From 14fe03cbfecf508848bcd1172ea8d2ee3e41fda4 Mon Sep 17 00:00:00 2001
From: Tyler Smith <tylersmith.me@gmail.com>
Date: Thu, 30 Jul 2020 22:00:38 -0700
Subject: TWEAK: Set minimum gas price.

---
 plugin/evm/block.go |  9 +++++++++
 plugin/evm/vm.go    | 10 ++++++++++
 2 files changed, 19 insertions(+)

diff --git a/plugin/evm/block.go b/plugin/evm/block.go
index 449e261..1a2bf9e 100644
--- a/plugin/evm/block.go
+++ b/plugin/evm/block.go
@@ -61,6 +61,15 @@ func (b *Block) Parent() snowman.Block {
 
 // Verify implements the snowman.Block interface
 func (b *Block) Verify() error {
+	// Ensure the minimum gas price is paid for every transaction
+	for _, tx := range b.ethBlock.Transactions() {
+		if tx.GasPrice().Cmp(minGasPrice) < 0 {
+			return errInvalidBlock
+		}
+	}
+
+	// Attempt to add the block to the chain and consider the block valid iff it's
+	// accepted
 	_, err := b.vm.chain.InsertChain([]*types.Block{b.ethBlock})
 	return err
 }
diff --git a/plugin/evm/vm.go b/plugin/evm/vm.go
index cf5ef8a..7b4d064 100644
--- a/plugin/evm/vm.go
+++ b/plugin/evm/vm.go
@@ -60,6 +60,10 @@ const (
 )
 
 var (
+	// minGasPrice is the number of nAVAX required per gas unit for a transaction
+	// to be valid
+	minGasPrice = big.NewInt(85)
+
 	errEmptyBlock     = errors.New("empty block")
 	errCreateBlock    = errors.New("couldn't create block")
 	errUnknownBlock   = errors.New("unknown block")
@@ -140,6 +144,12 @@ func (vm *VM) Initialize(
 	config.Genesis = g
 	config.Miner.ManualMining = true
 	config.Miner.DisableUncle = true
+
+	// Set minimum price for mining and default gas price oracle value to the min
+	// gas price to prevent so transactions and blocks all use the correct fees
+	config.Miner.GasPrice = minGasPrice
+	config.GPO.Default = minGasPrice
+
 	if err := config.SetGCMode("archive"); err != nil {
 		panic(err)
 	}
-- 
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