Rotate external validators for non-beacon shards. (#4373)

* Rotate only non beacon shards.

* Rotate all shards, but only hmy validators for beacon.

* Fix type.

* Revert "Fix type."

This reverts commit 0a8b506c763d9f8609abff7395ba32b18e43b149.

* Revert "Rotate all shards, but only hmy validators for beacon."

This reverts commit 70b09e2de81aa2cbffae3ccdfd4e334e7d938759.

* Fixed failed test.

* Revert "Revert "Rotate all shards, but only hmy validators for beacon.""

This reverts commit 66cfaa9817488be60ed5b5cfee1fe833ede237c8.

* Frequency by slots count.

* Fix config.

* First validator produce rest blocks.

* Updated.

* Add lock.

consensus/consensus.go

@@ -218,6 +218,8 @@ func (consensus *Consensus) getConsensusLeaderPrivateKey() (*bls.PrivateKeyWrapp
 
 // SetBlockVerifier sets the block verifier
 func (consensus *Consensus) SetBlockVerifier(verifier VerifyBlockFunc) {
+	consensus.mutex.Lock()
+	defer consensus.mutex.Unlock()
 	consensus.BlockVerifier = verifier
 	consensus.vc.SetVerifyBlock(consensus.verifyBlock)
 }

consensus/consensus_service.go

@@ -547,7 +547,7 @@ func (consensus *Consensus) GetFinality() int64 {
 	return consensus.finality
 }
 
-// switchPhase will switch FBFTPhase to nextPhase if the desirePhase equals the nextPhase
+// switchPhase will switch FBFTPhase to desired phase.
 func (consensus *Consensus) switchPhase(subject string, desired FBFTPhase) {
 	consensus.getLogger().Info().
 		Str("from:", consensus.phase.String()).

consensus/consensus_v2.go

@@ -13,7 +13,6 @@ import (
 	"github.com/harmony-one/harmony/consensus/signature"
 	nodeconfig "github.com/harmony-one/harmony/internal/configs/node"
 	"github.com/harmony-one/harmony/internal/utils"
-
 	"github.com/rs/zerolog"
 
