# Staking Contracts ⚠️ This page only applies to very early farms, though many newer farms share features and function names ⚠️ Based on Synthetix's staking contract: ## Description Frax users are able to stake in select Uniswap liquidity pool tokens in exchange for FXS rewards. Future pools and incentives can be added by governance. ## Deployment *Liquidity Pool Tokens (LP)* Uniswap FRAX/WETH LP: `0xFD0A40Bc83C5faE4203DEc7e5929B446b07d1C76` Uniswap FRAX/USDC LP: `0x97C4adc5d28A86f9470C70DD91Dc6CC2f20d2d4D` Uniswap FRAX/FXS LP: `0xE1573B9D29e2183B1AF0e743Dc2754979A40D237` Uniswap FXS/WETH LP: `0xecBa967D84fCF0405F6b32Bc45F4d36BfDBB2E81` *Staking Contracts* Uniswap FRAX/WETH staking: `0xD875628B942f8970De3CcEaf6417005F68540d4f` Uniswap FRAX/USDC staking: `0xa29367a3f057F3191b62bd4055845a33411892b6` Uniswap FRAX/FXS staking: `0xda2c338350a0E59Ce71CDCED9679A3A590Dd9BEC` Uniswap FXS/WETH staking (deprecated): `0xDc65f3514725206Dd83A8843AAE2aC3D99771C88` ## State Variables ``` FRAXStablecoin private FRAX ``` Instance of the FRAX contract. ``` ERC20 public rewardsToken ``` Instance for the reward token. ``` ERC20 public stakingToken ``` Instance for the staking token. ``` uint256 public periodFinish ``` Block when the staking period will finish. ``` uint256 public rewardRate ``` Maximum reward per second. ``` uint256 public rewardsDuration ``` Reward period, in seconds. ``` uint256 public lastUpdateTime ``` Last timestamp where the contract was updated / state change. ``` uint256 public rewardPerTokenStored ``` Actual reward per token in the current period. ``` uint256 public locked_stake_max_multiplier ``` Maximum boost / weight multiplier for locked stakes. ``` uint256 public locked_stake_time_for_max_multiplier ``` The time, in seconds, to reach `locked_stake_max_multiplier` . ``` uint256 public locked_stake_min_time ``` Minimum staking time for a locked staked, in seconds. ``` string public locked_stake_min_time_str ``` String version is `locked_stake_min_time_str` . ``` uint256 public cr_boost_max_multiplier ``` Maximum boost / weight multiplier from the collateral ratio (CR). This is applied to both locked and unlocked stakes. ``` mapping(address => uint256) public userRewardPerTokenPaid ``` Keeps track of when an address last collected a reward. If they collect it some time later, they will get the correct amount because `rewardPerTokenStored` is constantly varying. ``` mapping(address => uint256) public rewards ``` Current rewards balance for a given address. ``` uint256 private _staking_token_supply ``` Total amount of pool tokens staked . ``` uint256 private _staking_token_boosted_supply ``` `_staking_token_supply` with the time and CR boosts accounted for. This is not an actual amount of pool tokens, but rather a 'weighed denominator'. ``` mapping(address => uint256) private _balances ``` Balance of pool tokens staked for a given address. ``` mapping(address => uint256) private _boosted_balances ``` `_balances` , but with the time and CR boosts accounted for, like `_staking_token_boosted_supply`. ``` mapping(address => LockedStake[]) private lockedStakes ``` Gives a list of locked stake lots for a given address. ``` struct LockedStake { bytes32 kek_id; uint256 start_timestamp; uint256 amount; uint256 ending_timestamp; uint256 multiplier; // 6 decimals of precision. 1x = 1000000 } ``` A locked stake 'lot'. ## **View Functions** **totalSupply** ``` totalSupply() external override view returns (uint256) ``` Get the total number of staked liquidity pool tokens. **stakingMultiplier** ``` stakingMultiplier(uint256 secs) public view returns (uint256) ``` Get the time-based staking multiplier, given the `secs` length of the stake. **crBoostMultiplier** ``` crBoostMultiplier() public view returns (uint256) ``` Get the collateral ratio (CR) - based staking multiplier. **stakingTokenSupply** ``` stakingTokenSupply() external view returns (uint256) ``` same as totalSupply(). **balanceOf** ``` balanceOf(address account) external override view returns (uint256) ``` Get the amount of staked liquidity pool tokens for a given `account`. **boostedBalanceOf** ``` boostedBalanceOf(address account) external view returns (uint256) ``` Get the boosted amount of staked liquidity pool tokens for a given `account`. Boosted accounts for the CR and time-based multipliers. **lockedBalanceOf** ``` lockedBalanceOf(address account) public view returns (uint256) ``` Get the amount of locked staked liquidity pool tokens for a given `account` . **unlockedBalanceOf** ``` unlockedBalanceOf(address account) external view returns (uint256) ``` Get the amount of unlocked / free staked liquidity pool tokens for a given `account` . **lockedStakesOf** ``` lockedStakesOf(address account) external view returns (LockedStake[] memory) ``` Return an array of all the locked stake 'lots' for **stakingDecimals** ``` stakingDecimals() external view returns (uint256) ``` Returns the `decimals()` for `stakingToken` . **rewardsFor** ``` rewardsFor(address account) external view returns (uint256) ``` Get the amount of FXS rewards for a given `account` . **lastTimeRewardApplicable** ``` lastTimeRewardApplicable() public override view returns (uint256) ``` Used internally to keep track of `rewardPerTokenStored` . **rewardPerToken** ``` rewardPerToken() public override view returns (uint256) ``` The current amount of FXS rewards for staking a liquidity pool token. **earned** ``` earned(address account) public override view returns (uint256) ``` Returns the amount of unclaimed FXS rewards for a given `account` . **getRewardForDuration** ``` getRewardForDuration() external override view returns (uint256) ``` Calculates the FXS reward for a given `rewardsDuration` period. ## Mutative Functions **stake** ``` stake(uint256 amount) external override nonReentrant notPaused updateReward(msg.sender) ``` Stakes some Uniswap liquidity pool tokens. These tokens are freely withdrawable and are only boosted by the `crBoostMultiplier()`**.** **stakeLocked** ``` stakeLocked(uint256 amount, uint256 secs) external nonReentrant notPaused updateReward(msg.sender) ``` Stakes some Uniswap liquidity pool tokens and also locks them for the specified `secs` . In return for having their tokens locked, the staker's base `amount` will be multiplied by a linear time-based multiplier, which ranges from 1 at `secs` = 0 to `locked_stake_max_multiplier` at `locked_stake_time_for_max_multiplier`**.** The staked value is also multiplied by the `crBoostMultiplier()` . This multiplied value is added to `_boosted_balances` and acts as a weighted amount when calculating the staker's share of a given period reward. **withdraw** ``` withdraw(uint256 amount) public override nonReentrant updateReward(msg.sender) ``` Withdraw unlocked Uniswap liquidity pool tokens. **withdrawLocked** ``` withdrawLocked(bytes32 kek_id) public nonReentrant updateReward(msg.sender) ``` Withdraw locked Uniswap liquidity pool tokens. Will fail if the staking time for the specific `kek_id` staking lot has not elapsed yet. **getReward** ``` getReward() public override nonReentrant updateReward(msg.sender) ``` Claim FXS rewards. **exit** ``` exit() external override ``` Withdraw all unlocked pool tokens and also collect rewards. **renewIfApplicable** ``` renewIfApplicable() external ``` Renew a reward period if the period's finish time has completed. Calls `retroCatchUp()` . **retroCatchUp** ``` retroCatchUp() internal ``` Renews the period and updates `periodFinish` , `rewardPerTokenStored` , and `lastUpdateTime` . ## Restricted Functions **notifyRewardAmount** ``` notifyRewardAmount(uint256 reward) external override onlyRewardsDistribution updateReward(address(0)) ``` This notifies people (via the event `RewardAdded` ) that the reward is being changed. **recoverERC20** ``` recoverERC20(address tokenAddress, uint256 tokenAmount) external onlyOwner ``` Added to support recovering LP Rewards from other systems to be distributed to holders. **setRewardsDuration** ``` setRewardsDuration(uint256 _rewardsDuration) external onlyOwner ``` Set the duration of the rewards period. **setLockedStakeMaxMultiplierUpdated** ``` setLockedStakeMaxMultiplierUpdated(uint256 _locked_stake_max_multiplier) external onlyOwner ``` Set the maximum multiplier for locked stakes. **setLockedStakeTimeForMaxMultiplier** ``` setLockedStakeTimeForMaxMultiplier(uint256 _locked_stake_time_for_max_multiplier) external onlyOwner ``` Set the time, in seconds, when the locked stake multiplier reaches `locked_stake_max_multiplier` . **setLockedStakeMinTime** ``` setLockedStakeMinTime(uint256 _locked_stake_min_time) external onlyOwner ``` Set the minimum time, in seconds, of a locked stake. **setMaxCRBoostMultiplier** ``` setMaxCRBoostMultiplier(uint256 _max_boost_multiplier) external onlyOwner ``` aaa **initializeDefault** ``` initializeDefault() external onlyOwner ``` Intended to only be called once in the lifetime of the contract. Initializes `lastUpdateTime` and `periodFinish` . ## Modifiers **updateReward** ``` updateReward(address account) ``` Calls `retroCatchUp()` , if applicable, and otherwise syncs `rewardPerTokenStored` and `lastUpdateTime` . Also, syncs the `rewards` and `userRewardPerTokenPaid` for the provided `account` .