Make difficulty consensus-polymorphic (part II)

A continuation of the original commit @ f8f3689

Author: Christos KK Loverdos

src/main/scala/io/iohk/ethereum/consensus/ConsensusConfig.scala

@@ -2,7 +2,7 @@ package io.iohk.ethereum.consensus
 
 import akka.util.ByteString
 import com.typesafe.config.{Config ⇒ TypesafeConfig}
-import io.iohk.ethereum.consensus.validators.std.StdBlockHeaderValidator
+import io.iohk.ethereum.consensus.validators.BlockHeaderValidator
 import io.iohk.ethereum.domain.Address
 import io.iohk.ethereum.nodebuilder.ShutdownHookBuilder
 import io.iohk.ethereum.utils.Logger
@@ -66,7 +66,7 @@ object ConsensusConfig extends Logger {
     val coinbase = Address(config.getString(Keys.Coinbase))
 
     val headerExtraData = ByteString(config.getString(Keys.HeaderExtraData).getBytes)
-      .take(StdBlockHeaderValidator.MaxExtraDataSize)
+      .take(BlockHeaderValidator.MaxExtraDataSize)
     val blockCacheSize = config.getInt(Keys.BlockCacheSize)
     val miningEnabled = config.getBoolean(Keys.MiningEnabled)
 

src/main/scala/io/iohk/ethereum/consensus/atomixraft/AtomixRaftConsensus.scala

@@ -17,9 +17,9 @@ import io.atomix.utils.concurrent.ThreadModel
 import io.atomix.utils.serializer.{KryoNamespace, Serializer}
 import io.iohk.ethereum.consensus.atomixraft.AtomixRaftForger.{IAmTheLeader, Init}
 import io.iohk.ethereum.consensus.atomixraft.blocks.AtomixRaftBlockGenerator
+import io.iohk.ethereum.consensus.atomixraft.validators.AtomixRaftValidators
 import io.iohk.ethereum.consensus.blocks.TestBlockGenerator
 import io.iohk.ethereum.consensus.validators.Validators
-import io.iohk.ethereum.consensus.validators.std.StdValidators
 import io.iohk.ethereum.domain.BlockchainImpl
 import io.iohk.ethereum.ledger.BlockPreparator
 import io.iohk.ethereum.ledger.Ledger.VMImpl
@@ -219,7 +219,7 @@ object AtomixRaftConsensus {
     config: FullConsensusConfig[AtomixRaftConfig]
   ): AtomixRaftConsensus = {
 
-    val validators = StdValidators(blockchainConfig)
+    val validators = AtomixRaftValidators(blockchainConfig)
 
     val blockPreparator = new BlockPreparator(
       vm = vm,

src/main/scala/io/iohk/ethereum/consensus/atomixraft/blocks/AtomixRaftBlockGenerator.scala

@@ -1,6 +1,7 @@
 package io.iohk.ethereum.consensus.atomixraft.blocks
 
 import io.iohk.ethereum.consensus.ConsensusConfig
+import io.iohk.ethereum.consensus.atomixraft.difficulty.AtomixRaftDifficulty
 import io.iohk.ethereum.consensus.blocks._
 import io.iohk.ethereum.domain._
 import io.iohk.ethereum.ledger.BlockPreparator
@@ -20,7 +21,7 @@ class AtomixRaftBlockGenerator(
   blockTimestampProvider
 ) {
 
-  protected def calculateDifficulty(blockNumber: BigInt, parent: Block, blockTimestamp: Long): BigInt = 0
+  protected val difficulty = AtomixRaftDifficulty
 
   def withBlockTimestampProvider(blockTimestampProvider: BlockTimestampProvider): AtomixRaftBlockGenerator =
     new AtomixRaftBlockGenerator(

src/main/scala/io/iohk/ethereum/consensus/atomixraft/difficulty/AtomixRaftDifficulty.scala

@@ -0,0 +1,5 @@
+package io.iohk.ethereum.consensus.atomixraft.difficulty
+
+import io.iohk.ethereum.consensus.difficulty.ConstantDifficulty
+
+object AtomixRaftDifficulty extends ConstantDifficulty(0)

src/main/scala/io/iohk/ethereum/consensus/atomixraft/validators/AtomixRaftBlockHeaderValidator.scala

