[PATCH 2/7] rewrite git_config() to use the config-set API

[Tanay Abhra <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>
---
 config.c | 29 +++++++++++++++++++++++++++--
 1 file changed, 27 insertions(+), 2 deletions(-)

diff --git a/config.c b/config.c
index 6db8f97..a7fb9a4 100644
--- a/config.c
+++ b/config.c
@@ -1232,11 +1232,36 @@ int git_config_with_options(config_fn_t fn, void *data,
 	return ret;
 }
 
-int git_config(config_fn_t fn, void *data)
+static int git_config_raw(config_fn_t fn, void *data)
 {
 	return git_config_with_options(fn, data, NULL, 1);
 }
 
+static int configset_iter(struct config_set *cs, config_fn_t fn, void *data)
+{
+	int i;
+	struct string_list *strptr;
+	struct config_set_element *entry;
+	struct hashmap_iter iter;
+	hashmap_iter_init(&cs->config_hash, &iter);
+	while ((entry = hashmap_iter_next(&iter))) {
+		strptr = &entry->value_list;
+		for (i = 0; i < strptr->nr; i++) {
+			if (fn(entry->key, strptr->items[i].string, data) < 0)
+				die("bad config file line in (TODO: file/line info)");
+		}
+	}
+	return 0;
+}
+
+static void git_config_check_init(void);
+
+int git_config(config_fn_t fn, void *data)
+{
+	git_config_check_init();
+	return 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;
@@ -1418,7 +1443,7 @@ 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)
-- 
1.9.0.GIT