Supply and Borrow

Overview

Suppliers can deposit their assets to Parallel Finance. For providing liquidity, in return, they will receive some of the borrower's interests.

Suppliers can also choose to collateralize their assets for borrowing other currencies. This is useful when the price of a certain currency fluctuates significantly and you want to borrow another currency for hedging. This also solves the liquidity of your cryptocurrency.

Currencies have different Collateral Rate which reflects the stability of their price. The more stable the currency's price, the higher the collateral rate. Stable coins USDT will have a higher Collateral Rate.

$$CollateralValue = CurrencyPrice \cdot CollateralRate \cdot CollateralAmount$$

After the deposit, users will be given some deposit certificates so that they can redeem the underlying assets. The number of issued deposited certificate is determined by the Exchange Rate

$$pTokenAmount = \frac {Currency}{Amount ExchangeRate}$$

Supply Interest Rate is proportional to Utilization Rate and Borrow Interest Rate

$$SupplyInterestRate = BorrowInterestRate \cdot UtilizationRate \cdot (1 - ReserveFactor)$$

Supply and Borrow Process

View Data Storage

LastBlockTimestamp

The timestamp of the previous block or defaults to timestamp at genesis.

Code

pub type LastBlockTimestamp<T: Config> = StorageValue<_, Timestamp, ValueQuery>;

View Method

LastBlockTimestamp::<T>::get()
Self::last_block_timestamp()

TotalSupply

Total number of collateral tokens in circulation, CollateralType -> Balance

Code

pub type TotalSupply<T: Config> = StorageMap<_, Twox64Concat, CurrencyId, Balance, ValueQuery>;

View Method

TotalSupply::T::get(currency_id: &CurrencyId)
Self::total_supply(currency_id: &CurrencyId)

Key Name	Type	Description
currency_id	CurrencyId	The currency's Id

Tip: Follow the link to know more about 'CurrencyId'.

TotalBorrows

The total amount of outstanding borrows of the underlying in this market, CurrencyType -> Balance

Code

pub type TotalBorrows<T: Config> = StorageMap<_, Twox64Concat, CurrencyId, Balance, ValueQuery>;

View Method

TotalBorrows::T::get(currency_id: &CurrencyId)
Self::total_borrows(currency_id: &CurrencyId)

Key Name	Type	Description
currency_id	CurrencyId	The currency's Id

TotalReserves

Total amount of reserves of the underlying held in this market, CurrencyType -> Balance

Code

pub type TotalReserves<T: Config> =
        StorageMap<_, Twox64Concat, CurrencyId, Balance, ValueQuery>;

View Method

TotalReserves::T::get(currency_id: &CurrencyId)
Self::total_reserves(currency_id: &CurrencyId)

Key Name	Type	Description
currency_id	CurrencyId	The currency's Id

AccountBorrows

Mapping of account addresses to outstanding borrow balances, CurrencyType -> Owner -> BorrowSnapshot

Code

pub type AccountBorrows<T: Config> = StorageDoubleMap<
        _,
        Twox64Concat,
        CurrencyId,
        Blake2_128Concat,
        T::AccountId,
        BorrowSnapshot,
        ValueQuery,
    >;

View Method

AccountBorrows::<T>::get(currency_id: &CurrencyId, account_id: &T::AccountId)
Self::account_borrows(currency_id: &CurrencyId, account_id: &T::AccountId)

Key Name	Type	Description
currency_id	CurrencyId	The currency's Id
account_id	T::AccountId	The borrower's account id

AccountDeposits

Mapping of account addresses to deposit details, CollateralType -> Owner -> Deposits

Code

pub type AccountDeposits<T: Config> = StorageDoubleMap<
        _,
        Twox64Concat,
        CurrencyId,
        Blake2_128Concat,
        T::AccountId,
        Deposits,
        ValueQuery,
    >;

View Method

AccountDeposits::<T>::get(currency_id: &CurrencyId, account_id: &T::AccountId)
Self::account_deposits(currency_id: &CurrencyId, account_id: &T::AccountId)