@@ -0,0 +1,18 @@
+package io.iohk.ethereum.consensus.atomixraft.validators
+
+import io.iohk.ethereum.consensus.atomixraft.difficulty.AtomixRaftDifficulty
+import io.iohk.ethereum.consensus.difficulty.DifficultyCalculator
+import io.iohk.ethereum.consensus.validators.{BlockHeaderError, BlockHeaderValid, BlockHeaderValidatorSkeleton}
+import io.iohk.ethereum.domain.BlockHeader
+import io.iohk.ethereum.utils.BlockchainConfig
+
+class AtomixRaftBlockHeaderValidator(blockchainConfig: BlockchainConfig)
+  extends BlockHeaderValidatorSkeleton(blockchainConfig) {
+
+  protected def difficulty: DifficultyCalculator = AtomixRaftDifficulty
+
+  protected def validateEvenMore(
+    blockHeader: BlockHeader,
+    parentHeader: BlockHeader
+  ): Either[BlockHeaderError, BlockHeaderValid] = Right(BlockHeaderValid) // mo more than the standard validation
+}

src/main/scala/io/iohk/ethereum/consensus/atomixraft/validators/AtomixRaftValidators.scala

@@ -0,0 +1,15 @@
+package io.iohk.ethereum.consensus.atomixraft.validators
+
+import io.iohk.ethereum.consensus.validators.std.{StdBlockValidator, StdSignedTransactionValidator, StdValidators}
+import io.iohk.ethereum.utils.BlockchainConfig
+
+
+object AtomixRaftValidators {
+  def apply(blockchainConfig: BlockchainConfig): AtomixRaftValidators = {
+    new StdValidators(
+      StdBlockValidator,
+      new AtomixRaftBlockHeaderValidator(blockchainConfig),
+      new StdSignedTransactionValidator(blockchainConfig)
+    )
+  }
+}

src/main/scala/io/iohk/ethereum/consensus/atomixraft/validators/package.scala

@@ -0,0 +1,7 @@
+package io.iohk.ethereum.consensus.atomixraft
+
+import io.iohk.ethereum.consensus.validators.std.StdValidators
+
+package object validators {
+  final type AtomixRaftValidators = StdValidators
+}

src/main/scala/io/iohk/ethereum/consensus/blocks/BlockGeneratorSkeleton.scala

@@ -4,6 +4,7 @@ import java.util.concurrent.atomic.AtomicReference
 
 import akka.util.ByteString
 import io.iohk.ethereum.consensus.ConsensusConfig
+import io.iohk.ethereum.consensus.difficulty.DifficultyCalculator
 import io.iohk.ethereum.consensus.ethash.blocks.Ommers
 import io.iohk.ethereum.consensus.validators.std.MptListValidator.intByteArraySerializable
 import io.iohk.ethereum.crypto.kec256
@@ -42,7 +43,7 @@ abstract class BlockGeneratorSkeleton(
 
   protected def newBlockBody(transactions: Seq[SignedTransaction], x: X): BlockBody
 
-  protected def calculateDifficulty(blockNumber: BigInt, parent: Block, blockTimestamp: Long): BigInt
+  protected def difficulty: DifficultyCalculator
 
   protected def defaultPrepareHeader(
     blockNumber: BigInt,
@@ -60,7 +61,7 @@ abstract class BlockGeneratorSkeleton(
         transactionsRoot = ByteString.empty,
         receiptsRoot = ByteString.empty,
         logsBloom = ByteString.empty,
-        difficulty = calculateDifficulty(blockNumber, parent, blockTimestamp),
+        difficulty = difficulty.calculateDifficulty(blockNumber, blockTimestamp, parent.header),
         number = blockNumber,
         gasLimit = calculateGasLimit(parent.header.gasLimit),
         gasUsed = 0,

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

@@ -0,0 +1,8 @@
+package io.iohk.ethereum.consensus.difficulty
+
+import io.iohk.ethereum.domain.BlockHeader
+
+class ConstantDifficulty(c: BigInt) extends DifficultyCalculator {
+  final def calculateDifficulty(blockNumber: BigInt, blockTimestamp: Long, parentHeader: BlockHeader): BigInt = c
+}
+

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

@@ -0,0 +1,7 @@
+package io.iohk.ethereum.consensus.difficulty
+
+import io.iohk.ethereum.domain.BlockHeader
+
+trait DifficultyCalculator {
+  def calculateDifficulty(blockNumber: BigInt, blockTimestamp: Long, parentHeader: BlockHeader): BigInt
+}

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

@@ -8,7 +8,7 @@ import akka.actor.ActorRef
 import io.iohk.ethereum.consensus.blocks.TestBlockGenerator
 import io.iohk.ethereum.consensus.ethash.EthashMiner.MinerMsg
 import io.iohk.ethereum.consensus.ethash.blocks.{EthashBlockGenerator, EthashBlockGeneratorImpl}
-import io.iohk.ethereum.consensus.ethash.validators.{EthashValidators, StdEthashValidators}
+import io.iohk.ethereum.consensus.ethash.validators.EthashValidators
 import io.iohk.ethereum.consensus.validators.Validators
 import io.iohk.ethereum.domain.BlockchainImpl
 import io.iohk.ethereum.ledger.BlockPreparator
@@ -157,7 +157,7 @@ object EthashConsensus {
     config: FullConsensusConfig[EthashConfig]
   ): EthashConsensus = {
 
