When your health turns negative, a well-timed self-liquidation can perform like a stop-loss mechanism. This lesson shows off the basics for manually running a self-liquidation.
This lesson also introduce Titanoboa's time_travel function, which allows you to fast forward a specified timeframe or number of blocks.
Fast forward, increase the chain timestamp and block number. Further details available in the Titanoboa documentation
time_travel(seconds: int = None, blocks: int = None, block_delta: int = 12)
Determine stablecoin quantity needed to liquidate a user. This amount may be different if a user is calling this function on their own loan (ie self-liquidation).
def tokens_to_liquidate(user: address, frac: uint256 = 10 ** 18) -> uint256:
"""
@notice Calculate the amount of stablecoins to have in liquidator's wallet to liquidate a user
@param user Address of the user to liquidate
@param frac Fraction to liquidate; 100% = 10**18
@return The amount of stablecoins needed
"""
Perform a liquidation on a user in bad health.
def liquidate(user: address, min_x: uint256):
"""
@notice Peform a bad liquidation (or self-liquidation) of user if health is not good
@param min_x Minimal amount of stablecoin to receive (to avoid liquidators being sandwiched)
"""
The AMM's get_dx function calculates the amount of input coin necessary to get a desired output amount
def get_dx(i: uint256, j: uint256, out_amount: uint256) -> uint256:
"""
@notice Method to use to calculate in amount required to receive the desired out_amount
@param i Input coin index
@param j Output coin index
@param out_amount Desired amount of output coin to receive
@return Amount of coin i to spend
"""
# i = 0: borrowable (USD) in, collateral (ETH) out; going up
# i = 1: collateral (ETH) in, borrowable (USD) out; going down
After granting approvals, the AMM's exchange function trades a quantity of tokens
def exchange(i: uint256, j: uint256, in_amount: uint256, min_amount: uint256, _for: address = msg.sender) -> uint256[2]:
@notice Exchanges two coins, callable by anyone
@param i Input coin index
@param j Output coin index
@param in_amount Amount of input coin to swap
@param min_amount Minimal amount to get as output
@param _for Address to send coins to
@return Amount of coins given in/out