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author | Wei-Ning Huang <w@cobinhood.com> | 2018-10-12 13:01:15 +0800 |
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committer | Wei-Ning Huang <w@dexon.org> | 2019-04-09 21:32:49 +0800 |
commit | efa16f95fce18659532cf650e4ce0b46ec9f9245 (patch) | |
tree | 8deaf1be29c0a3d839940f1cde1c7409953397a5 /dex/gasprice | |
parent | 47b4be274b72cecfd653702413d4cae0f97f710e (diff) | |
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dex: add api_backend.go and it's dependencies
Diffstat (limited to 'dex/gasprice')
-rw-r--r-- | dex/gasprice/gasprice.go | 189 |
1 files changed, 189 insertions, 0 deletions
diff --git a/dex/gasprice/gasprice.go b/dex/gasprice/gasprice.go new file mode 100644 index 000000000..9af33c682 --- /dev/null +++ b/dex/gasprice/gasprice.go @@ -0,0 +1,189 @@ +// 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/dexon-foundation/dexon/common" + "github.com/dexon-foundation/dexon/core/types" + "github.com/dexon-foundation/dexon/internal/ethapi" + "github.com/dexon-foundation/dexon/params" + "github.com/dexon-foundation/dexon/rpc" +) + +var maxPrice = big.NewInt(500 * params.GWei) + +type Config struct { + Blocks int + Percentile int + Default *big.Int `toml:",omitempty"` +} + +// Oracle recommends gas prices based on the content of recent +// blocks. Suitable for both light and full clients. +type Oracle struct { + backend ethapi.Backend + lastHead common.Hash + lastPrice *big.Int + cacheLock sync.RWMutex + fetchLock sync.Mutex + + checkBlocks, maxEmpty, maxBlocks int + percentile int +} + +// NewOracle returns a new oracle. +func NewOracle(backend ethapi.Backend, params Config) *Oracle { + blocks := params.Blocks + if blocks < 1 { + blocks = 1 + } + percent := params.Percentile + if percent < 0 { + percent = 0 + } + if percent > 100 { + percent = 100 + } + return &Oracle{ + backend: backend, + lastPrice: params.Default, + checkBlocks: blocks, + maxEmpty: blocks / 2, + maxBlocks: blocks * 5, + percentile: percent, + } +} + +// SuggestPrice returns the recommended gas price. +func (gpo *Oracle) SuggestPrice(ctx context.Context) (*big.Int, error) { + gpo.cacheLock.RLock() + lastHead := gpo.lastHead + lastPrice := gpo.lastPrice + gpo.cacheLock.RUnlock() + + head, _ := gpo.backend.HeaderByNumber(ctx, rpc.LatestBlockNumber) + headHash := head.Hash() + 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 = gpo.lastHead + lastPrice = gpo.lastPrice + gpo.cacheLock.RUnlock() + if headHash == lastHead { + return lastPrice, nil + } + + blockNum := head.Number.Uint64() + ch := make(chan getBlockPricesResult, gpo.checkBlocks) + sent := 0 + exp := 0 + var blockPrices []*big.Int + for sent < gpo.checkBlocks && blockNum > 0 { + go gpo.getBlockPrices(ctx, types.MakeSigner(gpo.backend.ChainConfig(), big.NewInt(int64(blockNum))), blockNum, ch) + sent++ + exp++ + blockNum-- + } + maxEmpty := gpo.maxEmpty + for exp > 0 { + res := <-ch + if res.err != nil { + return lastPrice, res.err + } + exp-- + if res.price != nil { + blockPrices = append(blockPrices, res.price) + continue + } + if maxEmpty > 0 { + maxEmpty-- + continue + } + if blockNum > 0 && sent < gpo.maxBlocks { + go gpo.getBlockPrices(ctx, types.MakeSigner(gpo.backend.ChainConfig(), big.NewInt(int64(blockNum))), blockNum, ch) + sent++ + exp++ + blockNum-- + } + } + price := lastPrice + if len(blockPrices) > 0 { + sort.Sort(bigIntArray(blockPrices)) + price = blockPrices[(len(blockPrices)-1)*gpo.percentile/100] + } + if price.Cmp(maxPrice) > 0 { + price = new(big.Int).Set(maxPrice) + } + + gpo.cacheLock.Lock() + gpo.lastHead = headHash + gpo.lastPrice = price + gpo.cacheLock.Unlock() + return price, nil +} + +type getBlockPricesResult struct { + price *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, price is nil. +func (gpo *Oracle) getBlockPrices(ctx context.Context, signer types.Signer, blockNum uint64, ch chan getBlockPricesResult) { + block, err := gpo.backend.BlockByNumber(ctx, rpc.BlockNumber(blockNum)) + if block == nil { + ch <- getBlockPricesResult{nil, err} + return + } + + blockTxs := block.Transactions() + txs := make([]*types.Transaction, len(blockTxs)) + copy(txs, blockTxs) + sort.Sort(transactionsByGasPrice(txs)) + + for _, tx := range txs { + sender, err := types.Sender(signer, tx) + if err == nil && sender != block.Coinbase() { + ch <- getBlockPricesResult{tx.GasPrice(), nil} + return + } + } + ch <- getBlockPricesResult{nil, nil} +} + +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] } |