Reduce min delegation from 1000 to 100 (#3712)

* Reduce min delegation from 1000 to 100

core/staking_verifier.go

@@ -4,6 +4,8 @@ import (
 	"bytes"
 	"math/big"
 
+	"github.com/harmony-one/harmony/internal/params"
+
 	"github.com/harmony-one/harmony/crypto/bls"
 
 	"github.com/ethereum/go-ethereum/common"
@@ -187,11 +189,14 @@ func VerifyAndEditValidatorFromMsg(
 }
 
 const oneThousand = 1000
+const oneHundred = 100
 
 var (
-	oneAsBigInt           = big.NewInt(denominations.One)
+	oneAsBigInt             = big.NewInt(denominations.One)
-	minimumDelegation     = new(big.Int).Mul(oneAsBigInt, big.NewInt(oneThousand))
+	minimumDelegation       = new(big.Int).Mul(oneAsBigInt, big.NewInt(oneThousand))
-	errDelegationTooSmall = errors.New("minimum delegation amount for a delegator has to be greater than or equal to 1000 ONE")
+	minimumDelegationV2     = new(big.Int).Mul(oneAsBigInt, big.NewInt(oneHundred))
+	errDelegationTooSmall   = errors.New("minimum delegation amount for a delegator has to be greater than or equal to 1000 ONE")
+	errDelegationTooSmallV2 = errors.New("minimum delegation amount for a delegator has to be greater than or equal to 100 ONE")
 )
 
 // VerifyAndDelegateFromMsg verifies the delegate message using the stateDB
@@ -200,7 +205,7 @@ var (
 //
 // Note that this function never updates the stateDB, it only reads from stateDB.
 func VerifyAndDelegateFromMsg(
-	stateDB vm.StateDB, epoch *big.Int, msg *staking.Delegate, delegations []staking.DelegationIndex, redelegation bool,
+	stateDB vm.StateDB, epoch *big.Int, msg *staking.Delegate, delegations []staking.DelegationIndex, chainConfig *params.ChainConfig,
 ) ([]*staking.ValidatorWrapper, *big.Int, map[common.Address]*big.Int, error) {
 	if stateDB == nil {
 		return nil, nil, nil, errStateDBIsMissing
@@ -212,7 +217,13 @@ func VerifyAndDelegateFromMsg(
 		return nil, nil, nil, errNegativeAmount
 	}
 	if msg.Amount.Cmp(minimumDelegation) < 0 {
-		return nil, nil, nil, errDelegationTooSmall
+		if chainConfig.IsMinDelegation100(epoch) {
+			if msg.Amount.Cmp(minimumDelegationV2) < 0 {
+				return nil, nil, nil, errDelegationTooSmallV2
+			}
+		} else {
+			return nil, nil, nil, errDelegationTooSmall
+		}
 	}
 
 	updatedValidatorWrappers := []*staking.ValidatorWrapper{}
@@ -220,7 +231,7 @@ func VerifyAndDelegateFromMsg(
 	fromLockedTokens := map[common.Address]*big.Int{}
 
 	var delegateeWrapper *staking.ValidatorWrapper
-	if redelegation {
+	if chainConfig.IsRedelegation(epoch) {
 		// Check if we can use tokens in undelegation to delegate (redelegate)
 		for i := range delegations {
 			delegationIndex := &delegations[i]

core/staking_verifier_test.go

@@ -7,6 +7,8 @@ import (
 	"strings"
 	"testing"
 
+	"github.com/harmony-one/harmony/internal/params"
+
 	"github.com/ethereum/go-ethereum/core/rawdb"
 
