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[PATCH 28/36] attr: keep attr stack for each check

From
Stefan Beller <sbeller@google.com>
Date
Oct 22, 2016, 23:32 UTC
Message-ID
<20161022233225.8883-29-sbeller@google.com>
In-Reply-To
<20161022233225.8883-1-sbeller@google.com>

Instead of having a global attr stack, attach the stack to each check. This allows to use the attr in a multithreaded way.

Signed-off-by: Stefan Beller <sbeller@google.com>
---
 attr.c    | 101 +++++++++++++++++++++++++++++++++++++++-----------------------
 attr.h    |   4 ++-
 hashmap.h |   2 ++
 3 files changed, 69 insertions(+), 38 deletions(-)
diff --git a/attr.c b/attr.c
index 89ae155..b65437d 100644
--- a/attr.c
+++ b/attr.c
@@ -372,15 +372,17 @@ static struct match_attr *parse_attr_line(const char *line, const char *src,
  * .gitignore file and info/excludes file as a fallback.
  */
 
-/* NEEDSWORK: This will become per git_attr_check */
-static struct attr_stack {
+struct attr_stack {
 	struct attr_stack *prev;
 	char *origin;
 	size_t originlen;
 	unsigned num_matches;
 	unsigned alloc;
 	struct match_attr **attrs;
-} *attr_stack;
+};
+
+struct hashmap all_attr_stacks;
+int all_attr_stacks_init;
 
 static void free_attr_elem(struct attr_stack *e)
 {
@@ -561,11 +563,23 @@ static void debug_set(const char *what, const char *match, struct git_attr *attr
 
 static void drop_attr_stack(void)
 {
-	while (attr_stack) {
-		struct attr_stack *elem = attr_stack;
-		attr_stack = elem->prev;
-		free_attr_elem(elem);
+	struct hashmap_iter iter;
+	struct git_attr_check *check;
+
+	attr_lock();
+	if (!all_attr_stacks_init) {
+		attr_unlock();
+		return;
 	}
+	hashmap_iter_init(&all_attr_stacks, &iter);
+	while ((check = hashmap_iter_next(&iter))) {
+		while (check->attr_stack) {
+			struct attr_stack *elem = check->attr_stack;
+			check->attr_stack = elem->prev;
+			free_attr_elem(elem);
+		}
+	}
+	attr_unlock();
 }
 
 static const char *git_etc_gitattributes(void)
@@ -595,40 +609,42 @@ static void push_stack(struct attr_stack **attr_stack_p,
 	}
 }
 
-static void bootstrap_attr_stack(void)
+static void bootstrap_attr_stack(struct git_attr_check *check)
 {
 	struct attr_stack *elem;
 
-	if (attr_stack)
+	if (check->attr_stack)
 		return;
 
-	push_stack(&attr_stack, read_attr_from_array(builtin_attr), NULL, 0);
+	push_stack(&check->attr_stack,
+		   read_attr_from_array(builtin_attr), NULL, 0);
 
 	if (git_attr_system())
-		push_stack(&attr_stack,
+		push_stack(&check->attr_stack,
 			   read_attr_from_file(git_etc_gitattributes(), 1),
 			   NULL, 0);
 
 	if (!git_attributes_file)
 		git_attributes_file = xdg_config_home("attributes");
 	if (git_attributes_file)
-		push_stack(&attr_stack,
+		push_stack(&check->attr_stack,
 			   read_attr_from_file(git_attributes_file, 1),
 			   NULL, 0);
 
 	if (!is_bare_repository() || direction == GIT_ATTR_INDEX) {
 		elem = read_attr(GITATTRIBUTES_FILE, 1);
-		push_stack(&attr_stack, elem, xstrdup(""), 0);
+		push_stack(&check->attr_stack, elem, xstrdup(""), 0);
 		debug_push(elem);
 	}
 
 	elem = read_attr_from_file(git_path_info_attributes(), 1);
 	if (!elem)
 		elem = xcalloc(1, sizeof(*elem));
-	push_stack(&attr_stack, elem, NULL, 0);
+	push_stack(&check->attr_stack, elem, NULL, 0);
 }
 
-static void prepare_attr_stack(const char *path, int dirlen)
+static void prepare_attr_stack(const char *path, int dirlen,
+			       struct git_attr_check *check)
 {
 	struct attr_stack *elem, *info;
 	const char *cp;
@@ -648,13 +664,13 @@ static void prepare_attr_stack(const char *path, int dirlen)
 	 * .gitattributes in deeper directories to shallower ones,
 	 * and finally use the built-in set as the default.
 	 */
-	bootstrap_attr_stack();
+	bootstrap_attr_stack(check);
 
