etcm-193 added possibility to configure target PoW time

src/ets/scala/io/iohk/ethereum/ets/blockchain/EthashTestBlockHeaderValidator.scala

@@ -1,7 +1,6 @@
 package io.iohk.ethereum.ets.blockchain
 
 import io.iohk.ethereum.consensus.difficulty.DifficultyCalculator
-import io.iohk.ethereum.consensus.ethash.difficulty.EthashDifficultyCalculator
 import io.iohk.ethereum.consensus.ethash.validators.EthashBlockHeaderValidator
 import io.iohk.ethereum.consensus.validators.{ BlockHeaderError, BlockHeaderValid, BlockHeaderValidatorSkeleton }
 import io.iohk.ethereum.domain.BlockHeader
@@ -14,7 +13,7 @@ class EthashTestBlockHeaderValidator(blockchainConfig: BlockchainConfig) extends
   // we need concurrent map since validators can be used from multiple places
   protected val powCaches: java.util.concurrent.ConcurrentMap[Long, PowCacheData] = new java.util.concurrent.ConcurrentHashMap[Long, PowCacheData]()
 
-  protected def difficulty: DifficultyCalculator = new EthashDifficultyCalculator(blockchainConfig)
+  protected def difficulty: DifficultyCalculator = DifficultyCalculator(blockchainConfig)
 
   def validateEvenMore(blockHeader: BlockHeader, parentHeader: BlockHeader): Either[BlockHeaderError, BlockHeaderValid] =
     Right(BlockHeaderValid)

src/main/resources/chains/etc-chain.conf

@@ -3,6 +3,10 @@
   # 1 - mainnet, 3 - ropsten, 7 - mordor
   network-id = 1
 
+  # Possibility to set Proof of Work target time for testing purposes.
+  # null means that the standard difficulty calculation rules are used
+  pow-target-time = null
+
   # Frontier block number
   frontier-block-number = "0"
 

src/main/resources/chains/eth-chain.conf

@@ -3,6 +3,10 @@
   # 1 - mainnet, 3 - ropsten, 7 - mordor
   network-id = 1
 
+  # Possibility to set Proof of Work target time for testing purposes.
+  # null means that the standard difficulty calculation rules are used
+  pow-target-time = null
+
   # Frontier block number
   frontier-block-number = "0"
 

src/main/resources/chains/mordor-chain.conf

@@ -3,6 +3,10 @@
   # 1 - mainnet, 3 - ropsten, 7 - mordor
   network-id = 7
 
+  # Possibility to set Proof of Work target time for testing purposes.
+  # null means that the standard difficulty calculation rules are used
+  pow-target-time = null
+
   # Frontier block number
   frontier-block-number = "0"
 

src/main/resources/chains/ropsten-chain.conf

@@ -3,6 +3,10 @@
   # 1 - mainnet, 3 - ropsten, 7 - mordor
   network-id = 3
 
+  # Possibility to set Proof of Work target time for testing purposes.
+  # null means that the standard difficulty calculation rules are used
+  pow-target-time = null
+
   # Frontier block number
   frontier-block-number = "0"
 

src/main/resources/chains/test-chain.conf

@@ -3,6 +3,10 @@
   # 1 - mainnet, 7 - mordor
   network-id = 1
 
+  # Possibility to set Proof of Work target time for testing purposes.
+  # null means that the standard difficulty calculation rules are used
+  pow-target-time = null
+
   # Frontier block number
   frontier-block-number = "0"
 

src/main/resources/chains/testnet-internal-chain.conf

@@ -3,6 +3,10 @@
     # 1 - mainnet, 3 - ropsten, 7 - mordor
     network-id = 42
 
