238 lines
7.4 KiB
Go
238 lines
7.4 KiB
Go
// Copyright 2015 The go-ethereum Authors
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// This file is part of the go-ethereum library.
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//
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// The go-ethereum library is free software: you can redistribute it and/or modify
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// it under the terms of the GNU Lesser General Public License as published by
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// the Free Software Foundation, either version 3 of the License, or
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// (at your option) any later version.
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//
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// The go-ethereum library is distributed in the hope that it will be useful,
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// but WITHOUT ANY WARRANTY; without even the implied warranty of
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// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
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// GNU Lesser General Public License for more details.
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//
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// You should have received a copy of the GNU Lesser General Public License
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// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.
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package gasprice
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import (
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"context"
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"math/big"
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"sort"
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"sync"
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"github.com/ethereum/go-ethereum/common"
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"github.com/ethereum/go-ethereum/core/types"
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"github.com/ethereum/go-ethereum/log"
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"github.com/ethereum/go-ethereum/params"
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"github.com/ethereum/go-ethereum/rpc"
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)
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const sampleNumber = 3 // Number of transactions sampled in a block
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var DefaultMaxPrice = big.NewInt(500 * params.GWei)
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type Config struct {
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Blocks int
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Percentile int
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Default *big.Int `toml:",omitempty"`
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MaxPrice *big.Int `toml:",omitempty"`
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OracleThreshold int `toml:",omitempty"`
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}
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// OracleBackend includes all necessary background APIs for oracle.
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type OracleBackend interface {
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HeaderByNumber(ctx context.Context, number rpc.BlockNumber) (*types.Header, error)
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BlockByNumber(ctx context.Context, number rpc.BlockNumber) (*types.Block, error)
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ChainConfig() *params.ChainConfig
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}
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// Oracle recommends gas prices based on the content of recent
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// blocks. Suitable for both light and full clients.
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type Oracle struct {
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backend OracleBackend
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lastHead common.Hash
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lastPrice *big.Int
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maxPrice *big.Int
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cacheLock sync.RWMutex
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fetchLock sync.Mutex
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defaultPrice *big.Int
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sampleTxThreshold int
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checkBlocks int
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percentile int
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}
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// NewOracle returns a new gasprice oracle which can recommend suitable
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// gasprice for newly created transaction.
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func NewOracle(backend OracleBackend, params Config) *Oracle {
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blocks := params.Blocks
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if blocks < 1 {
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blocks = 1
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log.Warn("Sanitizing invalid gasprice oracle sample blocks", "provided", params.Blocks, "updated", blocks)
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}
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percent := params.Percentile
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if percent < 0 {
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percent = 0
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log.Warn("Sanitizing invalid gasprice oracle sample percentile", "provided", params.Percentile, "updated", percent)
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}
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if percent > 100 {
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percent = 100
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log.Warn("Sanitizing invalid gasprice oracle sample percentile", "provided", params.Percentile, "updated", percent)
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}
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maxPrice := params.MaxPrice
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if maxPrice == nil || maxPrice.Int64() <= 0 {
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maxPrice = DefaultMaxPrice
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log.Warn("Sanitizing invalid gasprice oracle price cap", "provided", params.MaxPrice, "updated", maxPrice)
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}
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return &Oracle{
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backend: backend,
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lastPrice: params.Default,
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maxPrice: maxPrice,
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checkBlocks: blocks,
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percentile: percent,
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defaultPrice: params.Default,
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sampleTxThreshold: params.OracleThreshold,
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}
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}
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// SuggestPrice returns a gasprice so that newly created transaction can
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// have a very high chance to be included in the following blocks.
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func (gpo *Oracle) SuggestPrice(ctx context.Context) (*big.Int, error) {
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head, _ := gpo.backend.HeaderByNumber(ctx, rpc.LatestBlockNumber)
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headHash := head.Hash()
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// If the latest gasprice is still available, return it.