 	msg_pb "github.com/harmony-one/harmony/api/proto/message"
@@ -688,40 +687,70 @@ func (consensus *Consensus) commitBlock(blk *types.Block, committedMsg *FBFTMess
 // rotateLeader rotates the leader to the next leader in the committee.
 // This function must be called with enabled leader rotation.
 func (consensus *Consensus) rotateLeader(epoch *big.Int) {
-	prev := consensus.getLeaderPubKey()
-	bc := consensus.Blockchain()
-	curNumber := bc.CurrentHeader().Number().Uint64()
-	utils.Logger().Info().Msgf("[Rotating leader] epoch: %v rotation:%v numblocks:%d", epoch.Uint64(), bc.Config().IsLeaderRotation(epoch), bc.Config().LeaderRotationBlocksCount)
-	leader := consensus.getLeaderPubKey()
-	for i := 0; i < bc.Config().LeaderRotationBlocksCount; i++ {
-		header := bc.GetHeaderByNumber(curNumber - uint64(i))
-		if header == nil {
+	var (
+		bc     = consensus.Blockchain()
+		prev   = consensus.getLeaderPubKey()
+		leader = consensus.getLeaderPubKey()
+	)
+	utils.Logger().Info().Msgf("[Rotating leader] epoch: %v rotation:%v external rotation %v", epoch.Uint64(), bc.Config().IsLeaderRotation(epoch), bc.Config().IsLeaderRotationExternalValidatorsAllowed(epoch, consensus.ShardID))
+	ss, err := bc.ReadShardState(epoch)
+	if err != nil {
+		utils.Logger().Error().Err(err).Msg("Failed to read shard state")
 		return
 	}
-		// Previous epoch, we should not change leader.
-		if header.Epoch().Uint64() != epoch.Uint64() {
+	committee, err := ss.FindCommitteeByID(consensus.ShardID)
+	if err != nil {
+		utils.Logger().Error().Err(err).Msg("Failed to find committee")
 		return
 	}
-		// Check if the same leader.
-		pub, err := bc.GetLeaderPubKeyFromCoinbase(header)
-		if err != nil {
-			utils.Logger().Error().Err(err).Msg("Failed to get leader public key from coinbase")
+	slotsCount := len(committee.Slots)
+	blocksPerEpoch := shard.Schedule.InstanceForEpoch(epoch).BlocksPerEpoch()
+	if blocksPerEpoch == 0 {
+		utils.Logger().Error().Msg("[Rotating leader] blocks per epoch is 0")
+		return
+	}
+	if slotsCount == 0 {
+		utils.Logger().Error().Msg("[Rotating leader] slots count is 0")
 		return
 	}
-		if !pub.Object.IsEqual(leader.Object) {
+	numBlocksProducedByLeader := blocksPerEpoch / uint64(slotsCount)
+	rest := blocksPerEpoch % uint64(slotsCount)
+	const minimumBlocksForLeaderInRow = 3
+	if numBlocksProducedByLeader < minimumBlocksForLeaderInRow {
+		// mine no less than 3 blocks in a row
+		numBlocksProducedByLeader = minimumBlocksForLeaderInRow
+	}
+	type stored struct {
+		pub    []byte
+		epoch  uint64
+		count  uint64
+		shifts uint64 // count how much changes validator per epoch
+	}
+	var s stored
+	s.pub, s.epoch, s.count, s.shifts, _ = bc.LeaderRotationMeta()
+	if !bytes.Equal(leader.Bytes[:], s.pub) {
 		// Another leader.
 		return
 	}
+	// if it is the first validator which produce blocks, then it should produce `rest` blocks too.
+	if s.shifts == 0 {
+		numBlocksProducedByLeader += rest
+	}
+	if s.count < numBlocksProducedByLeader {
+		// Not enough blocks produced by the leader.
+		return
 	}
 	// Passed all checks, we can change leader.
+	// NthNext will move the leader to the next leader in the committee.
+	// It does not know anything about external or internal validators.
 	var (
 		wasFound bool
 		next     *bls.PublicKeyWrapper
 	)
-	if consensus.ShardID == shard.BeaconChainShardID {
-		wasFound, next = consensus.Decider.NthNextHmy(shard.Schedule.InstanceForEpoch(epoch), leader, 1)
-	} else {
+	if bc.Config().IsLeaderRotationExternalValidatorsAllowed(epoch, consensus.ShardID) {
 		wasFound, next = consensus.Decider.NthNext(leader, 1)
+	} else {
+		wasFound, next = consensus.Decider.NthNextHmy(shard.Schedule.InstanceForEpoch(epoch), leader, 1)
 	}
 	if !wasFound {
 		utils.Logger().Error().Msg("Failed to get next leader")

consensus/validator.go

@@ -63,9 +63,8 @@ func (consensus *Consensus) onAnnounce(msg *msg_pb.Message) {
 		go func() {
 			// Best effort check, no need to error out.
 			_, err := consensus.ValidateNewBlock(recvMsg)
-
 			if err == nil {
-				consensus.getLogger().Info().
+				consensus.GetLogger().Info().
 					Msg("[Announce] Block verified")
 			}
 		}()

consensus/view_change.go

@@ -203,13 +203,13 @@ func (consensus *Consensus) getNextLeaderKey(viewID uint64) *bls.PublicKeyWrappe
 	var wasFound bool
 	var next *bls.PublicKeyWrapper
 	if blockchain != nil && blockchain.Config().IsLeaderRotation(epoch) {
-		if consensus.ShardID == shard.BeaconChainShardID {
-			wasFound, next = consensus.Decider.NthNextHmy(
-				shard.Schedule.InstanceForEpoch(epoch),
+		if blockchain.Config().IsLeaderRotationExternalValidatorsAllowed(epoch, consensus.ShardID) {
+			wasFound, next = consensus.Decider.NthNext(
 				lastLeaderPubKey,
 				gap)
 		} else {
-			wasFound, next = consensus.Decider.NthNext(
+			wasFound, next = consensus.Decider.NthNextHmy(
+				shard.Schedule.InstanceForEpoch(epoch),
 				lastLeaderPubKey,
 				gap)
 		}