+    # Possibility to set Proof of Work target time for testing purposes.
+    # null means that the standard difficulty calculation rules are used
+    pow-target-time = null
+
     # Frontier block number
     frontier-block-number = "0"
 

src/main/scala/io/iohk/ethereum/consensus/difficulty/DifficultyCalculator.scala

@@ -1,7 +1,22 @@
 package io.iohk.ethereum.consensus.difficulty
 
+import io.iohk.ethereum.consensus.ethash.difficulty.{TargetTimeDifficultyCalculator, EthashDifficultyCalculator}
 import io.iohk.ethereum.domain.BlockHeader
+import io.iohk.ethereum.utils.BlockchainConfig
 
 trait DifficultyCalculator {
   def calculateDifficulty(blockNumber: BigInt, blockTimestamp: Long, parent: BlockHeader): BigInt
 }
+
+object DifficultyCalculator {
+  def apply(blockchainConfig: BlockchainConfig): DifficultyCalculator = {
+    blockchainConfig.powTargetTime match {
+      case Some(targetTime) => new TargetTimeDifficultyCalculator(targetTime)
+      case None => new EthashDifficultyCalculator(blockchainConfig)
+    }
+  }
+
+  val DifficultyBoundDivision: Int = 2048
+  val FrontierTimestampDiffLimit: Int = -99
+  val MinimumDifficulty: BigInt = 131072
+}

src/main/scala/io/iohk/ethereum/consensus/ethash/EthashConsensus.scala

@@ -2,10 +2,13 @@ package io.iohk.ethereum
 package consensus
 package ethash
 
+import java.util.concurrent.atomic.AtomicReference
+
 import akka.actor.ActorRef
 import akka.util.Timeout
 import io.iohk.ethereum.consensus.Protocol.{Ethash, MockedPow}
 import io.iohk.ethereum.consensus.blocks.TestBlockGenerator
+import io.iohk.ethereum.consensus.difficulty.DifficultyCalculator
 import io.iohk.ethereum.consensus.ethash.MinerResponses.MinerNotExist
 import io.iohk.ethereum.consensus.ethash.blocks.{EthashBlockGenerator, EthashBlockGeneratorImpl}
 import io.iohk.ethereum.consensus.ethash.validators.ValidatorsExecutor
@@ -15,9 +18,6 @@ import io.iohk.ethereum.ledger.BlockPreparator
 import io.iohk.ethereum.ledger.Ledger.VMImpl
 import io.iohk.ethereum.nodebuilder.Node
 import io.iohk.ethereum.utils.{BlockchainConfig, Logger}
-import java.util.concurrent.atomic.AtomicReference
-
-import io.iohk.ethereum.consensus.ethash.difficulty.EthashDifficultyCalculator
 
 import scala.concurrent.Future
 import scala.concurrent.duration._
@@ -32,7 +32,7 @@ class EthashConsensus private (
     val config: FullConsensusConfig[EthashConfig],
     val validators: ValidatorsExecutor,
     val blockGenerator: EthashBlockGenerator,
-    val difficultyCalculator: EthashDifficultyCalculator
+    val difficultyCalculator: DifficultyCalculator
 ) extends TestConsensus
     with Logger {
 
@@ -178,7 +178,7 @@ object EthashConsensus {
       validators: ValidatorsExecutor
   ): EthashConsensus = {
 
-    val difficultyCalculator = new EthashDifficultyCalculator(blockchainConfig)
+    val difficultyCalculator = DifficultyCalculator(blockchainConfig)
 
     val blockPreparator = new BlockPreparator(
       vm = vm,

src/main/scala/io/iohk/ethereum/consensus/ethash/difficulty/EthashDifficultyCalculator.scala

@@ -6,13 +6,11 @@ import io.iohk.ethereum.utils.BlockchainConfig
 
 class EthashDifficultyCalculator(blockchainConfig: BlockchainConfig) extends DifficultyCalculator {
   import blockchainConfig._
+  import DifficultyCalculator._
 
