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[PATCH v6 4/7] rewrite git_config() to use the config-set API

From
Tanay Abhra <tanayabh@gmail.com>
Date
Jul 31, 2014, 15:47 UTC
Message-ID
<1406821662-1570-5-git-send-email-tanayabh@gmail.com>
In-Reply-To
<1406821662-1570-1-git-send-email-tanayabh@gmail.com>

Of all the functions in `git_config*()` family, `git_config()` has the most invocations in the whole code base. Each `git_config()` invocation causes config file rereads which can be avoided using the config-set API.

Use the config-set API to rewrite `git_config()` to use the config caching layer to avoid config file rereads on each invocation during a git process lifetime. First invocation constructs the cache, and after that for each successive invocation, `git_config()` feeds values from the config cache instead of rereading the configuration files.

Signed-off-by: Tanay Abhra <tanayabh@gmail.com>
---
 cache.h                 | 24 +++++++++++++++++++++
 config.c                | 57 ++++++++++++++++++++++++++++++++++++++++++-------
 t/t4055-diff-context.sh |  2 +-
 3 files changed, 74 insertions(+), 9 deletions(-)
diff --git a/cache.h b/cache.h
index c61919d..4d3c6bd 100644
--- a/cache.h
+++ b/cache.h
@@ -8,6 +8,7 @@
 #include "gettext.h"
 #include "convert.h"
 #include "trace.h"
+#include "string-list.h"
 
 #include SHA1_HEADER
 #ifndef git_SHA_CTX
@@ -1351,9 +1352,32 @@ extern int parse_config_key(const char *var,
 			    const char **subsection, int *subsection_len,
 			    const char **key);
 
+struct config_set_element {
+	struct hashmap_entry ent;
+	char *key;
+	struct string_list value_list;
+};
+
+struct configset_list_item {
+	struct config_set_element *e;
+	int value_index;
+};
+
+/*
+ * the contents of the list are ordered according to their
+ * position in the config files and order of parsing the files.
+ * (i.e. key-value pair at the last position of .git/config will
+ * be at the last item of the list)
+ */
+struct configset_list {
+	struct configset_list_item *items;
+	unsigned int nr, alloc;
+};
+
 struct config_set {
 	struct hashmap config_hash;
 	int hash_initialized;
+	struct configset_list list;
 };
 
 extern void git_configset_init(struct config_set *cs);
diff --git a/config.c b/config.c
index ecbe14f..6b4dd65 100644
--- a/config.c
+++ b/config.c
@@ -35,12 +35,6 @@ struct config_source {
 	long (*do_ftell)(struct config_source *c);
 };
 
-struct config_set_element {
-	struct hashmap_entry ent;
-	char *key;
-	struct string_list value_list;
-};
-
 static struct config_source *cf;
 
 static int zlib_compression_seen;
@@ -1235,7 +1229,7 @@ struct key_value_info {
 	int linenr;
 };
 
-void git_config(config_fn_t fn, void *data)
+static void git_config_raw(config_fn_t fn, void *data)
 {
 	if (git_config_with_options(fn, data, NULL, 1) < 0)
 		/*
@@ -1252,6 +1246,39 @@ void git_config(config_fn_t fn, void *data)
 		die(_("unknown error occured while reading the configuration files"));
 }
 
+static void configset_iter(struct config_set *cs, config_fn_t fn, void *data)
+{
+	int i, value_index;
+	struct string_list *values;
+	struct config_set_element *entry;
+	struct configset_list *list = &cs->list;
+	struct key_value_info *kv_info;
+
+	for (i = 0; i < list->nr; i++) {
+		entry = list->items[i].e;
+		value_index = list->items[i].value_index;
+		values = &entry->value_list;
+		if (fn(entry->key, values->items[value_index].string, data) < 0) {
+			kv_info = values->items[value_index].util;
+			if (!kv_info->linenr)
+				die(_("unable to parse '%s' from command-line config"), entry->key);
+			else
+				die(_("bad config variable '%s' at file line %d in %s"),
+					entry->key,
+					kv_info->linenr,
+					kv_info->filename);
+		}
+	}
+}
+
+static void git_config_check_init(void);
+
+void git_config(config_fn_t fn, void *data)
+{
+	git_config_check_init();
+	configset_iter(&the_config_set, fn, data);
+}
+
 static struct config_set_element *configset_find_element(struct config_set *cs, const char *key)
 {
 	struct config_set_element k;
@@ -1278,6 +1305,7 @@ static int configset_add_value(struct config_set *cs, const char *key, const cha
 {
 	struct config_set_element *e;
 	struct string_list_item *si;
+	struct configset_list_item *l_item;
 	struct key_value_info *kv_info = xmalloc(sizeof(*kv_info));
 
