Prep for full sync after snap make 5 (#1286)

* Update docu and logging

* Extracted and updated constants from `worker_desc` into separate file

* Update and re-calibrate communication error handling

* Allow simplified pivot negotiation

why:
  This feature allows to turn off pivot negotiation so that peers agree
  on a a pivot header.

  For snap sync with fast changing pivots this only throttles the sync
  process. The finally downloaded DB snapshot is typically a merged
  version of different pivot states augmented by a healing process.

* Re-model worker queues for accounts download & healing

why:
  Currently there is only one data fetch per download or healing task.
  This task is then repeated by the scheduler after a short time. In
  many cases, this short time seems enough for some peers to decide to
  terminate connection.

* Update main task batch `runMulti()`

details:
  The function `runMulti()` is activated in quasi-parallel mode by the
  scheduler. This function calls the download, healing and fast-sync
  functions.

  While in debug mode, after each set of jobs run by this function the
  database is analysed (by the `snapdb_check` module) and the result
  printed.

nimbus/sync/misc/best_pivot.nim

@@ -30,7 +30,7 @@ const
   extraTraceMessages = false or true
     ## Additional trace commands
 
-  minPeersToStartSync = 2
+  pivotMinPeersToStartSync* = 2
     ## Wait for consensus of at least this number of peers before syncing.
 
 type
@@ -39,6 +39,7 @@ type
     rng: ref HmacDrbgContext    ## Random generator
     untrusted: seq[Peer]        ## Clean up list
     trusted: HashSet[Peer]      ## Peers ready for delivery
+    relaxedMode: bool           ## Not using strictly `trusted` set
 
   BestPivotWorkerRef* = ref object of RootRef
     ## Data for this peer only
@@ -242,13 +243,30 @@ proc clear*(bp: BestPivotWorkerRef) =
 # Public functions
 # ------------------------------------------------------------------------------
 
+proc pivotRelaxedMode*(ctx: BestPivotCtxRef; enable = false) =
+  ## Controls relaxed mode. In relaxed mode, the *best header* is fetched
+  ## from the network and used as pivot if its block number is large enough.
+  ## Otherwise, the default is to find at least `pivotMinPeersToStartSync`
+  ## peers (this one included) that agree on a minimum pivot.
+  ctx.relaxedMode = enable
+
 proc pivotHeader*(bp: BestPivotWorkerRef): Result[BlockHeader,void] =
   ## Returns cached block header if available and the buddy `peer` is trusted.
+  ## In relaxed mode (see `pivotRelaxedMode()`), also lesser trusted pivots
+  ## are returned.
   if bp.header.isSome and
-     bp.peer notin bp.global.untrusted and
+     bp.peer notin bp.global.untrusted:
-     minPeersToStartSync <= bp.global.trusted.len and
+
+    if pivotMinPeersToStartSync <= bp.global.trusted.len and
        bp.peer in bp.global.trusted:
       return ok(bp.header.unsafeGet)
+
+    if bp.global.relaxedMode:
+      when extraTraceMessages:
+        trace "Returning not fully trusted pivot", peer=bp.peer,
+           trusted=bp.global.trusted.len, untrusted=bp.global.untrusted.len
+      return ok(bp.header.unsafeGet)
+
   err()
 
 proc pivotNegotiate*(
@@ -261,6 +279,10 @@ proc pivotNegotiate*(
   ## the current `buddy` can be used for syncing and the function
   ## `bestPivotHeader()` will succeed returning a `BlockHeader`.
   ##
+  ## In relaxed mode (see `pivotRelaxedMode()`), negotiation stopps when there
+  ## is a *best header*. It caches the best header and returns `true` it the
+  ## block number is large enough.
+  ##
   ## Ackn: nim-eth/eth/p2p/blockchain_sync.nim: `startSyncWithPeer()`
   ##
   let peer = bp.peer
@@ -291,9 +313,14 @@ proc pivotNegotiate*(
       trace "Useless peer, best number too low", peer,
         trusted=bp.global.trusted.len, runState=bp.ctrl.state,
         minNumber, bestNumber
+      return false
     bp.header = some(rc.value)
 
