83 lines
3 KiB
Markdown
83 lines
3 KiB
Markdown
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BSIP: 0033
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Title: Maker Orders With Better Prices Take Precedence
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Author: Abit More <https://github.com/abitmore>
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Status: Draft
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Type: Protocol
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Created: 2018-02-17
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Discussion: https://github.com/bitshares/bitshares-core/issues/625
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Replaces: -
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Worker: To be done
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# Abstract
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Currently, when matching taker limit orders with maker limit orders, the maker
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limit orders with better prices will always be matched first.
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For example, if trader A has a limit order selling 100 BTS at
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0.1 USD per BTS, trader B has a limit order selling 100 BTS at 0.09 USD per BTS,
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which means B's limit order has a better price for the opposite side to buy.
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Now if trader C placed an order that buys 10 BTS at 0.105 USD per BTS, B's
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limit order will take precedence, A's limit order won't be matched.
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However, when there are margin call orders in the market which have met the
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requirements that to be matched, they always take precedence over limit orders
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on the same side, no matter whether the limit orders provided better price.
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For example, if trader A's margin call order is selling 100 BTS at no less than
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0.1 USD per BTS, trader B has a limit order selling 100 BTS at 0.09 USD per BTS,
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which means B's limit order has a better price for the opposite side to buy.
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Now if trader C placed an order that buys 10 BTS at 0.105 USD per BTS, A's
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margin call order will take precedence, B's limit order won't be matched. That
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means C is forced to "buy high" when have chance to "buy low".
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This BSIP proposes a mechanism to change this behavior to: always match taker
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orders with maker orders with better prices first.
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# Motivation
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Make the exchange system more user-friendly.
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# Rational
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To attract more users, the system should be fair.
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It's common sense that, in a continuous trading market, new orders should be
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matched with the orders on the opposite side which offerred best prices first.
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# Specifications
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There is a parameter in price feed named MSSR, which stands for "maximum short
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squeeze ratio". Maker price of margin call orders is MSSP, which stands for
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"maximum short squeeze price", is calculated as `feed_price / ( 100% + MSSR )`.
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Note: `feed_price` here is in terms of debt/collateral, aka "how much debt per
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collateral".
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New limit order is being processed in `apply_order(...)` function of `database`
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class.
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Currently, in the function, firstly call orders will be checked and matched.
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After that, limit orders on the opposite side will be checked and matched.
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Need to change the logic to:
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* match the new limit order with limit orders on the opposite side whose price
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is below MSSP first,
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* if the new order is still there, match it with call orders,
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* if the new order is still there, match it with rest limit orders.
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# Discussion
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[to be added if any]
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# Summary for Shareholders
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[to be added if any]
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# Copyright
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This document is placed in the public domain.
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# See Also
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* https://github.com/bitshares/bitshares-core/issues/625
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* https://bitsharestalk.org/index.php?topic=25926.0
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