Re: 2.18.0 Regression: packing performance and effectiveness
- From
Junio C Hamano <gitster@pobox.com>
- Date
- Jul 19, 2018, 19:25 UTC
- Message-ID
- <xmqqlga7do3r.fsf@gitster-ct.c.googlers.com>
- In-Reply-To
- <20180719151640.GA24997@duynguyen.home>
Duy Nguyen <pclouds@gmail.com> writes:
Show 32 quoted lines
> @@ -330,20 +330,27 @@ static inline void oe_set_size(struct packing_data *pack,
> static inline unsigned long oe_delta_size(struct packing_data *pack,
> const struct object_entry *e)
> {
> - if (e->delta_size_valid)
> + if (!pack->delta_size)
> return e->delta_size_;
> - return oe_size(pack, e);
> + return pack->delta_size[e - pack->objects];
> }
>
> +void oe_prepare_delta_size_array(struct packing_data *pack);
> static inline void oe_set_delta_size(struct packing_data *pack,
> struct object_entry *e,
> unsigned long size)
> {
> e->delta_size_ = size;
> - e->delta_size_valid = e->delta_size_ == size;
> - if (!e->delta_size_valid && size != oe_size(pack, e))
> - BUG("this can only happen in check_object() "
> - "where delta size is the same as entry size");
> + if (!pack->delta_size && e->delta_size_ == size)
> + return;
> + /*
> + * We have had at least one delta size exceeding OE_DELTA_SIZE_BITS
> + * limit. delta_size_ will not be used anymore. All delta sizes are now
> + * from the delta_size[] array.
> + */
> + if (!pack->delta_size)
> + oe_prepare_delta_size_array(pack);
> + pack->delta_size[e - pack->objects] = size;
> }Imagine that you create a delta and set its size (which happens to fit in the entry) and then create another whose size does not fit in the entry. How does oe_delta_size() know not to look at pack->delta_size[] and instead look at e->delta_size_ when it wants to know the delta for the first one? IOW, shouldn't there be a "backfill" procedure when oe_set_delta_size() notices that we now switch to pack->delta_size[] array?