core/blockchain.go

@@ -107,6 +107,8 @@ type BlockChain interface {
 	//
 	// After insertion is done, all accumulated events will be fired.
 	InsertChain(chain types.Blocks, verifyHeaders bool) (int, error)
+	// LeaderRotationMeta returns the number of continuous blocks by the leader.
+	LeaderRotationMeta() (publicKeyBytes []byte, epoch, count, shifts uint64, err error)
 	// BadBlocks returns a list of the last 'bad blocks' that
 	// the client has seen on the network.
 	BadBlocks() []BadBlock

core/blockchain_impl.go

@@ -114,6 +114,7 @@ const (
 	validatorListByDelegatorCacheLimit = 128
 	pendingCrossLinksCacheLimit        = 2
 	blockAccumulatorCacheLimit         = 64
+	leaderPubKeyFromCoinbaseLimit      = 8
 	maxPendingSlashes                  = 256
 	// BlockChainVersion ensures that an incompatible database forces a resync from scratch.
 	BlockChainVersion = 3
@@ -240,7 +241,7 @@ func newBlockChainWithOptions(
 	validatorListByDelegatorCache, _ := lru.New(validatorListByDelegatorCacheLimit)
 	pendingCrossLinksCache, _ := lru.New(pendingCrossLinksCacheLimit)
 	blockAccumulatorCache, _ := lru.New(blockAccumulatorCacheLimit)
-	leaderPubKeyFromCoinbase, _ := lru.New(chainConfig.LeaderRotationBlocksCount + 2)
+	leaderPubKeyFromCoinbase, _ := lru.New(leaderPubKeyFromCoinbaseLimit)
 
 	bc := &BlockChainImpl{
 		chainConfig:                   chainConfig,
@@ -1522,6 +1523,18 @@ func (bc *BlockChainImpl) InsertChain(chain types.Blocks, verifyHeaders bool) (i
 
 	n, events, logs, err := bc.insertChain(chain, verifyHeaders)
 	bc.PostChainEvents(events, logs)
+	if err == nil {
+		// there should be only 1 block.
+		for _, b := range chain {
+			if b.Epoch().Uint64() > 0 {
+				err := bc.saveLeaderRotationMeta(b.Header())
+				if err != nil {
+					utils.Logger().Error().Err(err).Msg("save leader continuous blocks count error")
+					return n, err
+				}
+			}
+		}
+	}
 	if bc.isInitTiKV() && err != nil {
 		// if has some error, master writer node will release the permission
 		_, _ = bc.redisPreempt.Unlock()
@@ -1529,6 +1542,47 @@ func (bc *BlockChainImpl) InsertChain(chain types.Blocks, verifyHeaders bool) (i
 	return n, err
 }
 
+func (bc *BlockChainImpl) saveLeaderRotationMeta(h *block.Header) error {
+	blockPubKey, err := bc.getLeaderPubKeyFromCoinbase(h)
+	if err != nil {
+		return err
+	}
+	type stored struct {
+		pub    []byte
+		epoch  uint64
+		count  uint64
+		shifts uint64
+	}
+	var s stored
+	// error is possible here only on the first iteration, so we can ignore it
+	s.pub, s.epoch, s.count, s.shifts, _ = rawdb.ReadLeaderRotationMeta(bc.db)
+
+	// increase counter only if the same leader and epoch
+	if bytes.Equal(s.pub, blockPubKey.Bytes[:]) && s.epoch == h.Epoch().Uint64() {
+		s.count++
+	} else {
+		s.count = 1
+	}
+	// we should increase shifts if the leader is changed.
+	if !bytes.Equal(s.pub, blockPubKey.Bytes[:]) {
+		s.shifts++
+	}
+	// but set to zero if new
+	if s.epoch != h.Epoch().Uint64() {
+		s.shifts = 0
+	}
+
+	err = rawdb.WriteLeaderRotationMeta(bc.db, blockPubKey.Bytes[:], h.Epoch().Uint64(), s.count, s.shifts)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (bc *BlockChainImpl) LeaderRotationMeta() (publicKeyBytes []byte, epoch, count, shifts uint64, err error) {
+	return rawdb.ReadLeaderRotationMeta(bc.db)
+}
+
 // insertChain will execute the actual chain insertion and event aggregation. The
 // only reason this method exists as a separate one is to make locking cleaner
 // with deferred statements.

