Struct MarginLedger 

pub struct MarginLedger { /* private fields */ }

Manages all isolated margin positions and free USDC balance.

This is the single source of truth for simulated account state, replacing the scattered tracking in PaperExchange and FillSimulator.

Implementations

impl MarginLedger

pub fn new(starting_balance: Decimal, fee_rate: Decimal) -> Self

Create a new ledger with starting USDC balance.

pub fn free_usdc(&self) -> Decimal

Free USDC available for new margin reservations.

pub fn set_free_usdc(&mut self, amount: Decimal)

Set free USDC directly (for compatibility with FillSimulator spot logic).

pub fn adjust_free_usdc(&mut self, delta: Decimal)

Adjust free_usdc by delta (positive = add, negative = subtract).

pub fn fee_rate(&self) -> Decimal

Fee rate used for margin calculations.

pub fn set_fee_rate(&mut self, fee_rate: Decimal)

Set fee rate.

pub fn position(&self, instrument: &InstrumentId) -> Option<&IsolatedPosition>

Get position for an instrument (if any).

pub fn position_mut( &mut self, instrument: &InstrumentId, ) -> Option<&mut IsolatedPosition>

Get mutable position for an instrument.

pub fn leverage_for(&self, instrument: &InstrumentId) -> Decimal

Get leverage for an instrument.

pub fn total_reserved_margin(&self) -> Decimal

Total reserved margin across all positions.

pub fn total_unrealized_pnl( &self, marks: &HashMap<InstrumentId, Decimal>, ) -> Decimal

Total unrealized PnL across all positions at given mark prices.

pub fn equity(&self, marks: &HashMap<InstrumentId, Decimal>) -> Decimal

Account equity = free_usdc + total_reserved_margin + total_unrealized_pnl

pub fn position_qty(&self, instrument: &InstrumentId) -> Decimal

Position quantity for an instrument (signed: +long, -short).

pub fn set_leverage( &mut self, instrument: &InstrumentId, leverage: Decimal, max_leverage: Decimal, )

Set leverage for an instrument. leverage is the user’s chosen leverage (e.g. 10x). max_leverage is the exchange maximum for this asset (determines MMR).

pub fn set_default_leverage(&mut self, leverage: Decimal)

Set default leverage for instruments without explicit settings.

pub fn check_margin_for_perp_order( &self, instrument: &InstrumentId, side: OrderSide, price: Decimal, qty: Decimal, reduce_only: bool, ) -> Result<(), String>

Check if there’s sufficient margin for a PERP order.

• Reducing orders always pass (they release margin).
• New/increasing orders need: notional / leverage + 2x fee buffer.
• Spot orders are not handled here (use FillSimulator’s check_balance).

pub fn apply_perp_fill( &mut self, instrument: &InstrumentId, side: OrderSide, fill_price: Decimal, fill_qty: Decimal, fee_amount: Decimal, ) -> Decimal

Apply a PERP fill to the margin ledger.

Handles all scenarios:

• Opening new position: reserve margin, set entry price
• Increasing existing position: reserve additional margin, update avg entry
• Reducing existing position: release margin proportionally, realize PnL
• Flipping position: close old + open new in opposite direction

Returns the realized PnL from this fill (zero for new positions).

pub fn check_liquidations( &self, marks: &HashMap<InstrumentId, Decimal>, ) -> Vec<InstrumentId>

Check all positions for liquidation at current mark prices. Returns list of instruments that should be liquidated.

pub fn liquidate(&mut self, instrument: &InstrumentId, mark_price: Decimal)

Force-liquidate a position at the given mark price. Closes the entire position, realizes the loss, releases remaining margin.

pub fn position_snapshots( &self, marks: &HashMap<InstrumentId, Decimal>, ) -> Vec<PositionSnapshot>

Generate position snapshots for poll_account_state(). Returns non-flat positions in the format expected by AccountState.

Trait Implementations

impl Debug for MarginLedger

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.