 	/*
 	 * Pop the "info" one that is always at the top of the stack.
 	 */
-	info = attr_stack;
-	attr_stack = info->prev;
+	info = check->attr_stack;
+	check->attr_stack = info->prev;
 
 	/*
 	 * Pop the ones from directories that are not the prefix of
@@ -662,17 +678,17 @@ static void prepare_attr_stack(const char *path, int dirlen)
 	 * the root one (whose origin is an empty string "") or the builtin
 	 * one (whose origin is NULL) without popping it.
 	 */
-	while (attr_stack->origin) {
-		int namelen = strlen(attr_stack->origin);
+	while (check->attr_stack->origin) {
+		int namelen = strlen(check->attr_stack->origin);
 
-		elem = attr_stack;
+		elem = check->attr_stack;
 		if (namelen <= dirlen &&
 		    !strncmp(elem->origin, path, namelen) &&
 		    (!namelen || path[namelen] == '/'))
 			break;
 
 		debug_pop(elem);
-		attr_stack = elem->prev;
+		check->attr_stack = elem->prev;
 		free_attr_elem(elem);
 	}
 
@@ -688,9 +704,9 @@ static void prepare_attr_stack(const char *path, int dirlen)
 		 */
 		struct strbuf pathbuf = STRBUF_INIT;
 
-		assert(attr_stack->origin);
+		assert(check->attr_stack->origin);
 		while (1) {
-			size_t len = strlen(attr_stack->origin);
+			size_t len = strlen(check->attr_stack->origin);
 			char *origin;
 
 			if (dirlen <= len)
@@ -704,7 +720,7 @@ static void prepare_attr_stack(const char *path, int dirlen)
 			elem = read_attr(pathbuf.buf, 0);
 			strbuf_setlen(&pathbuf, cp - path);
 			origin = strbuf_detach(&pathbuf, &len);
-			push_stack(&attr_stack, elem, origin, len);
+			push_stack(&check->attr_stack, elem, origin, len);
 			debug_push(elem);
 		}
 
@@ -714,7 +730,13 @@ static void prepare_attr_stack(const char *path, int dirlen)
 	/*
 	 * Finally push the "info" one at the top of the stack.
 	 */
-	push_stack(&attr_stack, info, NULL, 0);
+	push_stack(&check->attr_stack, info, NULL, 0);
+	if (!all_attr_stacks_init) {
+		hashmap_init(&all_attr_stacks, NULL, 0);
+		all_attr_stacks_init = 1;
+	}
+	if (!hashmap_get(&all_attr_stacks, check, NULL))
+		hashmap_put(&all_attr_stacks, check);
 }
 
 static int path_matches(const char *pathname, int pathlen,
@@ -740,9 +762,10 @@ static int path_matches(const char *pathname, int pathlen,
 			      pattern, prefix, pat->patternlen, pat->flags);
 }
 
-static int macroexpand_one(int attr_nr, int rem);
+static int macroexpand_one(int attr_nr, int rem, struct git_attr_check *check);
 
-static int fill_one(const char *what, struct match_attr *a, int rem)
+static int fill_one(const char *what, struct match_attr *a, int rem,
+		    struct git_attr_check *check)
 {
 	struct git_attr_check_elem *celem = check_all_attr;
 	int i;
@@ -758,14 +781,14 @@ static int fill_one(const char *what, struct match_attr *a, int rem)
 				  attr, v);
 			*n = v;
 			rem--;
-			rem = macroexpand_one(attr->attr_nr, rem);
+			rem = macroexpand_one(attr->attr_nr, rem, check);
 		}
 	}
 	return rem;
 }
 
 static int fill(const char *path, int pathlen, int basename_offset,
-		struct attr_stack *stk, int rem)
+		struct attr_stack *stk, int rem, struct git_attr_check *check)
 {
 	int i;
 	const char *base = stk->origin ? stk->origin : "";
@@ -776,12 +799,12 @@ static int fill(const char *path, int pathlen, int basename_offset,
 			continue;
 		if (path_matches(path, pathlen, basename_offset,
 				 &a->u.pat, base, stk->originlen))
-			rem = fill_one("fill", a, rem);
+			rem = fill_one("fill", a, rem, check);
 	}
 	return rem;
 }
 
-static int macroexpand_one(int nr, int rem)
+static int macroexpand_one(int nr, int rem, struct git_attr_check *check)
 {
 	struct attr_stack *stk;
 	int i;
@@ -790,13 +813,13 @@ static int macroexpand_one(int nr, int rem)
 	    !check_all_attr[nr].attr->maybe_macro)
 		return rem;
 
