BSIP: 0031 Title: Update Short Position's Margin Call Price After Partially Called Or Settled Author: Abit More Status: Draft Type: Protocol Created: 2018-02-16 Discussion: https://github.com/bitshares/bitshares-core/issues/343, https://github.com/bitshares/bitshares-core/issues/649 Replaces: - Worker: To be done # Abstract Currently, when a short position get partially called or settled, the call price won't change, that said, even if its actual collateral ratio is higher than others, higher than minimum required, it will still be selling collateral at a low price, taking precedence over other short positions. This behavior is causing several issues: * it's somehow unfair, thus brought bad experience to shorters, and * it prevents black swan event from being triggered in time when needed, because the collateral ratio of the 2nd even overall short positions may be too low but not being checked, thus risks the pegging system. This BSIP proposes a mechanism to improve this situation. # Motivation Make the exchange system more user-friendly. # Rationale To attract more users, the system should be fair, should be well balanced. It's common sense that short positions with least collateral ratio should get margin called first. This can be achieved if always update the margin call price after every fill. # Specifications In `fill_order( const call_order_object& ...)` function of `database` class, update `call_price` field of `call_order_object` after debt or collateral changed to a non-zero value. In addtion, after `call_price` get updated, the iterators initialized with `by_price` index may be invalidated, so need to review / revise involved code, E.G. `check_call_orders(...)` function of `database` class. # 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/343 * https://github.com/bitshares/bitshares-core/issues/649 * https://bitsharestalk.org/index.php?topic=25926.0