[pool] Update pool logic to accept Delegate transactions using redelegation tokens (#3344)

* [config] Fix confusing variable name

* [pool] Allow pool to accept Delegate transactions that utilize the locked redelegation amount

	* [pool] Bypass balance check for Delegate transactions, let validation be done with validateStakingTx
	* [list] Perform validation on staking transactions when filtering for overpriced/invalid transactions
	* [list] Rename FilterCost to FilterValid, to reflect changes & update comment
	* [pool] Remove now unnecessary staking logic in demotion logic

* [list] Fix imports

core/tx_list.go

@@ -23,9 +23,9 @@ import (
 	"sort"
 
 	"github.com/ethereum/go-ethereum/common"
-
 	"github.com/harmony-one/harmony/core/types"
 	"github.com/harmony-one/harmony/internal/utils"
+	staking "github.com/harmony-one/harmony/staking/types"
 )
 
 // nonceHeap is a heap.Interface implementation over 64bit unsigned integers for
@@ -283,16 +283,13 @@ func (l *txList) Forward(threshold uint64) types.PoolTransactions {
 	return l.txs.Forward(threshold)
 }
 
-// FilterCost removes all transactions from the list with a cost or gas limit higher
-// than the provided thresholds. Every removed transaction is returned for any
-// post-removal maintenance. Strict-mode invalidated transactions are also
-// returned.
-//
-// This method uses the cached costcap and gascap to quickly decide if there's even
-// a point in calculating all the costs or if the balance covers all. If the threshold
-// is lower than the costgas cap, the caps will be reset to a new high after removing
-// the newly invalidated transactions.
-func (l *txList) FilterCost(costLimit *big.Int, gasLimit uint64) (types.PoolTransactions, types.PoolTransactions) {
+// FilterValid returns all regular transactions from the list with a cost or gas limit higher
+// than the provided thresholds and all staking transactions that can not be validated.
+func (l *txList) FilterValid(
+	txPool *TxPool, address common.Address,
+) (types.PoolTransactions, types.PoolTransactions) {
+	costLimit := txPool.currentState.GetBalance(address)
+	gasLimit := txPool.currentMaxGas
 	// If all transactions are below the threshold, short circuit
 	if l.costcap.Cmp(costLimit) <= 0 && l.gascap <= gasLimit {
 		return nil, nil
@@ -305,7 +302,11 @@ func (l *txList) FilterCost(costLimit *big.Int, gasLimit uint64) (types.PoolTran
 		if err != nil {
 			return true // failure should lead to removal of the tx
 		}
-		return cost.Cmp(costLimit) > 0 || tx.Gas() > gasLimit
+		if _, ok := tx.(*staking.StakingTransaction); ok {
+			err := txPool.validateTx(tx, false)
+			return err != nil
+		}
+		return cost.Cmp(costLimit) == 1 || tx.Gas() > gasLimit
 	})
 }
 

core/tx_pool.go

@@ -728,6 +728,8 @@ func (pool *TxPool) validateTx(tx types.PoolTransaction, local bool) error {
 	if err != nil {
 		return err
 	}
+	stakingTx, isStakingTx := tx.(*staking.StakingTransaction)
+	if !isStakingTx || (isStakingTx && stakingTx.StakingType() != staking.DirectiveDelegate) {
 		if pool.currentState.GetBalance(from).Cmp(cost) < 0 {
 			return errors.Wrapf(
 				ErrInsufficientFunds,
@@ -735,8 +737,8 @@ func (pool *TxPool) validateTx(tx types.PoolTransaction, local bool) error {
 				pool.chain.CurrentBlock().ShardID(),
 			)
 		}
+	}
 	intrGas := uint64(0)
-	stakingTx, isStakingTx := tx.(*staking.StakingTransaction)
 	if isStakingTx {
 		intrGas, err = IntrinsicGas(tx.Data(), false, pool.homestead, stakingTx.StakingType() == staking.DirectiveCreateValidator)
 	} else {
@@ -832,10 +834,7 @@ func (pool *TxPool) validateStakingTx(tx *staking.StakingTransaction) error {
 		if err != nil {
 			return err
 		}
-		pendingEpoch := pool.chain.CurrentBlock().Epoch()
-		if shard.Schedule.IsLastBlock(pool.chain.CurrentBlock().Number().Uint64()) {
-			pendingEpoch = new(big.Int).Add(pendingEpoch, big.NewInt(1))
-		}
+		pendingEpoch := pool.pendingEpoch()
 		_, _, _, err = VerifyAndDelegateFromMsg(
 			pool.currentState, pendingEpoch, stkMsg, delegations, pool.chainconfig.IsRedelegation(pendingEpoch))
 		return err
@@ -851,12 +850,8 @@ func (pool *TxPool) validateStakingTx(tx *staking.StakingTransaction) error {
 		if from != stkMsg.DelegatorAddress {
 			return errors.WithMessagef(ErrInvalidSender, "staking transaction sender is %s", b32)
 		}
-		pendingEpoch := pool.chain.CurrentBlock().Epoch()
-		if shard.Schedule.IsLastBlock(pool.chain.CurrentBlock().Number().Uint64()) {
-			pendingEpoch = new(big.Int).Add(pendingEpoch, big.NewInt(1))
-		}
 
