Add BSIP 32

bsip-0032.md

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+    BSIP: 0032
+    Title: Always Match Orders At Maker Price
+    Author: Abit More <https://github.com/abitmore>
+    Status: Draft
+    Type: Protocol
+    Created: 2018-02-16
+    Discussion: https://github.com/bitshares/bitshares-core/issues/338
+    Replaces: -
+    Worker: To be done
+
+# Abstract
+
+Currently, under most circumstances, when matching two orders, the maker price
+will be used. That said, the order that is placed earlier sets a price,
+another order that is placed later accepts the price, thus a match, two orders
+pay to each other at that price. For example, if one person (A) placed a limit
+order to sell 100 BTS at 0.1 USD per BTS, another person (B) then placed a new
+limit order to buy 100 BTS at 0.105 USD per BTS, the two orders will match at
+0.1 USD per BTS, so A will pay 100 BTS and get 10 USD, B will pay 10 USD and
+get 100 BTS.
+
+However, when matching a taker limit order with a maker margin call order,
+the taker price is being used. For example, if trader A's margin call order is
+selling 100 BTS at no less than 0.1 USD per BTS, then trader B placed an order
+that buys 100 BTS at 0.105 USD per BTS, the two order will match at 0.105 USD
+per BTS, so A will pay 100 BTS and get 10.5 USD, B will pay 10.5 USD and get
+100 BTS.
+
+This BSIP proposes a mechanism to change this behavior: always match orders
+at maker price.
+
+# Motivation
+
+Make the exchange system more user-friendly.
+
+# Rational
+
+To attract more users, the system should be fair.
+
+It's common sense that orders should be matched at maker price.
+
+# Specifications
+
+There is a parameter in price feed named MSSR, which stands for "maximum short
+squeeze ratio". Maker price of margin call orders is MSSP, which stands for
+"maximum short squeeze price", is calculated as `feed_price / ( 100% + MSSR )`.
+Note: `feed_price` here is in terms of debt/collateral, aka "how much debt per
+collateral".
+
+Matching between a limit order and a call order is done in
+`check_call_orders(...)` function of `database` class, price of limit order
+is always used. It need to be changed to use MSSP when the call order is maker.
+
+# Discussion
+
+[to be added if any]
+
+# Summary for Shareholders
+
+[to be added if any]
+
+# Copyright
+
+This document is placed in the public domain.
+
+# See Also
+
+* https://github.com/bitshares/bitshares-core/issues/338
+* https://bitsharestalk.org/index.php?topic=25926.0