eth/gasprice: implement feeHistory API

cmd/utils/flags.go

@@ -1302,8 +1302,7 @@ func setGPO(ctx *cli.Context, cfg *gasprice.Config, light bool) {
 	// If we are running the light client, apply another group
 	// settings for gas oracle.
 	if light {
-		cfg.Blocks = ethconfig.LightClientGPO.Blocks
-		cfg.Percentile = ethconfig.LightClientGPO.Percentile
+		*cfg = ethconfig.LightClientGPO
 	}
 	if ctx.GlobalIsSet(GpoBlocksFlag.Name) {
 		cfg.Blocks = ctx.GlobalInt(GpoBlocksFlag.Name)

eth/api_backend.go

@@ -133,6 +133,10 @@ func (b *EthAPIBackend) BlockByNumberOrHash(ctx context.Context, blockNrOrHash r
 	return nil, errors.New("invalid arguments; neither block nor hash specified")
 }
 
+func (b *EthAPIBackend) PendingBlockAndReceipts() (*types.Block, types.Receipts) {
+	return b.eth.miner.PendingBlockAndReceipts()
+}
+
 func (b *EthAPIBackend) StateAndHeaderByNumber(ctx context.Context, number rpc.BlockNumber) (*state.StateDB, *types.Header, error) {
 	// Pending state is only known by the miner
 	if number == rpc.PendingBlockNumber {
@@ -279,6 +283,10 @@ func (b *EthAPIBackend) SuggestGasTipCap(ctx context.Context) (*big.Int, error)
 	return b.gpo.SuggestTipCap(ctx)
 }
 
+func (b *EthAPIBackend) FeeHistory(ctx context.Context, blockCount int, lastBlock rpc.BlockNumber, rewardPercentiles []float64) (firstBlock rpc.BlockNumber, reward [][]*big.Int, baseFee []*big.Int, gasUsedRatio []float64, err error) {
+	return b.gpo.FeeHistory(ctx, blockCount, lastBlock, rewardPercentiles)
+}
+
 func (b *EthAPIBackend) ChainDb() ethdb.Database {
 	return b.eth.ChainDb()
 }

eth/ethconfig/config.go

@@ -41,18 +41,22 @@ import (
 
 // FullNodeGPO contains default gasprice oracle settings for full node.
 var FullNodeGPO = gasprice.Config{
-	Blocks:      20,
-	Percentile:  60,
-	MaxPrice:    gasprice.DefaultMaxPrice,
-	IgnorePrice: gasprice.DefaultIgnorePrice,
+	Blocks:           20,
+	Percentile:       60,
+	MaxHeaderHistory: 0,
+	MaxBlockHistory:  0,
+	MaxPrice:         gasprice.DefaultMaxPrice,
+	IgnorePrice:      gasprice.DefaultIgnorePrice,
 }
 
 // LightClientGPO contains default gasprice oracle settings for light client.
 var LightClientGPO = gasprice.Config{
-	Blocks:      2,
-	Percentile:  60,
-	MaxPrice:    gasprice.DefaultMaxPrice,
-	IgnorePrice: gasprice.DefaultIgnorePrice,
+	Blocks:           2,
+	Percentile:       60,
+	MaxHeaderHistory: 300,
+	MaxBlockHistory:  5,
+	MaxPrice:         gasprice.DefaultMaxPrice,
+	IgnorePrice:      gasprice.DefaultIgnorePrice,
 }
 
 // Defaults contains default settings for use on the Ethereum main net.