-    val validators = StdEthashValidators(blockchainConfig)
+    val validators = EthashValidators(blockchainConfig)
 
     val blockPreparator = new BlockPreparator(
       vm = vm,

src/main/scala/io/iohk/ethereum/consensus/ethash/blocks/EthashBlockGenerator.scala

@@ -5,6 +5,7 @@ import java.util.function.UnaryOperator
 import akka.util.ByteString
 import io.iohk.ethereum.consensus.ConsensusConfig
 import io.iohk.ethereum.consensus.blocks._
+import io.iohk.ethereum.consensus.ethash.difficulty.EthashDifficultyCalculator
 import io.iohk.ethereum.consensus.ethash.validators.EthashValidators
 import io.iohk.ethereum.crypto.kec256
 import io.iohk.ethereum.domain._
@@ -38,10 +39,7 @@ class EthashBlockGeneratorImpl(
   blockTimestampProvider
 ) with EthashBlockGenerator {
 
-  protected val difficulty = new DifficultyCalculator(blockchainConfig)
-
-  protected def calculateDifficulty(blockNumber: BigInt, parent: Block, blockTimestamp: Long): BigInt =
-    difficulty.calculateDifficulty(blockNumber, blockTimestamp, parent.header)
+  protected val difficulty = new EthashDifficultyCalculator(blockchainConfig)
 
   protected def newBlockBody(transactions: Seq[SignedTransaction], x: Ommers): BlockBody =
     BlockBody(transactions, x)

src/main/scala/io/iohk/ethereum/domain/DifficultyCalculator.scala renamed to src/main/scala/io/iohk/ethereum/consensus/ethash/difficulty/EthashDifficultyCalculator.scala

@@ -1,15 +1,17 @@
-package io.iohk.ethereum.domain
+package io.iohk.ethereum.consensus.ethash.difficulty
 
+import io.iohk.ethereum.consensus.difficulty.DifficultyCalculator
+import io.iohk.ethereum.domain.BlockHeader
 import io.iohk.ethereum.utils.BlockchainConfig
 
-class DifficultyCalculator(blockchainConfig: BlockchainConfig) {
+class EthashDifficultyCalculator(blockchainConfig: BlockchainConfig) extends DifficultyCalculator {
   val DifficultyBoundDivision: Int = 2048
   val FrontierTimestampDiffLimit: Int = -99
   val ExpDifficultyPeriod: Int = 100000
   val MinimumDifficulty: BigInt = 131072
 
   def calculateDifficulty(blockNumber: BigInt, blockTimestamp: Long, parentHeader: BlockHeader): BigInt = {
-    import blockchainConfig.{homesteadBlockNumber, difficultyBombPauseBlockNumber, difficultyBombContinueBlockNumber}
+    import blockchainConfig.{difficultyBombContinueBlockNumber, difficultyBombPauseBlockNumber, homesteadBlockNumber}
 
     val x: BigInt = parentHeader.difficulty / DifficultyBoundDivision
     val c: BigInt =

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

@@ -1,32 +1,28 @@
 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.HeaderPoWError
-import io.iohk.ethereum.consensus.validators.std.StdBlockHeaderValidator
-import io.iohk.ethereum.consensus.validators.std.StdBlockHeaderValidator.PowCacheData
-import io.iohk.ethereum.consensus.validators.{BlockHeaderError, BlockHeaderValid}
+import io.iohk.ethereum.consensus.validators.{BlockHeaderError, BlockHeaderValid, BlockHeaderValidatorSkeleton}
 import io.iohk.ethereum.crypto
 import io.iohk.ethereum.domain.BlockHeader
 import io.iohk.ethereum.utils.BlockchainConfig
 
 /**
  * A block header validator for Ethash.
  */
-class EthashBlockHeaderValidator(blockchainConfig: BlockchainConfig) extends StdBlockHeaderValidator(blockchainConfig) {
+class EthashBlockHeaderValidator(blockchainConfig: BlockchainConfig) extends BlockHeaderValidatorSkeleton(blockchainConfig) {
   import EthashBlockHeaderValidator._
 
-  /** This method allows validate a BlockHeader (stated on
-   * section 4.4.4 of http://paper.gavwood.com/).
-   *
-   * @param blockHeader BlockHeader to validate.
-   * @param parentHeader BlockHeader of the parent of the block to validate.
-   */
-  override def validate(blockHeader: BlockHeader, parentHeader: BlockHeader): Either[BlockHeaderError, BlockHeaderValid] = {
-    for {
-      _ ← super.validate(blockHeader, parentHeader)
-      _ ← validatePoW(blockHeader)
-    } yield BlockHeaderValid
-  }
+  // NOTE the below comment is from before PoW decoupling
+  // 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)
+
+  def validateEvenMore(blockHeader: BlockHeader, parentHeader: BlockHeader): Either[BlockHeaderError, BlockHeaderValid] =
+    validatePoW(blockHeader)
 
