There is an increasing need for off-chain infrastructure in the Supefluid ecosystem as more projects, protocols, and individuals need to interact with contracts in complex, scheduled, or automated ways. This includes, but is not limited to, insolvent stream liquidation, pre-insolvency courtesy stream closures, scheduled transactions, and meta transactions.
Each project implements their own variant of a Sentinel, and each faces similar problems of block reorganizations, aggregating data reliably, maintaining a synchronization with the most recently mined block, and executing arbitrary actions.
The objective is to create a modular, configurable Sentinel that not only aggregates Superfluid-specific data, but also can execute any number of arbitrary actions on smart contracts.
The Superfluid protocol enables novel and unique functionality for thieir custom designed super tokens. This functionality comes from the ERC20 standard, ERC777 standard, and their own innovation, agreements. These agreements encode and store arbitrary data on super tokens, which then account for a real-time balance of a given user. Instead of an account balance being solely a single uint256 being read from a storage slot, there's also the per-second balance change from the Constant Flow Agreement, and the active subscriptions in the Instant Distribution Agreement.
Since the functions called to create agreements are complex, this will be a list
of contracts and their respective functions that will need to be taken into
account. Format is ContractName.functionToCall.
- Superfluid.callAgreement
- ConstantFlowAgreementV1.createFlow
- ConstantFlowAgreementV1.updateFlow
- ConstantFlowAgreementV1.deleteFlow
- InstantDistributionAgreementV1.createIndex
- InstantDistributionAgreementV1.updateIndex
- InstantDistributionAgreementV1.distribute
- InstantDistributionAgreementV1.approveSubscription
- InstantDistributionAgreementV1.updateSubscription
- InstantDistributionAgreementV1.deleteSubscription
- InstantDistributionAgreementV1.claim
- SuperToken.transfer
- SuperToken.transferFrom
- SuperToken.send
- SuperToken.burn
- SuperToken.operatorSend
- SuperToken.operatorBurn
- SuperToken.selfMint
- SuperToken.selfBurn
- SuperToken.upgrade
- SuperToken.upgradeTo
- SuperToken.operationTransfer
- SuperToken.operationUpgrade
- SuperToken.operationDowngrade
Each of these functions contribute to balance changes directly, so each will need to be considered.
Since a Sentinel might be used in a variety of ways, there should be an extreme degree of configurability to handle as many use cases as possible. A standard JSON schema should be implemented, where a Sentinel needs no code-changes to handle the use case.
{
"name": "Superfluid Liquidation",
"version": "1",
"networkId": "137",
"target": "0x3E14dC1b13c488a8d5D310918780c983bD5982E7",
"abi": [],
"executables": [
{
"functionName": "callAgreement",
"condition": {
"target": "0xCAa7349CEA390F89641fe306D93591f87595dc1F",
"functionName": "isAccountSolventNow",
"requiredReturn": false,
"prediction": {
"shouldPredict": true,
"secondsBefore": 0
}
}
"estimatedGas": "3000000",
"estimatedGasPrice": "30",
"maxGas": "10000000",
}
]
}This is an example spec, targeting superfluid liquidations on USDCx on Polygon.
Instead of looping an calling isAccountSolventNow, it should use the
aggregated data to predict insolvency based on the current account flow state.
One-off transfers cannot be predicted, however, and this is why the Sentinel has to maintain its sync with the blockchain by polling continuously. If a new block is found to include a trasnfer that makes an account insolvent based on the data on hand, the Sentinel should also trigger the function call.
This will need further discussion to make this as agnostic as possible. Though in the context of Superfluid, the Sentinel will likely need to focus on solvency maintenance and transaction scheduling.
- Block Reorganization
- RPC Provider Rate Limits
- Gas Price Fluctuation
- Meta Transaction Validation and Execution
This is a work in progress, discussion is welcome, and proposals are encouraged!