Staking Pool

StakingPool is one of the most important pieces of the protocol as it handles the liquid staking of tokens. When a user stakes some amount of tokens (such as LINK), they receive liquid staking tokens (such as stLINK) at a 1:1 ratio. These liquid staking tokens represent a user’s staked balance and must be burned to withdraw the underlying tokens they represent.

Once tokens have been staked into the pool, they are deposited into one or more strategy contracts controlled by the pool. These strategies then take the deposited tokens and use them to earn rewards which are distributed to stakers.

In the case of LINK staking, the tokens are deposited into the Chainlink staking contracts.

The liquid staking token issued by StakingPool is a rebasing token so rewards will be automatically distributed to stakers without any action on their part. This is possible by using a “shares” accounting model where a share represents a certain percentage ownership of the pool. When a user stakes, they receive a number of shares determined by the ratio of total shares to total tokens in the pool. The amount of shares a user owns remains constant unless they stake or withdraw but the ratio of total shares to total tokens changes with each rebase so their shares will be worth more tokens after each rebase. The new token value of their shares will be automatically reflected in their token balance.

While unlikely, it is also possible for a rebase to be negative if strategies earned net negative rewards since the last rebase due to slashing penalties. In this case, each share will be worth less tokens so a user’s token balance will decrease.

ERC20 Functions

All standard ERC20 functions are implemented for StakingPool

View Functions

token

Returns the staking token for the pool

function token() external view returns (address)

Return Values

Name	Type	Description
token	address	Address of staking token

priorityPool

Returns the address of the priority pool for this pool

function priorityPool() external view returns (address)

Return Values

Name	Type	Description
priorityPool	address	address of priority pool

totalShares

Returns the total amount of shares in the pool

function totalShares() external view returns (uint256)

Return Values

Name	Type	Description
sharesAmount	uint256	Total shares in the pool

sharesOf

Returns the amount of shares owned by an account

function sharesOf(address _account) public view returns (uint256)

Parameters

Name	Type	Description
_account	address	Address of account

Return Values

Name	Type	Description
sharesBalance	uint256	Total shares owned by account

getSharesByStake

Returns the amount of shares that corresponds to an amount of stake

function getSharesByStake(uint256 _amount) public view returns (uint256)

Parameters

Name	Type	Description
_amount	uint256	Amount of stake

Return Values

Name	Type	Description
sharesAmount	uint256	Corresponding amount of shares

getStakeByShares

Returns the amount of stake that corresponds to an amount of shares

function getStakeByShares(uint256 _amount) public view returns (uint256)

Parameters

Name	Type	Description
_amount	uint256	Amount of shares

Return Values

Name	Type	Description
stakeAmount	uint256	Corresponding amount of stake

totalStaked

Returns the total amount of tokens in the pool

function totalStaked() external view returns (uint256)

Return Values

Name	Type	Description
stakedAmount	uint256	Total tokens in the pool

getStrategies

Returns a list of all active strategies

function getStrategies() external view returns (address[])

Return Values

Name	Type	Description
strategies	address[]	List of strategy contract addresses

getFees

Returns a list of all fees

function getFees() external view returns (struct StakingPool.Fee[])

Return Values

Name	Type	Description
fees	struct Fee[]	list of fees

getMaxDeposits

Returns the maximum amount of tokens that the pool can hold

function getMaxDeposits() public view returns (uint256)

Return Values

Name	Type	Description
maxDeposits	uint256	maximum deposit limit

getMinDeposits

Returns the minimum amount of tokens that must remain in the pool

function getMinDeposits() public view returns (uint256)

Return Values

Name	Type	Description
minDeposits	uint256	minimum deposit limit

getUnusedDeposits

Returns the amount of unused asset tokens sitting in this pool outside a strategy

These tokens earn no yield and will be deposited ASAP on the next call to _depositLiquidity

function getUnusedDeposits() external view returns (uint256)

Return Values

Name	Type	Description
unusedDeposits	uint256	amount of unused tokens

getStrategyDepositRoom

Returns the sum of available deposit room across all strategies

Does not account for unused deposits sitting in pool

function getStrategyDepositRoom() external view returns (uint256)

Return Values

Name	Type	Description
strategyDepositRoom	uint256	available deposit room in strategies

canDeposit

Returns the total available deposit room for this pool

Accounts for unused deposits sitting in pool

function canDeposit() external view returns (uint256)

Return Values

Name	Type	Description
canDeposit	uint256	available deposit room

canWithdraw

Returns the total available withdrawal room for this pool

function canWithdraw() external view returns (uint256)

Return Values

Name	Type	Description
canWithdraw	uint256	available withdrawal room

getStrategyRewards

Returns the amount of rewards earned since the last call to updateStrategyRewards and the amount of fees that will be paid on the rewards

function getStrategyRewards(uint256[] _strategyIdxs) external view returns (int256, uint256)

