Subject: Re: [PATCH/RFC 4/4] attr: avoid heavy work when we know the specified attr is not defined

From: Junio C Hamano <[email-masked]>
Date: Mon, 15 Dec 2014 09:30:35 -0800

Duy Nguyen <[email-masked]> writes:

> On Tue, Dec 09, 2014 at 04:18:57PM -0800, Junio C Hamano wrote:
> ...
>> I smell that a much better split is possible.
>> ...
>
> Something like this? Definitely looks better.

Yeah, I was lazy and did not try it myself to see what the end
result would look like when I commented, but doing it this way
avoids needless repetitions.

The comment block before the collect_*_attrs function need to be
adjusted to match the updated behaviour, though.

Thanks.

> -- 8< --
> diff --git a/attr.c b/attr.c
> index b80e52b..0f828e3 100644
> --- a/attr.c
> +++ b/attr.c
> @@ -33,9 +33,11 @@ struct git_attr {
>  	unsigned h;
>  	int attr_nr;
>  	int maybe_macro;
> +	int maybe_real;
>  	char name[FLEX_ARRAY];
>  };
>  static int attr_nr;
> +static int cannot_trust_maybe_real;
>  
>  static struct git_attr_check *check_all_attr;
>  static struct git_attr *(git_attr_hash[HASHSIZE]);
> @@ -97,6 +99,7 @@ static struct git_attr *git_attr_internal(const char *name, int len)
>  	a->next = git_attr_hash[pos];
>  	a->attr_nr = attr_nr++;
>  	a->maybe_macro = 0;
> +	a->maybe_real = 0;
>  	git_attr_hash[pos] = a;
>  
>  	REALLOC_ARRAY(check_all_attr, attr_nr);
> @@ -269,6 +272,10 @@ static struct match_attr *parse_attr_line(const char *line, const char *src,
>  	/* Second pass to fill the attr_states */
>  	for (cp = states, i = 0; *cp; i++) {
>  		cp = parse_attr(src, lineno, cp, &(res->state[i]));
> +		if (!is_macro)
> +			res->state[i].attr->maybe_real = 1;
> +		if (res->state[i].attr->maybe_macro)
> +			cannot_trust_maybe_real = 1;
>  	}
>  
>  	return res;
> @@ -713,7 +720,9 @@ static int macroexpand_one(int nr, int rem)
>   * Collect all attributes for path into the array pointed to by
>   * check_all_attr.
>   */
> -static void collect_all_attrs(const char *path)
> +static void collect_some_attrs(const char *path, int num,
> +			       struct git_attr_check *check)
> +
>  {
>  	struct attr_stack *stk;
>  	int i, pathlen, rem, dirlen;
> @@ -736,6 +745,19 @@ static void collect_all_attrs(const char *path)
>  	prepare_attr_stack(path, dirlen);
>  	for (i = 0; i < attr_nr; i++)
>  		check_all_attr[i].value = ATTR__UNKNOWN;
> +	if (num && !cannot_trust_maybe_real) {
> +		rem = 0;
> +		for (i = 0; i < num; i++) {
> +			if (!check[i].attr->maybe_real) {
> +				struct git_attr_check *c;
> +				c = check_all_attr + check[i].attr->attr_nr;
> +				c->value = ATTR__UNSET;
> +				rem++;
> +			}
> +		}
> +		if (rem == num)
> +			return;
> +	}
>  
>  	rem = attr_nr;
>  	for (stk = attr_stack; 0 < rem && stk; stk = stk->prev)
> @@ -746,7 +768,7 @@ int git_check_attr(const char *path, int num, struct git_attr_check *check)
>  {
>  	int i;
>  
> -	collect_all_attrs(path);
> +	collect_some_attrs(path, num, check);
>  
>  	for (i = 0; i < num; i++) {
>  		const char *value = check_all_attr[check[i].attr->attr_nr].value;
> @@ -762,7 +784,7 @@ int git_all_attrs(const char *path, int *num, struct git_attr_check **check)
>  {
>  	int i, count, j;
>  
> -	collect_all_attrs(path);
> +	collect_some_attrs(path, 0, NULL);
>  
>  	/* Count the number of attributes that are set. */
>  	count = 0;
> -- 8< --