TLDR
asynchronous productivity can be manually exploited for free crafts, so make productivity output synchronously.what?
when a machine’s productivity progress bar fills up, add its productivity results to the output of the machine only when the “main” green crafting progress bar fills up.for example, let’s say a centrifuge somehow has 210 % productivity and is crafting Kovarex enrichment: when the productivity crafting completes (which will happen twice before the “main” crafting completes), add the single uranium‑235 produced to a “pending” output slot (or some other GUI indication, maybe a purple superscript “1” on the regular output slot) and only make it available (truly output it) when the main crafting cycle completes.
note that the productivity bar still increases asynchronously to the “main” bar and isn’t reset when the other finishes, so the productivity value is still asymptotically correct, no matter then its outputs are made available.
this should apply to every machine with discrete outputs, so every one except the labs.
why?
currently, productivity results are immediately output when the productivity progress bar reaches 100 %. this can be easily manually exploited to achieve an effective productivity higher than the productivity value itself.(the following example is taken from this video from Michael Hendriks, where he demonstrates another productivity exploit which was fixed by the developers in version 1.1.110. they even linked to his video in the release notes, so one of them definitely watched it.)
for example, given an assembling machine 3 filled with four productivity module 3s (all normal‐quality), it’s possible to achieve an effective productivity of 50 % (instead of the expected 40 %) by deconstructing or changing the recipe of the assembler immediately after the productivity results are output: after waiting for two and a half regular outputs, the productivity results are output, then the machine is deconstructed, giving back the ingredients to the third craft, which results in one productivity output for every two crafts (50 % effective productivity).
this becomes even worse with productivity values above 100 % (which are possible in Space age), where the effective productivity becomes infinite:
simply put in one set of ingredients, wait until the bonus results are output but before the regular craft is completed, deconstruct the assembler (which gives back the ingredients) and voilà, you’ve successfully crafted a recipe for free!
in general, using this exploit, a machine’s productivity value p is increased to the effective productivity P = 1/floor(1/p).
my solution fixes this exploit by making the deconstruction of a machine (or other ways to cancel the craft) “waste” the productivity cycles completed without a set of ingredients consumed in return. instead of the exploited effective productivity always being greater than or equal to the productivity value, the effective productivity is always less than or equal to the productivity value and tends towards it as more products are crafted.