-		_, err = VerifyAndUndelegateFromMsg(pool.currentState, pendingEpoch, stkMsg)
+		_, err = VerifyAndUndelegateFromMsg(pool.currentState, pool.pendingEpoch(), stkMsg)
 		return err
 	case staking.DirectiveCollectRewards:
 		msg, err := staking.RLPDecodeStakeMsg(tx.Data(), staking.DirectiveCollectRewards)
@@ -887,6 +882,15 @@ func (pool *TxPool) validateStakingTx(tx *staking.StakingTransaction) error {
 	}
 }
 
+func (pool *TxPool) pendingEpoch() *big.Int {
+	currentBlock := pool.chain.CurrentBlock()
+	pendingEpoch := currentBlock.Epoch()
+	if shard.Schedule.IsLastBlock(currentBlock.Number().Uint64()) {
+		pendingEpoch.Add(pendingEpoch, big.NewInt(1))
+	}
+	return pendingEpoch
+}
+
 // add validates a transaction and inserts it into the non-executable queue for
 // later pending promotion and execution. If the transaction is a replacement for
 // an already pending or queued one, it overwrites the previous and returns this
@@ -1297,7 +1301,7 @@ func (pool *TxPool) promoteExecutables(accounts []common.Address) {
 			// Do not report to error sink as old txs are on chain or meaningful error caught elsewhere.
 		}
 		// Drop all transactions that are too costly (low balance or out of gas)
-		drops, _ := list.FilterCost(pool.currentState.GetBalance(addr), pool.currentMaxGas)
+		drops, _ := list.FilterValid(pool, addr)
 		for _, tx := range drops {
 			hash := tx.Hash()
 			pool.all.Remove(hash)
@@ -1470,18 +1474,7 @@ func (pool *TxPool) demoteUnexecutables() {
 			// Do not report to error sink as old txs are on chain or meaningful error caught elsewhere.
 		}
 		// Drop all transactions that are too costly (low balance or out of gas), and queue any invalids back for later
-		drops, invalids := list.FilterCost(pool.currentState.GetBalance(addr), pool.currentMaxGas)
-		// Drop all staking transactions that are now invalid, queue any invalids back for later
-		stakingDrops, stakingInvalids := list.Filter(func(tx types.PoolTransaction) bool {
-			if _, ok := tx.(*staking.StakingTransaction); !ok {
-				// Do not remove anything other than staking transactions
-				return false
-			}
-			err := pool.validateTx(tx, false)
-			return err != nil
-		})
-		drops = append(drops, stakingDrops...)
-		invalids = append(invalids, stakingInvalids...)
+		drops, invalids := list.FilterValid(pool, addr)
 		for _, tx := range drops {
 			hash := tx.Hash()
 			pool.all.Remove(hash)

internal/configs/sharding/localnet.go

@@ -20,7 +20,7 @@ const (
 	localnetV1Epoch = 1
 
 	localnetEpochBlock1    = 10
-	twoOne              = 5
+	localnetBlocksPerEpoch = 5
 
 	localnetVdfDifficulty  = 5000 // This takes about 10s to finish the vdf
 	localnetConsensusRatio = float64(0.1)
@@ -40,7 +40,7 @@ func (ls localnetSchedule) InstanceForEpoch(epoch *big.Int) Instance {
 }
 
 func (ls localnetSchedule) BlocksPerEpoch() uint64 {
-	return twoOne
+	return localnetBlocksPerEpoch
 }
 
 func (ls localnetSchedule) CalcEpochNumber(blockNum uint64) *big.Int {