core/blockchain_stub.go

@@ -423,3 +423,7 @@ func (a Stub) SyncFromTiKVWriter(newBlkNum uint64, logs []*types.Log) error {
 func (a Stub) InitTiKV(conf *harmonyconfig.TiKVConfig) {
 	return
 }
+
+func (a Stub) LeaderRotationMeta() (publicKeyBytes []byte, epoch, count, shifts uint64, err error) {
+	return nil, 0, 0, 0, errors.Errorf("method LeaderRotationMeta not implemented for %s", a.Name)
+}

core/rawdb/accessors_metadata.go

@@ -17,14 +17,17 @@
 package rawdb
 
 import (
+	"encoding/binary"
 	"encoding/json"
 	"time"
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/ethdb"
 	"github.com/ethereum/go-ethereum/rlp"
+	"github.com/harmony-one/harmony/crypto/bls"
 	"github.com/harmony-one/harmony/internal/params"
 	"github.com/harmony-one/harmony/internal/utils"
+	"github.com/pkg/errors"
 )
 
 // ReadDatabaseVersion retrieves the version number of the database.
@@ -192,3 +195,34 @@ func WriteTransitionStatus(db ethdb.KeyValueWriter, data []byte) {
 		utils.Logger().Error().Err(err).Msg("Failed to store the eth2 transition status")
 	}
 }
+
+// WriteLeaderRotationMeta writes the leader continuous blocks count to the database.
+func WriteLeaderRotationMeta(db DatabaseWriter, leader []byte, epoch uint64, count, shifts uint64) error {
+	if len(leader) != bls.PublicKeySizeInBytes {
+		return errors.New("invalid leader public key size")
+	}
+	value := make([]byte, bls.PublicKeySizeInBytes+8*3)
+	copy(value, leader)
+	binary.LittleEndian.PutUint64(value[len(leader)+8*0:], epoch)
+	binary.LittleEndian.PutUint64(value[len(leader)+8*1:], count)
+	binary.LittleEndian.PutUint64(value[len(leader)+8*2:], shifts)
+	if err := db.Put(leaderContinuousBlocksCountKey(), value); err != nil {
+		utils.Logger().Error().Err(err).Msg("Failed to store leader continuous blocks count")
+		return err
+	}
+	return nil
+}
+
+// ReadLeaderRotationMeta retrieves the leader continuous blocks count from the database.
+func ReadLeaderRotationMeta(db DatabaseReader) (pubKeyBytes []byte, epoch, count, shifts uint64, err error) {
+	data, _ := db.Get(leaderContinuousBlocksCountKey())
+	if len(data) != bls.PublicKeySizeInBytes+24 {
+		return nil, 0, 0, 0, errors.New("invalid leader continuous blocks count")
+	}
+
+	pubKeyBytes = data[:bls.PublicKeySizeInBytes]
+	epoch = binary.LittleEndian.Uint64(data[bls.PublicKeySizeInBytes:])
+	count = binary.LittleEndian.Uint64(data[bls.PublicKeySizeInBytes+8:])
+	shifts = binary.LittleEndian.Uint64(data[bls.PublicKeySizeInBytes+16:])
+	return pubKeyBytes, epoch, count, shifts, nil
+}