eth/gasprice/feehistory.go

@@ -0,0 +1,293 @@
+// Copyright 2021 The go-ethereum Authors
+// This file is part of the go-ethereum library.
+//
+// The go-ethereum library is free software: you can redistribute it and/or modify
+// it under the terms of the GNU Lesser General Public License as published by
+// the Free Software Foundation, either version 3 of the License, or
+// (at your option) any later version.
+//
+// The go-ethereum library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
+// GNU Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public License
+// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
+
+package gasprice
+
+import (
+	"context"
+	"errors"
+	"math/big"
+	"sort"
+	"sync/atomic"
+
+	"github.com/ethereum/go-ethereum/consensus/misc"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/log"
+	"github.com/ethereum/go-ethereum/rpc"
+)
+
+var (
+	errInvalidPercentiles = errors.New("Invalid reward percentiles")
+	errRequestBeyondHead  = errors.New("Request beyond head block")
+)
+
+const maxBlockCount = 1024 // number of blocks retrievable with a single query
+
+// blockFees represents a single block for processing
+type blockFees struct {
+	// set by the caller
+	blockNumber rpc.BlockNumber
+	header      *types.Header
+	block       *types.Block // only set if reward percentiles are requested
+	receipts    types.Receipts
+	// filled by processBlock
+	reward               []*big.Int
+	baseFee, nextBaseFee *big.Int
+	gasUsedRatio         float64
+	err                  error
+}
+
+// txGasAndReward is sorted in ascending order based on reward
+type (
+	txGasAndReward struct {
+		gasUsed uint64
+		reward  *big.Int
+	}
+	sortGasAndReward []txGasAndReward
+)
+
+func (s sortGasAndReward) Len() int { return len(s) }
+func (s sortGasAndReward) Swap(i, j int) {
+	s[i], s[j] = s[j], s[i]
+}
+func (s sortGasAndReward) Less(i, j int) bool {
+	return s[i].reward.Cmp(s[j].reward) < 0
+}
+
+// processBlock takes a blockFees structure with the blockNumber, the header and optionally
+// the block field filled in, retrieves the block from the backend if not present yet and
+// fills in the rest of the fields.
+func (oracle *Oracle) processBlock(bf *blockFees, percentiles []float64) {
+	chainconfig := oracle.backend.ChainConfig()
+	if bf.baseFee = bf.header.BaseFee; bf.baseFee == nil {
+		bf.baseFee = new(big.Int)
+	}
+	if chainconfig.IsLondon(big.NewInt(int64(bf.blockNumber + 1))) {
+		bf.nextBaseFee = misc.CalcBaseFee(chainconfig, bf.header)
+	} else {
+		bf.nextBaseFee = new(big.Int)
+	}
+	bf.gasUsedRatio = float64(bf.header.GasUsed) / float64(bf.header.GasLimit)
+	if len(percentiles) == 0 {
+		// rewards were not requested, return null
+		return
+	}
+	if bf.block == nil || (bf.receipts == nil && len(bf.block.Transactions()) != 0) {
+		log.Error("Block or receipts are missing while reward percentiles are requested")
+		return
+	}
+
+	bf.reward = make([]*big.Int, len(percentiles))
+	if len(bf.block.Transactions()) == 0 {
+		// return an all zero row if there are no transactions to gather data from
+		for i := range bf.reward {
+			bf.reward[i] = new(big.Int)
+		}
+		return
+	}
+
+	sorter := make(sortGasAndReward, len(bf.block.Transactions()))
+	for i, tx := range bf.block.Transactions() {
+		reward, _ := tx.EffectiveGasTip(bf.block.BaseFee())
+		sorter[i] = txGasAndReward{gasUsed: bf.receipts[i].GasUsed, reward: reward}
+	}
+	sort.Sort(sorter)
+
+	var txIndex int
+	sumGasUsed := sorter[0].gasUsed
+
+	for i, p := range percentiles {
