Ring Miners

Ring miners were a role in the early versions of the Loopring protocol, a 2017 system for building decentralised exchanges on Ethereum. Users signed orders off-chain, and ring miners searched the pool of open orders for combinations that formed a closed loop, for example one trader selling token A for B, a second selling B for C and a third selling C for A. Settling the ring at once could fill orders no simple pair of trades would match. The miner submitted the ring to Loopring's smart contract, which settled every trade together, and earned part of the fees or the price margin. Despite the name, the role involved no mining in the usual sense; it was closer to the work of a matching engine or relayer, as in the 0x protocol. Loopring later rebuilt itself as a zero-knowledge rollup, dropping ring mining.