use rev-list to
+                       # get the expected oids.
+                       git rev-list --objects --no-object-names \
+                               HEAD ^$obj >expect.raw &&
+
+                       # Blobs are shared by all commits, so evethough a commit/tree
+                       # might be skipped, its blob must be accounted for.
+                       if [ $obj != "HEAD:1.t" ]; then
+                               echo $(git rev-parse HEAD:1.t) >>expect.raw &&
+                               echo $(git rev-parse HEAD:2.t) >>expect.raw
+                       fi &&
+
+                       mv "$path" "$path.hidden" &&
+                       test_when_finished "mv $path.hidden $path" &&
+
+                       git rev-list --missing=$action --objects --no-object-names \
+                               HEAD >actual.raw &&
+
+                       # When the action is to print, we should also add the missing
+                       # oid to the expect list.
+                       case $action in
+                       allow-any)
+                               ;;
+                       print)
+                               grep ?$oid actual.raw &&
+                               echo ?$oid >>expect.raw
+                               ;;
+                       esac &&
+
+                       sort actual.raw >actual &&
+                       sort expect.raw >expect &&
+                       test_cmp expect actual
+               '
+       done
+done
+
+test_done