 	"github.com/harmony-one/harmony/crypto/bls"
@@ -1000,9 +1002,49 @@ func TestVerifyAndDelegateFromMsg(t *testing.T) {
 			}(),
 			expAmt: tenKOnes,
 		},
+		{
+			// 17: small amount v2
+			sdb: makeStateDBForStake(t),
+			msg: func() staking.Delegate {
+				msg := defaultMsgDelegate()
+				msg.Amount = new(big.Int).Mul(big.NewInt(90), oneBig)
+				return msg
+			}(),
+			ds:         makeMsgCollectRewards(),
+			epoch:      big.NewInt(100),
+			redelegate: false,
+
+			expErr: errDelegationTooSmallV2,
+		},
+		{
+			// 18: valid amount v2
+			sdb: makeStateDBForStake(t),
+			msg: func() staking.Delegate {
+				msg := defaultMsgDelegate()
+				msg.Amount = new(big.Int).Mul(big.NewInt(500), oneBig)
+				return msg
+			}(),
+			ds:         makeMsgCollectRewards(),
+			epoch:      big.NewInt(100),
+			redelegate: false,
+
+			expVWrappers: func() []staking.ValidatorWrapper {
+				wrapper := defaultExpVWrapperDelegate()
+				wrapper.Delegations[1].Amount = new(big.Int).Mul(big.NewInt(500), oneBig)
+				return []staking.ValidatorWrapper{wrapper}
+			}(),
+			expAmt: new(big.Int).Mul(big.NewInt(500), oneBig),
+		},
 	}
 	for i, test := range tests {
-		ws, amt, amtRedel, err := VerifyAndDelegateFromMsg(test.sdb, test.epoch, &test.msg, test.ds, test.redelegate)
+		config := &params.ChainConfig{}
+		config.MinDelegation100Epoch = big.NewInt(100)
+		if test.redelegate {
+			config.RedelegationEpoch = test.epoch
+		} else {
+			config.RedelegationEpoch = big.NewInt(test.epoch.Int64() + 1)
+		}
+		ws, amt, amtRedel, err := VerifyAndDelegateFromMsg(test.sdb, test.epoch, &test.msg, test.ds, config)
 
 		if assErr := assertError(err, test.expErr); assErr != nil {
 			t.Errorf("Test %v: %v", i, assErr)

core/state_transition.go

@@ -456,7 +456,7 @@ func (st *StateTransition) verifyAndApplyDelegateTx(delegate *staking.Delegate)
 		return err
 	}
 	updatedValidatorWrappers, balanceToBeDeducted, fromLockedTokens, err := VerifyAndDelegateFromMsg(
-		st.state, st.evm.EpochNumber, delegate, delegations, st.evm.ChainConfig().IsRedelegation(st.evm.EpochNumber))
+		st.state, st.evm.EpochNumber, delegate, delegations, st.evm.ChainConfig())
 	if err != nil {
 		return err
 	}

core/tx_pool.go

@@ -840,7 +840,7 @@ func (pool *TxPool) validateStakingTx(tx *staking.StakingTransaction) error {
 		}
 		pendingEpoch := pool.pendingEpoch()
 		_, delegateAmt, _, err := VerifyAndDelegateFromMsg(
-			pool.currentState, pendingEpoch, stkMsg, delegations, pool.chainconfig.IsRedelegation(pendingEpoch))
+			pool.currentState, pendingEpoch, stkMsg, delegations, pool.chainconfig)
 		if err != nil {
 			return err
 		}

