Transaction Fees

[mustermeiszer]

Description

Base is this RFC: https://gov.centrifuge.io/t/cp74-updating-transaction-fees-for-pools/5773

The idea is that governance should be able to control the fees that certain transactions are costing. In order to make this as easy as possible the following idea is proposes:

• Include pallet orml-parameters (needs polkadot-v1.0.0 or higher)
  • The additional fees would be set by governance here and be retrieved by the logic in the SignedExtra
• Extend SignedExtra either by
  • Wrapping pub struct ChargeTransactionPayment<T: Config>(#[codec(compact)] BalanceOf<T>); to have some logic that runs before the or after the one of that struct
  • Extend SignedExtra by a SignedExtension that has AdditionalSigned = () type (needed as we can not change SignedExtra due to wallet integrations breaking

This would allow

Requirements

• NOT break existing wallet integrations
• Show the additional fees as part of the fees logic that is provided by the runtime api pallet_transaction_payment_rpc_runtime_api::TransactionPaymentApi

Research/based on

• Discussion here

How will this affect the code base

• Increase CFG utility as stated by the governance proposal above

What are foreseen obstacles or hurdles to overcome?

None so far

[mustermeiszer]

Although I am not convinced that orml-parameters is the best idea to be used.
We could still extend pallet-fees IMO and have a better event resolution.