consensus, core, tests: implement Metropolis EIP 649

1 files changed, 20 insertions, 5 deletions

diff --git a/consensus/ethash/consensus.go b/consensus/ethash/consensus.go
index 01d97a470..b71420445 100644
--- a/consensus/ethash/consensus.go
+++ b/consensus/ethash/consensus.go
@@ -36,8 +36,9 @@ import (
 
 // Ethash proof-of-work protocol constants.
 var (
-	blockReward *big.Int = big.NewInt(5e+18) // Block reward in wei for successfully mining a block
-	maxUncles            = 2                 // Maximum number of uncles allowed in a single block
+	frontierBlockReward   *big.Int = big.NewInt(5e+18) // Block reward in wei for successfully mining a block
+	metropolisBlockReward *big.Int = big.NewInt(3e+18) // Block reward in wei for successfully mining a block upward from Metropolis
+	maxUncles                      = 2                 // Maximum number of uncles allowed in a single block
 )
 
 // Various error messages to mark blocks invalid. These should be private to
@@ -306,6 +307,7 @@ var (
 	big9          = big.NewInt(9)
 	big10         = big.NewInt(10)
 	bigMinus99    = big.NewInt(-99)
+	big2999999    = big.NewInt(2999999)
 )
 
 // calcDifficultyMetropolis is the difficulty adjustment algorithm. It returns
@@ -346,8 +348,15 @@ func calcDifficultyMetropolis(time uint64, parent *types.Header) *big.Int {
 	if x.Cmp(params.MinimumDifficulty) < 0 {
 		x.Set(params.MinimumDifficulty)
 	}
+	// calculate a fake block numer for the ice-age delay:
+	//   https://github.com/ethereum/EIPs/pull/669
+	//   fake_block_number = min(0, block.number - 3_000_000
+	fakeBlockNumber := new(big.Int)
+	if parent.Number.Cmp(big2999999) >= 0 {
+		fakeBlockNumber = fakeBlockNumber.Sub(parent.Number, big2999999) // Note, parent is 1 less than the actual block number
+	}
 	// for the exponential factor
-	periodCount := new(big.Int).Add(parent.Number, big1)
+	periodCount := fakeBlockNumber
 	periodCount.Div(periodCount, expDiffPeriod)
 
 	// the exponential factor, commonly referred to as "the bomb"
@@ -501,7 +510,7 @@ func (ethash *Ethash) Prepare(chain consensus.ChainReader, header *types.Header)
 // setting the final state and assembling the block.
 func (ethash *Ethash) Finalize(chain consensus.ChainReader, header *types.Header, state *state.StateDB, txs []*types.Transaction, uncles []*types.Header, receipts []*types.Receipt) (*types.Block, error) {
 	// Accumulate any block and uncle rewards and commit the final state root
-	AccumulateRewards(state, header, uncles)
+	AccumulateRewards(chain.Config(), state, header, uncles)
 	header.Root = state.IntermediateRoot(chain.Config().IsEIP158(header.Number))
 
 	// Header seems complete, assemble into a block and return
@@ -518,7 +527,13 @@ var (
 // reward. The total reward consists of the static block reward and rewards for
 // included uncles. The coinbase of each uncle block is also rewarded.
 // TODO (karalabe): Move the chain maker into this package and make this private!
-func AccumulateRewards(state *state.StateDB, header *types.Header, uncles []*types.Header) {
+func AccumulateRewards(config *params.ChainConfig, state *state.StateDB, header *types.Header, uncles []*types.Header) {
+	// Select the correct block reward based on chain progression
+	blockReward := frontierBlockReward
+	if config.IsMetropolis(header.Number) {
+		blockReward = metropolisBlockReward
+	}
+	// Accumulate the rewards for the miner and any included uncles
 	reward := new(big.Int).Set(blockReward)
 	r := new(big.Int)
 	for _, uncle := range uncles {