Key Name	Type	Description
currency_id	CurrencyId	The currency's Id
account_id	T::AccountId	The depositor's account id

AccountEarned

Mapping of account addresses to total deposit interest accrual, CurrencyType -> Owner -> EarnedSnapshot

Code

pub type AccountEarned<T: Config> = StorageDoubleMap<
        _,
        Twox64Concat,
        CurrencyId,
        Blake2_128Concat,
        T::AccountId,
        EarnedSnapshot,
        ValueQuery,
    >;

View Method

AccountEarned::<T>::get(currency_id: &CurrencyId, account_id: &T::AccountId)
Self::account_earned(currency_id: &CurrencyId, account_id: &T::AccountId)

Key Name	Type	Description
currency_id	CurrencyId	The currency's Id
account_id	T::AccountId	The depositor's account id

BorrowIndex

Accumulator of the total earned interest rate since the opening of the market, CurrencyType -> u128

Code

pub type BorrowIndex<T: Config> = StorageMap<_, Twox64Concat, CurrencyId, Rate, ValueQuery>;

View Method

BorrowIndex::T::get(currency_id: &CurrencyId)
Self::borrow_index(currency_id: &CurrencyId)

Key Name	Type	Description
currency_id	CurrencyId	The currency's Id

Currencies

The currency types support on lending markets

Code

pub type Currencies<T: Config> = StorageValue<_, Vec<CurrencyId>, ValueQuery>;

View Method

Currencies::<T>::get()
Self::currencies()

ExchangeRate

The exchange rate from the underlying to the internal collateral

Code

pub type ExchangeRate<T: Config> = StorageMap<_, Twox64Concat, CurrencyId, Rate, ValueQuery>;

View Method

ExchangeRate::T::get(currency_id: &CurrencyId)
Self::exchange_rate(currency_id: &CurrencyId)

Key Name	Type	Description
currency_id	CurrencyId	The currency's Id

CurrencyInterestModel

The utilization point at which the jump multiplier is applied

Code

pub type CurrencyInterestModel<T: Config> =
        StorageMap<_, Twox64Concat, CurrencyId, InterestRateModel, ValueQuery>;

View Method

CurrencyInterestModel::T::get(currency_id: &CurrencyId)
Self::currency_interest_model(currency_id: &CurrencyId)

Key Name	Type	Description
currency_id	CurrencyId	The currency's Id

BorrowRate

Mapping of borrow rate to currency type

Code

pub type BorrowRate<T: Config> = StorageMap<_, Twox64Concat, CurrencyId, Rate, ValueQuery>;

View Method

BorrowRate::T::get(currency_id: &CurrencyId)
Self::borrow_rate(currency_id: &CurrencyId)

Key Name	Type	Description
currency_id	CurrencyId	The currency's Id

SupplyRate

Mapping of supply rate to currency type

Code

pub type SupplyRate<T: Config> = StorageMap<_, Twox64Concat, CurrencyId, Rate, ValueQuery>;

View Method

SupplyRate::T::get(currency_id: &CurrencyId)
Self::supply_rate(currency_id: &CurrencyId)

Key Name	Type	Description
currency_id	CurrencyId	The currency's Id

UtilizationRatio

The collateral utilization ratio

Code

pub type UtilizationRatio<T: Config> =
        StorageMap<_, Twox64Concat, CurrencyId, Ratio, ValueQuery>;

View Method

UtilizationRatio::T::get(currency_id: &CurrencyId)
Self::utilization_ratio(currency_id: &CurrencyId)

Key Name	Type	Description
currency_id	CurrencyId	The currency's Id

CollateralFactor

The collateral utilization ratio

Code

pub type CollateralFactor<T: Config> =
        StorageMap<_, Twox64Concat, CurrencyId, Ratio, ValueQuery>;

View Method

CollateralFactor::T::get(currency_id: &CurrencyId)
Self::collateral_factor(currency_id: &CurrencyId)

