go-ethereum/eth/gasprice/feehistory.go

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// 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"
"encoding/binary"
"errors"
"fmt"
"math"
"math/big"
"sync/atomic"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/consensus/misc/eip1559"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/rpc"
"golang.org/x/exp/slices"
)
var (
errInvalidPercentile = errors.New("invalid reward percentile")
errRequestBeyondHead = errors.New("request beyond head block")
)
const (
// maxBlockFetchers is the max number of goroutines to spin up to pull blocks
// for the fee history calculation (mostly relevant for LES).
maxBlockFetchers = 4
)
// blockFees represents a single block for processing
type blockFees struct {
// set by the caller
blockNumber uint64
header *types.Header
block *types.Block // only set if reward percentiles are requested
receipts types.Receipts
// filled by processBlock
results processedFees
err error
}
type cacheKey struct {
number uint64
percentiles string
}
// processedFees contains the results of a processed block.
type processedFees struct {
reward []*big.Int
baseFee, nextBaseFee *big.Int
gasUsedRatio float64
}
// txGasAndReward is sorted in ascending order based on reward
type txGasAndReward struct {
gasUsed uint64
reward *big.Int
}
// 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.results.baseFee = bf.header.BaseFee; bf.results.baseFee == nil {
bf.results.baseFee = new(big.Int)
}
if chainconfig.IsLondon(big.NewInt(int64(bf.blockNumber + 1))) {
bf.results.nextBaseFee = eip1559.CalcBaseFee(chainconfig, bf.header)
} else {
bf.results.nextBaseFee = new(big.Int)
}
bf.results.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.results.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.results.reward {
bf.results.reward[i] = new(big.Int)
}
return
}
sorter := make([]txGasAndReward, 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}
}
slices.SortStableFunc(sorter, func(a, b txGasAndReward) int {
return a.reward.Cmp(b.reward)
})
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.results.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, reqEnd rpc.BlockNumber, blocks uint64) (*types.Block, []*types.Receipt, uint64, uint64, error) {
var (
headBlock *types.Header
pendingBlock *types.Block
pendingReceipts types.Receipts
err error
)
// Get the chain's current head.
if headBlock, err = oracle.backend.HeaderByNumber(ctx, rpc.LatestBlockNumber); err != nil {
return nil, nil, 0, 0, err
}
head := rpc.BlockNumber(headBlock.Number.Uint64())
// Fail if request block is beyond the chain's current head.
if head < reqEnd {
return nil, nil, 0, 0, fmt.Errorf("%w: requested %d, head %d", errRequestBeyondHead, reqEnd, head)
}
// Resolve block tag.
if reqEnd < 0 {
var (
resolved *types.Header
err error
)
switch reqEnd {
case rpc.PendingBlockNumber:
if pendingBlock, pendingReceipts = oracle.backend.PendingBlockAndReceipts(); pendingBlock != nil {
resolved = pendingBlock.Header()
} else {
// Pending block not supported by backend, process only until latest block.
resolved = headBlock
// Update total blocks to return to account for this.
blocks--
}
case rpc.LatestBlockNumber:
// Retrieved above.
resolved = headBlock
case rpc.SafeBlockNumber:
resolved, err = oracle.backend.HeaderByNumber(ctx, rpc.SafeBlockNumber)
case rpc.FinalizedBlockNumber:
resolved, err = oracle.backend.HeaderByNumber(ctx, rpc.FinalizedBlockNumber)
case rpc.EarliestBlockNumber:
resolved, err = oracle.backend.HeaderByNumber(ctx, rpc.EarliestBlockNumber)
}
if resolved == nil || err != nil {
return nil, nil, 0, 0, err
}
// Absolute number resolved.
reqEnd = rpc.BlockNumber(resolved.Number.Uint64())
}
// If there are no blocks to return, short circuit.
if blocks == 0 {
return nil, nil, 0, 0, nil
}
// Ensure not trying to retrieve before genesis.