-  val DifficultyBoundDivision: Int = 2048
-  val FrontierTimestampDiffLimit: Int = -99
-  val ExpDifficultyPeriod: Int = 100000
-  val MinimumDifficulty: BigInt = 131072
-  val ByzantiumRelaxDifficulty: BigInt = 3000000
-  val ConstantinopleRelaxDifficulty: BigInt = 5000000
+  private val ExpDifficultyPeriod: Int = 100000
+  private val ByzantiumRelaxDifficulty: BigInt = 3000000
+  private val ConstantinopleRelaxDifficulty: BigInt = 5000000
 
   def calculateDifficulty(blockNumber: BigInt, blockTimestamp: Long, parentHeader: BlockHeader): BigInt = {
     lazy val timestampDiff = blockTimestamp - parentHeader.unixTimestamp

src/main/scala/io/iohk/ethereum/consensus/ethash/difficulty/TargetTimeDifficultyCalculator.scala

@@ -0,0 +1,34 @@
+package io.iohk.ethereum.consensus.ethash.difficulty
+
+import io.iohk.ethereum.consensus.difficulty.DifficultyCalculator
+import io.iohk.ethereum.domain.BlockHeader
+
+class TargetTimeDifficultyCalculator(powTargetTime: Long) extends DifficultyCalculator {
+
+  import DifficultyCalculator._
+
+  /**
+    * The lowerBoundExpectedRatio (l for abbreviation below) divides the timestamp diff into ranges:
+    *   [0, l)   => c = 1, difficulty increases
+    *   [l, 2*l) => c = 0. difficulty stays the same
+    *   ...
+    *   [l*i, l*(i+1) ) => c = 1-i, difficulty decreases
+    *
+    *  example:
+    *  powTargetTime := 45 seconds
+    *  l := 30 seconds
+    *   [0, 0.5 min)         => difficulty increases
+    *   [0.5 min, 1 min)   => difficulty stays the same (the average should be powTargetTime)
+    *   [1 min, +infinity) => difficulty decreases
+    */
+  private val lowerBoundExpectedRatio: Long = (powTargetTime / 1.5).toLong
+
+  def calculateDifficulty(blockNumber: BigInt, blockTimestamp: Long, parentHeader: BlockHeader): BigInt = {
+    val timestampDiff = blockTimestamp - parentHeader.unixTimestamp
+
+    val x: BigInt = parentHeader.difficulty / DifficultyBoundDivision
+    val c: BigInt = math.max(1 - (timestampDiff / lowerBoundExpectedRatio), FrontierTimestampDiffLimit)
+
+    MinimumDifficulty.max(parentHeader.difficulty + x * c)
+  }
+}

src/main/scala/io/iohk/ethereum/consensus/ethash/validators/EthashBlockHeaderValidator.scala

@@ -3,7 +3,6 @@ package validators
 
 import akka.util.ByteString
 import io.iohk.ethereum.consensus.difficulty.DifficultyCalculator
-import io.iohk.ethereum.consensus.ethash.difficulty.EthashDifficultyCalculator
 import io.iohk.ethereum.consensus.validators.BlockHeaderError.HeaderPoWError
 import io.iohk.ethereum.consensus.validators.{BlockHeaderError, BlockHeaderValid, BlockHeaderValidatorSkeleton}
 import io.iohk.ethereum.crypto
@@ -22,7 +21,7 @@ class EthashBlockHeaderValidator(blockchainConfig: BlockchainConfig)
   // we need atomic since validators can be used from multiple places
   protected val powCaches: AtomicAny[List[PowCacheData]] = Atomic(List.empty[PowCacheData])
 
-  protected def difficulty: DifficultyCalculator = new EthashDifficultyCalculator(blockchainConfig)
+  protected def difficulty: DifficultyCalculator = DifficultyCalculator(blockchainConfig)
 
   def validateEvenMore(
       blockHeader: BlockHeader,

src/main/scala/io/iohk/ethereum/consensus/ethash/validators/MockedPowBlockHeaderValidator.scala

