Price aggregator

Overview

The price-aggregator smart contract keeps track of the price between multiple pairs of tokens. Compared to the other chainlink contracts, it is a simplified and easier to use version.

Deployment

Arguments:

• staking_token - the token used for staking and slashing
• staking_amount - the minimum staked amount required for a used to be considered a board member
• slash_amount - the amount to be slashed from a board member on a successful slash vote
• slash_quorum - the minimum number of board members required for a vote to be considered successful
• oracles - the list of addresses which are allowed to submit price feed updates
• submission_count - the minimum number of submissions from different oracles which trigger an update of the price feed

Configuring the number of decimals

The number of decimals for a given token pair can be set by calling setPairDecimals(from, to, decimals). Notes:

• only the owner can configure the number of decimals
• the contract must be paused first
• this method also clears the submissions accumulated so far
• no submissions will be accepted for any given pair unless the number of decimals is configured first
• every oracle must change its configuration to provide submissions with the new number of decimals, as any mismatch will be considered a configuration error and the submission will be rejected

Submitting price feed updates

An oracle can submit a price feed update using one of the endpoints:

• submit - submit a single price feed as 5 arguments (from, to, submission_timestamp, price and decimals).
• submitBatch - submit multiple price feeds simultaneously. The number of arguments must be a multiple of 5.

Note: the decimals argument must match the value returned by getPairDecimals for that specific pair, otherwise the submission will be rejected.

Rounds

Price feeds from multiple oracles are collected. When a certain threshold number of submissions has been reached (given by submission_count), a new round is created. The price feed recorded in the round is the median value out of all submissions made.

Querying the price feeds

Endpoints:

• latestRoundData takes no arguments and returns all the latest price feeds.
• latestPriceFeed takes a filter (as the from and to token identifiers) and returns a single price feed. The transaction fails if there is no price feed for the given filter.
• latestPriceFeedOptional behaves like latestPriceFeed but it returns an option so that the caller can handle the lack of a price feed.

A price feed contains:

• round_id - the ID of the current round (not related to the blockchain round ID)
• from - the first token
• to - the second token
• price - the price between the two tokens
• decimals - the number of decimals for the price