Batch Precompile Clean-up

[gitofdeepanshu]

Description

Clean up related to Batch Precompile after removing the revert code.

Required Tasks

• archive docs #1046
• remove code from the runtime

[HyunggyuJang]

Can I ask the background for this decision? IMHO, it is quite valuable utility function.

[Dinonard]

Can I ask the background for this decision? IMHO, it is quite valuable utility function.

We decided it's not needed to have on the runtime level.
The main motivation for adding this was a specific UI requirement, but we found out it can be handled differently.

If you want to utilize batch calls in EVM, there are prexisting contracts which allow for this.
We could deploy one such contract and document how to use it in Astar docs.
However, there hasn't been a requirement for this so far, except good to have.

[HyunggyuJang]

If you want to utilize batch calls in EVM, there are prexisting contracts which allow for this.

I guess, you mean Multicall, but it doesn't allow to call methods from the caller address; also there is no general way to do that from plain EVM contract, unless the target contract provides some batch call methods that utilize delegate call.

I agree that it might not have great impact on the production as the state query methods can be achieved via multicall, but when it comes to mutate the state of blockchain, as I wrote above, there is no general way to batch the calls, except to execute them one by one from the client side, which costs a lot of transmission time. I found the batch precompile is sweet feature. It's sad that it will be gone.

[Dinonard]

From the client side it's possible to achieve the same functionality via dispatch precompile.
However, it's not allowed to be used by smart contracts.

Our portal is using this functionality right now.

[HyunggyuJang]

From the client side it's possible to achieve the same functionality via dispatch precompile. However, it's not allowed to be used by smart contracts.

Our portal is using this functionality right now.

It makes sense. So, currently runtime call filter blocks dispatch precompile, but is allowed from direct call from client side, right? Then my use case also can be handled similarly. Thanks a lot!

[Dinonard]

Yes, but there's also a filter for distpatch - right now batch, dApp staking and some pallet-asset calls are allowed.

But if needed, e.g. by you, we can consider adding more of those.
I'd suggest to open a Github issue if there's a feature you need.

[HyunggyuJang]

I'd suggest to open a Github issue if there's a feature you need.

Noticed! Thanks for your sincere response. I'll open an issue if I found some use cases that I might use the dispatch precompile :)

[Dinonard]

Noticed! Thanks for your sincere response. I'll open an issue if I found some use cases that I might use the dispatch precompile :)

No problem! And please don't hesitate to do so! We'll be happy to receive requirements like this! 😄

[HyunggyuJang]

TL;DR dispatch precompile doesn't cover batch precompile, is there any way to batch EVM calls?

@Dinonard Sorry for the delay, I have a chance to use batch call as you gave advice. I believe what you referred at

Our portal is using this functionality right now.

comes from https://github.com/AstarNetwork/astar-apps/pull/930/files#diff-e08c21311328ec6676f39662564895de8cbb99cb0542e0e41cbf372d199d8427.

I inspected it, and found that it uses batch utility for extrinsics. Unlike batch precompile, this way, it doesn't allow batch EVM calls as the CallOrigin is currently set as a root origin. I.e., we cannot call evm call as a extrinsic.

[Dinonard]

If you want to call other EVM smart contracts as part of a batch call, you shouldn't use the pallet-evm. That call is not supposed to be used by anyone (hence the root only filter).

There are ways to create batch call in EVM, e.g. like this: https://docs.openzeppelin.com/contracts/4.x/api/utils#Multicall.

[HyunggyuJang]

Yep, but as I said above, multicall doesn't allow to call methods with caller address :( That was the reason why I valued batch precompile.

I guess, you mean Multicall, but it doesn't allow to call methods from the caller address; also there is no general way to do that from plain EVM contract, unless the target contract provides some batch call methods that utilize delegate call.

[Dinonard]

There's this too: https://github.com/mds1/multicall/tree/main/src

This allows you to change addresses and construct complex calls.

[HyunggyuJang]

It does allow the target address, but not the caller address. With multicall, the caller address is the address of multicall contract, not the msg.sender.

[Dinonard]

You can use delegatecall though, right?

EDIT: Anyhow, if there's a concrete scenario and/or business case, and same functionality cannot be achieved via existing EVM capabilities, we will consider it.
We don't want to add functionality because it's just good to have, unless there's a demand for it.

[HyunggyuJang]

You can use delegatecall though, right?

It requires contracts to inherit multicall contract; cannot batch the calls across different contracts.

Anyhow, if there's a concrete scenario and/or business case, and same functionality cannot be achieved via existing EVM capabilities, we will consider it.
We don't want to add functionality because it's just good to have, unless there's a demand for it.

Agree. For now, it is a utility function for the backend side, not the frontend; i.e., not critical from the user perspective of dapp. Thanks for your sincere elaboration! Much appreciated.