-	for (stk = attr_stack; stk; stk = stk->prev) {
+	for (stk = check->attr_stack; stk; stk = stk->prev) {
 		for (i = stk->num_matches - 1; 0 <= i; i--) {
 			struct match_attr *ma = stk->attrs[i];
 			if (!ma->is_macro)
 				continue;
 			if (ma->u.attr->attr_nr == nr)
-				return fill_one("expand", ma, rem);
+				return fill_one("expand", ma, rem, check);
 		}
 	}
 
@@ -845,7 +868,7 @@ static void collect_some_attrs(const char *path, int pathlen,
 		dirlen = 0;
 	}
 
-	prepare_attr_stack(path, dirlen);
+	prepare_attr_stack(path, dirlen, check);
 
 	for (i = 0; i < attr_nr; i++)
 		check_all_attr[i].value = ATTR__UNKNOWN;
@@ -865,8 +888,8 @@ static void collect_some_attrs(const char *path, int pathlen,
 	}
 
 	rem = attr_nr;
-	for (stk = attr_stack; 0 < rem && stk; stk = stk->prev)
-		rem = fill(path, pathlen, basename_offset, stk, rem);
+	for (stk = check->attr_stack; 0 < rem && stk; stk = stk->prev)
+		rem = fill(path, pathlen, basename_offset, stk, rem, check);
 
 	if (collect_all) {
 		int check_nr = 0, check_alloc = 0;
@@ -898,6 +921,8 @@ static int git_check_attrs(const char *path, int pathlen,
 {
 	int i;
 
+	attr_lock();
+
 	collect_some_attrs(path, pathlen, check, &result, 0);
 
 	for (i = 0; i < check->check_nr; i++) {
@@ -907,6 +932,8 @@ static int git_check_attrs(const char *path, int pathlen,
 		result[i].value = value;
 	}
 
+	attr_unlock();
+
 	return 0;
 }
 
diff --git a/attr.h b/attr.h
index 219b8c7..60d90f2 100644
--- a/attr.h
+++ b/attr.h
@@ -32,12 +32,14 @@ extern const char git_attr__false[];
 #define ATTR_UNSET(v) ((v) == NULL)
 
 struct git_attr_check {
+	struct hashmap_entry entry;
 	int finalized;
 	int check_nr;
 	int check_alloc;
 	const struct git_attr **attr;
+	struct attr_stack *attr_stack;
 };
-#define GIT_ATTR_CHECK_INIT {0, 0, 0, NULL}
+#define GIT_ATTR_CHECK_INIT {HASHMAP_ENTRY_INIT, 0, 0, 0, NULL, NULL}
 
 struct git_attr_result {
 	const char *value;
diff --git a/hashmap.h b/hashmap.h
index ab7958a..d247c62 100644
--- a/hashmap.h
+++ b/hashmap.h
@@ -31,6 +31,8 @@ struct hashmap_entry {
 	unsigned int hash;
 };
 
+#define HASHMAP_ENTRY_INIT {NULL, 0}
+
 typedef int (*hashmap_cmp_fn)(const void *entry, const void *entry_or_key,
 		const void *keydata);
 
