1 files changed, 229 insertions, 0 deletions
diff --git a/eth/gasprice/gasprice.go b/eth/gasprice/gasprice.go
new file mode 100644
index 000000000..eb2df4a96
--- /dev/null
+++ b/eth/gasprice/gasprice.go
@@ -0,0 +1,229 @@
+// 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 (
+	"math/big"
+	"math/rand"
+	"sync"
+
+	"github.com/ethereum/go-ethereum/core"
+	"github.com/ethereum/go-ethereum/core/types"
+	"github.com/ethereum/go-ethereum/ethdb"
+	"github.com/ethereum/go-ethereum/event"
+	"github.com/ethereum/go-ethereum/logger"
+	"github.com/ethereum/go-ethereum/logger/glog"
+)
+
+const (
+	gpoProcessPastBlocks = 100
+
+	// for testing
+	gpoDefaultBaseCorrectionFactor = 110
+	gpoDefaultMinGasPrice          = 10000000000000
+)
+
+type blockPriceInfo struct {
+	baseGasPrice *big.Int
+}
+
+type GpoParams struct {
+	GpoMinGasPrice          *big.Int
+	GpoMaxGasPrice          *big.Int
+	GpoFullBlockRatio       int
+	GpobaseStepDown         int
+	GpobaseStepUp           int
+	GpobaseCorrectionFactor int
+}
+
+// GasPriceOracle recommends gas prices based on the content of recent
+// blocks.
+type GasPriceOracle struct {
+	chain         *core.BlockChain
+	db            ethdb.Database
+	evmux         *event.TypeMux
+	params        *GpoParams
+	initOnce      sync.Once
+	minPrice      *big.Int
+	lastBaseMutex sync.Mutex
+	lastBase      *big.Int
+
+	// state of listenLoop
+	blocks                        map[uint64]*blockPriceInfo
+	firstProcessed, lastProcessed uint64
+	minBase                       *big.Int
+}
+
+// NewGasPriceOracle returns a new oracle.
+func NewGasPriceOracle(chain *core.BlockChain, db ethdb.Database, evmux *event.TypeMux, params *GpoParams) *GasPriceOracle {
+	minprice := params.GpoMinGasPrice
+	if minprice == nil {
+		minprice = big.NewInt(gpoDefaultMinGasPrice)
+	}
+	minbase := new(big.Int).Mul(minprice, big.NewInt(100))
+	if params.GpobaseCorrectionFactor > 0 {
+		minbase = minbase.Div(minbase, big.NewInt(int64(params.GpobaseCorrectionFactor)))
+	}
+	return &GasPriceOracle{
+		chain:    chain,
+		db:       db,
+		evmux:    evmux,
+		params:   params,
+		blocks:   make(map[uint64]*blockPriceInfo),
+		minBase:  minbase,
+		minPrice: minprice,
+		lastBase: minprice,
+	}
+}
+
+func (gpo *GasPriceOracle) init() {
+	gpo.initOnce.Do(func() {
+		gpo.processPastBlocks()
+		go gpo.listenLoop()
+	})
+}
+
+func (self *GasPriceOracle) processPastBlocks() {
+	last := int64(-1)
+	cblock := self.chain.CurrentBlock()
+	if cblock != nil {
+		last = int64(cblock.NumberU64())
+	}
+	first := int64(0)
+	if last > gpoProcessPastBlocks {
+		first = last - gpoProcessPastBlocks
+	}
+	self.firstProcessed = uint64(first)
+	for i := first; i <= last; i++ {
+		block := self.chain.GetBlockByNumber(uint64(i))
+		if block != nil {
+			self.processBlock(block)
+		}
+	}
+
+}
+
+func (self *GasPriceOracle) listenLoop() {
+	events := self.evmux.Subscribe(core.ChainEvent{}, core.ChainSplitEvent{})
+	defer events.Unsubscribe()
+
+	for event := range events.Chan() {
+		switch event := event.Data.(type) {
+		case core.ChainEvent:
+			self.processBlock(event.Block)
+		case core.ChainSplitEvent:
+			self.processBlock(event.Block)
+		}
+	}
+}
+
+func (self *GasPriceOracle) processBlock(block *types.Block) {
+	i := block.NumberU64()
+	if i > self.lastProcessed {
+		self.lastProcessed = i
+	}
+
+	lastBase := self.minPrice
+	bpl := self.blocks[i-1]
+	if bpl != nil {
+		lastBase = bpl.baseGasPrice
+	}
+	if lastBase == nil {
+		return
+	}
+
+	var corr int
+	lp := self.lowestPrice(block)
+	if lp == nil {
+		return
+	}
+
+	if lastBase.Cmp(lp) < 0 {
+		corr = self.params.GpobaseStepUp
+	} else {
+		corr = -self.params.GpobaseStepDown
+	}
+
+	crand := int64(corr * (900 + rand.Intn(201)))
+	newBase := new(big.Int).Mul(lastBase, big.NewInt(1000000+crand))
+	newBase.Div(newBase, big.NewInt(1000000))
+
+	if newBase.Cmp(self.minBase) < 0 {
+		newBase = self.minBase
+	}
+
+	bpi := self.blocks[i]
+	if bpi == nil {
+		bpi = &blockPriceInfo{}
+		self.blocks[i] = bpi
+	}
+	bpi.baseGasPrice = newBase
+	self.lastBaseMutex.Lock()
+	self.lastBase = newBase
+	self.lastBaseMutex.Unlock()
+
+	glog.V(logger.Detail).Infof("Processed block #%v, base price is %v\n", i, newBase.Int64())
+}
+
+// returns the lowers possible price with which a tx was or could have been included
+func (self *GasPriceOracle) lowestPrice(block *types.Block) *big.Int {
+	gasUsed := big.NewInt(0)
+
+	receipts := core.GetBlockReceipts(self.db, block.Hash(), block.NumberU64())
+	if len(receipts) > 0 {
+		if cgu := receipts[len(receipts)-1].CumulativeGasUsed; cgu != nil {
+			gasUsed = receipts[len(receipts)-1].CumulativeGasUsed
+		}
+	}
+
+	if new(big.Int).Mul(gasUsed, big.NewInt(100)).Cmp(new(big.Int).Mul(block.GasLimit(),
+		big.NewInt(int64(self.params.GpoFullBlockRatio)))) < 0 {
+		// block is not full, could have posted a tx with MinGasPrice
+		return big.NewInt(0)
+	}
+
+	txs := block.Transactions()
+	if len(txs) == 0 {
+		return big.NewInt(0)
+	}
+	// block is full, find smallest gasPrice
+	minPrice := txs[0].GasPrice()
+	for i := 1; i < len(txs); i++ {
+		price := txs[i].GasPrice()
+		if price.Cmp(minPrice) < 0 {
+			minPrice = price
+		}
+	}
+	return minPrice
+}
+
+// SuggestPrice returns the recommended gas price.
+func (self *GasPriceOracle) SuggestPrice() *big.Int {
+	self.init()
+	self.lastBaseMutex.Lock()
+	price := new(big.Int).Set(self.lastBase)
+	self.lastBaseMutex.Unlock()
+
+	price.Mul(price, big.NewInt(int64(self.params.GpobaseCorrectionFactor)))
+	price.Div(price, big.NewInt(100))
+	if price.Cmp(self.minPrice) < 0 {
+		price.Set(self.minPrice)
+	} else if self.params.GpoMaxGasPrice != nil && price.Cmp(self.params.GpoMaxGasPrice) > 0 {
+		price.Set(self.params.GpoMaxGasPrice)
+	}
+	return price
+}