core/rawdb/accessors_metadata_test.go

@@ -0,0 +1,32 @@
+package rawdb
+
+import (
+	"testing"
+
+	ethRawDB "github.com/ethereum/go-ethereum/core/rawdb"
+	"github.com/harmony-one/harmony/crypto/bls"
+)
+
+func TestLeaderRotationMeta(t *testing.T) {
+	db := ethRawDB.NewMemoryDatabase()
+	err := WriteLeaderRotationMeta(db, make([]byte, bls.PublicKeySizeInBytes), 1, 2, 3)
+	if err != nil {
+		t.Fatal(err)
+	}
+	pub, epoch, count, shifts, err := ReadLeaderRotationMeta(db)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if len(pub) != bls.PublicKeySizeInBytes {
+		t.Fatal("invalid leader public key size")
+	}
+	if epoch != 1 {
+		t.Fatal("invalid epoch")
+	}
+	if count != 2 {
+		t.Fatal("invalid count")
+	}
+	if shifts != 3 {
+		t.Fatal("invalid shifts")
+	}
+}

core/rawdb/schema.go

@@ -100,6 +100,7 @@ var (
 	pendingCrosslinkKey          = []byte("pendingCL")        // prefix for shard last pending crosslink
 	pendingSlashingKey           = []byte("pendingSC")        // prefix for shard last pending slashing record
 	preimagePrefix               = []byte("secure-key-")      // preimagePrefix + hash -> preimage
+	continuousBlocksCountKey     = []byte("continuous")       // key for continuous blocks count
 	configPrefix                 = []byte("ethereum-config-") // config prefix for the db
 	crosslinkPrefix              = []byte("cl")               // prefix for crosslink
 	delegatorValidatorListPrefix = []byte("dvl")              // prefix for delegator's validator list
@@ -285,6 +286,10 @@ func preimageKey(hash common.Hash) []byte {
 	return append(preimagePrefix, hash.Bytes()...)
 }
 
+func leaderContinuousBlocksCountKey() []byte {
+	return continuousBlocksCountKey
+}
+
 // configKey = configPrefix + hash
 func configKey(hash common.Hash) []byte {
 	return append(configPrefix, hash.Bytes()...)

internal/configs/sharding/shardingconfig.go

@@ -72,8 +72,9 @@ type Instance interface {
 	// ReshardingEpoch returns a list of Epoch while off-chain resharding happens
 	ReshardingEpoch() []*big.Int
 
-	// Count of blocks per epoch
+	// BlocksPerEpoch returns the number of blocks per epoch.
 	BlocksPerEpoch() uint64
+
 	// HIP-16: The absolute number of maximum effective slots per shard limit for each validator. 0 means no limit.
 	SlotsLimit() int
 

internal/params/config.go

@@ -70,8 +70,8 @@ var (
 		CrossShardXferPrecompileEpoch:          big.NewInt(1323), // Around Wed 8 Feb 11:30PM UTC
 		AllowlistEpoch:                         EpochTBD,
 		FeeCollectEpoch:                        EpochTBD,
-		LeaderRotationEpoch:           EpochTBD,
-		LeaderRotationBlocksCount:     64,
+		LeaderRotationExternalNonBeaconLeaders: EpochTBD,
+		LeaderRotationExternalBeaconLeaders:    EpochTBD,
 		ValidatorCodeFixEpoch:                  EpochTBD,
 	}
 