Key Name	Type	Description
currency_id	CurrencyId	The currency's Id

ReserveFactor

Fraction of interest currently set aside for reserves

Code

pub type ReserveFactor<T: Config> = StorageMap<_, Twox64Concat, CurrencyId, Ratio, ValueQuery>;

View Method

ReserveFactor::T::get(currency_id: &CurrencyId)
Self::reserve_factor(currency_id: &CurrencyId)

Key Name	Type	Description
currency_id	CurrencyId	The currency's Id

LiquidationIncentive

Liquidation incentive ratio

Code

pub type LiquidationIncentive<T: Config> =
        StorageMap<_, Twox64Concat, CurrencyId, Rate, ValueQuery>

View Method

LiquidationIncentive::T::get(currency_id: &CurrencyId)
Self::liquidation_incentive(currency_id: &CurrencyId)

Key Name	Type	Description
currency_id	CurrencyId	The currency's Id

CloseFactor

The percent, ranging from 0% to 100%, of a liquidatable account's borrow that can be repaid in a single liquidate transaction.

Code

pub type CloseFactor<T: Config> = StorageMap<_, Twox64Concat, CurrencyId, Ratio, ValueQuery>;

View Method

CloseFactor::T::get(currency_id: &CurrencyId)
Self::close_factor(currency_id: &CurrencyId)

Key Name	Type	Description
currency_id	CurrencyId	The currency's Id

View Methods

Mint()

Sender supplies assets into the market and receives internal supplies in exchange.

pub fn mint(origin: OriginFor<T>, currency_id: CurrencyId, mint_amount: Balance,) -> DispatchResultWithPostInfo

Name	Substrate Config	Runtime Type	Description
origin	T::Origin	RawOrigin	The account signed this transaction
currency_id	-	CurrencyId	the asset to be deposited
mint_amount	T::Balance	u128	the amount to be deposited

RETURN: Returns Ok() when mint succeeds, otherwise return a substrate error type.

Tip: Follow the link to know more about 'RawOrigin', 'CurrencyId'.

Redeem()

Sender redeems some of internal supplies in exchange for the underlying asset.

pub fn redeem(origin: OriginFor<T>, currency_id: CurrencyId, redeem_amount: Balance,) -> DispatchResultWithPostInfo

Name	Substrate Config	Runtime Type	Description
origin	T::Origin	RawOrigin	The account signed this transaction
currency_id	-	CurrencyId	the asset to be redeemed
redeem_amount	T::Balance	u128	the amount to be redeemed

RETURN: Returns Ok() when redeem succeeds, otherwise return a substrate error type.

Redeem_all()

Senders redeem all internal supplies in exchange for the underlying asset.

pub fn redeem_all(origin: OriginFor<T>, currency_id: CurrencyId,) -> DispatchResultWithPostInfo

Name	Substrate Config	Runtime Type	Description
origin	T::Origin	RawOrigin	The account signed this transaction
currency_id	-	CurrencyId	the asset to be redeemed

RETURN: Returns Ok() when redeem_all succeeds, otherwise return a substrate error type.

Borrow()

Sender borrows assets from the protocol to their own address.

pub fn borrow(origin: OriginFor<T>, currency_id: CurrencyId, borrow_amount: Balance,) -> DispatchResultWithPostInfo

Name	Substrate Config	Runtime Type	Description
origin	T::Origin	RawOrigin	The account signed this transaction
currency_id	-	CurrencyId	the asset to be borrowed
borrow_amount	T::Balance	u128	the amount to be borrowed

RETURN: Returns Ok() when borrow succeeds, otherwise return a substrate error type.

Repay_borrow()

Sender repays some of their debts.

pub fn repay_borrow(origin: OriginFor<T>, currency_id: CurrencyId, repay_amount: Balance,) -> DispatchResultWithPostInfo

Name	Substrate Config	Runtime Type	Description
origin	T::Origin	RawOrigin	The account signed this transaction
currency_id	-	CurrencyId	the asset to be repaid
repay_amount	T::Balance	u128	the amount to be repaid

RETURN: Returns Ok() when repay_borrow succeeds, otherwise return a substrate error type.

