On Fri, Aug 25, 2023 at 03:24:19PM +0200, Thomas Haller wrote:
> When we parse/output a larger set of data, we should only call time()
> once. With every call of time(), the value keeps ticking (and is subject
> to time reset). Previously, one parse/output operation will make
> decisions on potentially different timestamps.
>
> Add a cache to the parse/output context, and only fetch time() once
> per operation.
>
> Signed-off-by: Thomas Haller <thaller@xxxxxxxxxx>
> ---
> include/datatype.h | 6 ++++++
> src/datatype.c | 16 ++++++++++++++++
> src/meta.c | 4 ++--
> 3 files changed, 24 insertions(+), 2 deletions(-)
>
> diff --git a/include/datatype.h b/include/datatype.h
> index 79d996edd348..abd093765703 100644
> --- a/include/datatype.h
> +++ b/include/datatype.h
> @@ -2,6 +2,7 @@
> #define NFTABLES_DATATYPE_H
>
> #include <json.h>
> +#include <time.h>
>
> /**
> * enum datatypes
> @@ -121,12 +122,17 @@ enum byteorder {
> struct expr;
>
> struct ops_cache {
> + time_t time;
> + bool has_time;
> };
>
> #define CTX_CACHE_INIT() \
> { \
> + .has_time = false, \
> }
>
> +extern time_t ops_cache_get_time(struct ops_cache *cache);
> +
> /**
> * enum datatype_flags
> *
> diff --git a/src/datatype.c b/src/datatype.c
> index dd6a5fbf5df8..933d832c4f4d 100644
> --- a/src/datatype.c
> +++ b/src/datatype.c
> @@ -35,6 +35,22 @@
>
> #include <netinet/ip_icmp.h>
>
> +time_t ops_cache_get_time(struct ops_cache *cache)
> +{
> + time_t t;
> +
> + if (!cache || !cache->has_time) {
> + t = time(NULL);
> + if (cache) {
> + cache->has_time = true;
> + cache->time = time(NULL);
> + }
> + } else
> + t = cache->time;
> +
> + return t;
> +}
> +
> static const struct datatype *datatypes[TYPE_MAX + 1] = {
> [TYPE_INVALID] = &invalid_type,
> [TYPE_VERDICT] = &verdict_type,
> diff --git a/src/meta.c b/src/meta.c
> index 4f383269d032..1d853b219fe6 100644
> --- a/src/meta.c
> +++ b/src/meta.c
> @@ -496,7 +496,7 @@ static void hour_type_print(const struct expr *expr, struct output_ctx *octx)
> time_t ts;
>
> /* Obtain current tm, so that we can add tm_gmtoff */
> - ts = time(NULL);
> + ts = ops_cache_get_time(octx->ops_cache);
Following the idea of adding a specific time cache, I'd suggest:
ts = nft_time_get(...);
or similar.
> if (ts != ((time_t) -1) && localtime_r(&ts, &cur_tm))
> seconds = (seconds + cur_tm.tm_gmtoff) % SECONDS_PER_DAY;
>
> @@ -534,7 +534,7 @@ static struct error_record *hour_type_parse(struct parse_ctx *ctx,
> result = 0;
>
> /* Obtain current tm, so that we can substract tm_gmtoff */
> - ts = time(NULL);
> + ts = ops_cache_get_time(ctx->ops_cache);
> if (ts != ((time_t) -1) && localtime_r(&ts, &cur_tm_data))
> cur_tm = &cur_tm_data;
> else
> --
> 2.41.0
>