@@ -110,8 +110,8 @@ var (
 		ChainIdFixEpoch:                        big.NewInt(0),
 		CrossShardXferPrecompileEpoch:          big.NewInt(2),
 		AllowlistEpoch:                         big.NewInt(2),
-		LeaderRotationEpoch:           EpochTBD,
-		LeaderRotationBlocksCount:     64,
+		LeaderRotationExternalNonBeaconLeaders: EpochTBD,
+		LeaderRotationExternalBeaconLeaders:    EpochTBD,
 		FeeCollectEpoch:                        EpochTBD,
 		ValidatorCodeFixEpoch:                  EpochTBD,
 	}
@@ -151,8 +151,8 @@ var (
 		SlotsLimitedEpoch:                      EpochTBD, // epoch to enable HIP-16
 		CrossShardXferPrecompileEpoch:          big.NewInt(1),
 		AllowlistEpoch:                         EpochTBD,
-		LeaderRotationEpoch:           EpochTBD,
-		LeaderRotationBlocksCount:     64,
+		LeaderRotationExternalNonBeaconLeaders: EpochTBD,
+		LeaderRotationExternalBeaconLeaders:    EpochTBD,
 		FeeCollectEpoch:                        EpochTBD,
 		ValidatorCodeFixEpoch:                  EpochTBD,
 	}
@@ -194,8 +194,8 @@ var (
 		CrossShardXferPrecompileEpoch:          big.NewInt(1),
 		AllowlistEpoch:                         EpochTBD,
 		FeeCollectEpoch:                        big.NewInt(574),
-		LeaderRotationEpoch:           EpochTBD,
-		LeaderRotationBlocksCount:     64,
+		LeaderRotationExternalNonBeaconLeaders: EpochTBD,
+		LeaderRotationExternalBeaconLeaders:    EpochTBD,
 		ValidatorCodeFixEpoch:                  EpochTBD,
 	}
 
@@ -236,8 +236,8 @@ var (
 		CrossShardXferPrecompileEpoch:          big.NewInt(1),
 		AllowlistEpoch:                         EpochTBD,
 		FeeCollectEpoch:                        EpochTBD,
-		LeaderRotationEpoch:           EpochTBD,
-		LeaderRotationBlocksCount:     64,
+		LeaderRotationExternalNonBeaconLeaders: EpochTBD,
+		LeaderRotationExternalBeaconLeaders:    EpochTBD,
 		ValidatorCodeFixEpoch:                  EpochTBD,
 	}
 
@@ -276,8 +276,8 @@ var (
 		SlotsLimitedEpoch:                      EpochTBD, // epoch to enable HIP-16
 		CrossShardXferPrecompileEpoch:          big.NewInt(1),
 		AllowlistEpoch:                         EpochTBD,
-		LeaderRotationEpoch:           EpochTBD,
-		LeaderRotationBlocksCount:     5,
+		LeaderRotationExternalNonBeaconLeaders: big.NewInt(5),
+		LeaderRotationExternalBeaconLeaders:    big.NewInt(6),
 		FeeCollectEpoch:                        big.NewInt(5),
 		ValidatorCodeFixEpoch:                  EpochTBD,
 	}
@@ -319,8 +319,8 @@ var (
 		big.NewInt(0),                      // SlotsLimitedEpoch
 		big.NewInt(1),                      // CrossShardXferPrecompileEpoch
 		big.NewInt(0),                      // AllowlistEpoch
-		big.NewInt(1),                      // LeaderRotationEpoch
-		64,                                 // LeaderRotationBlocksCount
+		big.NewInt(1),                      // LeaderRotationExternalNonBeaconLeaders
+		big.NewInt(1),                      // LeaderRotationExternalBeaconLeaders
 		big.NewInt(0),                      // FeeCollectEpoch
 		big.NewInt(0),                      // ValidatorCodeFixEpoch
 	}
@@ -362,8 +362,8 @@ var (
 		big.NewInt(0),        // SlotsLimitedEpoch
 		big.NewInt(1),        // CrossShardXferPrecompileEpoch
 		big.NewInt(0),        // AllowlistEpoch
-		big.NewInt(1),        // LeaderRotationEpoch
-		64,                   // LeaderRotationBlocksCount
+		big.NewInt(1),        // LeaderRotationExternalNonBeaconLeaders
+		big.NewInt(1),        // LeaderRotationExternalBeaconLeaders
 		big.NewInt(0),        // FeeCollectEpoch
 		big.NewInt(0),        // ValidatorCodeFixEpoch
 	}
@@ -505,9 +505,9 @@ type ChainConfig struct {
 	// AllowlistEpoch is the first epoch to support allowlist of HIP18
 	AllowlistEpoch *big.Int
 
-	LeaderRotationEpoch *big.Int `json:"leader-rotation-epoch,omitempty"`
+	LeaderRotationExternalNonBeaconLeaders *big.Int `json:"leader-rotation-external-non-beacon-leaders,omitempty"`
 