Repay_borrow_all()

Sender repays all of their debts.

pub fn repay_borrow_all(origin: OriginFor<T>, currency_id: CurrencyId,) -> DispatchResultWithPostInfo

Name	Substrate Config	Runtime Type	Description
origin	T::Origin	RawOrigin	The account signed this transaction
currency_id	-	CurrencyId	the asset to be repaid

RETURN: Returns Ok() when repay_borrow_all succeeds, otherwise return a substrate error type.

Set_liquidation_incentive()

Sets a new liquidation incentive percentage for currency_id. Returns Err if the provided asset is not attached to an existent incentive.

pub fn set_liquidation_incentive(origin: OriginFor<T>, currency_id: CurrencyId, liquidate_incentive: Rate,) -> DispatchResultWithPostInfo

Name	Substrate Config	Runtime Type	Description
origin	T::Origin	RawOrigin	The account signed this transaction
currency_id	-	CurrencyId	the asset that is going to be modified
liquidate_incentive	-	Rate	FixedU128 type that represents liquidate incentive rate

RETURN: Returns Ok() when set_liquidation_incentive succeeds, otherwise return a substrate error type.

Tip: Follow the link to know more about 'FixedU128'.

Transfer_token()

Using for development

pub fn transfer_token(
            origin: OriginFor<T>,
            to: T::AccountId,
            currency_id: CurrencyId,
            amount: Balance,
        ) -> DispatchResultWithPostInfo

Name	Substrate Config	Runtime Type	Description
origin	T::Origin	RawOrigin	The account signed this transaction
to	T::AccountId	AccountId	The received account
currency_id	-	CurrencyId	The transferred asset
amount	T::Balance	u128	The number of transfer assets

RETURN: Returns Ok() when transfer_token succeeds, otherwise return a substrate error type.

Collateral_asset()

Set the collateral asset.

pub fn collateral_asset(origin: OriginFor<T>, currency_id: CurrencyId, enable: bool,) -> DispatchResultWithPostInfo

Name	Substrate Config	Runtime Type	Description
origin	T::Origin	RawOrigin	The account signed this transaction
currency_id	-	CurrencyId	the asset to be set
enable	-	bool	Turn on/off the collateral option.

RETURN: Returns Ok() when collateral_asset succeeds, otherwise return a substrate error type.

Liquidate_borrow()

The sender liquidates the borrower's collateral.

pub fn liquidate_borrow(
            origin: OriginFor<T>,
            borrower: T::AccountId,
            liquidate_token: CurrencyId,
            repay_amount: Balance,
            collateral_token: CurrencyId,
        ) -> DispatchResultWithPostInfo

Name	Substrate Config	Runtime Type	Description
origin	T::Origin	RawOrigin	The account signed this transaction
borrower	T::AccountId	AccountId	The borrower to be liquidated
liquidate_token	-	CurrencyId	The asset to be liquidated
repay_amount	T::Balance	u128	The amount to be repaid borrow
collateral_token	-	CurrencyId	The collateral to seize from the borrower

RETURN: Returns Ok() when liquidate_borrow succeeds, otherwise return a substrate error type.

Set_rate_model()

Update the interest rate model for a given asset. May only be called from T::UpdateOrigin.

pub fn set_rate_model(origin: OriginFor<T>, currency_id: CurrencyId, new_model: InterestRateModel,) -> DispatchResultWithPostInfo

Name	Substrate Config	Runtime Type	Description
origin	T::Origin	RawOrigin	The account signed this transaction
currency_id	-	CurrencyId	the asset to be set
new_model	-	InterestRateModel	The interest rate model to be set

RETURN: Returns Ok() when set_rate_model succeeds, otherwise return a substrate error type.

Tip: Follow the link to know more about 'InterestRateModel'.

