[EVM-696] eth_FeeHistory

gasprice/feehistory.go

@@ -0,0 +1,160 @@
+package gasprice
+
+import (
+	"encoding/binary"
+	"errors"
+	"math"
+	"math/big"
+	"sort"
+)
+
+var (
+	ErrInvalidPercentile = errors.New("invalid percentile")
+	ErrBlockCount        = errors.New("blockCount must be greater than 0")
+	ErrBlockNotFound     = errors.New("could not find block")
+)
+
+const (
+	maxBlockRequest = 1024
+)
+
+type cacheKey struct {
+	number      uint64
+	percentiles string
+}
+
+// processedFees contains the results of a processed block.
+type processedFees struct {
+	reward       []uint64
+	baseFee      uint64
+	gasUsedRatio float64
+}
+
+type txGasAndReward struct {
+	gasUsed *big.Int
+	reward  *big.Int
+}
+
+func (g *GasHelper) FeeHistory(blockCount uint64, newestBlock uint64, rewardPercentiles []float64) (
+	*uint64, *[]uint64, *[]float64, *[][]uint64, error) {
+	if blockCount < 1 {
+		return nil, nil, nil, nil, ErrBlockCount
+	}
+
+	if newestBlock > g.backend.Header().Number {
+		newestBlock = g.backend.Header().Number
+	}
+
+	if blockCount > maxBlockRequest {
+		blockCount = maxBlockRequest
+	}
+
+	if blockCount > newestBlock {
+		blockCount = newestBlock
+	}
+
+	for i, p := range rewardPercentiles {
+		if p < 0 || p > 100 {
+			return nil, nil, nil, nil, ErrInvalidPercentile
+		}
+
+		if i > 0 && p < rewardPercentiles[i-1] {
+			return nil, nil, nil, nil, ErrInvalidPercentile
+		}
+	}
+
+	var (
+		oldestBlock   = newestBlock - blockCount + 1
+		baseFeePerGas = make([]uint64, blockCount+1)
+		gasUsedRatio  = make([]float64, blockCount)
+		reward        = make([][]uint64, blockCount)
+	)
+
+	if oldestBlock < 1 {
+		oldestBlock = 1
+	}
+
+	percentileKey := make([]byte, 8*len(rewardPercentiles))
+	for i, p := range rewardPercentiles {
+		binary.LittleEndian.PutUint64(percentileKey[i*8:(i+1)*8], math.Float64bits(p))
+	}
+
+	for i := oldestBlock; i <= newestBlock; i++ {
+		cacheKey := cacheKey{number: i, percentiles: string(percentileKey)}
+		//cache is hit, load from cache and continue to next block
+		if p, ok := g.historyCache.Get(cacheKey); ok {
+			processedFee, isOk := p.(*processedFees)
+			if !isOk {
+				return nil, nil, nil, nil, errors.New("could not convert catched processed fee")
+			}
+
+			baseFeePerGas[i-oldestBlock] = processedFee.baseFee
+			gasUsedRatio[i-oldestBlock] = processedFee.gasUsedRatio
+			reward[i-oldestBlock] = processedFee.reward
+
+			continue
+		}
+
+		block, ok := g.backend.GetBlockByNumber(i, true)
+		if !ok {
+			return nil, nil, nil, nil, ErrBlockNotFound
+		}
+
+		baseFeePerGas[i-oldestBlock] = block.Header.BaseFee
+		gasUsedRatio[i-oldestBlock] = float64(block.Header.GasUsed) / float64(block.Header.GasLimit)
+
+		if len(rewardPercentiles) == 0 {
+			//reward percentiles not requested, skip rest of this loop
+			continue
+		}
+
+		reward[i-oldestBlock] = make([]uint64, len(rewardPercentiles))
+		if len(block.Transactions) == 0 {
+			for j := range reward[i-oldestBlock] {
+				reward[i-oldestBlock][j] = 0
+			}
+			//no transactions in block, set rewards to 0 and move to next block
+			continue
+		}
+
+		sorter := make([]*txGasAndReward, len(block.Transactions))
+
+		for j, tx := range block.Transactions {
+			cost := tx.Cost()
+			sorter[j] = &txGasAndReward{
+				gasUsed: cost.Sub(cost, tx.Value),
+				reward:  tx.EffectiveTip(block.Header.BaseFee),
+			}
+		}
+
+		sort.Slice(sorter, func(i, j int) bool {
+			return sorter[i].reward.Cmp(sorter[j].reward) < 0
+		})
+
+		var txIndex int
+
+		sumGasUsed := sorter[0].gasUsed.Uint64()
+
+		// calculate reward for each percentile
+		for c, v := range rewardPercentiles {
+			thresholdGasUsed := uint64(float64(block.Header.GasUsed) * v / 100)
+			for sumGasUsed < thresholdGasUsed && txIndex < len(block.Transactions)-1 {
+				txIndex++
+				sumGasUsed += sorter[txIndex].gasUsed.Uint64()
+			}
+
+			reward[i-oldestBlock][c] = sorter[txIndex].reward.Uint64()
+		}
+
+		blockFees := &processedFees{
+			reward:       reward[i-oldestBlock],
+			baseFee:      block.Header.BaseFee,
+			gasUsedRatio: gasUsedRatio[i-oldestBlock],
+		}
+		g.historyCache.Add(cacheKey, blockFees)
+	}
+
+	baseFeePerGas[blockCount] = g.backend.Header().BaseFee
+
+	return &oldestBlock, &baseFeePerGas, &gasUsedRatio, &reward, nil
+}

