Chainlink Median

1. Summary
The ChainlinkPriceFeedMedianizer has a similar interface to the Governance Led Median although, instead of relying on governance whitelisted oracles, it simply keeps a reference to a Chainlink price reference contract (price aggregator).
2. Contract Variables & Functions
Variables
authorizedAccounts [usr: address] - addAuthorization/removeAuthorization/isAuthorized - auth mechanisms
staleThreshold - time since linkAggregatorTimestamp after which the median value is considered stale 
chainlinkAggregator - address of the Chainlink price reference contract
rewardRelayer - address of the contract that rewards addresses that call updateResult
medianPrice - latest fetched price 
lastUpdateTime - latest timestamp when the contract pulled a price update from Chainlink
multiplier - scaling factor for the Chainlink result (e.g if the price has 8 decimals and we want it to be scaled to 18 decimals, multiplier = 10 and medianPrice = fetchedPrice * 10 ^ multiplier)
symbol - the price oracle type (ex: ETHUSD)
periodSize - the minimum delay between two consecutive updates after which the reward for updating again starts to increase
linkAggregatorTimestamp - the timestamp of the Chainlink aggregator's latest price update
Modifiers
isAuthorized - checks whether an address is part of authorizedAddresses (and thus can call authed functions).
Functions
modifyParameters - allows governance to change contract parameters
read() public view returns (uint256) - gets a non-zero price or fails
getResultWithValidity() public view returns (uint256,bool) - gets the price and its validity
updateResult(feeReceiver: address) - updates the price stored in the contract by calling the Chainlink aggregator
Events
AddAuthorization - emitted when a new address becomes authorized. Contains:
account - the new authorized account
RemoveAuthorization - emitted when an address is de-authorized. Contains:
account - the address that was de-authorized
ModifyParameters - emitted when a parameter is updated
UpdateResult - emitted when updateResult is called. Contains:
medianPrice - the latest median price
lastUpdateTime - timestamp of the call
3. Walkthrough
When reading the latest price feed, the contract also stores the timestamp when the price coming from Chainlink was posted on-chain. The system can incentivize anyone to call updateResult and update the median price regularly using a rewardRelayer.

Governance Led Median

Uniswap V2 Median

Last modified 1yr ago

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Contents

1. Summary

2. Contract Variables & Functions

3. Walkthrough