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[PATCH 21/35] attr.c: correct ugly hack for git_all_attrs()

From
Stefan Beller <sbeller@google.com>
Date
Nov 10, 2016, 20:34 UTC
Message-ID
<20161110203428.30512-22-sbeller@google.com>
In-Reply-To
<20161110203428.30512-1-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>
Signed-off-by: Junio C Hamano <gitster@pobox.com>
---
 attr.c | 24 ++++++++----------------
 1 file changed, 8 insertions(+), 16 deletions(-)
diff --git a/attr.c b/attr.c
index e18098c..48460d2 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;
 	}
 
-- 
2.10.1.469.g00a8914
Previous: Stefan BellerNext: Stefan Beller
Message 36 of 43 in “[PATCHv3 00/35] Revamp the attr subsystem!”
  1. Stefan BellerNov 10, 2016
  2. 02/35 attr.c: use strchrnul() to scan for one lineStefan Beller, Nov 10, 2016
  3. 06/35 attr.c: mark where #if DEBUG ends more clearlyStefan Beller, Nov 10, 2016
  4. 05/35 attr.c: complete a sentence in a commentStefan Beller, Nov 10, 2016
  5. 09/35 attr.c: plug small leak in parse_attr_line()Stefan Beller, Nov 10, 2016
  6. 10/35 attr: rename function and struct related to checking attributesStefan Beller, Nov 10, 2016
  7. 12/35 attr: convert git_all_attrs() to use "struct git_attr_check"Stefan Beller, Nov 10, 2016
  8. 11/35 attr: (re)introduce git_check_attr() and struct git_attr_checkStefan Beller, Nov 10, 2016
  9. 13/35 attr: convert git_check_attrs() callers to use the new APIStefan Beller, Nov 10, 2016
  10. 18/35 attr.c: add push_stack() helperStefan Beller, Nov 10, 2016
  11. 20/35 attr.c: rename a local variable checkStefan Beller, Nov 10, 2016
  12. 22/35 attr.c: introduce empty_attr_check_elems()Stefan Beller, Nov 10, 2016
  13. 19/35 attr.c: pass struct git_attr_check down the callchainStefan Beller, Nov 10, 2016
  14. 17/35 attr: support quoting pathname patterns in C styleStefan Beller, Nov 10, 2016
  15. 16/35 attr: expose validity check for attribute namesStefan Beller, Nov 10, 2016
  16. 34/35 clone: add --init-submodule=<pathspec> switchStefan Beller, Nov 10, 2016
  17. 26/35 attr: convert to new threadsafe APIStefan Beller, Nov 10, 2016
  18. 35/35 completion: clone can initialize specific submodulesStefan Beller, Nov 10, 2016
  19. 27/35 attr: keep attr stack for each checkStefan Beller, Nov 10, 2016
  20. 33/35 submodule update: add `--init-default-path` switchStefan Beller, Nov 10, 2016
  21. 28/35 Documentation: fix a typoStefan Beller, Nov 10, 2016
  22. 31/35 pathspec: allow querying for attributesStefan Beller, Nov 10, 2016
  23. Duy NguyenNov 22, 2016
  24. Stefan BellerNov 22, 2016
  25. Duy NguyenNov 23, 2016
  26. Brandon WilliamsNov 28, 2016
  27. Brandon WilliamsNov 28, 2016
  28. Brandon WilliamsNov 28, 2016
  29. Stefan BellerNov 29, 2016
  30. 32/35 pathspec: allow escaped query valuesStefan Beller, Nov 10, 2016
  31. 30/35 pathspec: move prefix check out of the inner loopStefan Beller, Nov 10, 2016
  32. 29/35 pathspec: move long magic parsing out of prefix_pathspecStefan Beller, Nov 10, 2016
  33. 23/35 attr.c: always pass check[] to collect_some_attrs()Stefan Beller, Nov 10, 2016
  34. 25/35 attr: make git_check_attr_counted staticStefan Beller, Nov 10, 2016
  35. 24/35 attr.c: outline the future plans by heavily commentingStefan Beller, Nov 10, 2016
  36. 21/35 attr.c: correct ugly hack for git_all_attrs()Stefan Beller, Nov 10, 2016
  37. 14/35 attr: retire git_check_attrs() APIStefan Beller, Nov 10, 2016
  38. 01/35 commit.c: use strchrnul() to scan for one lineStefan Beller, Nov 10, 2016
  39. 15/35 attr: add counted string version of git_check_attr()Stefan Beller, Nov 10, 2016
  40. 08/35 attr.c: tighten constness around "git_attr" structureStefan Beller, Nov 10, 2016
  41. 03/35 attr.c: update a stale comment on "struct match_attr"Stefan Beller, Nov 10, 2016
  42. 07/35 attr.c: simplify macroexpand_one()Stefan Beller, Nov 10, 2016
  43. 04/35 attr.c: explain the lack of attr-name syntax check in parse_attr()Stefan Beller, Nov 10, 2016

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