gasprice/feehistory_test.go

@@ -0,0 +1,107 @@
+package gasprice
+
+import (
+	"testing"
+
+	"github.com/0xPolygon/polygon-edge/types"
+	"github.com/stretchr/testify/mock"
+	"github.com/stretchr/testify/require"
+)
+
+func TestGasHelper_FeeHistory(t *testing.T) {
+	t.Parallel()
+
+	var cases = []struct {
+		Name                  string
+		ExpectedOldestBlock   uint64
+		ExpectedBaseFeePerGas []uint64
+		ExpectedGasUsedRatio  []float64
+		ExpectedRewards       [][]uint64
+		BlockRange            uint64
+		NewestBlock           uint64
+		RewardPercentiles     []float64
+		Error                 bool
+		GetBackend            func() Blockchain
+	}{
+		{
+			Name:              "Block does not exist",
+			Error:             true,
+			BlockRange:        10,
+			NewestBlock:       30,
+			RewardPercentiles: []float64{15, 20},
+			GetBackend: func() Blockchain {
+				header := &types.Header{
+					Number: 1,
+					Hash:   types.StringToHash("some header"),
+				}
+				backend := new(backendMock)
+				backend.On("Header").Return(header)
+				backend.On("GetBlockByNumber", mock.Anything, mock.Anything).Return(&types.Block{}, false)
+
+				return backend
+			},
+		},
+		{
+			Name:              "Block Range < 1",
+			Error:             true,
+			BlockRange:        0,
+			NewestBlock:       30,
+			RewardPercentiles: []float64{10, 15},
+			GetBackend: func() Blockchain {
+				backend := createTestBlocks(t, 30)
+				createTestTxs(t, backend, 3, 200)
+
+				return backend
+			},
+		},
+		{
+			Name:              "Invalid rewardPercentile",
+			Error:             true,
+			BlockRange:        10,
+			NewestBlock:       30,
+			RewardPercentiles: []float64{101, 0},
+			GetBackend: func() Blockchain {
+				backend := createTestBlocks(t, 50)
+				createTestTxs(t, backend, 1, 200)
+
+				return backend
+			},
+		},
+	}
+
+	for _, tc := range cases {
+		tc := tc
+		t.Run(tc.Name, func(t *testing.T) {
+			t.Parallel()
+
+			backend := tc.GetBackend()
+			gasHelper, err := NewGasHelper(DefaultGasHelperConfig, backend)
+			require.NoError(t, err)
+			oldestBlock, baseFeePerGas, gasUsedRatio, rewards, err := gasHelper.FeeHistory(tc.BlockRange, tc.NewestBlock, tc.RewardPercentiles)
+
+			if tc.Error {
+				require.Error(t, err)
+			} else {
+				require.NoError(t, err)
+				require.True(t, oldestBlock == &tc.ExpectedOldestBlock)
+				require.True(t, baseFeePerGas == &tc.ExpectedBaseFeePerGas)
+				require.True(t, gasUsedRatio == &tc.ExpectedGasUsedRatio)
+				require.True(t, rewards == &tc.ExpectedRewards)
+			}
+		})
+	}
+}
+
+var _ Blockchain = (*backendMock)(nil)
+
+func (b *backendMock) GetBlockByNumber(number uint64, full bool) (*types.Block, bool) {
+	if len(b.blocks) == 0 {
+		args := b.Called(number, full)
+
+		return args.Get(0).(*types.Block), args.Get(1).(bool) //nolint:forcetypeassert
+	}
+
+	block, exists := b.blocksByNumber[number]
+
+	return block, exists
+}

