nimbus-eth1/nimbus/core/sealer.nim

# Nimbus
# Copyright (c) 2018-2023 Status Research & Development GmbH
# Licensed under either of
#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE))
#  * MIT license ([LICENSE-MIT](LICENSE-MIT))
# at your option.
# This file may not be copied, modified, or distributed except according to
# those terms.

import
  pkg/[chronos,
    stew/results,
    chronicles,
    eth/keys],
  ".."/[config,
    constants],
  "."/[
    chain,
    tx_pool,
    validate],
  "."/clique/[
    clique_desc,
    clique_cfg,
    clique_sealer],
  ../utils/utils,
  ../common/[common, context]

type
  EngineState* = enum
    EngineStopped,
    EngineRunning,
    EnginePostMerge

  SealingEngineRef* = ref SealingEngineObj
  SealingEngineObj = object of RootObj
    state: EngineState
    engineLoop: Future[void]
    chain*: ChainRef
    ctx: EthContext
    signer: EthAddress
    txPool: TxPoolRef

proc validateSealer*(conf: NimbusConf, ctx: EthContext, chain: ChainRef): Result[void, string] =
  if conf.engineSigner == ZERO_ADDRESS:
    return err("signer address should not zero, use --engine-signer to set signer address")

  let res = ctx.am.getAccount(conf.engineSigner)
  if res.isErr:
    return err("signer address not in registered accounts, use --import-key/account to register the account")

  let acc = res.get()
  if not acc.unlocked:
    return err("signer account not unlocked, please unlock it first via rpc/password file")

  let com = chain.com
  if com.consensus != ConsensusType.POA:
    return err("currently only PoA engine is supported")

  ok()

proc generateBlock(engine: SealingEngineRef,
                   outBlock: var EthBlock): Result[void, string] =

  outBlock = engine.txPool.assembleBlock().valueOr:
    return err(error)

  if engine.chain.com.consensus == ConsensusType.POS:
    # Stop the block generator if we reach TTD
    engine.state = EnginePostMerge

  if engine.state != EnginePostMerge:
    # Post merge, Clique should not be executing
    let sealRes = engine.chain.clique.seal(outBlock)
    if sealRes.isErr:
      return err("error sealing block header: " & $sealRes.error)

  debug "generated block",
        blockNumber = outBlock.header.blockNumber,
        blockHash = blockHash(outBlock.header)

  ok()

proc sealingLoop(engine: SealingEngineRef): Future[void] {.async.} =
  let clique = engine.chain.clique

  proc signerFunc(signer: EthAddress, message: openArray[byte]):
                  Result[RawSignature, cstring] {.gcsafe.} =
    let
      hashData = keccakHash(message)
      ctx      = engine.ctx
      acc      = ctx.am.getAccount(signer).tryGet()
      rawSign  = sign(acc.privateKey, SkMessage(hashData.data)).toRaw

    ok(rawSign)

  clique.authorize(engine.signer, signerFunc)

  # convert times.Duration to chronos.Duration
  let period = chronos.seconds(clique.cfg.period.int64)

  while engine.state == EngineRunning:
    # the sealing engine will tick every `cliquePeriod` seconds
    await sleepAsync(period)

    if engine.state != EngineRunning:
      break

    # deviation from 'correct' sealing engine:
    # - no queue for chain reorgs
    # - no async lock/guard against race with sync algo
    var blk: EthBlock
    let blkRes = engine.generateBlock(blk)
    if blkRes.isErr:
      error "sealing engine generateBlock error", msg=blkRes.error
      break

    let res = engine.chain.persistBlocks([blk.header], [
      BlockBody(transactions: blk.txs, uncles: blk.uncles)
    ])

    if res == ValidationResult.Error:
      error "sealing engine: persistBlocks error"
      break

    discard engine.txPool.smartHead(blk.header) # add transactions update jobs
    info "block generated", number=blk.header.blockNumber

proc new*(_: type SealingEngineRef,
          chain: ChainRef,
          ctx: EthContext,
          signer: EthAddress,
          txPool: TxPoolRef,
          initialState: EngineState): SealingEngineRef =
  SealingEngineRef(
    chain: chain,
    ctx: ctx,
    signer: signer,
    txPool: txPool,
    state: initialState
  )

proc start*(engine: SealingEngineRef) =
  ## Starts sealing engine.
  if engine.state == EngineStopped:
    engine.state = EngineRunning
    engine.engineLoop = sealingLoop(engine)
    info "sealing engine started"

proc stop*(engine: SealingEngineRef) {.async.} =
  ## Stop sealing engine from producing more blocks.
  if engine.state == EngineRunning:
    engine.state = EngineStopped
    await engine.engineLoop.cancelAndWait()
    info "sealing engine stopped"