88 lines
4.0 KiB
Markdown
88 lines
4.0 KiB
Markdown
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order: 3
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-->
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# Begin Block
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At each `BeginBlock`, all fees received in the previous block are transferred to
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the distribution `ModuleAccount` account. When a delegator or validator
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withdraws their rewards, they are taken out of the `ModuleAccount`. During begin
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block, the different claims on the fees collected are updated as follows:
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- The block proposer of the previous height and its delegators receive between 1% and 5% of fee rewards.
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- The reserve community tax is charged.
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- The remainder is distributed proportionally by voting power to all bonded validators
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To incentivize validators to wait and include additional pre-commits in the block, the block proposer reward is calculated from Tendermint pre-commit messages.
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## The Distribution Scheme
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See [params](07_params.md) for description of parameters.
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Let `fees` be the total fees collected in the previous block, including
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inflationary rewards to the stake. All fees are collected in a specific module
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account during the block. During `BeginBlock`, they are sent to the
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`"distribution"` `ModuleAccount`. No other sending of tokens occurs. Instead, the
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rewards each account is entitled to are stored, and withdrawals can be triggered
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through the messages `FundCommunityPool`, `WithdrawValidatorCommission` and
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`WithdrawDelegatorReward`.
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### Reward to the Community Pool
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The community pool gets `community_tax * fees`, plus any remaining dust after
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validators get their rewards that are always rounded down to the nearest
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integer value.
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### Reward To the Validators
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The proposer receives a base reward of `fees * baseproposerreward` and a bonus
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of `fees * bonusproposerreward * P`, where `P = (total power of validators with
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included precommits / total bonded validator power)`. The more precommits the
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proposer includes, the larger `P` is. `P` can never be larger than `1.00` (since
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only bonded validators can supply valid precommits) and is always larger than
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`2/3`.
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Any remaining fees are distributed among all the bonded validators, including
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the proposer, in proportion to their consensus power.
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```
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powFrac = validator power / total bonded validator power
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proposerMul = baseproposerreward + bonusproposerreward * P
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voteMul = 1 - communitytax - proposerMul
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```
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In total, the proposer receives `fees * (voteMul * powFrac + proposerMul)`.
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All other validators receive `fees * voteMul * powFrac`.
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### Rewards to Delegators
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Each validator's rewards are distributed to its delegators. The validator also
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has a self-delegation that is treated like a regular delegation in
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distribution calculations.
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The validator sets a commission rate. The commission rate is flexible, but each
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validator sets a maximum rate and a maximum daily increase. These maximums cannot be exceeded and protect delegators from sudden increases of validator commission rates to prevent validators from taking all of the rewards.
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The outstanding rewards that the operator is entitled to are stored in
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`ValidatorAccumulatedCommission`, while the rewards the delegators are entitled
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to are stored in `ValidatorCurrentRewards`. The [F1 fee distribution
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scheme](01_concepts.md) is used to calculate the rewards per delegator as they
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withdraw or update their delegation, and is thus not handled in `BeginBlock`.
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### Example Distribution
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For this example distribution, the underlying consensus engine selects block proposers in
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proportion to their power relative to the entire bonded power.
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All validators are equally performant at including pre-commits in their proposed
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blocks. Then hold `(precommits included) / (total bonded validator power)`
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constant so that the amortized block reward for the validator is `( validator power / total bonded power) * (1 - community tax rate)` of
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the total rewards. Consequently, the reward for a single delegator is:
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```
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(delegator proportion of the validator power / validator power) * (validator power / total bonded power)
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* (1 - community tax rate) * (1 - validator commision rate)
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= (delegator proportion of the validator power / total bonded power) * (1 -
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community tax rate) * (1 - validator commision rate)
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```
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