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- // 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 gasprice
- 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
- var DefaultMaxPrice = big.NewInt(500 * params.GWei)
- 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.
- 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()
- 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))), 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))), number, sampleNumber, result, quit)
- 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].GasPriceCmp(t[j]) < 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.
- 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.GasPriceIntCmp(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] }
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