# Begin Block At the start of every block the BeginBlock of the cdp module: - updates the status of the pricefeed for each collateral asset - If the pricefeed is active (reporting a price): - updates fees for CDPs - liquidates CDPs under the collateral ratio - nets out system debt and, if necessary, starts auctions to re-balance it - pays out the savings rate if sufficient time has past - records the last savings rate distribution, if one occurred ## Update Fees - The total fees accumulated since the last block for each CDP are calculated. - If the fee amount is non-zero: - Set the updated value for fees - Set the fees updated time for the CDP to the current block time - An equal amount of debt coins are minted and sent to the system's CDP module account. - An equal amount of stable asset coins are minted and sent to the system's liquidator module account - Increment total principal. ## Liquidate CDP - Get every cdp that is under the liquidation ratio for its collateral type. - For each cdp: - Remove all collateral and internal debt coins from cdp and deposits and delete it. Send the coins to the liquidator module account. - Start auctions of a fixed size from this collateral (with any remainder in a smaller sized auction), sending collateral and debt coins to the auction module account. - Decrement total principal. ## Net Out System Debt, Re-Balance - Burn the maximum possible equal amount of debt and stable asset from the liquidator module account. - If there is enough debt remaining for an auction, start one. - If there is enough surplus stable asset, minus surplus reserved for the savings rate, remaining for an auction, start one. - Otherwise do nothing, leave debt/surplus to accumulate over subsequent blocks. ## Distribute Surplus Stable Asset According to the Savings Rate - If `SavingsDistributionFrequency` seconds have elapsed since the previous distribution, the savings rate is applied to all accounts that hold stable asset. - Each account that holds stable asset is distributed a ratable portion of the surplus that is apportioned to the savings rate. - If distribution occurred, the time of the distribution is recorded.