[Asterisk-code-review] config: Speed up config template lookup (asterisk[13])

[Sean Bright]

Sean Bright has uploaded this change for review. ( https://gerrit.asterisk.org/7408


Change subject: config: Speed up config template lookup
......................................................................

config: Speed up config template lookup

ast_category_get() has an (undocumented) implementation detail where it
tries to match the category name first by an explicit pointer comparison
and if that fails falls back to a normal match.

When initially building an ast_config during ast_config_load, this
pointer comparison can never succeed, but we will end up iterating all
categories twice. As the number of categories using a template
increases, this dual looping becomes quite expensive. So we pass a flag
to category_get_sep() indicating if a pointer match is even possible
before trying to do so, saving us a full pass over the list of current
categories.

In my tests, loading a file with 3 template categories and 12000
additional categories that use those 3 templates (this file configures
4000 PJSIP endpoints with AOR & Auth) takes 1.2 seconds. After this
change, that drops to 22ms.

Change-Id: I59b95f288e11eb6bb34f31ce4cc772136b275e4a
---
M main/config.c
1 file changed, 9 insertions(+), 7 deletions(-)



  git pull ssh://gerrit.asterisk.org:29418/asterisk refs/changes/08/7408/1

diff --git a/main/config.c b/main/config.c
index 9be7581..e686c23 100644
--- a/main/config.c
+++ b/main/config.c
@@ -988,13 +988,15 @@
 }
 
 static struct ast_category *category_get_sep(const struct ast_config *config,
-	const char *category_name, const char *filter, char sep)
+	const char *category_name, const char *filter, char sep, char pointer_match_possible)
 {
 	struct ast_category *cat;
 
-	for (cat = config->root; cat; cat = cat->next) {
-		if (cat->name == category_name && does_category_match(cat, category_name, filter, sep)) {
-			return cat;
+	if (pointer_match_possible) {
+		for (cat = config->root; cat; cat = cat->next) {
+			if (cat->name == category_name && does_category_match(cat, category_name, filter, sep)) {
+				return cat;
+			}
 		}
 	}
 
@@ -1010,7 +1012,7 @@
 struct ast_category *ast_category_get(const struct ast_config *config,
 	const char *category_name, const char *filter)
 {
-	return category_get_sep(config, category_name, filter, ',');
+	return category_get_sep(config, category_name, filter, ',', 1);
 }
 
 const char *ast_category_get_name(const struct ast_category *category)
@@ -1794,7 +1796,7 @@
 					if (cur[1] != ',') {
 						filter = &cur[1];
 					}
-					*cat = category_get_sep(cfg, catname, filter, '&');
+					*cat = category_get_sep(cfg, catname, filter, '&', 0);
 					if (!(*cat)) {
 						if (newcat) {
 							ast_category_destroy(newcat);
@@ -1812,7 +1814,7 @@
 				} else {
 					struct ast_category *base;
 
-					base = ast_category_get(cfg, cur, "TEMPLATES=include");
+					base = category_get_sep(cfg, cur, "TEMPLATES=include", ',', 0);
 					if (!base) {
 						if (newcat) {
 							ast_category_destroy(newcat);

-- 
To view, visit https://gerrit.asterisk.org/7408
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Gerrit-Project: asterisk
Gerrit-Branch: 13
Gerrit-MessageType: newchange
Gerrit-Change-Id: I59b95f288e11eb6bb34f31ce4cc772136b275e4a
Gerrit-Change-Number: 7408
Gerrit-PatchSet: 1
Gerrit-Owner: Sean Bright <sean.bright at gmail.com>
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