-  if minPeersToStartSync <= bp.global.trusted.len:
+  # No further negotiation if in relaxed mode
+  if bp.global.relaxedMode:
+    return true
+
+  if pivotMinPeersToStartSync <= bp.global.trusted.len:
     # We have enough trusted peers. Validate new peer against trusted
     let rc = bp.getRandomTrustedPeer()
     if rc.isOK:
@@ -311,10 +338,11 @@ proc pivotNegotiate*(
       if not rx.error:
         # Other peer is dead
         bp.global.trusted.excl rc.value
+    return false
 
   # If there are no trusted peers yet, assume this very peer is trusted,
   # but do not finish initialisation until there are more peers.
-  elif bp.global.trusted.len == 0:
+  if bp.global.trusted.len == 0:
     bp.global.trusted.incl peer
     when extraTraceMessages:
       let bestHeader =
@@ -322,12 +350,12 @@ proc pivotNegotiate*(
         else: "nil"
       trace "Assume initial trusted peer", peer,
         trusted=bp.global.trusted.len, runState=bp.ctrl.state, bestHeader
+    return false
 
-  elif bp.global.trusted.len == 1 and bp.peer in bp.global.trusted:
+  if bp.global.trusted.len == 1 and bp.peer in bp.global.trusted:
     # Ignore degenerate case, note that `trusted.len < minPeersToStartSync`
-    discard
+    return false
 
-  else:
   # At this point we have some "trusted" candidates, but they are not
   # "trusted" enough. We evaluate `peer` against all other candidates. If
   # one of the candidates disagrees, we swap it for `peer`. If all candidates
@@ -383,7 +411,7 @@ proc pivotNegotiate*(
     discard
 
   # Evaluate status, finally
-    if minPeersToStartSync <= bp.global.trusted.len:
+  if pivotMinPeersToStartSync <= bp.global.trusted.len:
     when extraTraceMessages:
       let bestHeader =
         if bp.header.isSome: "#" & $bp.header.get.blockNumber

