From 856d00d308e526a1e57dbf908f7e72663e1b3645 Mon Sep 17 00:00:00 2001
From: Zsolt Felfoldi <zsfelfoldi@gmail.com>
Date: Thu, 6 Apr 2017 15:51:10 +0200
Subject: [PATCH] eth/gasprice: max limit, maxEmpty

---
 cmd/utils/flags.go       |  2 +-
 eth/gasprice/gasprice.go | 14 ++++++++++----
 2 files changed, 11 insertions(+), 5 deletions(-)

diff --git a/cmd/utils/flags.go b/cmd/utils/flags.go
index f0e80fd10d..c2aa3c5fa1 100644
--- a/cmd/utils/flags.go
+++ b/cmd/utils/flags.go
@@ -412,7 +412,7 @@ var (
 	GpoBlocksFlag = cli.IntFlag{
 		Name:  "gpoblocks",
 		Usage: "Number of recent blocks to check for gas prices",
-		Value: 5,
+		Value: 10,
 	}
 	GpoPercentileFlag = cli.IntFlag{
 		Name:  "gpopercentile",
diff --git a/eth/gasprice/gasprice.go b/eth/gasprice/gasprice.go
index 3cf2146c20..bac048c88a 100644
--- a/eth/gasprice/gasprice.go
+++ b/eth/gasprice/gasprice.go
@@ -24,9 +24,12 @@ import (
 
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/ethereum/go-ethereum/internal/ethapi"
+	"github.com/ethereum/go-ethereum/params"
 	"github.com/ethereum/go-ethereum/rpc"
 )
 
+var maxPrice = big.NewInt(500 * params.Shannon)
+
 type Config struct {
 	Blocks     int
 	Percentile int
@@ -42,8 +45,8 @@ type Oracle struct {
 	cacheLock sync.RWMutex
 	fetchLock sync.Mutex
 
-	checkBlocks, minBlocks, maxBlocks int
-	percentile                        int
+	checkBlocks, maxEmpty, maxBlocks int
+	percentile                       int
 }
 
 // NewOracle returns a new oracle.
@@ -63,7 +66,7 @@ func NewOracle(backend ethapi.Backend, params Config) *Oracle {
 		backend:     backend,
 		lastPrice:   params.Default,
 		checkBlocks: blocks,
-		minBlocks:   (blocks + 1) / 2,
+		maxEmpty:    blocks / 2,
 		maxBlocks:   blocks * 5,
 		percentile:  percent,
 	}
@@ -105,7 +108,7 @@ func (gpo *Oracle) SuggestPrice(ctx context.Context) (*big.Int, error) {
 		exp++
 		blockNum--
 	}
-	maxEmpty := gpo.checkBlocks - gpo.minBlocks
+	maxEmpty := gpo.maxEmpty
 	for exp > 0 {
 		res := <-ch
 		if res.err != nil {
@@ -132,6 +135,9 @@ func (gpo *Oracle) SuggestPrice(ctx context.Context) (*big.Int, error) {
 		sort.Sort(bigIntArray(txPrices))
 		price = txPrices[(len(txPrices)-1)*gpo.percentile/100]
 	}
+	if price.Cmp(maxPrice) > 0 {
+		price = new(big.Int).Set(maxPrice)
+	}
 
 	gpo.cacheLock.Lock()
 	gpo.lastHead = headHash