 	e = configset_find_element(cs, key);
@@ -1293,6 +1321,12 @@ static int configset_add_value(struct config_set *cs, const char *key, const cha
 		hashmap_add(&cs->config_hash, e);
 	}
 	si = string_list_append_nodup(&e->value_list, value ? xstrdup(value) : NULL);
+
+	ALLOC_GROW(cs->list.items, cs->list.nr + 1, cs->list.alloc);
+	l_item = &cs->list.items[cs->list.nr++];
+	l_item->e = e;
+	l_item->value_index = e->value_list.nr - 1;
+
 	if (cf) {
 		kv_info->filename = strintern(cf->name);
 		kv_info->linenr = cf->linenr;
@@ -1316,6 +1350,9 @@ void git_configset_init(struct config_set *cs)
 {
 	hashmap_init(&cs->config_hash, (hashmap_cmp_fn)config_set_element_cmp, 0);
 	cs->hash_initialized = 1;
+	cs->list.nr = 0;
+	cs->list.alloc = 0;
+	cs->list.items = NULL;
 }
 
 void git_configset_clear(struct config_set *cs)
@@ -1332,6 +1369,10 @@ void git_configset_clear(struct config_set *cs)
 	}
 	hashmap_free(&cs->config_hash, 1);
 	cs->hash_initialized = 0;
+	free(cs->list.items);
+	cs->list.nr = 0;
+	cs->list.alloc = 0;
+	cs->list.items = NULL;
 }
 
 static int config_set_callback(const char *key, const char *value, void *cb)
@@ -1450,7 +1491,7 @@ static void git_config_check_init(void)
 	if (the_config_set.hash_initialized)
 		return;
 	git_configset_init(&the_config_set);
-	git_config(config_set_callback, &the_config_set);
+	git_config_raw(config_set_callback, &the_config_set);
 }
 
 void git_config_clear(void)
diff --git a/t/t4055-diff-context.sh b/t/t4055-diff-context.sh
index cd04543..741e080 100755
--- a/t/t4055-diff-context.sh
+++ b/t/t4055-diff-context.sh
@@ -79,7 +79,7 @@ test_expect_success 'non-integer config parsing' '
 test_expect_success 'negative integer config parsing' '
 	git config diff.context -1 &&
 	test_must_fail git diff 2>output &&
-	test_i18ngrep "bad config file" output
+	test_i18ngrep "bad config variable" output
 '
 
 test_expect_success '-U0 is valid, so is diff.context=0' '

-- 
1.9.0.GIT
Previous: Tanay AbhraNext: Tanay Abhra
Message 5 of 20 in “Rewrite `git_config()` using config-set API”
  1. 0/7 Rewrite `git_config()` using config-set APITanay Abhra, Jul 31, 2014
  2. 1/7 config.c: fix accuracy of line number in errorsTanay Abhra, Jul 31, 2014
  3. 2/7 add line number and file name info to `config_set`Tanay Abhra, Jul 31, 2014
  4. 3/7 change `git_config()` return value to voidTanay Abhra, Jul 31, 2014
  5. 4/7 rewrite git_config() to use the config-set APITanay Abhra, Jul 31, 2014
  6. 5/7 add a test for semantic errors in config filesTanay Abhra, Jul 31, 2014
  7. 6/7 config: add `git_die_config()` to the config-set APITanay Abhra, Jul 31, 2014
  8. Matthieu MoyJul 31, 2014
  9. Tanay AbhraJul 31, 2014
  10. Matthieu MoyJul 31, 2014
  11. Tanay AbhraJul 31, 2014
  12. Matthieu MoyJul 31, 2014
  13. Tanay AbhraJul 31, 2014
  14. Matthieu MoyJul 31, 2014
  15. Junio C HamanoJul 31, 2014
  16. Matthieu MoyAug 1, 2014
  17. Tanay AbhraAug 1, 2014
  18. Matthieu MoyAug 1, 2014
  19. 7/7 add tests for `git_config_get_string_const()`Tanay Abhra, Jul 31, 2014
  20. Matthieu MoyJul 31, 2014

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