gasprice/gasprice.go

@@ -9,6 +9,7 @@ import (
 	"github.com/0xPolygon/polygon-edge/chain"
 	"github.com/0xPolygon/polygon-edge/crypto"
 	"github.com/0xPolygon/polygon-edge/types"
+	lru "github.com/hashicorp/golang-lru"
 	"github.com/umbracle/ethgo"
 )
 
@@ -44,6 +45,7 @@ type Config struct {
 
 // Blockchain is the interface representing blockchain
 type Blockchain interface {
+	GetBlockByNumber(number uint64, full bool) (*types.Block, bool)
 	GetBlockByHash(hash types.Hash, full bool) (*types.Block, bool)
 	Header() *types.Header
 	Config() *chain.Params
@@ -53,6 +55,7 @@ type Blockchain interface {
 type GasStore interface {
 	// MaxPriorityFeePerGas calculates the priority fee needed for transaction to be included in a block
 	MaxPriorityFeePerGas() (*big.Int, error)
+	FeeHistory(uint64, uint64, []float64) (*uint64, *[]uint64, *[]float64, *[][]uint64, error)
 }
 
 var _ GasStore = (*GasHelper)(nil)
@@ -78,15 +81,22 @@ type GasHelper struct {
 	lastHeaderHash types.Hash
 
 	lock sync.Mutex
+
+	historyCache *lru.Cache
 }
 
 // NewGasHelper is the constructor function for GasHelper struct
-func NewGasHelper(config *Config, backend Blockchain) *GasHelper {
+func NewGasHelper(config *Config, backend Blockchain) (*GasHelper, error) {
 	pricePercentile := config.PricePercentile
 	if pricePercentile > 100 {
 		pricePercentile = 100
 	}
 
+	cache, err := lru.New(100)
+	if err != nil {
+		return nil, err
+	}
+
 	return &GasHelper{
 		numOfBlocksToCheck: config.NumOfBlocksToCheck,
 		pricePercentile:    pricePercentile,
@@ -95,7 +105,8 @@ func NewGasHelper(config *Config, backend Blockchain) *GasHelper {
 		lastPrice:          config.LastPrice,
 		maxPrice:           config.MaxPrice,
 		backend:            backend,
-	}
+		historyCache:       cache,
+	}, nil
 }
 
 // MaxPriorityFeePerGas calculates the priority fee needed for transaction to be included in a block

gasprice/gasprice_test.go

@@ -154,7 +154,8 @@ func TestGasHelper_MaxPriorityFeePerGas(t *testing.T) {
 			t.Parallel()
 
 			backend := tc.GetBackend()
-			gasHelper := NewGasHelper(DefaultGasHelperConfig, backend)
+			gasHelper, err := NewGasHelper(DefaultGasHelperConfig, backend)
+			require.NoError(t, err)
 			price, err := gasHelper.MaxPriorityFeePerGas()
 
 			if tc.Error {
@@ -237,7 +238,8 @@ var _ Blockchain = (*backendMock)(nil)
 
 type backendMock struct {
 	mock.Mock
-	blocks map[types.Hash]*types.Block
+	blocks         map[types.Hash]*types.Block
+	blocksByNumber map[uint64]*types.Block
 }
 
 func (b *backendMock) Header() *types.Header {