Staking ValidatorPowerRank should use "Potential Consensus Power"

[rigelrozanski]

Referring to "Potential Tendermint Power" as the tokens reduced by a threshold (as is currently used within the ABCI)

cosmos-sdk/types/staking.go

Line 48 in d00a15b

func TokensToTendermintPower(tokens Int) int64 {

This issue is followup to this comment in the code which contains incorrect variable names:

cosmos-sdk/x/staking/keeper/key.go

Lines 72 to 79 in 9cf9e6f

	func getValidatorPowerRank(validator types.Validator) []byte {
	potentialPower := validator.Tokens
	// todo: deal with cases above 2**64, ref https://github.com/cosmos/cosmos-sdk/issues/2439#issuecomment-427167556
	tendermintPower := potentialPower.Int64()
	tendermintPowerBytes := make([]byte, 8)
	binary.BigEndian.PutUint64(tendermintPowerBytes[:], uint64(tendermintPower))

Which was referenced recently in #2439

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By using the Potential Tendermint Power we remove any Int64 overflow issues, not to mention make the variable names in the code reflective of reality (currently these variable names are misleading/incorrect - this is NOT the tendermint power, the tendermint power is equivalent to Potential Tendermint Power)

CC @alexanderbez @keichiri @cwgoes

[rigelrozanski]

the actionable item is modify:

tendermintPower := potentialPower.Int64() 

to

tendermintPower := TokensToTendermintPower(validator.Tokens)

As well as any legacy conversion necessary

[ValarDragon]

Perhaps it would make sense to make tendermintPower its own type? (Or rather "ConsensusPower" to be mechanism agnostic)

[rigelrozanski]

nice, I like ConsensusPower - and yeah making its own type makes sense I think