io.iohk.metronome.checkpointing.models.Ledger.scala Maven / Gradle / Ivy

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Checkpointing domain models, including the checkpoint certificate and its validation logic.

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package io.iohk.metronome.checkpointing.models

/** Current state of the ledger after applying all previous blocks.
  *
  * Basically it's the last checkpoint, plus any accumulated proposer blocks
  * since then. Initially the last checkpoint is empty; conceptually it could
  * be the genesis block of the PoW chain, but we don't know what that is
  * until we talk to the interpreter, and we also can't produce it on our
  * own since it's opaque data.
  */
case class Ledger(
    maybeLastCheckpoint: Option[Transaction.CheckpointCandidate],
    proposerBlocks: IndexedSeq[Transaction.ProposerBlock]
) extends RLPHash[Ledger, Ledger.Hash] {

  /** Apply a validated transaction to produce the next ledger state.
    *
    * The transaction should have been validated against the PoW ledger
    * by this point, so we know for example that the new checkpoint is
    * a valid extension of the previous one.
    */
  def update(transaction: Transaction): Ledger =
    transaction match {
      case t @ Transaction.ProposerBlock(_) =>
        if (proposerBlocks.contains(t))
          this
        else
          copy(proposerBlocks = proposerBlocks :+ t)

      case t @ Transaction.CheckpointCandidate(_) =>
        Ledger(Some(t), Vector.empty)
    }

  def update(transactions: Iterable[Transaction]): Ledger =
    transactions.foldLeft(this)(_ update _)
}

object Ledger extends RLPHashCompanion[Ledger]()(RLPCodecs.rlpLedger) {
  val empty = Ledger(None, Vector.empty)
}