Flash loan

The Cetus CLMM (Concentrated Liquidity Market Maker) provides a flash loan mechanism, allowing users to borrow assets from a liquidity pool without requiring upfront collateral, as long as the borrowed amount is repaid within the same transaction. This feature is particularly useful for arbitrage, liquidations, and high-frequency trading strategies.

Flash loan fee

For each pool, the fee rate for flash loans is equal to the fee rate for swaps. We currently have six different fee rates. Additionally, different tick spacings correspond to distinct fee rates; please refer to the diagram below for more details.

tick spacing	fee rate
2	0.0001 (100)
10	0.0005 (500)
20	0.001 (1000)
60	0.0025 (2500)
200	0.01 (10000)
220	0.02 (20000)

The module includes the following functions:

1. Flash loan from pool

/// Flash loan from pool
/// Params
///     - `config` The global config of clmm package.
///     - `pool` The clmm pool object.
///     - `loan_a` A flag indicating whether to loan coin A (true) or coin B (false).
///     - `amount` The amount to loan.
/// Returns
///     - `Balance<CoinTypeA>` The balance of coin A to loan.
///     - `Balance<CoinTypeB>` The balance of coin B to loan.
///     - `FlashLoanReceipt` The receipt for repaying the flash loan.
public fun flash_loan<CoinTypeA, CoinTypeB>(
    _config: &GlobalConfig,
    _pool: &mut Pool<CoinTypeA, CoinTypeB>,
    _loan_a: bool,
    _amount: u64
): (Balance<CoinTypeA>, Balance<CoinTypeB>, FlashLoanReceipt) {}

2. Flash loan from pool with partner

In addition to Swap with Partner, the Cetus protocol also enables the sharing of protocol fees with a designated partner. Partner can collect ref fee by partner cap. Details can refer to Partner.

/// Flash loan with partner, like flash loan but there has a partner object for receive ref fee.
/// Params
///     - `config` The global config of clmm package.
///     - `pool` The clmm pool object.
///     - `partner` The partner object for receiving ref fee.
///     - `loan_a` A flag indicating whether to loan coin A (true) or coin B (false).
///     - `amount` The amount to loan.
///     - `clock` The CLOCK of sui framework, used to get current timestamp.
/// Returns
///     - `Balance<CoinTypeA>` The balance of coin A to loan.
///     - `Balance<CoinTypeB>` The balance of coin B to loan.
///     - `FlashLoanReceipt` The receipt for repaying the flash loan.
public fun flash_loan_with_partner<CoinTypeA, CoinTypeB>(
    _config: &GlobalConfig,
    _pool: &mut Pool<CoinTypeA, CoinTypeB>,
    _partner: &Partner,
    _loan_a: bool,
    _amount: u64,
    _clock: &Clock
): (Balance<CoinTypeA>, Balance<CoinTypeB>, FlashLoanReceipt) {}

3. Repay flash loan

/// Repay for flash loan
/// Params
///     - `config` The global config of clmm package.
///     - `pool` The clmm pool object.
///     - `balance_a` The balance of `CoinTypeA` will pay for flash loan,
/// if `loan_a` is true the value need equal `amount + fee_amount` else it need with zero value.
///     - `balance_b` The balance of `CoinTypeB` will pay for flash loan,
/// if `loan_a` is false the value need equal `amount + fee_amount` else it need with zero value.
///     - `receipt` The receipt which will be destroyed.
/// Returns
///     Null
public fun repay_flash_loan<CoinTypeA, CoinTypeB>(
    _config: &GlobalConfig,
    _pool: &mut Pool<CoinTypeA, CoinTypeB>,
    _balance_a: Balance<CoinTypeA>,
    _balance_b: Balance<CoinTypeB>,
    _receipt: FlashLoanReceipt,
) {}

4. Repay flash loan with partner id

/// Repay flash loan with partner id to receive ref fee.
/// Params
///     - `config` The global config of clmm package.
///     - `pool` The clmm pool object.
///     - `partner` The partner object which will receive ref fee.
///     - `balance_a` The balance of `CoinTypeA` will pay for flash loan,
/// if `loan_a` is true the value need equal `amount + fee_amount` else it need with zero value.
///     - `balance_b` The balance of `CoinTypeB` will pay for flash loan,
/// if `loan_a` is false the value need equal `amount + fee_amount` else it need with zero value.
///     - `receipt` The receipt which will be destroyed.
/// Returns
///     Null
public fun repay_flash_loan_with_partner<CoinTypeA, CoinTypeB>(
    _config: &GlobalConfig,
    _pool: &mut Pool<CoinTypeA, CoinTypeB>,
    _partner: &mut Partner,
    _balance_a: Balance<CoinTypeA>,
    _balance_b: Balance<CoinTypeB>,
    _receipt: FlashLoanReceipt,
) {}