WIP: use evm chains as the settlement chain

[imotai]

Overview

1. db3 erc20 contract, db3 token contract
2. db3 rollup contract, a bridge contract for db3 bridge
3. db3 bridge

deposit

1. User deposits at least 10 $db3 to db3 rollup contract
2. the rollup contract dispatches messages with address and balance
3. the bridge processes the message and mints 10 $db3 credits on every sharding chains

we will add a new mutation operation named Mint Credits

detailed implementation

settle

the db3 bridge will process all bills from every sharding chains

1. get bills from a block
2. generate a new state with <account, bill>
3. post the state to db3 rollup contract
4. the rollup contract dispatches settle event message
5. the bridge processes the message and mints related credits on every sharding chains

Solution

Alternatives

Additional context

Related Issue

• demo: add evm chain bridge and faucet #319
• settle the bills when a new block has been processed

Reference

• https://vitalik.ca/general/2021/01/05/rollup.html
• https://github.com/attestate/indexed-sparse-merkle-tree