Contracts Overview
Venus Protocol contracts are divided in these repositories:
isolated-pools: Contains core contracts for isolated lending, including logic for supplying, borrowing, liquidations, pool and market deployments, and interest rate models.
oracle: This repo has contracts for oracles that we support as well as logic for validating prices returned from those oracles.
venus-protocol: The core protocol is located in this repo. It contains logic central to lending and borrowing of the core pool.
governance-contracts: The contracts used for proposing, voting and executing changes are kept in the `governance-contracts repo.
token-bridge: The contracts use to bridge XVS to different networks.
Isolated Pools Contracts
There are 2 categories of isolated pools contracts:
Pool
Risk Management
Pool
Pool contracts can be divided into 4 categories:
Configuration
Logic
Miscellaneous
Configuration
Configuration contracts are used to deploy, configure, and manage pools.
Creating and managing pools is done by the PoolRegistry. It can add markets to pools, update pool metadata, and return pool information.
Logic contracts
The Comptroller contract is the central contract for each lending pool. It contains functionality central to borrowing activity in the pool like supplying and borrowing assets and liquidations. Configuration values for the pool such as the liquidation incentive, close factor, and collateral factor can also be set and retrieved from the comptroller. Account liquidity and positions can also be retrieved from the comptroller.
vTokens in isolated lending play an identical role as vTokens in the Core Pool. They represent a users supplied tokens to the protocol and can be redeemed (burned) for those tokens.
Miscellaneous contracts
Isolated Pools use additional contracts such as lenses, rewards, ect.
Users are rewarded for borrowing and lending activities with a reward tokens. The RewardsDistributor manages these distributions using a configurable rate.
To make querying pool data easier, Isolated Pools contains a lens that queries and formats pool data. These calls can be gas intensive so as a general rule of thumb this contract should not be used in transactions.
Risk Management
Lending comes with the inherent risk that borrows will not be able to repay their loan, which is a threat to the protocol's insolvency. Venus mitigates this risk with a RiskFund. A percentage of protocol revenues is transferred to the RiskFund as it is accrued. When bad debt is detected, this fund can be auctioned off and used to cover the bad debt.
When bad deb is auctioned off the Shortfall contract is responsible for running the action and paying the winner.
The ProtocolShareReserve acts as a treasury where each isolated pool can transfer their revenue.
Oracle Contracts
Venus Protocol implements secondary, primary and pivot oracles to create a validation and fallback strategy that avoids creating a single point of a failure by relying on a single source for prices. The ResilientOracle contract is responsible for fetching and validating prices for a given vToken and managing which oracles are used for a particular vToken.
Oracles
ChainLinkOracle is the primary oracle. If a token isn't support by Chainlink then prices will be fetched from a secondary oracle.
RedstoneOracle is used in the Classic model (Chainlink-compatible interface) as a pivot oracle to validate prices returned by main and fallback oracles.
BinanceOracle contract is responsible for fetching token prices from the Binance oracle. It is used as a secondary oracle.
PythOracle is used as a pivot oracle to validate prices returned by primary and secondary oracles.
Venus Protocol
Venus Protocol contracts can be grouped as follows:
Lending
Tokens
Vault
Lens
Lending Contracts
At the heart of the Core Pool is the comptroller. The latest version is Comptroller. The comptroller is responsible for listing markets, managing user's positions in markets, liquidations, and emitting rewards. It contains setters and getters for market configuration variables such as collateral factor, close factor, and liquidation incentive. Lending actions can be be paused globally or per market from the comptroller.
Each market gets deployed with an interest rate model. The JumpRateModel uses a linear curve to determine interest rates based on supply and demand of the asset until it reaches the kink after which there is a sharp increase in rates.
Another interest rate model that can be deployed with markets is the WhitePaperInterestRateModel. It is similar to the JumpRateModel except it doesn't include a kink. Instead it contains a fixed base rate.
When a borrow becomes insolvent it may be liquidated. The Liquidator handles this process. When a borrow is liquidated the seized amount is split between the liquidator and the treasury
Revenue earned by the protocol is kept in the VTreasury.
Token Contracts
XVS is an important token in the Venus ecosystem because it powers Venus governance. The XVS token contract defines a lockable BEP20 token with additional methods that enable voting and vote delegation. To vote, a user must first lock their XVS in the vault. The XVSVesting controlled XVS emissions when converting VRT to XVS. The time period to convert VRT to XVS has expired.
VAI is the Venus stable coin that can be minted against collateral. Users who mint VAI are charged a fee based on the outstanding supply and price of VAI to keep its value pegged at $1. The VAIController controls the amount of VAI a user is allowed to mint which is determined by the collateral a user has provided and their liquidity.
VRT
The Venus Rewards Token (VRT) is composed two contracts - the token contract and the converter contract. The VRT token contract defines a lockable BEP20 token, which allows the token to be staked in order to earn additional VRT tokens. The VRTConverter allows VRT to be converted to XVS.
When a user supplies a token to the protocol, vTokens are minted to represent their supply. The VToken contract contains methods that support lending activities for the asset including lending, borrowing and liquidating
Vault Contracts
XVS Vault
XVS can be locked in the XVSVault to earn XVS and enable voting. Each XVS locked gives the locking address one vote to use or delegate.
VAI Vault
VAI staked in the VAIVault earn XVS. Staking rewards are accumulated daily.
VRT Vault
The VRTVault allows users to stake VRT and earn VRT daily. Rewards are accrued daily similar to the other vaults.
Misc Contracts
ComptrollerLens
The ComptrollerLens contains methods for fetching the liquidity of an account and the amount of tokens that can be seized for a repayable amount
SnapshotLens
The SnapshotLens contains methods for getting the details of account for a specific market or all markets where an account is active.
VenusLens
Protocol level data is made available through the VenusLens. It contains getters related to XVS distribution, governance, and markets.
Governance Contracts
There are three main Governance contracts:
GovernorBravoDelegate
AccessControlManager
Timelock
GovernorBravoDelegate
The core logic for governance proposals is in the GovernorBraveDelegate contract. It enables submitting proposals, moving proposals through time-gated stages, canceling and executing proposals as well as voting logic. The voting threshold as well as timelocks are set on this contract.
AccessControlManager
To enhance security of the protocol, Venus Protocol uses the AccessControlManager to grant accounts access to call specific functions on contracts. This contract is responsible for granting and revoking those permissions. It also provides a getter to check if an address is allowed to call a specific function.
Timelock Once a proposal has succeeded its execution is managed by the Timelock contract. The Timelock can place the proposal in a queue for execution and execute the proposal. It also enables canceling the proposal.
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