nimbus/sync/snap/constants.nim

@@ -0,0 +1,109 @@
+# 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.
+
+{.push raises: [Defect].}
+
+const
+  pivotBlockDistanceMin* = 128
+    ## The minimal depth of two block headers needed to activate a new state
+    ## root pivot.
+    ##
+    ## Effects on assembling the state via `snap/1` protocol:
+    ##
+    ## * A small value of this constant increases the propensity to update the
+    ##   pivot header more often. This is so because each new peer negoiates a
+    ##   pivot block number at least the current one.
+    ##
+    ## * A large value keeps the current pivot more stable but some experiments
+    ##   suggest that the `snap/1` protocol is answered only for later block
+    ##   numbers (aka pivot blocks.) So a large value tends to keep the pivot
+    ##   farther away from the chain head.
+    ##
+    ##   Note that 128 is the magic distance for snapshots used by *Geth*.
+
+  pivotEnvStopChangingIfComplete* = true
+    ## If set `true`, new peers will not change the pivot even if the
+    ## negotiated pivot would be newer. This should be the default.
+
+  # --------------
+
+  snapRequestBytesLimit* = 2 * 1024 * 1024
+    ## Soft bytes limit to request in `snap` protocol calls.
+
+  snapStoragesSlotsFetchMax* = 2 * 1024
+    ## Maximal number of storage tries to fetch with a single message.
+
+  snapTrieNodeFetchMax* = 1024
+    ## Informal maximal number of trie nodes to fetch at once. This is not
+    ## an official limit but found on several implementations (e.g. Geth.)
+    ##
+    ## Resticting the fetch list length early allows to better paralellise
+    ## healing.
+
+  snapAccountsHealBatchFetchMax* = 5 * snapTrieNodeFetchMax
+    ## Keap on gloing in healing task up until this many nodes have been
+    ## fetched from the network or some error contition therminates the task.
+
+  # --------------
+
+  healAccountsTrigger* = 0.95
+    ## Apply accounts healing if the global snap download coverage factor
+    ## exceeds this setting. The global coverage factor is derived by merging
+    ## all account ranges retrieved for all pivot state roots (see
+    ## `coveredAccounts` in `CtxData`.)
+    ##
+    ## A small value of this constant leads to early healing. This produces
+    ## stray leaf account records so fragmenting larger intervals of missing
+    ## account ranges. This in turn leads to smaller but more range requests
+    ## over the network. More requests might be a disadvantage if peers only
+    ## serve a maximum number requests (rather than data.)
+
+  healSlorageSlotsTrigger* = 0.70
+    ## Consider per account storage slost healing if a per-account hexary
+    ## sub-trie has reached this factor of completeness.
+
+  healStoragesSlotsBatchMax* = 32
+    ## Maximal number of storage tries to to heal in a single batch run. Only
+    ## this many items will be removed from the batch queue. These items will
+    ## then be processed one by one.
+
+  # --------------
+
+  comErrorsTimeoutMax* = 4
+    ## Maximal number of non-resonses accepted in a row. If there are more than
+    ## `comErrorsTimeoutMax` consecutive errors, the worker will be degraded
+    ## as zombie.
+
+  comErrorsTimeoutSleepMSecs* = 5000
+    ## Wait/suspend for this many seconds after a timeout error if there are
+    ## not more than `comErrorsTimeoutMax` errors in a row (maybe some other
+    ## network or no-data errors mixed in.) Set 0 to disable.
+
+
+  comErrorsNetworkMax* = 5
+    ## Similar to `comErrorsTimeoutMax` but for network errors.
+
+  comErrorsNetworkSleepMSecs* = 5000
+    ## Similar to `comErrorsTimeoutSleepSecs` but for network errors.
+    ## Set 0 to disable.
+
+  comErrorsNoDataMax* = 3
+    ## Similar to `comErrorsTimeoutMax` but for missing data errors.
+
+  comErrorsNoDataSleepMSecs* = 0
+    ## Similar to `comErrorsTimeoutSleepSecs` but for missing data errors.
+    ## Set 0 to disable.
+
+static:
+  doAssert healAccountsTrigger < 1.0 # larger values make no sense
+
+# ------------------------------------------------------------------------------
+# End
+# ------------------------------------------------------------------------------

nimbus/sync/snap/worker.nim

@@ -12,20 +12,20 @@ import
   std/[hashes, math, options, sets, strutils],
   chronicles,
   chronos,
-  eth/[common/eth_types, p2p],
+  eth/[common, 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,
+  ./worker/db/[snapdb_check, snapdb_desc],
-  "."/[range_desc, worker_desc]
+  "."/[constants, range_desc, worker_desc]
 
 {.push raises: [Defect].}
 
 logScope:
-  topics = "snap-sync"
+  topics = "snap-buddy"
 
 const
   extraTraceMessages = false or true
@@ -121,7 +121,7 @@ proc appendPivotEnv(buddy: SnapBuddyRef; header: BlockHeader) =
     ctx = buddy.ctx
     minNumber = block:
       let rc = ctx.data.pivotTable.lastValue
-      if rc.isOk: rc.value.stateHeader.blockNumber + minPivotBlockDistance
+      if rc.isOk: rc.value.stateHeader.blockNumber + pivotBlockDistanceMin
       else: 1.toBlockNumber
 
   # Check whether the new header follows minimum depth requirement. This is
@@ -151,19 +151,20 @@ proc updateSinglePivot(buddy: SnapBuddyRef): Future[bool] {.async.} =
     var header = buddy.pivot.pivotHeader.value
 
