From 7d42ec547cb8edea8cb1c527a646cfd21aa1c295 Mon Sep 17 00:00:00 2001 From: Junio C Hamano Date: Fri, 27 Jan 2017 18:01:53 -0800 Subject: attr.c: outline the future plans by heavily commenting Signed-off-by: Junio C Hamano Signed-off-by: Stefan Beller Signed-off-by: Brandon Williams Signed-off-by: Junio C Hamano diff --git a/attr.c b/attr.c index 8026d68..50e5ee3 100644 --- a/attr.c +++ b/attr.c @@ -30,6 +30,11 @@ static const char git_attr__unknown[] = "(builtin)unknown"; #define DEBUG_ATTR 0 #endif +/* + * NEEDSWORK: the global dictionary of the interned attributes + * must stay a singleton even after we become thread-ready. + * Access to these must be surrounded with mutex when it happens. + */ struct git_attr { struct git_attr *next; unsigned h; @@ -39,10 +44,19 @@ struct git_attr { char name[FLEX_ARRAY]; }; static int attr_nr; +static struct git_attr *(git_attr_hash[HASHSIZE]); + +/* + * NEEDSWORK: maybe-real, maybe-macro are not property of + * an attribute, as it depends on what .gitattributes are + * read. Once we introduce per git_attr_check attr_stack + * and check_all_attr, the optimization based on them will + * become unnecessary and can go away. So is this variable. + */ static int cannot_trust_maybe_real; +/* NEEDSWORK: This will become per git_attr_check */ static struct git_attr_check *check_all_attr; -static struct git_attr *(git_attr_hash[HASHSIZE]); const char *git_attr_name(const struct git_attr *attr) { @@ -102,6 +116,11 @@ static struct git_attr *git_attr_internal(const char *name, int len) a->maybe_real = 0; git_attr_hash[pos] = a; + /* + * NEEDSWORK: per git_attr_check check_all_attr + * will be initialized a lot more lazily, not + * like this, and not here. + */ REALLOC_ARRAY(check_all_attr, attr_nr); check_all_attr[a->attr_nr].attr = a; check_all_attr[a->attr_nr].value = ATTR__UNKNOWN; @@ -318,6 +337,7 @@ fail_return: * .gitignore file and info/excludes file as a fallback. */ +/* NEEDSWORK: This will become per git_attr_check */ static struct attr_stack { struct attr_stack *prev; char *origin; @@ -382,6 +402,24 @@ static struct attr_stack *read_attr_from_array(const char **list) return res; } +/* + * NEEDSWORK: these two are tricky. The callers assume there is a + * single, system-wide global state "where we read attributes from?" + * and when the state is flipped by calling git_attr_set_direction(), + * attr_stack is discarded so that subsequent attr_check will lazily + * read from the right place. And they do not know or care who called + * by them uses the attribute subsystem, hence have no knowledge of + * existing git_attr_check instances or future ones that will be + * created). + * + * Probably we need a thread_local that holds these two variables, + * and a list of git_attr_check instances (which need to be maintained + * by hooking into git_attr_check_alloc(), git_attr_check_initl(), and + * git_attr_check_clear(). Then git_attr_set_direction() updates the + * fields in that thread_local for these two variables, iterate over + * all the active git_attr_check instances and discard the attr_stack + * they hold. Yuck, but it sounds doable. + */ static enum git_attr_direction direction; static struct index_state *use_index; -- cgit v0.10.2-6-g49f6