Rewards

Rewards Blockchain Pallet

Overview

The rewards pallet is responsible for the logic of parameterizing and depositing block rewards to validators and the stake rewards vault. The stake rewards vault is a storage value of the rewards balance that is rewarded to peers on each epoch.

Terminology

  • IncreaseStakeVault: The function to set and increase the balance of the stake vault in the Network Pallet.

  • HalvingInterval: A constant of how many blocks are in each halving event.

  • InitialBlockSubsidy: The initial reward per block which the halvening interval equates from.

  • FindAuthor: A trait for finding the author of a block header based on the PreRuntime digests contained within it.

Annotation

The following is a near replication of the Bitcoin block subsidy mechanics.

Given:

  • block_number: The block height for which we want to calculate the subsidy.

  • T::HalvingInterval::get(): The halving interval retrieved from the runtime configuration.

  • T::InitialBlockSubsidy::get(): The initial block subsidy retrieved from the runtime configuration.

  • BalanceOf<T>: The balance type for the runtime module T.

  1. Retrieve the halving interval from the runtime configuration

    • halving_interval: u32 = T::HalvingInterval::get()

  2. Convert the block number to a u64 value

    • block_num_as_u64: u64 = TryInto::try_into(block_number).ok().expect("fn get_block_subsidy block_num_as_u64 Err.");

  3. Calculate the number of halvings that have occurred by dividing the block number by the halving interval

    • halvings: u64 = block_num_as_u64 / halving_interval as u64

  4. If the number of halvings exceeds or equals 64, return zero subsidy

    • if halvings >= 64 { return (0 as u128).saturated_into::<BalanceOf<T>>(); }

  5. Otherwise, calculate the block subsidy:

    • a. Retrieve the initial block subsidy from the runtime configuration

      • initial_block_subsidy: u128 = T::InitialBlockSubsidy::get();

    • b. Right shift the initial subsidy based on the number of halvings

      • initial_block_subsidy >>= halvings;

    • c. Convert the calculated block subsidy to BalanceOf

      • block_subsidy: BalanceOf = initial_block_subsidy.saturated_into::<BalanceOf>();

  6. Return the calculated block subsidy

    • block_subsidy

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