Subject: Re: [PATCH] blame.c: prepare_lines should not call xrealloc for every line

From: Junio C Hamano <[email-masked]>
Date: Wed, 12 Feb 2014 11:36:44 -0800

David Kastrup <[email-masked]> writes:

> Making a single preparation run for counting the lines will avoid memory
> fragmentation.  Also, fix the allocated memory size which was wrong
> when sizeof(int *) != sizeof(int), and would have been too small
> for sizeof(int *) < sizeof(int), admittedly unlikely.
>
> Signed-off-by: David Kastrup <[email-masked]>
> ---

I think I took sizeof(int*)->sizeof(int) patch to the 'next' branch
already, which might have to conflict with this clean-up, but it
should be trivial to resolve.

Thanks for resending.  I was busy elsewhere (i.e. "no feedback" does
not mean "silent rejection" nor "silent agreement" at least from
me), and such a resend does help prevent patches fall thru cracks.

> diff --git a/builtin/blame.c b/builtin/blame.c
> index e44a6bb..1aefedf 100644
> --- a/builtin/blame.c
> +++ b/builtin/blame.c
> @@ -1772,25 +1772,41 @@ static int prepare_lines(struct scoreboard *sb)
>  {
>  	const char *buf = sb->final_buf;
>  	unsigned long len = sb->final_buf_size;
> +	const char *end = buf + len;
> +	const char *p;
> +	int *lineno;
> +	int num = 0, incomplete = 0;
>  
> +	for (p = buf;;) {
> +		p = memchr(p, '\n', end - p);
> +		if (p) {
> +			p++;
>  			num++;
> +			continue;
>  		}
> +		break;
>  	}
> +
> +	if (len && end[-1] != '\n')
> +		incomplete++; /* incomplete line at the end */
> +
> +	sb->lineno = xmalloc(sizeof(*sb->lineno) * (num + incomplete + 1));
> +	lineno = sb->lineno;
> +
> +	*lineno++ = 0;
> +	for (p = buf;;) {
> +		p = memchr(p, '\n', end - p);
> +		if (p) {
> +			p++;
> +			*lineno++ = p - buf;
> +			continue;
> +		}
> +		break;
> +	}
> +
> +	if (incomplete)
> +		*lineno++ = len;
> +
>  	sb->num_lines = num + incomplete;
>  	return sb->num_lines;
>  }