cosmos-sdk/x/stake/inflation.go

57 lines
2.0 KiB
Go

package stake
import (
sdk "github.com/cosmos/cosmos-sdk/types"
)
const (
hrsPerYr = 8766 // as defined by a julian year of 365.25 days
precision = 100000000000 // increased to this precision for accuracy with tests on tick_test.go
)
var hrsPerYrRat = sdk.NewRat(hrsPerYr) // as defined by a julian year of 365.25 days
// process provisions for an hour period
func (k Keeper) processProvisions(ctx sdk.Context) Pool {
pool := k.GetPool(ctx)
pool.Inflation = k.nextInflation(ctx)
// Because the validators hold a relative bonded share (`GlobalStakeShare`), when
// more bonded tokens are added proportionally to all validators the only term
// which needs to be updated is the `BondedPool`. So for each previsions cycle:
provisions := pool.Inflation.Mul(sdk.NewRatFromInt(pool.TokenSupply())).Quo(hrsPerYrRat).EvaluateInt()
// TODO add to the fees provisions
pool.LooseUnbondedTokens = pool.LooseUnbondedTokens.Add(provisions)
return pool
}
// get the next inflation rate for the hour
func (k Keeper) nextInflation(ctx sdk.Context) (inflation sdk.Rat) {
params := k.GetParams(ctx)
pool := k.GetPool(ctx)
// The target annual inflation rate is recalculated for each previsions cycle. The
// inflation is also subject to a rate change (positive or negative) depending on
// the distance from the desired ratio (67%). The maximum rate change possible is
// defined to be 13% per year, however the annual inflation is capped as between
// 7% and 20%.
// (1 - bondedRatio/GoalBonded) * InflationRateChange
inflationRateChangePerYear := sdk.OneRat().Sub(pool.bondedRatio().Quo(params.GoalBonded)).Mul(params.InflationRateChange)
inflationRateChange := inflationRateChangePerYear.Quo(hrsPerYrRat)
// increase the new annual inflation for this next cycle
inflation = pool.Inflation.Add(inflationRateChange)
if inflation.GT(params.InflationMax) {
inflation = params.InflationMax
}
if inflation.LT(params.InflationMin) {
inflation = params.InflationMin
}
return inflation.Round(precision)
}