Function: postFillOrder(byte[32] asset, address account, PostFillOrderArgs args)

This function attempts to open or adjust a position by executing an order. It matches the order against existing orders in the order book using the specified parameters. The user can specify how much to buy or sell, at what price limit, and whether to allow partial fills.

If the order is filled, the user's position is updated: either opened, increased, or reduced (if opposite direction). The function supports both FILL_OR_KILL (fills fully or reverts) and IMMEDIATE_OR_CANCEL (partially fills).

Inputs

• asset

  • Control: Full control.

  • Constraints: Market should exist.

  • Impact: Determines which asset market the fill operation applies to.

• account

  • Control: Full control.

  • Constraints: The caller should be the account itself or an approved operator.

  • Impact: Position, margin, and balance updates are applied to this account.

• args.amount

  • Control: Full control.

  • Constraints: Must be greater than zero.

  • Impact: Sets how much the user wants to buy or sell.

• args.price

  • Control: Full control.

  • Constraints: Must be greater than zero, price % tickSize == 0.

  • Impact: Defines the worst price the user is willing to accept for the trade.

• args.amountIsBase

  • Control: Full control.

  • Constraints: Boolean — affects interpretation of args.amount.

  • Impact: Defines whether amount is in base asset units or quote.

• args.fillOrderType

  • Control: Full control.

  • Constraints: Must be valid enum value.

  • Impact: Sets how the order should be filled, either completely or partially.

• args.subaccount

  • Control: Full control.

  • Constraints: N/A.

  • Impact: Determines which subaccount to apply the trade to.

• args.leverage

  • Control: Full control.

  • Constraints: (1e18 * 1e18) / leverage should be less than settings.initMarginReq.

  • Impact: Controls how much borrowed funds are used — affects margin and liquidation risk.

• args.settlement

  • Control: Full control.

  • Constraints: Must be a valid settlement type (INSTANT, ACCOUNT). For settlement INSTANT, immediately returns, or for ACCOUNT, keeps funds inside protocol.

  • Impact: Defines where the resulting funds go after the position is closed.

Branches and code coverage

Intended branches

• Opens a new long position using BUY.

  Test coverage

• Opens a new short position using SELL.

  Test coverage

• Increases an existing long.

  Test coverage

• Increases an existing short.

  Test coverage

• Decreases a position by filling with the opposite side (partial close).

  Test coverage

• Fully closes a position with an opposite-side fill.

  Test coverage

• Opens a new position after closing the previous one.

  Test coverage

• Executes fill against multiple matching maker orders.

  Test coverage

• IMMEDIATE_OR_CANCEL partially fills.

  Test coverage

• Position updates correctly on increase.

  Test coverage

• Position decreases correctly.

  Test coverage

• Position amount and openNotional update correctly on open.

  Test coverage

• Realized PNL is correctly applied on partial close.

  Test coverage

• Full close resets the position to zero and cleans storage.

  Test coverage

• Margin is correctly calculated.

  Test coverage

• Funding is settled before fill occurs.

  Test coverage

• Reverses open with exact 2× amount.

  Test coverage

• Opens new position with opposite side.

  Test coverage

• Reverses open from long to short with amountIsBase == false.

  Test coverage

• Realized PNL is correctly calculated for the closed part of the position.

  Test coverage

• Margin is released correctly from the closed position before applying to the new one.

  Test coverage

• Reverses open. Price and openNotional are recalculated correctly for the new position.

  Test coverage

• Fees are charged properly.

  Test coverage

Negative behavior

• Price deviates too much from the current fair market value.

  Negative test

• price == 0.

  Negative test

• asset is not supported.

  Negative test

• price % tickSize != 0.

  Negative test

• FILL_OR_KILL is partly filled.

  Negative test

• FILL_OR_KILL is not filled at all — no orders.

  Negative test

• Reverts if reverse open causes undercollateralization.

  Negative test

• For BUY, order book contains only higher prices.

  Negative test

• For SELL, order book contains only smaller prices.

  Negative test

• User does not have enough funds to post margin.

  Negative test

• Order book is empty.

  Negative test