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[PATCH 22/28] attr.c: correct ugly hack for git_all_attrs()

From
Stefan Beller <sbeller@google.com>
Date
Oct 11, 2016, 00:21 UTC
Message-ID
<20161011002115.23312-23-sbeller@google.com>
In-Reply-To
<20161011002115.23312-1-sbeller@google.com>
From: Junio C Hamano <gitster@pobox.com>
The collect_some_attrs() function has an ugly hack since

06a604e6 (attr: avoid heavy work when we know the specified attr is not defined, 2014-12-28) added an optimization that relies on the fact that the caller knows what attributes it is interested in, so that we can leave once we know the final answer for all the attributes the caller asked.

git_all_attrs() that asks "what attributes are on this path?" however does not know what attributes it is interested in, other than the vague "we are interested in all of them", which is not a very useful thing to say. As a way to disable this optimization for this caller, the said commit added a code to skip it when the caller passes a NULL for the check structure.

However, it skipped the optimization not when check is NULL, but when the number of attributes being checked is 0, which is unnecessarily pessimistic.

Signed-off-by: Junio C Hamano <gitster@pobox.com>
Signed-off-by: Stefan Beller <sbeller@google.com>
---
 attr.c | 24 ++++++++----------------
 1 file changed, 8 insertions(+), 16 deletions(-)
diff --git a/attr.c b/attr.c
index abf23d8..8d8df20 100644
--- a/attr.c
+++ b/attr.c
@@ -748,8 +748,8 @@ static int attr_check_is_dynamic(const struct git_attr_check *check)
 
 /*
  * Collect attributes for path into the array pointed to by
- * check_all_attr. If num is non-zero, only attributes in check[] are
- * collected. Otherwise all attributes are collected.
+ * check_all_attr.  If check is not NULL, only attributes in
+ * check[] are collected. Otherwise all attributes are collected.
  */
 static void collect_some_attrs(const char *path, int pathlen,
 			       struct git_attr_check *check)
@@ -759,17 +759,6 @@ static void collect_some_attrs(const char *path, int pathlen,
 	int i, rem, dirlen;
 	const char *cp, *last_slash = NULL;
 	int basename_offset;
-	int num;
-	struct git_attr_check_elem *celem;
-
-	if (!check) {
-		/* Yuck - ugly git_all_attrs() hack! */
-		celem = NULL;
-		num = 0;
-	} else {
-		celem = check->check;
-		num = check->check_nr;
-	}
 
 	for (cp = path; cp < path + pathlen; cp++) {
 		if (*cp == '/' && cp[1])
@@ -786,9 +775,12 @@ static void collect_some_attrs(const char *path, int pathlen,
 	prepare_attr_stack(path, dirlen);
 	for (i = 0; i < attr_nr; i++)
 		check_all_attr[i].value = ATTR__UNKNOWN;
-	if (num && !cannot_trust_maybe_real) {
+
+	if (check && !cannot_trust_maybe_real) {
+		struct git_attr_check_elem *celem = check->check;
+
 		rem = 0;
-		for (i = 0; i < num; i++) {
+		for (i = 0; i < check->check_nr; i++) {
 			if (!celem[i].attr->maybe_real) {
 				struct git_attr_check_elem *c;
 				c = check_all_attr + celem[i].attr->attr_nr;
@@ -796,7 +788,7 @@ static void collect_some_attrs(const char *path, int pathlen,
 				rem++;
 			}
 		}
-		if (rem == num)
+		if (rem == check->check_nr)
 			return;
 	}
 
-- 
2.10.1.382.ga23ca1b.dirty
Previous: Stefan BellerNext: Stefan Beller
Message 40 of 44 in “Revamping the attr subsystem!”
  1. 00/28 Revamping the attr subsystem!Stefan Beller, Oct 11, 2016
  2. 01/28 commit.c: use strchrnul() to scan for one lineStefan Beller, Oct 11, 2016
  3. 02/28 attr.c: use strchrnul() to scan for one lineStefan Beller, Oct 11, 2016
  4. 03/28 attr.c: update a stale comment on "struct match_attr"Stefan Beller, Oct 11, 2016
  5. 07/28 attr.c: simplify macroexpand_one()Stefan Beller, Oct 11, 2016
  6. 05/28 attr.c: complete a sentence in a commentStefan Beller, Oct 11, 2016
  7. 04/28 attr.c: explain the lack of attr-name syntax check in parse_attr()Stefan Beller, Oct 11, 2016
  8. 06/28 attr.c: mark where #if DEBUG ends more clearlyStefan Beller, Oct 11, 2016
  9. 09/28 attr.c: plug small leak in parse_attr_line()Stefan Beller, Oct 11, 2016
  10. 08/28 attr.c: tighten constness around "git_attr" structureStefan Beller, Oct 11, 2016
  11. 10/28 attr: rename function and struct related to checking attributesStefan Beller, Oct 11, 2016
  12. 14/28 attr: retire git_check_attrs() APIStefan Beller, Oct 11, 2016
  13. 13/28 attr: convert git_check_attrs() callers to use the new APIStefan Beller, Oct 11, 2016
  14. 16/28 attr: add counted string version of git_attr()Stefan Beller, Oct 11, 2016
  15. 17/28 attr: expose validity check for attribute namesStefan Beller, Oct 11, 2016
  16. Brandon WilliamsOct 11, 2016
  17. Stefan BellerOct 11, 2016
  18. Brandon WilliamsOct 11, 2016
  19. Stefan BellerOct 11, 2016
  20. Brandon WilliamsOct 11, 2016
  21. 15/28 attr: add counted string version of git_check_attr()Stefan Beller, Oct 11, 2016
  22. 19/28 attr.c: add push_stack() helperStefan Beller, Oct 11, 2016
  23. 18/28 attr: support quoting pathname patterns in C styleStefan Beller, Oct 11, 2016
  24. 21/28 attr.c: rename a local variable checkStefan Beller, Oct 11, 2016
  25. 25/28 attr.c: outline the future plans by heavily commentingStefan Beller, Oct 11, 2016
  26. 20/28 attr.c: pass struct git_attr_check down the callchainStefan Beller, Oct 11, 2016
  27. 26/28 attr: make git_attr_counted staticStefan Beller, Oct 11, 2016
  28. Brandon WilliamsOct 11, 2016
  29. Stefan BellerOct 11, 2016
  30. 27/28 attr: make git_check_attr_counted staticStefan Beller, Oct 11, 2016
  31. 23/28 attr.c: introduce empty_attr_check_elems()Stefan Beller, Oct 11, 2016
  32. 28/28 attr: convert to new threadsafe APIStefan Beller, Oct 11, 2016
  33. Brandon WilliamsOct 11, 2016
  34. Junio C HamanoOct 11, 2016
  35. Stefan BellerOct 11, 2016
  36. Junio C HamanoOct 11, 2016
  37. Stefan BellerOct 11, 2016
  38. Junio C HamanoOct 11, 2016
  39. 24/28 attr.c: always pass check[] to collect_some_attrs()Stefan Beller, Oct 11, 2016
  40. 22/28 attr.c: correct ugly hack for git_all_attrs()Stefan Beller, Oct 11, 2016
  41. 11/28 attr: (re)introduce git_check_attr() and struct git_attr_checkStefan Beller, Oct 11, 2016
  42. Brandon WilliamsOct 11, 2016
  43. Junio C HamanoOct 11, 2016
  44. 12/28 attr: convert git_all_attrs() to use "struct git_attr_check"Stefan Beller, Oct 11, 2016

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