nimbus-eth1/nimbus/sync/snap/worker.nim

# Nimbus
# Copyright (c) 2021 Status Research & Development GmbH
# Licensed under either of
#  * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
#    http://www.apache.org/licenses/LICENSE-2.0)
#  * MIT license ([LICENSE-MIT](LICENSE-MIT) or
#    http://opensource.org/licenses/MIT)
# at your option. This file may not be copied, modified, or distributed
# except according to those terms.

import
  std/[hashes, math, options, sets, strutils],
  chronicles,
  chronos,
  eth/[common/eth_types, p2p],
  stew/[interval_set, keyed_queue],
  ../../db/select_backend,
  ".."/[handlers, misc/best_pivot, protocol, sync_desc],
  ./worker/[heal_accounts, heal_storage_slots,
            range_fetch_accounts, range_fetch_storage_slots, ticker],
  ./worker/com/com_error,
  ./worker/db/snapdb_desc,
  "."/[range_desc, worker_desc]

{.push raises: [Defect].}

logScope:
  topics = "snap-sync"

const
  extraTraceMessages = false or true
    ## Enabled additional logging noise

# ------------------------------------------------------------------------------
# Private helpers
# ------------------------------------------------------------------------------

proc meanStdDev(sum, sqSum: float; length: int): (float,float) =
  if 0 < length:
    result[0] = sum / length.float
    result[1] = sqrt(sqSum / length.float - result[0] * result[0])

template noExceptionOops(info: static[string]; code: untyped) =
  try:
    code
  except CatchableError as e:
    raiseAssert "Inconveivable (" & info & ": name=" & $e.name & " msg=" & e.msg
  except Defect as e:
    raise e
  except Exception as e:
    raiseAssert "Ooops " & info & ": name=" & $e.name & " msg=" & e.msg

# ------------------------------------------------------------------------------
# Private helpers: integration of pivot finder
# ------------------------------------------------------------------------------

proc pivot(ctx: SnapCtxRef): BestPivotCtxRef =
  # Getter
  ctx.data.pivotFinderCtx.BestPivotCtxRef

proc `pivot=`(ctx: SnapCtxRef; val: BestPivotCtxRef) =
  # Setter
  ctx.data.pivotFinderCtx = val

proc pivot(buddy: SnapBuddyRef): BestPivotWorkerRef =
  # Getter
  buddy.data.pivotFinder.BestPivotWorkerRef

proc `pivot=`(buddy: SnapBuddyRef; val: BestPivotWorkerRef) =
  # Setter
  buddy.data.pivotFinder = val

# ------------------------------------------------------------------------------
# Private functions
# ------------------------------------------------------------------------------

proc init(batch: var SnapTrieRangeBatch; ctx: SnapCtxRef) =
  ## Returns a pair of account hash range lists with the full range of hashes
  ## smartly spread across the mutually disjunct interval sets.
  for n in 0 ..< batch.unprocessed.len:
    batch.unprocessed[n] = NodeTagRangeSet.init()

  # Initialise accounts range fetch batch, the pair of `fetchAccounts[]`
  # range sets.
  if ctx.data.coveredAccounts.total == 0 and
     ctx.data.coveredAccounts.chunks == 1:
    # All (i.e. 100%) of accounts hashes are covered by completed range fetch
    # processes for all pivot environments. Do a random split distributing the
    # full accounts hash range across the pair of range sats.
    var nodeKey: NodeKey
    ctx.data.rng[].generate(nodeKey.ByteArray32)

    let partition = nodeKey.to(NodeTag)
    discard batch.unprocessed[0].merge(partition, high(NodeTag))
    if low(NodeTag) < partition:
      discard batch.unprocessed[1].merge(low(NodeTag), partition - 1.u256)
  else:
    # Not all account hashes are covered, yet. So keep the uncovered
    # account hashes in the first range set, and the other account hashes
    # in the second range set.

    # Pre-filled with the first range set with largest possible interval
    discard batch.unprocessed[0].merge(low(NodeTag),high(NodeTag))

    # Move covered account ranges (aka intervals) to the second set.
    for iv in ctx.data.coveredAccounts.increasing:
      discard batch.unprocessed[0].reduce(iv)
      discard batch.unprocessed[1].merge(iv)


proc appendPivotEnv(buddy: SnapBuddyRef; header: BlockHeader) =
  ## Activate environment for state root implied by `header` argument. This
  ## function appends a new environment unless there was any not far enough
  ## apart.
  ##
  ## Note that this function relies on a queue sorted by the block numbers of
  ## the pivot header. To maintain the sort order, the function `lruFetch()`
  ## must not be called and only records appended with increasing block
  ## numbers.
  let
    ctx = buddy.ctx
    minNumber = block:
      let rc = ctx.data.pivotTable.lastValue
      if rc.isOk: rc.value.stateHeader.blockNumber + minPivotBlockDistance
      else: 1.toBlockNumber