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gpo.cacheLock.RLock()
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lastHead, lastPrice := gpo.lastHead, gpo.lastPrice
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gpo.cacheLock.RUnlock()
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if headHash == lastHead {
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return lastPrice, nil
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}
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gpo.fetchLock.Lock()
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defer gpo.fetchLock.Unlock()
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// Try checking the cache again, maybe the laest fetch fetched what we need
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gpo.cacheLock.RLock()
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lastHead, lastPrice = gpo.lastHead, gpo.lastPrice
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gpo.cacheLock.RUnlock()
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if headHash == lastHead {
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return lastPrice, nil
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}
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var (
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sent, exp int
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number = head.Number.Uint64()
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result = make(chan getBlockPricesResult, gpo.checkBlocks)
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quit = make(chan struct{})
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txPrices []*big.Int
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totalTxSamples int
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)
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for sent < gpo.checkBlocks && number > 0 {
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go gpo.getBlockPrices(ctx, types.MakeSigner(gpo.backend.ChainConfig(), big.NewInt(int64(number))), number, sampleNumber, result, quit)
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sent++
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exp++
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number--
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}
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for exp > 0 {
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res := <-result
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if res.err != nil {
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close(quit)
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return lastPrice, res.err
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}
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exp--
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// Nothing returned. There are two special cases here:
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// - The block is empty
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// - All the transactions included are sent by the miner itself.
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// In these cases, use the latest calculated price for samping.
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if len(res.prices) == 0 {
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res.prices = []*big.Int{lastPrice}
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} else {
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totalTxSamples = totalTxSamples + res.number
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}
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// Besides, in order to collect enough data for sampling, if nothing
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// meaningful returned, try to query more blocks. But the maximum
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// is 2*checkBlocks.
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if len(res.prices) == 1 && len(txPrices)+1+exp < gpo.checkBlocks*2 && number > 0 {
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go gpo.getBlockPrices(ctx, types.MakeSigner(gpo.backend.ChainConfig(), big.NewInt(int64(number))), number, sampleNumber, result, quit)
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sent++
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exp++
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number--
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}
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txPrices = append(txPrices, res.prices...)
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}
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price := lastPrice
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if len(txPrices) > 0 && totalTxSamples > gpo.sampleTxThreshold {
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sort.Sort(bigIntArray(txPrices))
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price = txPrices[(len(txPrices)-1)*gpo.percentile/100]
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} else {
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price = gpo.defaultPrice
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}
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if price.Cmp(gpo.maxPrice) > 0 {
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price = new(big.Int).Set(gpo.maxPrice)
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}
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gpo.cacheLock.Lock()
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gpo.lastHead = headHash
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gpo.lastPrice = price
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gpo.cacheLock.Unlock()
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return price, nil
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}
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type getBlockPricesResult struct {
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number int
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prices []*big.Int
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err error
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}
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type transactionsByGasPrice []*types.Transaction
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func (t transactionsByGasPrice) Len() int { return len(t) }
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func (t transactionsByGasPrice) Swap(i, j int) { t[i], t[j] = t[j], t[i] }
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func (t transactionsByGasPrice) Less(i, j int) bool { return t[i].GasPriceCmp(t[j]) < 0 }
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// getBlockPrices calculates the lowest transaction gas price in a given block
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// and sends it to the result channel. If the block is empty or all transactions
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// are sent by the miner itself(it doesn't make any sense to include this kind of
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// transaction prices for sampling), nil gasprice is returned.
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func (gpo *Oracle) getBlockPrices(ctx context.Context, signer types.Signer, blockNum uint64, limit int, result chan getBlockPricesResult, quit chan struct{}) {
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block, err := gpo.backend.BlockByNumber(ctx, rpc.BlockNumber(blockNum))
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if block == nil {
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select {
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case result <- getBlockPricesResult{0, nil, err}:
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case <-quit:
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}
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return
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}
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blockTxs := block.Transactions()
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txs := make([]*types.Transaction, len(blockTxs))
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copy(txs, blockTxs)
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sort.Sort(transactionsByGasPrice(txs))
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var prices []*big.Int
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for _, tx := range txs {
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if tx.GasPriceIntCmp(common.Big1) <= 0 {
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continue
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}
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sender, err := types.Sender(signer, tx)
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if err == nil && sender != block.Coinbase() {
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prices = append(prices, tx.GasPrice())
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if len(prices) >= limit {
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break
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}
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}
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}
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select {
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case result <- getBlockPricesResult{len(prices), prices, nil}:
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case <-quit:
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}
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}
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type bigIntArray []*big.Int
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func (s bigIntArray) Len() int { return len(s) }
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func (s bigIntArray) Less(i, j int) bool { return s[i].Cmp(s[j]) < 0 }
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func (s bigIntArray) Swap(i, j int) { s[i], s[j] = s[j], s[i] }
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