From 56235aee90a4e8e3bb1e81cbd79dc9955218e032 Mon Sep 17 00:00:00 2001
From: Jakub Sztandera <kubuxu@protocol.ai>
Date: Mon, 31 Aug 2020 18:12:06 +0200
Subject: [PATCH 1/2] Fix GasEstimateGasPremium when there is only one message
 on chain

Signed-off-by: Jakub Sztandera <kubuxu@protocol.ai>
---
 node/impl/full/gas.go | 21 ++++++++-------------
 1 file changed, 8 insertions(+), 13 deletions(-)

diff --git a/node/impl/full/gas.go b/node/impl/full/gas.go
index b4124ed913f..267d7e4cafc 100644
--- a/node/impl/full/gas.go
+++ b/node/impl/full/gas.go
@@ -109,27 +109,22 @@ func (a *GasAPI) GasEstimateGasPremium(ctx context.Context, nblocksincl uint64,
 		return prices[i].price.GreaterThan(prices[j].price)
 	})
 
-	// todo: account for how full blocks are
-
 	at := build.BlockGasTarget * int64(blocks) / 2
-	prev := big.Zero()
-
-	premium := big.Zero()
+	prev1, prev2 := big.Zero(), big.Zero()
 	for _, price := range prices {
+		prev1, prev2 = price.price, prev1
 		at -= price.limit
 		if at > 0 {
-			prev = price.price
 			continue
 		}
+	}
 
-		if prev.Equals(big.Zero()) {
-			return types.BigAdd(price.price, big.NewInt(1)), nil
-		}
-
-		premium = types.BigAdd(big.Div(types.BigAdd(price.price, prev), types.NewInt(2)), big.NewInt(1))
+	premium := prev1
+	if types.BigCmp(prev2, big.Zero()) != 0 {
+		premium = big.Div(types.BigAdd(prev1, prev2), types.NewInt(2))
 	}
 
-	if types.BigCmp(premium, big.Zero()) == 0 {
+	if types.BigCmp(premium, types.NewInt(MinGasPremium)) < 0 {
 		switch nblocksincl {
 		case 1:
 			premium = types.NewInt(2 * MinGasPremium)
@@ -144,7 +139,7 @@ func (a *GasAPI) GasEstimateGasPremium(ctx context.Context, nblocksincl uint64,
 	const precision = 32
 	// mean 1, stddev 0.005 => 95% within +-1%
 	noise := 1 + rand.NormFloat64()*0.005
-	premium = types.BigMul(premium, types.NewInt(uint64(noise*(1<<precision))))
+	premium = types.BigMul(premium, types.NewInt(uint64(noise*(1<<precision))+1))
 	premium = types.BigDiv(premium, types.NewInt(1<<precision))
 	return premium, nil
 }

From cfe513437529047b45b0542f3dc021ad3759d28b Mon Sep 17 00:00:00 2001
From: Aayush Rajasekaran <arajasek94@gmail.com>
Date: Mon, 31 Aug 2020 18:53:14 -0400
Subject: [PATCH 2/2] Use Sign() to check zero-equality

---
 node/impl/full/gas.go | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/node/impl/full/gas.go b/node/impl/full/gas.go
index 267d7e4cafc..6ee79c93a33 100644
--- a/node/impl/full/gas.go
+++ b/node/impl/full/gas.go
@@ -120,7 +120,7 @@ func (a *GasAPI) GasEstimateGasPremium(ctx context.Context, nblocksincl uint64,
 	}
 
 	premium := prev1
-	if types.BigCmp(prev2, big.Zero()) != 0 {
+	if prev2.Sign() != 0 {
 		premium = big.Div(types.BigAdd(prev1, prev2), types.NewInt(2))
 	}