  # Check whether the new header follows minimum depth requirement. This is
  # where the queue is assumed to have increasing block numbers.
  if minNumber <= header.blockNumber:
    # Ok, append a new environment
    let env = SnapPivotRef(stateHeader: header)
    env.fetchAccounts.init(ctx)

    # Append per-state root environment to LRU queue
    discard ctx.data.pivotTable.lruAppend(header.stateRoot, env, ctx.buddiesMax)


proc updateSinglePivot(buddy: SnapBuddyRef): Future[bool] {.async.} =
  ## Helper, negotiate pivot unless present
  if buddy.pivot.pivotHeader.isOk:
    return true

  let
    ctx = buddy.ctx
    peer = buddy.peer
    env = ctx.data.pivotTable.lastValue.get(otherwise = nil)
    nMin = if env.isNil: none(BlockNumber)
           else: some(env.stateHeader.blockNumber)

  if await buddy.pivot.pivotNegotiate(nMin):
    var header = buddy.pivot.pivotHeader.value

    # Check whether there is no environment change needed
    when noPivotEnvChangeIfComplete:
      let rc = ctx.data.pivotTable.lastValue
      if rc.isOk and rc.value.serialSync:
        # No neede to change
        if extraTraceMessages:
          trace "No need to change snap pivot", peer,
            pivot=("#" & $rc.value.stateHeader.blockNumber),
            multiOk=buddy.ctrl.multiOk, runState=buddy.ctrl.state
        return true

    buddy.appendPivotEnv(header)

    trace "Snap pivot initialised", peer, pivot=("#" & $header.blockNumber),
      multiOk=buddy.ctrl.multiOk, runState=buddy.ctrl.state

    return true


proc tickerUpdate*(ctx: SnapCtxRef): TickerStatsUpdater =
  result = proc: TickerStats =
    var
      aSum, aSqSum, uSum, uSqSum, sSum, sSqSum: float
      count = 0
    for kvp in ctx.data.pivotTable.nextPairs:

      # Accounts mean & variance
      let aLen = kvp.data.nAccounts.float
      if 0 < aLen:
        count.inc
        aSum += aLen
        aSqSum += aLen * aLen

        # Fill utilisation mean & variance
        let fill = kvp.data.fetchAccounts.unprocessed.emptyFactor
        uSum += fill
        uSqSum += fill * fill

        let sLen = kvp.data.nSlotLists.float
        sSum += sLen
        sSqSum += sLen * sLen

    let
      env = ctx.data.pivotTable.lastValue.get(otherwise = nil)
      pivotBlock = if env.isNil: none(BlockNumber)
                   else: some(env.stateHeader.blockNumber)
      stoQuLen = if env.isNil: none(uint64)
                 else: some(env.fetchStorage.len.uint64)
      accCoverage = ctx.data.coveredAccounts.fullFactor
      accFill = meanStdDev(uSum, uSqSum, count)

    TickerStats(
      pivotBlock:    pivotBlock,
      nQueues:       ctx.data.pivotTable.len,
      nAccounts:     meanStdDev(aSum, aSqSum, count),
      nSlotLists:    meanStdDev(sSum, sSqSum, count),
      accountsFill:  (accFill[0], accFill[1], accCoverage),
      nStorageQueue: stoQuLen)

# ------------------------------------------------------------------------------
# Public start/stop and admin functions
# ------------------------------------------------------------------------------

proc setup*(ctx: SnapCtxRef; tickerOK: bool): bool =
  ## Global set up
  noExceptionOops("worker.setup()"):
    ctx.ethWireCtx.poolEnabled(false)
  ctx.data.coveredAccounts = NodeTagRangeSet.init()
  ctx.data.snapDb =
    if ctx.data.dbBackend.isNil: SnapDbRef.init(ctx.chain.db.db)
    else: SnapDbRef.init(ctx.data.dbBackend)
  ctx.pivot = BestPivotCtxRef.init(ctx.data.rng)
  if tickerOK:
    ctx.data.ticker = TickerRef.init(ctx.tickerUpdate)
  else:
    trace "Ticker is disabled"
  result = true

proc release*(ctx: SnapCtxRef) =
  ## Global clean up
  ctx.pivot = nil
  if not ctx.data.ticker.isNil:
    ctx.data.ticker.stop()
    ctx.data.ticker = nil

proc start*(buddy: SnapBuddyRef): bool =
  ## Initialise worker peer
  let
    ctx = buddy.ctx
    peer = buddy.peer
  if peer.supports(protocol.snap) and
     peer.supports(protocol.eth) and
     peer.state(protocol.eth).initialized:
    buddy.pivot = BestPivotWorkerRef.init(
      buddy.ctx.pivot, buddy.ctrl, buddy.peer)
    buddy.data.errors = ComErrorStatsRef()
    if not ctx.data.ticker.isNil:
      ctx.data.ticker.startBuddy()
    return true

proc stop*(buddy: SnapBuddyRef) =
  ## Clean up this peer
  let
    ctx = buddy.ctx
    peer = buddy.peer
  buddy.ctrl.stopped = true
  buddy.pivot.clear()
  if not ctx.data.ticker.isNil:
    ctx.data.ticker.stopBuddy()

