Re: [PATCH 2/2] read-cache: use time_t instead of unsigned long

From: Junio C Hamano <gitster@pobox.com>
Date: Nov 12, 2018, 10:53 UTC
Message-ID: <xmqqftw61sa0.fsf@gitster-ct.c.googlers.com>
In-Reply-To: <20181112084031.11769-3-carenas@gmail.com>

Carlo Marcelo Arenas Belón  <carenas@gmail.com> writes:

Show 28 quoted lines

> b968372279 ("read-cache: unlink old sharedindex files", 2017-03-06)
> introduced get_shared_index_expire_date using unsigned long to track
> the modification times of a shared index.
>
> dddbad728c ("timestamp_t: a new data type for timestamps", 2017-04-26)
> shows why that might problematic so move to time_t instead.
>
> Signed-off-by: Carlo Marcelo Arenas Belón <carenas@gmail.com>
> ---
>  read-cache.c | 6 +++---
>  1 file changed, 3 insertions(+), 3 deletions(-)
>
> diff --git a/read-cache.c b/read-cache.c
> index 7b1354d759..5525d8e679 100644
> --- a/read-cache.c
> +++ b/read-cache.c
> @@ -2625,9 +2625,9 @@ static int write_split_index(struct index_state *istate,
>  
>  static const char *shared_index_expire = "2.weeks.ago";
>  
> -static unsigned long get_shared_index_expire_date(void)
> +static time_t get_shared_index_expire_date(void)
>  {
> -	static unsigned long shared_index_expire_date;
> +	static time_t shared_index_expire_date;
>  	static int shared_index_expire_date_prepared;
>  
>  	if (!shared_index_expire_date_prepared) {

After this line, the post-context reads like this:

		git_config_get_expiry("splitindex.sharedindexexpire",
				      &shared_index_expire);
		shared_index_expire_date = approxidate(shared_index_expire);
		shared_index_expire_date_prepared = 1;
	}

	return shared_index_expire_date;

Given that the function returns the value obtained from approxidate(), which is approxidate_careful() in disguise, time_t is not as appropriate as timestamp_t, no?

IOW, what if time_t were narrower than timestamp_t?

Show 9 quoted lines

> @@ -2643,7 +2643,7 @@ static unsigned long get_shared_index_expire_date(void)
>  static int should_delete_shared_index(const char *shared_index_path)
>  {
>  	struct stat st;
> -	unsigned long expiration;
> +	time_t expiration;
>  
>  	/* Check timestamp */
>  	expiration = get_shared_index_expire_date();