Crate pallet_transaction_payment

Transaction Payment Pallet

This pallet provides the basic logic needed to pay the absolute minimum amount needed for a transaction to be included. This includes:

• base fee: This is the minimum amount a user pays for a transaction. It is declared as a base weight in the runtime and converted to a fee using WeightToFee.
• weight fee: A fee proportional to amount of weight a transaction consumes.
• length fee: A fee proportional to the encoded length of the transaction.
• tip: An optional tip. Tip increases the priority of the transaction, giving it a higher chance to be included by the transaction queue.

The base fee and adjusted weight and length fees constitute the inclusion fee, which is the minimum fee for a transaction to be included in a block.

The formula of final fee:

inclusion_fee = base_fee + length_fee + [targeted_fee_adjustment * weight_fee];
final_fee = inclusion_fee + tip;

• targeted_fee_adjustment: This is a multiplier that can tune the final fee based on the congestion of the network.

Additionally, this pallet allows one to configure:

• The mapping between one unit of weight to one unit of fee via Config::WeightToFee.
• A means of updating the fee for the next block, via defining a multiplier, based on the final state of the chain at the end of the previous block. This can be configured via Config::FeeMultiplierUpdate
• How the fees are paid via Config::OnChargeTransaction.

Re-exports

• pub use pallet::*;

Modules

• pallet
  The module that hosts all the FRAME types needed to add this pallet to a runtime.

Structs

• ChargeTransactionPayment
  Require the transactor pay for themselves and maybe include a tip to gain additional priority in the queue.
• ConstFeeMultiplier
  A struct to make the fee multiplier a constant
• CurrencyAdapter
  Implements the transaction payment for a pallet implementing the Currency trait (eg. the pallet_balances) using an unbalance handler (implementing OnUnbalanced).
• FeeDetails
  The FeeDetails is composed of:
• InclusionFee
  The base fee and adjusted weight and length fees constitute the inclusion fee.
• RuntimeDispatchInfo
  Information related to a dispatchable’s class, weight, and fee that can be queried from the runtime.
• TargetedFeeAdjustment
  A struct to update the weight multiplier per block. It implements Convert<Multiplier, Multiplier>, meaning that it can convert the previous multiplier to the next one. This should be called on on_finalize of a block, prior to potentially cleaning the weight data from the system pallet.

Traits

• MultiplierUpdate
  Something that can convert the current multiplier to the next one.
• OnChargeTransaction
  Handle withdrawing, refunding and depositing of transaction fees.

Type Definitions

• Multiplier
  Fee multiplier.