# ------------------------------------------------------------------------------
# Public functions
# ------------------------------------------------------------------------------

proc runSingle*(buddy: SnapBuddyRef) {.async.} =
  ## This peer worker is invoked if the peer-local flag `buddy.ctrl.multiOk`
  ## is set `false` which is the default mode. This flag is updated by the
  ## worker when deemed appropriate.
  ## * For all workers, there can be only one `runSingle()` function active
  ##   simultaneously for all worker peers.
  ## * There will be no `runMulti()` function active for the same worker peer
  ##   simultaneously
  ## * There will be no `runPool()` iterator active simultaneously.
  ##
  ## Note that this function runs in `async` mode.
  ##
  let peer = buddy.peer
  # This pivot finder one harmonises assigned difficulties of at least two
  # peers. There can only be one  `pivot2Exec()` instance active/unfinished
  # (which is wrapped into the helper function `updateSinglePivot()`.)
  if not await buddy.updateSinglePivot():
    # Wait if needed, then return => repeat
    if not buddy.ctrl.stopped:
      await sleepAsync(2.seconds)
    return

  buddy.ctrl.multiOk = true


proc runPool*(buddy: SnapBuddyRef, last: bool) =
  ## Ocne started, the function `runPool()` is called for all worker peers in
  ## a row (as the body of an iteration.) There will be no other worker peer
  ## functions activated simultaneously.
  ##
  ## This procedure is started if the global flag `buddy.ctx.poolMode` is set
  ## `true` (default is `false`.) It is the responsibility of the `runPool()`
  ## instance to reset the flag `buddy.ctx.poolMode`, typically at the first
  ## peer instance.
  ##
  ## The argument `last` is set `true` if the last entry is reached.
  ##
  ## Note that this function does not run in `async` mode.
  ##
  let ctx = buddy.ctx
  if ctx.poolMode:
    ctx.poolMode = false

    let rc = ctx.data.pivotTable.lastValue
    if rc.isOk:
      # Check whether accounts and storage might be complete.
      let env = rc.value
      if not env.serialSync:
        # Check whether accounts download is complete
        block checkAccountsComplete:
          for ivSet in env.fetchAccounts.unprocessed:
            if ivSet.chunks != 0:
              break checkAccountsComplete
          env.accountsDone = true
          # Check whether storage slots are complete
          if env.fetchStorage.len == 0:
            env.serialSync = true

      if extraTraceMessages:
        trace "Checked for pivot DB completeness",
          nAccounts=env.nAccounts, accountsDone=env.accountsDone,
          nSlotLists=env.nSlotLists, storageDone=env.serialSync


proc runMulti*(buddy: SnapBuddyRef) {.async.} =
  ## This peer worker is invoked if the `buddy.ctrl.multiOk` flag is set
  ## `true` which is typically done after finishing `runSingle()`. This
  ## instance can be simultaneously active for all peer workers.
  ##
  let
    ctx = buddy.ctx
    peer = buddy.peer

  # Set up current state root environment for accounts snapshot
  let env = block:
    let rc = ctx.data.pivotTable.lastValue
    if rc.isErr:
      return # nothing to do
    rc.value

  buddy.data.pivotEnv = env

  if env.serialSync:
    trace "Snap serial sync -- not implemented yet", peer
    await sleepAsync(5.seconds)

  else:
    # Snapshot sync processing. Note that *serialSync => accountsDone*.
    await buddy.rangeFetchAccounts()
    if buddy.ctrl.stopped: return

    await buddy.rangeFetchStorageSlots()
    if buddy.ctrl.stopped: return

    # Pivot might have changed, so restart with the latest one
    if env != ctx.data.pivotTable.lastValue.value: return

    # If the current database is not complete yet
    if 0 < env.fetchAccounts.unprocessed[0].chunks or
       0 < env.fetchAccounts.unprocessed[1].chunks:

      await buddy.healAccounts()
      if buddy.ctrl.stopped: return

      await buddy.healStorageSlots()
      if buddy.ctrl.stopped: return

      # Check whether accounts might be complete.
      if env.fetchStorage.len == 0:
        # Possibly done but some buddies might wait for an account range to be
        # received from the network. So we need to sync.
        buddy.ctx.poolMode = true

# ------------------------------------------------------------------------------
# End
# ------------------------------------------------------------------------------