Add_reserves()

Add reserves by transferring from the payer. May only be called from T::ReserveOrigin.

pub fn add_reserves(
            origin: OriginFor<T>,
            payer: <T::Lookup as StaticLookup>::Source,
            currency_id: CurrencyId,
            add_amount: Balance,
        ) -> DispatchResultWithPostInfo

Name	Substrate Config	Runtime Type	Description
origin	T::Origin	RawOrigin	The account signed this transaction
payer	T::Lookup::Source	MultiAddress	The payer account
currency_id	-	CurrencyId	The assets to be added
add_amount	T::Balance	u128	The amount to be added

RETURN: Returns Ok() when add_reserves succeeds, otherwise return a substrate error type.

Tip: Follow the link to know more about 'MultiAddress'.

Reduce_reserves()

Reduces reserves by transferring to receiver. May only be called from T::ReserveOrigin.

pub fn reduce_reserves(
            origin: OriginFor<T>,
            receiver: <T::Lookup as StaticLookup>::Source,
            currency_id: CurrencyId,
            reduce_amount: Balance,
        ) -> DispatchResultWithPostInfo

Name	Substrate Config	Runtime Type	Description
origin	T::Origin	RawOrigin	The account signed this transaction
receiver	T::Lookup::Source	MultiAddress	The receiver account
currency_id	-	CurrencyId	The assets to be reduced
reduce_amount	T::Balance	u128	The amount to be reduced

RETURN: Returns Ok() when reduce_reserves succeeds, otherwise return a substrate error type.

View Event

CollateralAssetAdded

Enable collateral for certain asset, [sender, currency_id]

CollateralAssetAdded(T::AccountId, CurrencyId)

CollateralAssetRemoved

Disable collateral for a certain asset, [sender, currency_id]

CollateralAssetRemoved(T::AccountId, CurrencyId)

Deposited

Event emitted when assets are deposited, [sender, currency_id, amount]

Deposited(T::AccountId, CurrencyId, Balance)

Redeemed

Event emitted when assets are redeemed, [sender, currency_id, amount]

Redeemed(T::AccountId, CurrencyId, Balance)

Borrowed

Event emitted when cash is borrowed, [sender, currency_id, amount]

Borrowed(T::AccountId, CurrencyId, Balance)

RepaidBorrow

Event emitted when a borrow is repaid, [sender, currency_id, amount]

RepaidBorrow(T::AccountId, CurrencyId, Balance)

LiquidatedBorrow

Event emitted when a borrow is liquidated,

[liquidator, borrower, liquidate_token, collateral_token, repay_amount, collateral_amount]

LiquidatedBorrow( T::AccountId, T::AccountId, CurrencyId, CurrencyId, Balance, Balance, )

NewInterestRateModel

New interest rate model is set, [new_interest_rate_model]

NewInterestRateModel(InterestRateModel)

ReservesReduced

Event emitted when the reserves are reduced, [admin, currency_id, reduced_amount, total_reserves]

ReservesReduced(T::AccountId, CurrencyId, Balance, Balance)

ReservesAdded

Event emitted when the reserves are added, [admin, currency_id, added_amount, total_reserves]

ReservesAdded(T::AccountId, CurrencyId, Balance, Balance)

View Error

Name	Description
InsufficientLiquidity	Insufficient liquidity to borrow more or disable collateral
InsufficientDeposit	Insufficient deposit to redeem
RepayAmountExceedsCloseFactor	Repay amount greater than borrow balance
DuplicateOperation	Asset already enabled/disabled collateral
NoDeposit	No deposit asset
RepayValueGreaterThanCollateral	Repay amount more than collateral amount
LiquidatorIsBorrower	Liquidator is same as borrower
NoBorrowBalance	There is no borrow balance
LiquidateValueOverflow	Liquidate value overflow
InsufficientReserves	Insufficient reserves
InvalidRateModelParam	Invalid rate model params
CurrencyNotEnabled	Currency not enabled
PriceOracleNotReady	Currency's oracle price not ready