ethergo/chain/gas/londinium/gasprice.go
// Copyright 2015 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 londinium
import (
"context"
"math/big"
"sort"
"sync"
"github.com/ethereum/go-ethereum/common"
"github.com/ethereum/go-ethereum/core/types"
"github.com/ethereum/go-ethereum/log"
"github.com/ethereum/go-ethereum/params"
"github.com/ethereum/go-ethereum/rpc"
)
const sampleNumber = 3 // Number of transactions sampled in a block
// DefaultMaxPrice is the default max price of a tx.
var DefaultMaxPrice = big.NewInt(500 * params.GWei)
// Config is the londinium config format.
type Config struct {
Blocks int
Percentile int
Default *big.Int `toml:",omitempty"`
MaxPrice *big.Int `toml:",omitempty"`
}
// OracleBackend includes all necessary background APIs for oracle.
type OracleBackend interface {
HeaderByNumber(ctx context.Context, number rpc.BlockNumber) (*types.Header, error)
BlockByNumber(ctx context.Context, number rpc.BlockNumber) (*types.Block, error)
ChainConfig() *params.ChainConfig
}
// Oracle recommends gas prices based on the content of recent
// blocks. Suitable for both light and full clients.
type Oracle struct {
backend OracleBackend
lastHead common.Hash
lastPrice *big.Int
maxPrice *big.Int
cacheLock sync.RWMutex
fetchLock sync.Mutex
checkBlocks int
percentile int
}
// NewOracle returns a new gasprice oracle which can recommend suitable
// gasprice for newly created transaction.
func NewOracle(backend OracleBackend, params Config) *Oracle {
blocks := params.Blocks
if blocks < 1 {
blocks = 1
log.Warn("Sanitizing invalid gasprice oracle sample blocks", "provided", params.Blocks, "updated", blocks)
}
percent := params.Percentile
if percent < 0 {
percent = 0
log.Warn("Sanitizing invalid gasprice oracle sample percentile", "provided", params.Percentile, "updated", percent)
}
if percent > 100 {
percent = 100
log.Warn("Sanitizing invalid gasprice oracle sample percentile", "provided", params.Percentile, "updated", percent)
}
maxPrice := params.MaxPrice
if maxPrice == nil || maxPrice.Int64() <= 0 {
maxPrice = DefaultMaxPrice
log.Warn("Sanitizing invalid gasprice oracle price cap", "provided", params.MaxPrice, "updated", maxPrice)
}
return &Oracle{
backend: backend,
lastPrice: params.Default,
maxPrice: maxPrice,
checkBlocks: blocks,
percentile: percent,
}
}
// SuggestPrice returns a gasprice so that newly created transaction can
// have a very high chance to be included in the following blocks.
//
//nolint:cyclop
func (gpo *Oracle) SuggestPrice(ctx context.Context) (*big.Int, error) {
head, _ := gpo.backend.HeaderByNumber(ctx, rpc.LatestBlockNumber)
headHash := head.Hash()
// If the latest gasprice is still available, return it.
gpo.cacheLock.RLock()
lastHead, lastPrice := gpo.lastHead, gpo.lastPrice
gpo.cacheLock.RUnlock()
if headHash == lastHead {
return lastPrice, nil
}
gpo.fetchLock.Lock()
defer gpo.fetchLock.Unlock()
// Try checking the cache again, maybe the last fetch fetched what we need
gpo.cacheLock.RLock()
lastHead, lastPrice = gpo.lastHead, gpo.lastPrice
gpo.cacheLock.RUnlock()
if headHash == lastHead {
return lastPrice, nil
}
var (
sent, exp int
number = head.Number.Uint64()
time = head.Time
result = make(chan getBlockPricesResult, gpo.checkBlocks)
quit = make(chan struct{})
txPrices []*big.Int
)
for sent < gpo.checkBlocks && number > 0 {
go gpo.getBlockPrices(ctx, types.MakeSigner(gpo.backend.ChainConfig(), big.NewInt(int64(number)), time), number, sampleNumber, result, quit)
sent++
exp++
number--
}
for exp > 0 {
res := <-result
if res.err != nil {
close(quit)
return lastPrice, res.err
}
exp--
// Nothing returned. There are two special cases here:
// - The block is empty
// - All the transactions included are sent by the miner itself.
// In these cases, use the latest calculated price for samping.
if len(res.prices) == 0 {
res.prices = []*big.Int{lastPrice}
}
// Besides, in order to collect enough data for sampling, if nothing
// meaningful returned, try to query more blocks. But the maximum
// is 2*checkBlocks.
if len(res.prices) == 1 && len(txPrices)+1+exp < gpo.checkBlocks*2 && number > 0 {
go gpo.getBlockPrices(ctx, types.MakeSigner(gpo.backend.ChainConfig(), big.NewInt(int64(number)), time), number, sampleNumber, result, quit)
//nolint: wastedassign
sent++
exp++
number--
}
txPrices = append(txPrices, res.prices...)
}
price := lastPrice
if len(txPrices) > 0 {
sort.Sort(bigIntArray(txPrices))
price = txPrices[(len(txPrices)-1)*gpo.percentile/100]
}
if price.Cmp(gpo.maxPrice) > 0 {
price = new(big.Int).Set(gpo.maxPrice)
}
gpo.cacheLock.Lock()
gpo.lastHead = headHash
gpo.lastPrice = price
gpo.cacheLock.Unlock()
return price, nil
}
type getBlockPricesResult struct {
prices []*big.Int
err error
}
type transactionsByGasPrice []*types.Transaction
func (t transactionsByGasPrice) Len() int { return len(t) }
func (t transactionsByGasPrice) Swap(i, j int) { t[i], t[j] = t[j], t[i] }
func (t transactionsByGasPrice) Less(i, j int) bool { return t[i].GasPrice().Cmp(t[j].GasPrice()) < 0 }
// getBlockPrices calculates the lowest transaction gas price in a given block
// and sends it to the result channel. If the block is empty or all transactions
// are sent by the miner itself(it doesn't make any sense to include this kind of
// transaction prices for sampling), nil gasprice is returned.
//
//nolint:cyclop
func (gpo *Oracle) getBlockPrices(ctx context.Context, signer types.Signer, blockNum uint64, limit int, result chan getBlockPricesResult, quit chan struct{}) {
block, err := gpo.backend.BlockByNumber(ctx, rpc.BlockNumber(blockNum))
if block == nil {
select {
case result <- getBlockPricesResult{nil, err}:
case <-quit:
}
return
}
blockTxs := block.Transactions()
txs := make([]*types.Transaction, len(blockTxs))
copy(txs, blockTxs)
sort.Sort(transactionsByGasPrice(txs))
var prices []*big.Int
for _, tx := range txs {
if tx.GasPrice().Cmp(common.Big1) <= 0 {
continue
}
sender, err := types.Sender(signer, tx)
if err == nil && sender != block.Coinbase() {
prices = append(prices, tx.GasPrice())
if len(prices) >= limit {
break
}
}
}
select {
case result <- getBlockPricesResult{prices, nil}:
case <-quit:
}
}
type bigIntArray []*big.Int
func (s bigIntArray) Len() int { return len(s) }
func (s bigIntArray) Less(i, j int) bool { return s[i].Cmp(s[j]) < 0 }
func (s bigIntArray) Swap(i, j int) { s[i], s[j] = s[j], s[i] }