PolicyPool

The PolicyPool is the main contract that keeps track of active policies and receives the spending allowances. It’s a single PolicyPool for each instance of the protocol. One of its attributes is currency(), which points to the coin (ERC20) used throughout the protocol. So far we support only USDC as currency.

It has methods for LP to deposit/withdraw, acting as a gateway for the eTokens. The PolicyPool is connected to a set of eTokens, premiums accounts, and risk modules.

The contract also follows the ERC721 standard, minting an NFT for each policy created. The owner of the NFT is the policyholder, and is who will receive the payout in case the policy is triggered. The NFTs are not burned when the policy expires or is triggered: they remain as a permanent record of each policy, while the policy is removed from the active set tracked by the pool.

Source: PolicyPool.sol · Full documentation: ensuro.readthedocs.io/en/latest/PolicyPool

Interactions

Parameters

Policy database

One of the responsibilities of the PolicyPool contract is to keep track of active policies with all the (immutable) data.

Given the Policy struct has many fields and storage is expensive on-chain, the struct isn’t stored as a storage variable of the contracts.

Instead, when the policy is created, only a hash of the struct is stored and an event with all the fields is emitted. Then, for any operation with the Policy (like resolution or expiration), all the policy needs to be sent as a parameter. The PolicyPool contract computes the hash of the parameter and compares it with the stored one.

The mapping from policyId to hash is stored in the _policies attribute.

Events

NewPolicy

event NewPolicy(IRiskModule indexed riskModule, Policy.PolicyData policy)

Event emitted every time a new policy is added to the pool. Contains all the data about the policy that is later required for doing operations with the policy like resolution or expiration.

PolicyReplaced

event PolicyReplaced(IRiskModule indexed riskModule, uint256 indexed oldPolicyId, uint256 indexed newPolicyId)

Event emitted every time a policy replaces an old policy. The full data of the new policy is available in the NewPolicy event.

PolicyCancelled

event PolicyCancelled(IRiskModule indexed riskModule, uint256 indexed cancelledPolicyId, uint256 purePremiumRefund, uint256 jrCocRefund, uint256 srCocRefund)

Event emitted when a policy is cancelled and part of the premium is refunded. After this, the policy is no longer active.

PolicyResolved

event PolicyResolved(IRiskModule indexed riskModule, uint256 indexed policyId, uint256 payout)

Event emitted every time a policy is removed from the pool. If the policy expired, the payout is 0, otherwise is the amount transferred to the policyholder.

Deposit

event Deposit(IEToken indexed eToken, address indexed sender, address indexed owner, uint256 amount)

Event emitted for every deposit into an eToken.

Withdraw

event Withdraw(IEToken indexed eToken, address indexed sender, address indexed receiver, address owner, uint256 amount)

Event emitted for every withdrawal from an eToken.

External Methods

expirePolicy

function expirePolicy(Policy.PolicyData calldata policy) external

Resolves a policy with a payout of 0, unlocking the solvency. Can be called by anyone, but only after Policy.expiration.

Requirements:

• policy: must be a Policy previously created with newPolicy (checked with policy.hash()) and not resolved before
• Policy expired: Policy.expiration <= block.timestamp

Events:

• {PolicyPool-PolicyResolved}: with payout == 0

Policy creation and resolution

The methods that create, replace, cancel and resolve policies — newPolicy, newPoliciesBatch, replacePolicy, cancelPolicy and resolvePolicy — are internal to the protocol and are meant to be called by active RiskModules, not by end users or integrations. See the full documentation for their complete signatures and behavior.