+		thresholdGasUsed := uint64(float64(bf.block.GasUsed()) * p / 100)
+		for sumGasUsed < thresholdGasUsed && txIndex < len(bf.block.Transactions())-1 {
+			txIndex++
+			sumGasUsed += sorter[txIndex].gasUsed
+		}
+		bf.reward[i] = sorter[txIndex].reward
+	}
+}
+
+// resolveBlockRange resolves the specified block range to absolute block numbers while also
+// enforcing backend specific limitations. The pending block and corresponding receipts are
+// also returned if requested and available.
+// Note: an error is only returned if retrieving the head header has failed. If there are no
+// retrievable blocks in the specified range then zero block count is returned with no error.
+func (oracle *Oracle) resolveBlockRange(ctx context.Context, lastBlockNumber rpc.BlockNumber, blockCount, maxHistory int) (*types.Block, types.Receipts, rpc.BlockNumber, int, error) {
+	var (
+		headBlockNumber rpc.BlockNumber
+		pendingBlock    *types.Block
+		pendingReceipts types.Receipts
+	)
+
+	// query either pending block or head header and set headBlockNumber
+	if lastBlockNumber == rpc.PendingBlockNumber {
+		if pendingBlock, pendingReceipts = oracle.backend.PendingBlockAndReceipts(); pendingBlock != nil {
+			lastBlockNumber = rpc.BlockNumber(pendingBlock.NumberU64())
+			headBlockNumber = lastBlockNumber - 1
+		} else {
+			// pending block not supported by backend, process until latest block
+			lastBlockNumber = rpc.LatestBlockNumber
+			blockCount--
+			if blockCount == 0 {
+				return nil, nil, 0, 0, nil
+			}
+		}
+	}
+	if pendingBlock == nil {
+		// if pending block is not fetched then we retrieve the head header to get the head block number
+		if latestHeader, err := oracle.backend.HeaderByNumber(ctx, rpc.LatestBlockNumber); err == nil {
+			headBlockNumber = rpc.BlockNumber(latestHeader.Number.Uint64())
+		} else {
+			return nil, nil, 0, 0, err
+		}
+	}
+	if lastBlockNumber == rpc.LatestBlockNumber {
+		lastBlockNumber = headBlockNumber
+	} else if pendingBlock == nil && lastBlockNumber > headBlockNumber {
+		return nil, nil, 0, 0, errRequestBeyondHead
+	}
+	if maxHistory != 0 {
+		// limit retrieval to the given number of latest blocks
+		if tooOldCount := int64(headBlockNumber) - int64(maxHistory) - int64(lastBlockNumber) + int64(blockCount); tooOldCount > 0 {
+			// tooOldCount is the number of requested blocks that are too old to be served
+			if int64(blockCount) > tooOldCount {
+				blockCount -= int(tooOldCount)
+			} else {
+				return nil, nil, 0, 0, nil
+			}
+		}
+	}
+	// ensure not trying to retrieve before genesis
+	if rpc.BlockNumber(blockCount) > lastBlockNumber+1 {
+		blockCount = int(lastBlockNumber + 1)
+	}
+	return pendingBlock, pendingReceipts, lastBlockNumber, blockCount, nil
+}
+
+// FeeHistory returns data relevant for fee estimation based on the specified range of blocks.
+// The range can be specified either with absolute block numbers or ending with the latest
+// or pending block. Backends may or may not support gathering data from the pending block
+// or blocks older than a certain age (specified in maxHistory). The first block of the
+// actually processed range is returned to avoid ambiguity when parts of the requested range
+// are not available or when the head has changed during processing this request.
+// Three arrays are returned based on the processed blocks:
+// - reward: the requested percentiles of effective priority fees per gas of transactions in each
+//   block, sorted in ascending order and weighted by gas used.
