BOND staking / locking + Rewards

Architecture

• Diamond Standard for upgradeability

  • started from the reference implementation here which was refactored
  • the features presented below are implemented on a single facet in BarnFacet.sol

• Diamond Storage for storage

BOND staking

Actions

• deposit
• withdraw
• lock
• delegate

Main Views

• balance - current and snapshot = the actual amount a user staked (bonus not included)
• delegated power - current and snapshot = how much power was delegated to a user by other users
• voting power - current and snapshot = balance * (1 + bonus) + delegated power
• total $BOND staked - current and snapshot

Specs

• user can stake BOND for vBOND
  • user can lock BOND for a period up to 1 year and he gets a bonus of vBOND
    • bonus is linear, max 1 year, max 2x multiplier
      • example:
        • lock 1000 BOND for 1 year → get back 2000 vBOND
        • lock 1000 BOND for 6 months → get back 1500 vBOND
    • bonus has a linear decay relative to locking duration
      • example: lock 1000 BOND for 1 year, get back 2000 vBOND at T0 → after 6 months, balance is 1500 vBOND → after 9 months, balance is 1250 vBOND
    • user can only withdraw their BOND balance after lock expires
  • user can keep BOND unlocked and no bonus is applied, vBOND balance = BOND balance
• user can stake more BOND
  • no lock → just get back the same amount of vBOND
  • lock
    • lock period stays the same
      • base balance is increased with the added BOND
      • multiplier stays the same
    • lock period is extended
      • base balance is increased with the added BOND
        • multiplier is recalculated relative to the new lock expiration date
• user can delegate vBOND to another user
  • there can be only one delegatee at a time
  • only actual balance can be delegated, not the bonus
  • delegated balance cannot be locked
  • user can take back the delegated vBONDs at any time

Rewards

The rewards contract is meant as a continuation of the pool 3 from BarnBridge's YieldFarming program. It is used to incentivize participation in the DAO.

The distribution mechanism is based on a continuous strategy (for example, if you staked for 5 minutes, you can claim a reward relative to those 5 minutes).

The Barn contract calls the registerUserAction hook on each deposit/withdraw the user executes.

How it works

1. every time the acKFunds function detects a balance change, the multiplier is recalculated by the following formula:

newMultiplier = oldMultiplier + amountAdded / totalBondStaked

2. whenever a user action is registered (either by automatic calls from the hook or by user action (claim)), we calculate the amount owed to the user by the following formula:

newOwed = currentlyOwed + userBalance * (currentMultiplier - oldUserMultiplier)

where:
- oldUserMultiplier is the multiplier at the time of last user action
- userBalance = barn.balanceOf(user) -- the amount of $BOND staked into the Barn

3. update the oldUserMultiplier with the current multiplier -- signaling that we already calculated how much was owed to the user since his last action

Audits

• QuantStamp
• Haechi