internal/params/config.go

@@ -51,6 +51,7 @@ var (
 		RedelegationEpoch:          big.NewInt(290),
 		NoEarlyUnlockEpoch:         big.NewInt(530), // Around Monday Apr 12th 2021, 22:30 UTC
 		VRFEpoch:                   EpochTBD,
+		MinDelegation100Epoch:      EpochTBD,
 		EIP155Epoch:                big.NewInt(28),
 		S3Epoch:                    big.NewInt(28),
 		IstanbulEpoch:              big.NewInt(314),
@@ -74,6 +75,7 @@ var (
 		RedelegationEpoch:          big.NewInt(36500),
 		NoEarlyUnlockEpoch:         big.NewInt(73580),
 		VRFEpoch:                   EpochTBD,
+		MinDelegation100Epoch:      EpochTBD,
 		EIP155Epoch:                big.NewInt(0),
 		S3Epoch:                    big.NewInt(0),
 		IstanbulEpoch:              big.NewInt(43800),
@@ -98,6 +100,7 @@ var (
 		RedelegationEpoch:          big.NewInt(0),
 		NoEarlyUnlockEpoch:         big.NewInt(0),
 		VRFEpoch:                   big.NewInt(0),
+		MinDelegation100Epoch:      big.NewInt(0),
 		EIP155Epoch:                big.NewInt(0),
 		S3Epoch:                    big.NewInt(0),
 		IstanbulEpoch:              big.NewInt(0),
@@ -122,6 +125,7 @@ var (
 		RedelegationEpoch:          big.NewInt(0),
 		NoEarlyUnlockEpoch:         big.NewInt(0),
 		VRFEpoch:                   big.NewInt(0),
+		MinDelegation100Epoch:      big.NewInt(0),
 		EIP155Epoch:                big.NewInt(0),
 		S3Epoch:                    big.NewInt(0),
 		IstanbulEpoch:              big.NewInt(0),
@@ -146,6 +150,7 @@ var (
 		RedelegationEpoch:          big.NewInt(0),
 		NoEarlyUnlockEpoch:         big.NewInt(0),
 		VRFEpoch:                   big.NewInt(0),
+		MinDelegation100Epoch:      big.NewInt(0),
 		EIP155Epoch:                big.NewInt(0),
 		S3Epoch:                    big.NewInt(0),
 		IstanbulEpoch:              big.NewInt(0),
@@ -169,6 +174,7 @@ var (
 		RedelegationEpoch:          big.NewInt(0),
 		NoEarlyUnlockEpoch:         big.NewInt(0),
 		VRFEpoch:                   big.NewInt(0),
+		MinDelegation100Epoch:      big.NewInt(0),
 		EIP155Epoch:                big.NewInt(0),
 		S3Epoch:                    big.NewInt(0),
 		IstanbulEpoch:              big.NewInt(0),
@@ -194,6 +200,7 @@ var (
 		big.NewInt(0),                      // RedelegationEpoch
 		big.NewInt(0),                      // NoEarlyUnlockEpoch
 		big.NewInt(0),                      // VRFEpoch
+		big.NewInt(0),                      // MinDelegation100Epoch
 		big.NewInt(0),                      // EIP155Epoch
 		big.NewInt(0),                      // S3Epoch
 		big.NewInt(0),                      // IstanbulEpoch
@@ -219,6 +226,7 @@ var (
 		big.NewInt(0),        // RedelegationEpoch
 		big.NewInt(0),        // NoEarlyUnlockEpoch
 		big.NewInt(0),        // VRFEpoch
+		big.NewInt(0),        // MinDelegation100Epoch
 		big.NewInt(0),        // EIP155Epoch
 		big.NewInt(0),        // S3Epoch
 		big.NewInt(0),        // IstanbulEpoch
@@ -299,6 +307,9 @@ type ChainConfig struct {
 	// VRFEpoch is the epoch when VRF randomness is enabled
 	VRFEpoch *big.Int `json:"vrf-epoch,omitempty"`
 
+	// MinDelegation100Epoch is the epoch when min delegation is reduced from 1000 ONE to 100 ONE
+	MinDelegation100Epoch *big.Int `json:"min-delegation-100-epoch,omitempty"`
+
 	// EIP155 hard fork epoch (include EIP158 too)
 	EIP155Epoch *big.Int `json:"eip155-epoch,omitempty"`
 
@@ -390,6 +401,11 @@ func (c *ChainConfig) IsVRF(epoch *big.Int) bool {
 	return isForked(c.VRFEpoch, epoch)
 }
 
+// IsMinDelegation100 determines whether it is the epoch to reduce min delegation to 100
+func (c *ChainConfig) IsMinDelegation100(epoch *big.Int) bool {
+	return isForked(c.MinDelegation100Epoch, epoch)
+}
+
 // IsPreStaking determines whether staking transactions are allowed
 func (c *ChainConfig) IsPreStaking(epoch *big.Int) bool {
 	return isForked(c.PreStakingEpoch, epoch)