-	LeaderRotationBlocksCount int `json:"leader-rotation-blocks-count,omitempty"`
+	LeaderRotationExternalBeaconLeaders *big.Int `json:"leader-rotation-external-beacon-leaders,omitempty"`
 
 	// FeeCollectEpoch is the first epoch that enables txn fees to be collected into the community-managed account.
 	// It should >= StakingEpoch.
@@ -725,7 +725,17 @@ func (c *ChainConfig) IsAllowlistEpoch(epoch *big.Int) bool {
 }
 
 func (c *ChainConfig) IsLeaderRotation(epoch *big.Int) bool {
-	return isForked(c.LeaderRotationEpoch, epoch)
+	return isForked(c.LeaderRotationExternalNonBeaconLeaders, epoch)
+}
+
+func (c *ChainConfig) IsLeaderRotationExternalValidatorsAllowed(epoch *big.Int, shardID uint32) bool {
+	if !c.IsLeaderRotation(epoch) {
+		return false
+	}
+	if shardID == 0 {
+		return isForked(c.LeaderRotationExternalBeaconLeaders, epoch)
+	}
+	return true
 }
 
 // IsFeeCollectEpoch determines whether Txn Fees will be collected into the community-managed account.

numeric/decimal.go

@@ -202,6 +202,12 @@ func (d Dec) Copy() Dec {
 	}
 }
 
+func (d Dec) Div(d2 Dec) Dec {
+	return Dec{
+		new(big.Int).Div(d.Int, d2.Int),
+	}
+}
+
 // IsNil ...
 func (d Dec) IsNil() bool { return d.Int == nil } // is decimal nil
 // IsZero ...

numeric/decimal_test.go

@@ -368,3 +368,27 @@ func TestDecCeil(t *testing.T) {
 		require.Equal(t, tc.expected, res, "unexpected result for test case %d, input: %v", i, tc.input)
 	}
 }
+
+func TestDiv(t *testing.T) {
+	tests := []struct {
+		d1, d2, exp Dec
+	}{
+		{mustNewDecFromStr(t, "0"), mustNewDecFromStr(t, "1"), ZeroDec()},
+		{mustNewDecFromStr(t, "1"), mustNewDecFromStr(t, "1"), NewDec(1)},
+		{mustNewDecFromStr(t, "1"), mustNewDecFromStr(t, "2"), mustNewDecFromStr(t, "0.5")},
+		{mustNewDecFromStr(t, "2"), mustNewDecFromStr(t, "1"), NewDec(2)},
+		{mustNewDecFromStr(t, "2"), mustNewDecFromStr(t, "3"), mustNewDecFromStr(t, "0.666666666666666667")},
+		{mustNewDecFromStr(t, "2"), mustNewDecFromStr(t, "4"), mustNewDecFromStr(t, "0.5")},
+		{mustNewDecFromStr(t, "2"), mustNewDecFromStr(t, "5"), mustNewDecFromStr(t, "0.4")},
+		{mustNewDecFromStr(t, "2"), mustNewDecFromStr(t, "6"), mustNewDecFromStr(t, "0.333333333333333333")},
+		{mustNewDecFromStr(t, "2"), mustNewDecFromStr(t, "7"), mustNewDecFromStr(t, "0.285714285714285714")},
+		{mustNewDecFromStr(t, "2"), mustNewDecFromStr(t, "8"), mustNewDecFromStr(t, "0.25")},
+		{mustNewDecFromStr(t, "2"), mustNewDecFromStr(t, "9"), mustNewDecFromStr(t, "0.222222222222222222")},
+		{mustNewDecFromStr(t, "2"), mustNewDecFromStr(t, "10"), mustNewDecFromStr(t, "0.2")},
+	}
+	for i, tc := range tests {
+		res := tc.d1.Quo(tc.d2)
+		require.True(t, res.Equal(tc.exp), "unexpected result for test case %d, input: %s %s %s", i, tc.d1, tc.d2, tc.exp)
+	}
+
+}