[PATCH v2 1/1] pack-objects: ignore ambiguous object warnings

From: Derrick Stolee via GitGitGadget <gitgitgadget@gmail.com>
Date: Nov 6, 2018, 20:34 UTC
Message-ID: <002868ee6bec3dac38749d0f05bf2db8da0969a5.1541536484.git.gitgitgadget@gmail.com>
In-Reply-To: <pull.68.v2.git.gitgitgadget@gmail.com>

From: Derrick Stolee <dstolee@microsoft.com>

A git push process runs several processes during its run, but one includes git send-pack which calls git pack-objects and passes the known have/wants into stdin using object ids. However, the default setting for core.warnAmbiguousRefs requires git pack-objects to check for ref names matching the ref_rev_parse_rules array in refs.c. This means that every object is triggering at least six "file exists?" queries. When there are a lot of refs, this can add up significantly! I observed a simple push spending three seconds checking these paths.

The fix here is similar to 4c30d50 "rev-list: disable object/refname ambiguity check with --stdin". Save the value of the global warn_on_object_refname_ambiguity variable (which is usually set to the boolean config variable core.warnAmbiguousRefs) and change the state to false. Do this only during the get_object_list() method which reads the objects from stdin.

Helped-by: Jeff King <peff@peff.net>
Signed-off-by: Derrick Stolee <dstolee@microsoft.com>
---
 builtin/pack-objects.c | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/builtin/pack-objects.c b/builtin/pack-objects.c
index d1144a8f7e..f703e6df9b 100644
--- a/builtin/pack-objects.c
+++ b/builtin/pack-objects.c
@@ -2988,6 +2988,7 @@ static void get_object_list(int ac, const char **av)
 	struct rev_info revs;
 	char line[1000];
 	int flags = 0;
+	int save_warning;
 
 	init_revisions(&revs, NULL);
 	save_commit_buffer = 0;
@@ -2996,6 +2997,9 @@ static void get_object_list(int ac, const char **av)
 	/* make sure shallows are read */
 	is_repository_shallow(the_repository);
 
+	save_warning = warn_on_object_refname_ambiguity;
+	warn_on_object_refname_ambiguity = 0;
+
 	while (fgets(line, sizeof(line), stdin) != NULL) {
 		int len = strlen(line);
 		if (len && line[len - 1] == '\n')
@@ -3022,6 +3026,8 @@ static void get_object_list(int ac, const char **av)
 			die(_("bad revision '%s'"), line);
 	}
 
+	warn_on_object_refname_ambiguity = save_warning;
+
 	if (use_bitmap_index && !get_object_list_from_bitmap(&revs))
 		return;

-- 
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