+// - baseFee: base fee per gas in the given block
+// - gasUsedRatio: gasUsed/gasLimit in the given block
+// Note: baseFee includes the next block after the newest of the returned range, because this
+// value can be derived from the newest block.
+func (oracle *Oracle) FeeHistory(ctx context.Context, blockCount int, lastBlockNumber rpc.BlockNumber, rewardPercentiles []float64) (firstBlockNumber rpc.BlockNumber, reward [][]*big.Int, baseFee []*big.Int, gasUsedRatio []float64, err error) {
+	if blockCount < 1 {
+		// returning with no data and no error means there are no retrievable blocks
+		return
+	}
+	if blockCount > maxBlockCount {
+		blockCount = maxBlockCount
+	}
+	for i, p := range rewardPercentiles {
+		if p < 0 || p > 100 || (i > 0 && p < rewardPercentiles[i-1]) {
+			return 0, nil, nil, nil, errInvalidPercentiles
+		}
+	}
+
+	processBlocks := len(rewardPercentiles) != 0
+	// limit retrieval to maxHistory if set
+	var maxHistory int
+	if processBlocks {
+		maxHistory = oracle.maxBlockHistory
+	} else {
+		maxHistory = oracle.maxHeaderHistory
+	}
+
+	var (
+		pendingBlock    *types.Block
+		pendingReceipts types.Receipts
+	)
+	if pendingBlock, pendingReceipts, lastBlockNumber, blockCount, err = oracle.resolveBlockRange(ctx, lastBlockNumber, blockCount, maxHistory); err != nil || blockCount == 0 {
+		return
+	}
+	firstBlockNumber = lastBlockNumber + 1 - rpc.BlockNumber(blockCount)
+
+	processNext := int64(firstBlockNumber)
+	resultCh := make(chan *blockFees, blockCount)
+	threadCount := 4
+	if blockCount < threadCount {
+		threadCount = blockCount
+	}
+	for i := 0; i < threadCount; i++ {
+		go func() {
+			for {
+				blockNumber := rpc.BlockNumber(atomic.AddInt64(&processNext, 1) - 1)
+				if blockNumber > lastBlockNumber {
+					return
+				}
+
+				bf := &blockFees{blockNumber: blockNumber}
+				if pendingBlock != nil && blockNumber >= rpc.BlockNumber(pendingBlock.NumberU64()) {
+					bf.block, bf.receipts = pendingBlock, pendingReceipts
+				} else {
+					if processBlocks {
+						bf.block, bf.err = oracle.backend.BlockByNumber(ctx, blockNumber)
+						if bf.block != nil {
+							bf.receipts, bf.err = oracle.backend.GetReceipts(ctx, bf.block.Hash())
+						}
+					} else {
+						bf.header, bf.err = oracle.backend.HeaderByNumber(ctx, blockNumber)
+					}
+				}
+				if bf.block != nil {
+					bf.header = bf.block.Header()
+				}
+				if bf.header != nil {
+					oracle.processBlock(bf, rewardPercentiles)
+				}
+				// send to resultCh even if empty to guarantee that blockCount items are sent in total
+				resultCh <- bf
+			}
+		}()
+	}
+
+	reward = make([][]*big.Int, blockCount)
+	baseFee = make([]*big.Int, blockCount+1)
+	gasUsedRatio = make([]float64, blockCount)
+	firstMissing := blockCount
+
+	for ; blockCount > 0; blockCount-- {
+		bf := <-resultCh
+		if bf.err != nil {
+			return 0, nil, nil, nil, bf.err
+		}
+		i := int(bf.blockNumber - firstBlockNumber)
+		if bf.header != nil {
+			reward[i], baseFee[i], baseFee[i+1], gasUsedRatio[i] = bf.reward, bf.baseFee, bf.nextBaseFee, bf.gasUsedRatio
+		} else {
+			// getting no block and no error means we are requesting into the future (might happen because of a reorg)
+			if i < firstMissing {
+				firstMissing = i
+			}
+		}
+	}
+	if firstMissing == 0 {
+		return 0, nil, nil, nil, nil
+	}
+	if processBlocks {
+		reward = reward[:firstMissing]
+	} else {
+		reward = nil
+	}
+	baseFee, gasUsedRatio = baseFee[:firstMissing+1], gasUsedRatio[:firstMissing]
+	return
+}