Cosmos-sdk: Launchpad: Make distKeeper.calculateDelegationRewards public

Created on 6 Oct 2020 · 5Comments · Source: cosmos/cosmos-sdk

Summary

I am trying to query the pending delegator rewards (this will be a very common request when people build staking derivates or other such instruments). But there is no public method to find this.

distKeeper.calculateDelegationRewards provides the info, but cannot be called from another module.

Problem Definition

It turns out the distribution.NewQuerier() indirectly exposes this call. My current workaround is:

    // Try to get *delegator* reward info!
    params := distribution.QueryDelegationRewardsParams{
        DelegatorAddress: contractAddr,
        ValidatorAddress: valAddr,
    }
    req := abci.RequestQuery{
        Data: mustMarshal(t, params),
    }
    qres, err := distribution.NewQuerier(distKeeper)(ctx, []string{distribution.QueryDelegationRewards}, req)
    require.NoError(t, err)
    var rewards sdk.DecCoins
    mustParse(t, qres, &rewards)
    fmt.Printf("delegator rewards: %#v\n", rewards)

It works, but I feel it is a bit ugly

Proposal

Make the needed functions public, so I can write this easily.

Actually, looking deeper, the above may have side effects... in the query logic I see:

    endingPeriod := k.incrementValidatorPeriod(ctx, val)
    rewards := k.calculateDelegationRewards(ctx, val, del, endingPeriod)

incrementValidatorPeriod??

It would be great to have k.GetValidatorPeriod() and then use period +1 or such. That is actually exposed via k.GetValidatorCurrentRewards().Period, but maybe we could make this nicer....

My final proposal would be to add a new function to distribution:

func (k Keeper)CalculateDelegationRewards(ctx sdk.Context, val sdk.ValAddress, del sdk.AccAddress) rewards sdk.DecCoins {
    endingPeriod := k.GetValidatorCurrentRewards(ctx, val).Period
    return k.calculateDelegationRewards(ctx, val, del, endingPeriod+1)
}