if uint64(reqEnd+1) < blocks {
blocks = uint64(reqEnd + 1)
}
return pendingBlock, pendingReceipts, uint64(reqEnd), blocks, 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, blocks uint64, unresolvedLastBlock rpc.BlockNumber, rewardPercentiles []float64) (*big.Int, [][]*big.Int, []*big.Int, []float64, error) {
if blocks < 1 {
return common.Big0, nil, nil, nil, nil // returning with no data and no error means there are no retrievable blocks
}
maxFeeHistory := oracle.maxHeaderHistory
if len(rewardPercentiles) != 0 {
maxFeeHistory = oracle.maxBlockHistory
}
if blocks > maxFeeHistory {
log.Warn("Sanitizing fee history length", "requested", blocks, "truncated", maxFeeHistory)
blocks = maxFeeHistory
}
for i, p := range rewardPercentiles {
if p < 0 || p > 100 {
return common.Big0, nil, nil, nil, fmt.Errorf("%w: %f", errInvalidPercentile, p)
}
if i > 0 && p <= rewardPercentiles[i-1] {
return common.Big0, nil, nil, nil, fmt.Errorf("%w: #%d:%f >= #%d:%f", errInvalidPercentile, i-1, rewardPercentiles[i-1], i, p)
}
}
var (
pendingBlock *types.Block
pendingReceipts []*types.Receipt
err error
)
pendingBlock, pendingReceipts, lastBlock, blocks, err := oracle.resolveBlockRange(ctx, unresolvedLastBlock, blocks)
if err != nil || blocks == 0 {
return common.Big0, nil, nil, nil, err
}
oldestBlock := lastBlock + 1 - blocks
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var next atomic.Uint64
next.Store(oldestBlock)
results := make(chan *blockFees, blocks)
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 := 0; i < maxBlockFetchers && i < int(blocks); i++ {
go func() {
for {
// Retrieve the next block number to fetch with this goroutine
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blockNumber := next.Add(1) - 1
if blockNumber > lastBlock {
return
}
fees := &blockFees{blockNumber: blockNumber}
if pendingBlock != nil && blockNumber >= pendingBlock.NumberU64() {
fees.block, fees.receipts = pendingBlock, pendingReceipts
fees.header = fees.block.Header()
oracle.processBlock(fees, rewardPercentiles)
results <- fees
} else {
cacheKey := cacheKey{number: blockNumber, percentiles: string(percentileKey)}
if p, ok := oracle.historyCache.Get(cacheKey); ok {
fees.results = p
results <- fees
} else {
if len(rewardPercentiles) != 0 {
fees.block, fees.err = oracle.backend.BlockByNumber(ctx, rpc.BlockNumber(blockNumber))
if fees.block != nil && fees.err == nil {
fees.receipts, fees.err = oracle.backend.GetReceipts(ctx, fees.block.Hash())
fees.header = fees.block.Header()
}
} else {
fees.header, fees.err = oracle.backend.HeaderByNumber(ctx, rpc.BlockNumber(blockNumber))
}
if fees.header != nil && fees.err == nil {
oracle.processBlock(fees, rewardPercentiles)
if fees.err == nil {
oracle.historyCache.Add(cacheKey, fees.results)
}
}
// send to results even if empty to guarantee that blocks items are sent in total
results <- fees
}
}
}
}()
}
var (
reward = make([][]*big.Int, blocks)
baseFee = make([]*big.Int, blocks+1)
gasUsedRatio = make([]float64, blocks)
firstMissing = blocks
)
for ; blocks > 0; blocks-- {
fees := <-results
if fees.err != nil {
return common.Big0, nil, nil, nil, fees.err
}
i := fees.blockNumber - oldestBlock
if fees.results.baseFee != nil {
reward[i], baseFee[i], baseFee[i+1], gasUsedRatio[i] = fees.results.reward, fees.results.baseFee, fees.results.nextBaseFee, fees.results.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 common.Big0, nil, nil, nil, nil
}
if len(rewardPercentiles) != 0 {
reward = reward[:firstMissing]
} else {
reward = nil
}
baseFee, gasUsedRatio = baseFee[:firstMissing+1], gasUsedRatio[:firstMissing]
return new(big.Int).SetUint64(oldestBlock), reward, baseFee, gasUsedRatio, nil
}