NablaBackstopPool
The backstop pool takes most of the risk of a set of swap pools backed by it. Whenever a swap pool is low on reserves and a LPer wants to withdraw some liquidity, they can conduct an insurance withdrawal (burn swap pool shares, reimbursed in backstop liquidity) to avoid paying a high slippage. The backstop pool owns all excess liquidity in its swap pools, but is also liable for potential liquidity gaps. In return, the backstop pool receives a cut of the swap fees.
Withdrawal
struct Withdrawal {
uint128 startClaimPeriod;
uint128 endClaimPeriod;
uint256 sharesToBurn;
}SwapPoolConfig
struct SwapPoolConfig {
uint128 insuranceFeeBps;
bool isCovered;
}router
contract IRouter routerrouter instance for this backstop pool
getBackedPool
enumerate swap pools backed by this backstop pool
Parameters
_index
uint256
index of the swap pool in coveredSwapPools array
Return Values
swapPool_
address
swap pool address
getBackedPoolCount
get swap pool count backed by this backstop pool
Return Values
count_
uint256
number of swap pools
getInsuranceFee
get insurance withdrawal fee for a given swap pool
Parameters
_swapPool
address
address of the swap pool
Return Values
feeBps_
uint256
insurance witdrawal fee, in basis points (0.01%)
deposit
Deposits amount of tokens into pool Will change cov ratio of pool, will increase delta to 0
By calling this function the price feeds get updated (IPriceOracleAdapter.updatePriceFeeds)
Parameters
_depositAmount
uint256
The amount of backstop pool tokens to be deposited
_minLPAmountOut
uint256
The minimum amount of backstop pool LP tokens to mint
_deadline
uint256
Unix timestamp after which the transaction will revert
_priceUpdateData
bytes[]
Array of price update data of all assets involved (backstop pool and all swapPools as within coveredSwapPools[])
Return Values
sharesToMint_
uint256
Total number of backstop pool LP tokens minted
initiateWithdraw
Starts the withdrawal process or overrides an existing one The user must finalize the withdrawal after the delay period has passed but before the claim period ends through finalizeWithdrawBackstopLiquidity() or finalizeWithdrawExcessSwapLiquidity()
Parameters
_sharesToBurn
uint256
The liquidity to be withdrawn, an amount of backstop pool LP tokens
Return Values
success_
bool
Confirmation of success
cancelWithdraw
Cancels an initiated withdrawal
Return Values
success_
bool
Confirmation of success
finalizeWithdrawBackstopLiquidity
Finalizes the withdrawal process after the delay period has passed but before the claim period ends Withdraws backstop liquidity amount of asset ensuring minimum amount required
By calling this function the price feeds get updated (IPriceOracleAdapter.updatePriceFeeds)
Parameters
_minimumAmount
uint256
Reject withdrawal if resulting amount is below
_deadline
uint256
Unix timestamp after which the transaction will revert
_priceUpdateData
bytes[]
Array of price update data of all assets involved (backstop pool and all swapPools as within coveredSwapPools[])
Return Values
payoutAmount_
uint256
Amount of asset() tokens withdrawn
redeemSwapPoolShares
Withdraw from a swap pool using backstop liquidity without slippage (backstop burn) only possible if swap pool's coverage ratio < 100%
By calling this function the price feeds get updated (IPriceOracleAdapter.updatePriceFeeds)
Parameters
_swapPool
address
swap pool address
_shares
uint256
number of swap pool LP tokens to redeem, uses decimals of swap pool
_minAmountOut
uint256
minimum amount of backstop liquidity to receive, uses decimals of backstop pool
_deadline
uint256
Unix timestamp after which the transaction will revert
_priceUpdateData
bytes[]
Array of price update data of all assets involved (backstop pool and this swapPool)
Return Values
amountOut_
uint256
amount of backstop liquidity paid-out, uses decimals of backstop pool
finalizeWithdrawExcessSwapLiquidity
Finalizes the withdrawal process after the delay period has passed but before the claim period ends Withdraw from backstop pool, but receive excess liquidity of a swap pool instead of backstop liquidity
By calling this function the price feeds get updated (IPriceOracleAdapter.updatePriceFeeds)
Parameters
_swapPool
address
swap pool address, must have a coverage ratio > 100%
_minAmount
uint256
minimum amount of swap pool liquidity to receive, uses decimals of swap pool
_deadline
uint256
Unix timestamp after which the transaction will revert
_priceUpdateData
bytes[]
Array of price update data of all assets involved (backstop pool and all swapPools as within coveredSwapPools[])
Return Values
swapAmount_
uint256
amount of swap pool liquidity paid-out, uses decimals of swap pool
redeemCrossSwapPoolShares
getTotalPoolWorth
return worth of the whole backstop pool in asset(), incl. all swap pools' excess liquidity and the backstop pool's liabilities this is a fixed point number, using the backstop pool decimals
ignoring if pools are paused or not, since liabilities still apply and we don't want the backstop pool worth to jump
Parameters
_allTokenPrices
uint256[]
array of all token prices ([0] backstop pool token, [1] swap pool token_i, [2] swap pool token_i+1, ... [n] swap pool token_n) as within coveredSwapPools[]
Return Values
value_
int256
total value of all backstop pool shares, in asset()
totalExcessLiquidity_
int256
total excess liquidity of all swap pools, in asset()
sharesTargetWorth
Returns the worth of an amount of pool shares (LP tokens) in underlying principle
Parameters
_sharesToBurn
uint256
The number of LP tokens to burn
_allTokenPrices
uint256[]
array of all token prices ([0] backstop pool token, [1] swap pool token_i, [2] swap pool token_i+1, ... [n] swap pool token_n) as within coveredSwapPools[]
Return Values
amount_
uint256
The amount of asset() tokens that the shares are worth
getPoolState
returns the backstop pool state
Parameters
_allTokenPrices
uint256[]
array of all token prices ([0] backstop pool token, [1] swap pool token_i, [2] swap pool token_i+1, ... [n] swap pool token_n) as within coveredSwapPools[]
Return Values
reserves_
uint256
current amount of asset in this pool
totalPoolWorth_
int256
total worth of the pool in asset()
totalSupply_
uint256
total amount of LP tokens minted
getWithdrawal
Get information about a user's initiated withdrawal
Parameters
_sender
address
The user who initiated the withdrawal
Return Values
startClaimPeriod_
uint128
The time when the withdrawal can be finalized, a unix timestamp
endClaimPeriod_
uint128
The time when the withdrawal can no longer be finalized, a unix timestamp
sharesToBurn_
uint256
The amount of LP tokens to burn
getWithdrawalDelayAndClaimPeriod
Get the delay and claim period for withdrawals
Return Values
delay_
uint128
The delay before initiated withdrawals can be finalized, in seconds
claimPeriod_
uint128
The period within which initiated withdrawals can be claimed, in seconds
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