-- 
2.10.1.508.g6572022
Previous: Stefan BellerNext: Ramsay Jones
Message 62 of 81 in “[PATCHv2 00/36] Revamping the attr subsystem!”
  1. Stefan BellerOct 22, 2016
  2. 01/36 commit.c: use strchrnul() to scan for one lineStefan Beller, Oct 22, 2016
  3. 02/36 attr.c: use strchrnul() to scan for one lineStefan Beller, Oct 22, 2016
  4. 04/36 attr.c: explain the lack of attr-name syntax check in parse_attr()Stefan Beller, Oct 22, 2016
  5. 06/36 attr.c: mark where #if DEBUG ends more clearlyStefan Beller, Oct 22, 2016
  6. 05/36 attr.c: complete a sentence in a commentStefan Beller, Oct 22, 2016
  7. 03/36 attr.c: update a stale comment on "struct match_attr"Stefan Beller, Oct 22, 2016
  8. 09/36 attr.c: plug small leak in parse_attr_line()Stefan Beller, Oct 22, 2016
  9. 07/36 attr.c: simplify macroexpand_one()Stefan Beller, Oct 22, 2016
  10. 10/36 attr: rename function and struct related to checking attributesStefan Beller, Oct 22, 2016
  11. 08/36 attr.c: tighten constness around "git_attr" structureStefan Beller, Oct 22, 2016
  12. 12/36 attr: convert git_all_attrs() to use "struct git_attr_check"Stefan Beller, Oct 22, 2016
  13. 14/36 attr: retire git_check_attrs() APIStefan Beller, Oct 22, 2016
  14. 11/36 attr: (re)introduce git_check_attr() and struct git_attr_checkStefan Beller, Oct 22, 2016
  15. 16/36 attr: add counted string version of git_attr()Stefan Beller, Oct 22, 2016
  16. 17/36 attr: expose validity check for attribute namesStefan Beller, Oct 22, 2016
  17. Ramsay JonesOct 23, 2016
  18. Stefan BellerOct 24, 2016
  19. Stefan BellerOct 27, 2016
  20. attr: expose error reporting function for invalid attribute namesStefan Beller, Oct 26, 2016
  21. 18/36 attr: support quoting pathname patterns in C styleStefan Beller, Oct 22, 2016
  22. 19/36 attr.c: add push_stack() helperStefan Beller, Oct 22, 2016
  23. 21/36 attr.c: rename a local variable checkStefan Beller, Oct 22, 2016
  24. 15/36 attr: add counted string version of git_check_attr()Stefan Beller, Oct 22, 2016
  25. 22/36 attr.c: correct ugly hack for git_all_attrs()Stefan Beller, Oct 22, 2016
  26. 23/36 attr.c: introduce empty_attr_check_elems()Stefan Beller, Oct 22, 2016
  27. 20/36 attr.c: pass struct git_attr_check down the callchainStefan Beller, Oct 22, 2016
  28. 27/36 attr: convert to new threadsafe APIStefan Beller, Oct 22, 2016
  29. Junio C HamanoOct 24, 2016
  30. Stefan BellerOct 24, 2016
  31. Duy NguyenOct 26, 2016
  32. Johannes SchindelinOct 26, 2016
  33. Simon RuderichOct 26, 2016
  34. Jeff KingOct 26, 2016
  35. Stefan BellerOct 26, 2016
  36. Jeff KingOct 26, 2016
  37. Johannes SixtOct 26, 2016
  38. Jeff KingOct 26, 2016
  39. Johannes SixtOct 26, 2016
  40. Stefan BellerOct 26, 2016
  41. 1/2 attr: convert to new threadsafe APIStefan Beller, Oct 26, 2016
  42. Junio C HamanoOct 26, 2016
  43. Stefan BellerOct 27, 2016
  44. Junio C HamanoOct 27, 2016
  45. Stefan BellerOct 27, 2016
  46. Junio C HamanoOct 27, 2016
  47. Junio C HamanoOct 27, 2016
  48. Stefan BellerOct 27, 2016
  49. Junio C HamanoOct 27, 2016
  50. Junio C HamanoOct 27, 2016
  51. attr: convert to new threadsafe APIStefan Beller, Oct 27, 2016
  52. Johannes SchindelinOct 28, 2016
  53. Junio C HamanoOct 28, 2016
  54. Junio C HamanoOct 28, 2016
  55. Johannes SixtOct 28, 2016
  56. Stefan BellerOct 26, 2016
  57. Duy NguyenOct 26, 2016
  58. 26/36 attr: make git_check_attr_counted staticStefan Beller, Oct 22, 2016
  59. 30/36 pathspec: move long magic parsing out of prefix_pathspecStefan Beller, Oct 22, 2016
  60. 31/36 pathspec: move prefix check out of the inner loopStefan Beller, Oct 22, 2016
  61. 29/36 Documentation: fix a typoStefan Beller, Oct 22, 2016
  62. 28/36 attr: keep attr stack for each checkStefan Beller, Oct 22, 2016
  63. Ramsay JonesOct 23, 2016
  64. Stefan BellerOct 26, 2016
  65. Junio C HamanoOct 24, 2016
  66. Stefan BellerOct 24, 2016
  67. Junio C HamanoOct 24, 2016
  68. 25/36 attr.c: outline the future plans by heavily commentingStefan Beller, Oct 22, 2016
  69. 24/36 attr.c: always pass check[] to collect_some_attrs()Stefan Beller, Oct 22, 2016
  70. 36/36 completion: clone can initialize specific submodulesStefan Beller, Oct 22, 2016
  71. 35/36 clone: add --init-submodule=<pathspec> switchStefan Beller, Oct 22, 2016
  72. 34/36 submodule update: add `--init-default-path` switchStefan Beller, Oct 22, 2016
  73. 33/36 pathspec: allow escaped query valuesStefan Beller, Oct 22, 2016
  74. 32/36 pathspec: allow querying for attributesStefan Beller, Oct 22, 2016
  75. Duy NguyenOct 26, 2016
  76. Stefan BellerOct 27, 2016
  77. Junio C HamanoOct 27, 2016
  78. Duy NguyenNov 9, 2016
  79. Stefan BellerNov 9, 2016
  80. Junio C HamanoNov 9, 2016
  81. 13/36 attr: convert git_check_attrs() callers to use the new APIStefan Beller, Oct 22, 2016

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