Integrate frontier

[boundless-forest]

Desc

This is the first PR to integrate the frontier into the Darwinia network.

Finished Tasks

1. Clone the whole frontier repo and ensure it works in a template single node. The only change i made in the frontier-cloned now was the Trait for ethereum-pallet.

/// Trait for Ethereum pallet.
/// Old version
pub trait Trait: frame_system::Trait<Hash=H256> + pallet_balances::Trait + pallet_timestamp::Trait + pallet_evm::Trait {

New version for darwinia network
pub trait Trait: frame_system::Trait<Hash=H256> + darwinia_balances::Trait::<RingInstance> + pallet_timestamp::Trait + pallet_evm::Trait {

2. Change the default address mapping functions from original HashedAddressMapping<BlakeTwo256> to ConcatAddressMapping.

3. A new EVM precompiled contract TransferBack added. The contract name and implementation might be changed later in future prs.

[aurexav]

I think consensus + frame + rpc is enough.

[boundless-forest]

I think consensus + frame + rpc is enough.

OK, I am going to clear the useless files and commit later.

[aurexav]

Which frontier version are we using?

I'll review this later.

[boundless-forest]

Which frontier version are we using?

I'll review this later.

Please check the first commit msg Squashed 'frontier/' content from commit 51bd10f.

[hackfisher]

Better to move frontier/frame/ethereum to frame/dvm

For frontier/rpc and frontier/consensus, maybe rpc/dvm and consensus/dvm is better.

DVM is the abbreviation of Darwinia Smart-contract VM, which is compatible and fork of EVM.

[boundless-forest]

Better to move frontier/frame/ethereum to frame/evm

For frontier/rpc and frontier/consensus, maybe rpc/evm and consensus/evm is better.

Yeap, It looks more clear to put frontier-related pallets under root/frame/.

How about putting frontier/rpc, frontier/frame/ethereum, frontier/consensus into a single subdirectory of root/frame named vm. Because of these three pallets all tight-related with one topic.

darwinia-common
    - bin
    - frame
          - balances
          - dvm
                - ethereum
                - consensus
                - rpc

[hackfisher]

Better to move frontier/frame/ethereum to frame/evm
For frontier/rpc and frontier/consensus, maybe rpc/evm and consensus/evm is better.

Yeap, It looks more clear to put frontier-related pallets under root/frame/.

How about putting frontier/rpc, frontier/frame/ethereum, frontier/consensus into a single subdirectory of root/frame named vm. Because of these three pallets all tight-related with one topic.

darwinia-common
    - bin
    - frame
          - balances
          - dvm
                - ethereum
                - consensus
                - rpc

Yes, I think it is a good idea to do it in this way, just like another example in substrate:

https://github.com/paritytech/substrate/blob/master/frame/contracts/rpc/src/lib.rs

There are some rpc package from ethereum web3 which might be not directly to evm pallet, and more like primitives, can also moved to primitives folder

[boundless-forest]

Better to move frontier/frame/ethereum to frame/evm
For frontier/rpc and frontier/consensus, maybe rpc/evm and consensus/evm is better.

Yeap, It looks more clear to put frontier-related pallets under root/frame/.
How about putting frontier/rpc, frontier/frame/ethereum, frontier/consensus into a single subdirectory of root/frame named vm. Because of these three pallets all tight-related with one topic.

darwinia-common
    - bin
    - frame
          - balances
          - dvm
                - ethereum
                - consensus
                - rpc

Yes, I think it is a good idea to do it in this way, just like another example in substrate:

https://github.com/paritytech/substrate/blob/master/frame/contracts/rpc/src/lib.rs

There are some rpc package from ethereum web3 which might be not directly to evm pallet, and more like primitives, can also moved to primitives folder

So, I guess the final skeleton looks like the file tree I painted above just now? If I am not misunderstand, I will work on this change. Thank you for making sure it again.

[hackfisher]

@wuminzhe IMO Withdraw is not a good name for the precompiled contract, withdraw seems to be "transfer to my own address", but this precompiled contract it to "transfer to any substrate address"

[hackfisher]

[boundless-forest]

Is it necessary to set the accountId Prefix to 11 length bytes? For the length of the checksum as short as possible?

4 bytes length Prefix might more understandable. Why not leave an 8 length checksum at the end and keep 4 bytes length prefix at the head.

[hackfisher]

Is it necessary to set the accountId Prefix to 11 length bytes? For the length of the checksum as short as possible?

4 bytes length Prefix might more understandable. Why not leave an 8 length checksum at the end and keep 4 bytes length prefix at the head.

1 byte is enough for checksum purpose.

The others are just leaving there for future extension such as version etc. It is not necessary, but make sense IMO.

[wuminzhe]

@hackfisher What precompile name will be better? Transfer?

[hackfisher]

@hackfisher What precompile name will be better? Transfer?

I have no idea, but I will suggestBalanceTransfer or NativeTransfer if no more choices available.

[boundless-forest]

@hackfisher What precompile name will be better? Transfer?

I have no idea, but I will suggestBalanceTransfer or NativeTransfer if no more choices available.

The final name: NativeTransfer.

[boundless-forest]

@AurevoirXavier @hackfisher @wuminzhe This PR based on the latest code is ready to review by all guys.