Stop calling getLastPageNumber() when not necessary

[midlan]

Community, what do you think?

When the $this->_curPage is 1 the $this->getLastPageNumber() is called. In eav collection it is slow operation, because $this->getSize() is called inside.

[colinmollenhour]

Very nice optimization!

[midlan]

I've got feedback that it may break some category listing. At this moment I don't see the reason, I will try to research.

[Flyingmana]

@midlan did you find anything out?

[midlan]

@Flyingmana I didn't, my Magento instance is pretty modified and I am not what broken the category listing. Can someone try it on yours Magento?

[sreichel]

Just played bit with ... no real usage, but if $displacement is something below -1 (yes, negative ints here) it could break custom code ....

[colinmollenhour]

I've been running this since April 23 on a project with tons of custom code and had no issues.

MySQL doesn't support negative limits: "LIMIT takes one or two numeric arguments, which must both be nonnegative integer constants". So, I don't see any reason anyone would ever use a negative $displacement argument.

[sreichel]

FYI $displacement with -1 is used in core. @midlan mentioned problems w/ category listings, that i cant reproduce .... maybe related to custom code?

[midlan]

@sreichel
Yes I think it is related to some custom/community code. Did someone tested that in combination with Lesti_Fpc?

[tmotyl]

I have tested the change and it works here.

The only place in the core where negative displacement is used is:
https://github.com/OpenMage/magento-lts/blob/performance_tuning/app/code/core/Mage/Page/Block/Html/Pager.php#L284-L284

This change could break 3rd party code, if the code depends on the side effect - assumes that collection is loaded after calling getCurPage(). Or do you see a different possibility @sreichel ?

btw, in Magento2 the getLastPageNumber was removed from the function

    public function getCurPage($displacement = 0)
    {
        if ($this->_curPage + $displacement < 1) {
            return 1;
        }

        return $this->_curPage + $displacement;
    }

[sreichel]

This change could break 3rd party code, if the code depends on the side effect

This it is. I also tested with vanilla install and it did work, but it could break 3rd-party code ...