   /**
    * Validates [[io.iohk.ethereum.domain.BlockHeader.nonce]] and [[io.iohk.ethereum.domain.BlockHeader.mixHash]] are correct
@@ -72,6 +68,8 @@ class EthashBlockHeaderValidator(blockchainConfig: BlockchainConfig) extends Std
 object EthashBlockHeaderValidator {
   final val MaxPowCaches: Int = 2 // maximum number of epochs for which PoW cache is stored in memory
 
+  class PowCacheData(val cache: Array[Int], val dagSize: Long)
+
   // NOTE The below is from before PoW decoupling.
   // FIXME [EC-331]: this is used to speed up ETS Blockchain tests. All blocks in those tests have low numbers (1, 2, 3 ...)
   // so keeping the cache for epoch 0 avoids recalculating it for each individual test. The difference in test runtime

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

@@ -3,10 +3,11 @@ package ethash.validators
 
 import akka.util.ByteString
 import io.iohk.ethereum.consensus.validators.Validators
-import io.iohk.ethereum.consensus.validators.std.StdValidators
+import io.iohk.ethereum.consensus.validators.std.{StdBlockValidator, StdSignedTransactionValidator, StdValidators}
 import io.iohk.ethereum.domain.{Block, Receipt}
 import io.iohk.ethereum.ledger.BlockExecutionError.ValidationBeforeExecError
 import io.iohk.ethereum.ledger.{BlockExecutionError, BlockExecutionSuccess}
+import io.iohk.ethereum.utils.BlockchainConfig
 
 trait EthashValidators extends Validators {
   def ommersValidator: OmmersValidator
@@ -43,6 +44,17 @@ trait EthashValidators extends Validators {
 }
 
 object EthashValidators {
+  def apply(blockchainConfig: BlockchainConfig): EthashValidators = {
+    val blockHeaderValidator = new EthashBlockHeaderValidator(blockchainConfig)
+
+    new StdEthashValidators(
+      StdBlockValidator,
+      blockHeaderValidator,
+      new StdSignedTransactionValidator(blockchainConfig),
+      new StdOmmersValidator(blockchainConfig, blockHeaderValidator)
+    )
+  }
+
   def validateBlockBeforeExecution(
     self: EthashValidators,
     block: Block,

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

@@ -1,25 +1,15 @@
 package io.iohk.ethereum.consensus.ethash.validators
 
-import io.iohk.ethereum.consensus.validators.std.{StdBlockValidator, StdSignedTransactionValidator}
 import io.iohk.ethereum.consensus.validators.{BlockValidator, SignedTransactionValidator}
-import io.iohk.ethereum.utils.BlockchainConfig
 
-class StdEthashValidators(
+/**
+ * Implements validators that adhere to the PoW-specific
+ * [[io.iohk.ethereum.consensus.ethash.validators.EthashValidators EthashValidators]]
+ * interface.
+ */
+final class StdEthashValidators private[validators](
   val blockValidator: BlockValidator,
   val blockHeaderValidator: EthashBlockHeaderValidator,
   val signedTransactionValidator: SignedTransactionValidator,
   val ommersValidator: OmmersValidator
 ) extends EthashValidators
-
-object StdEthashValidators {
-  def apply(blockchainConfig: BlockchainConfig): StdEthashValidators = {
-    val blockHeaderValidator = new EthashBlockHeaderValidator(blockchainConfig)
-
-    new StdEthashValidators(
-      StdBlockValidator,
-      blockHeaderValidator,
-      new StdSignedTransactionValidator(blockchainConfig),
-      new StdOmmersValidator(blockchainConfig, blockHeaderValidator)
-    )
-  }
-}

src/main/scala/io/iohk/ethereum/consensus/validators/BlockHeaderValidator.scala

@@ -13,6 +13,13 @@ trait BlockHeaderValidator {
   ): Either[BlockHeaderError, BlockHeaderValid]
 }
 
+object BlockHeaderValidator {
+  val MaxExtraDataSize: Int = 32
+  val GasLimitBoundDivisor: Int = 1024
+  val MinGasLimit: BigInt = 5000 //Although the paper states this value is 125000, on the different clients 5000 is used
+  val MaxGasLimit: Long = Long.MaxValue // max gasLimit is equal 2^63-1 according to EIP106
+}
+
 sealed trait BlockHeaderError
 
 object BlockHeaderError {