@@ -2,15 +2,14 @@ package io.iohk.ethereum.consensus.ethash
 package validators
 
 import io.iohk.ethereum.consensus.difficulty.DifficultyCalculator
-import io.iohk.ethereum.consensus.ethash.difficulty.EthashDifficultyCalculator
 import io.iohk.ethereum.consensus.validators.{BlockHeaderError, BlockHeaderValid, BlockHeaderValidatorSkeleton}
 import io.iohk.ethereum.domain.BlockHeader
 import io.iohk.ethereum.utils.BlockchainConfig
 
 class MockedPowBlockHeaderValidator(blockchainConfig: BlockchainConfig)
     extends BlockHeaderValidatorSkeleton(blockchainConfig) {
 
-  protected def difficulty: DifficultyCalculator = new EthashDifficultyCalculator(blockchainConfig)
+  protected def difficulty: DifficultyCalculator = DifficultyCalculator(blockchainConfig)
 
   def validateEvenMore(
       blockHeader: BlockHeader,

src/main/scala/io/iohk/ethereum/testmode/TestmodeConsensus.scala

@@ -5,7 +5,6 @@ import io.iohk.ethereum.consensus._
 import io.iohk.ethereum.consensus.blocks.{BlockTimestampProvider, NoOmmersBlockGenerator, TestBlockGenerator}
 import io.iohk.ethereum.consensus.difficulty.DifficultyCalculator
 import io.iohk.ethereum.consensus.ethash.MinerResponses.MinerNotExist
-import io.iohk.ethereum.consensus.ethash.difficulty.EthashDifficultyCalculator
 import io.iohk.ethereum.consensus.ethash.{MinerProtocol, MinerResponse}
 import io.iohk.ethereum.consensus.validators._
 import io.iohk.ethereum.consensus.validators.std.{StdBlockValidator, StdSignedTransactionValidator}
@@ -99,6 +98,6 @@ trait TestmodeConsensusBuilder extends ConsensusBuilder {
     blockchain,
     blockchainConfig,
     consensusConfig,
-    new EthashDifficultyCalculator(blockchainConfig)
+    DifficultyCalculator(blockchainConfig)
   )
 }

src/main/scala/io/iohk/ethereum/utils/BlockchainConfig.scala

@@ -1,15 +1,15 @@
 package io.iohk.ethereum.utils
 
 import akka.util.ByteString
+import com.typesafe.config.{Config => TypesafeConfig}
 import io.iohk.ethereum.domain.{Address, UInt256}
 import io.iohk.ethereum.utils.NumericUtils._
 
 import scala.collection.JavaConverters._
-import com.typesafe.config.{Config => TypesafeConfig}
-
 import scala.util.Try
 
 case class BlockchainConfig(
+    powTargetTime: Option[Long] = None,
     frontierBlockNumber: BigInt,
     homesteadBlockNumber: BigInt,
     eip106BlockNumber: BigInt,
@@ -50,6 +50,9 @@ object BlockchainConfig {
 
   // scalastyle:off method.length
   def fromRawConfig(blockchainConfig: TypesafeConfig): BlockchainConfig = {
+    val powTargetTime: Option[Long] =
+      ConfigUtils
+        .getOptionalValue(blockchainConfig, "pow-target-time", _.getDuration("pow-target-time").getSeconds)
     val frontierBlockNumber: BigInt = BigInt(blockchainConfig.getString("frontier-block-number"))
     val homesteadBlockNumber: BigInt = BigInt(blockchainConfig.getString("homestead-block-number"))
     val eip106BlockNumber: BigInt = BigInt(blockchainConfig.getString("eip106-block-number"))
@@ -105,6 +108,7 @@ object BlockchainConfig {
     val ecip1099BlockNumber: BigInt = BigInt(blockchainConfig.getString("ecip1099-block-number"))
 
     BlockchainConfig(
+      powTargetTime = powTargetTime,
       frontierBlockNumber = frontierBlockNumber,
       homesteadBlockNumber = homesteadBlockNumber,
       eip106BlockNumber = eip106BlockNumber,

src/test/resources/application.conf

@@ -22,6 +22,7 @@ mantis {
     network = "test"
 
     test {
+      pow-target-time = null
       frontier-block-number = "0"
       eip106-block-number = "1000000000000000000"
       eip150-block-number = "2463000"