Merge pull request #926 from ArtemGr/dev

MM2 rewrite, the goals RFC

iguana/exchanges/mm2.md

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+# Market Maker 2
+
+This document will help us track the information related to the MarketMaker Rust rewrite.
+
+## Rewrite goals
+
+Rewrites and ports
+[are costly](http://nibblestew.blogspot.com/2017/04/why-dont-you-just-rewrite-it-in-x.html).
+We tend to think that porting is simple, and on some level this intuition is true
+because we can skip some high-level design decisions and focus on translating the existing logic,
+but it still takes a lot of time
+and though we don't need to make some of the new design decisions,
+we might spend no less effort to reverse-engineer and understand the old ones.
+
+So why the rewrite then?
+
+Carol, in her talk about rewrites, offers some possible reasons:
+
+"*If* you have some code in C or another language, and need to change it, or it’s slow, or it crashes a
+lot, or no one understands it anymore, THEN maybe a rewrite in Rust would be a good fit.
+I would also posit that more people are *able* to write production Rust than production C, so if your
+team *is* willing to learn Rust, it might actually expand the number of
+maintainers." - https://github.com/carols10cents/rust-out-your-c-talk, https://www.youtube.com/watch?v=SKGVItFlK3w.
+
+And we have some of these:
+
+* We *need to change* the MarketMaker:
+A more approachable and reliable API.
+Ability to embed the MarketMaker in the GUI applications.
+Ways to more easily deploy it at home by running it from small computers like on a spare mobile phone or on a Raspberry Pi 3.
+Ability to process multiple API calls in parallel.
+A faster version of the `swapstatus` API call.
+
+* The MarketMaker *crashes a lot*,
+to quote hyperDEX: "The biggest issue with the MM right now, is bobs crash or does not have the orders in users orderbook, or when users try to do a order it doesnt work or goes unmatched or other random stuff"
+and lukechilds: "We've frequently experienced crashes while querying all swaps with swapstatus".
+We want it to be stable and reliable instead.