Parameters

Name	Type	Description
_strategyIdxs	uint256[]	Indexes of strategies to sum rewards/fees for

Return Values

Name	Type	Description
rewards	int256	Total rewards
fees	uint256	Total fees

Write Functions

deposit

Deposits staking tokens and mints liquid staking tokens

function deposit(address _account, uint256 _amount, bytes _data) external

Parameters

Name	Type	Description
_account	address	address of account to stake for
_amount	uint256	amount to stake
_data	bytes	list of deposit data passed to strategies

withdraw

Withdraws staking tokens and burns liquid staking tokens

function withdraw(address _account, address _receiver, uint256 _amount, bytes _data) external

Parameters

Name	Type	Description
_account	address	Address of account to withdraw for
_receiver	address	Address to receive withdrawal
_amount	uint256	Amount to withdraw
_data	bytes	list of withdrawal data passed to strategies

transferAndCall

Transfers tokens to an address and calls onTokenTransfer with additional data if the recipient is a contract

function transferAndCall(address _to, uint256 _value, bytes _data) external returns (bool)

Parameters

Name	Type	Description
_to	address	Address to send the tokens to
_value	uint256	Value of token transfer
_data	bytes	Calldata included in the transfer

strategyDeposit

Manually deposits asset tokens into a specific strategy

function strategyDeposit(uint256 _index, uint256 _amount) external

Parameters

Name	Type	Description
_index	uint256	Index of strategy
_amount	uint256	Amount to deposit

strategyWithdraw

Manually withdraws asset tokens from a strategy

function strategyWithdraw(uint256 _index, uint256 _amount) external

Parameters

Name	Type	Description
_index	uint256	Index of strategy
_amount	uint256	Amount to withdraw

addStrategy

Adds a new strategy

function addStrategy(address _strategy) external

Parameters

Name	Type	Description
_strategy	address	Address of strategy contract

removeStrategy

Removes a strategy

function removeStrategy(uint256 _index, bytes _strategyUpdateData, bytes _strategyWithdrawalData) external

Parameters

Name	Type	Description
_index	uint256	Index of strategy
_strategyUpdateData	bytes	update data passed to strategy
_strategyWithdrawalData	bytes	withdrawal data passed to strategy

reorderStrategies

Reorders strategies

function reorderStrategies(uint256[] _newOrder) external

Parameters

Name	Type	Description
_newOrder	uint256[]	List containing strategy indexes in a new order

addFee

Adds a new fee

function addFee(address _receiver, uint256 _feeBasisPoints) external

Parameters

Name	Type	Description
_receiver	address	Address of fee receiver
_feeBasisPoints	uint256	Fee in basis points

updateFee

Updates an existing fee

function updateFee(uint256 _index, address _receiver, uint256 _feeBasisPoints) external

Parameters

Name	Type	Description
_index	uint256	Index of fee
_receiver	address	Address of fee receiver
_feeBasisPoints	uint256	Fee in basis points

updateStrategyRewards

Distributes rewards/fees based on balance changes in strategies since the last update

function updateStrategyRewards(uint256[] _strategyIdxs, bytes _data) public

Parameters

Name	Type	Description
_strategyIdxs	uint256[]	Indexes of strategies to update rewards for
_data	bytes	update data passed to each strategy

transferShares

Transfers shares from the sender to another account

function transferShares(address _receipient, uint256 _sharesAmount) external

Parameters

Name	Type	Description
_receipient	address	account to transfer shares to
_sharesAmount	uint256	amount of shares to transfer

transferShares

Transfers shares between accounts

function transferSharesFrom(address _sender, address _receipient, uint256 _sharesAmount) external

Parameters

Name	Type	Description
_sender	address	account to transfer shares from
_receipient	address	account to transfer shares to
_sharesAmount	uint256	amount of shares to transfer

setPriorityPool

Sets the address of the priority pool

function setPriorityPool(address _priorityPool) external

Parameters

Name	Type	Description
_priorityPool	address	address of priority pool

setUnusedDepositLimit

Sets the maximum amount of unused deposits that can sit in the pool

function setUnusedDepositLimit(uint256 _unusedDepositLimit) external

Parameters

Name	Type	Description
_unusedDepositLimit	uint256	maximum amount of unused deposits

setRebaseController

Sets the address of the rebase controller

function setRebaseController(address _rebaseController) external

Parameters

Name	Type	Description
_rebaseController	address	address of rebase controller

burn

Burns the sender's liquid staking tokens, effectively donating their underlying stake to the pool

function burn(uint256 _amount) external

Parameters

Name	Type	Description
_amount	uint256	amount to burn

donateTokens

Deposits asset tokens into the pool without minting liquid staking tokens, effectively donating them to the pool

function donateTokens(uint256 _amount) external

Parameters

Name	Type	Description
_amount	uint256	amount to deposit