User Instructions

Interact program to program via these instructions, or refer to the GitHub link below:

solana-program-library/instruction.rs at mainnet · solendprotocol/solana-program-libraryGitHub

DepositReserveLiquidityAndObligationCollateral (Supply)

• Deposit reserve liquidity (Transfer) + mint cTokens (MintTo) + Transfer cTokens into CollateralSupplyAddress (Transfer)

• Does not require RefreshReserve as it is impossible to worsen an obligation’s health by repaying.

• Sample TX

WithdrawObligationCollateralAndRedeemReserveCollateral

• Redeem cTokens from CollateralSupplyAddress

• Exchange cTokens into Tokens using the cToken Rate

• Requires RefreshReserve to ensure that the user is able to withdraw without defaulting their existing borrows

• RefreshReserve → RefreshObligation → WithdrawObligationCollateralAndRedeemReserveCollateral

BorrowObligationLiquidity

• Bundled with Refresh Reserve

• if “borrow_reserve.last_update.is_stale(clock.slot)? {” fails, reserve is considered stale (refreshreserve + borrow must be in the same slot)

• RefreshReserve → RefreshObligation → Borrow

RepayObligationLiquidity

• Does not require RefreshReserve as it is impossible to worsen an obligation’s health by repaying.

cToken Instructions:

DepositReserveLiquidity

• Deposit funds into the reserve, mint cToken

• No need to escrow the cTokens in the CollateralSupplyAddress

• Relies on cToken:Token Ratio

RedeemReserveCollateral

• Withdraw Funds, burn cTokens

• Relies on cToken:Token Ratio

Monitoring/Misc Instructions

RefreshReserve

• Update the price of every reserve, usually done before RefreshObligation

• Pull Oracle prices

• Update CumulativeBorrowRate to calculate interest paid since last refreshed block

• Update the Obligation CumulativeBorrowRate to apply an increase in borrow value

• Update cToken Rate for supply side users

• Done 2x for every reserve, supply and borrow side

RefreshObligation

• Done after RefreshReserves

• Calculate individual obligations that ran the Withdraw or Borrow tx to calculate LTV before borrows

• Assess whether the tx can go through based on account health

Notes:

RefreshReserve/RefreshObligation used to be required for all transactions, but were removed to reduce oracle reliance after Jan 2022’s network issues.

Liquidator will call RefreshObligation before liquidating

However, borrow/withdraw has to check whether the obligation is refreshed in the SAME slot. But obligations require that reserves are refreshed.

RefreshReserve → RefreshObligation (repeated through all the positions) requires a lot of memory, which is limited by Solana, and thus limits our positions to 6.