     # Check whether there is no environment change needed
-    when noPivotEnvChangeIfComplete:
+    when pivotEnvStopChangingIfComplete:
       let rc = ctx.data.pivotTable.lastValue
-      if rc.isOk and rc.value.serialSync:
+      if rc.isOk and rc.value.storageDone:
         # No neede to change
         if extraTraceMessages:
           trace "No need to change snap pivot", peer,
             pivot=("#" & $rc.value.stateHeader.blockNumber),
+            stateRoot=rc.value.stateHeader.stateRoot,
             multiOk=buddy.ctrl.multiOk, runState=buddy.ctrl.state
         return true
 
     buddy.appendPivotEnv(header)
 
-    trace "Snap pivot initialised", peer, pivot=("#" & $header.blockNumber),
+    info "Snap pivot initialised", peer, pivot=("#" & $header.blockNumber),
       multiOk=buddy.ctrl.multiOk, runState=buddy.ctrl.state
 
     return true
@@ -222,6 +223,7 @@ proc setup*(ctx: SnapCtxRef; tickerOK: bool): bool =
     if ctx.data.dbBackend.isNil: SnapDbRef.init(ctx.chain.db.db)
     else: SnapDbRef.init(ctx.data.dbBackend)
   ctx.pivot = BestPivotCtxRef.init(ctx.data.rng)
+  ctx.pivot.pivotRelaxedMode(enable = true)
   if tickerOK:
     ctx.data.ticker = TickerRef.init(ctx.tickerUpdate)
   else:
@@ -309,23 +311,31 @@ proc runPool*(buddy: SnapBuddyRef, last: bool) =
 
     let rc = ctx.data.pivotTable.lastValue
     if rc.isOk:
-      # Check whether accounts and storage might be complete.
+
-      let env = rc.value
+      # Check whether last pivot accounts and storage are complete.
-      if not env.serialSync:
+      let
+        env = rc.value
+        peer = buddy.peer
+        pivot = "#" & $env.stateHeader.blockNumber # for logging
+
+      if not env.storageDone:
+
         # Check whether accounts download is complete
-        block checkAccountsComplete:
+        if env.fetchAccounts.unprocessed.isEmpty():
-          for ivSet in env.fetchAccounts.unprocessed:
+
-            if ivSet.chunks != 0:
+          # FIXME: This check might not be needed. It will visit *every* node
-              break checkAccountsComplete
+          #        in the hexary trie for checking the account leaves.
-          env.accountsDone = true
+          if buddy.checkAccountsTrieIsComplete(env):
+            env.accountsState = HealerDone
+
             # Check whether storage slots are complete
             if env.fetchStorage.len == 0:
-            env.serialSync = true
+              env.storageDone = true
 
       if extraTraceMessages:
-        trace "Checked for pivot DB completeness",
+        trace "Checked for pivot DB completeness", peer, pivot,
-          nAccounts=env.nAccounts, accountsDone=env.accountsDone,
+          nAccounts=env.nAccounts, accountsState=env.accountsState,
-          nSlotLists=env.nSlotLists, storageDone=env.serialSync
+          nSlotLists=env.nSlotLists, storageDone=env.storageDone
 
 
 proc runMulti*(buddy: SnapBuddyRef) {.async.} =
@@ -338,43 +348,84 @@ proc runMulti*(buddy: SnapBuddyRef) {.async.} =
     peer = buddy.peer
 
   # Set up current state root environment for accounts snapshot
-  let env = block:
+  let
+    env = block:
       let rc = ctx.data.pivotTable.lastValue
       if rc.isErr:
         return # nothing to do
       rc.value
+    pivot = "#" & $env.stateHeader.blockNumber # for logging
 
   buddy.data.pivotEnv = env
 
-  if env.serialSync:
+  # Full sync processsing based on current snapshot
-    trace "Snap serial sync -- not implemented yet", peer
+  # -----------------------------------------------
+  if env.storageDone:
+    if not buddy.checkAccountsTrieIsComplete(env):
+      error "Ooops, all accounts fetched but DvnB still incomplete", peer, pivot
+
+      if not buddy.checkStorageSlotsTrieIsComplete(env):
+        error "Ooops, all storages fetched but DB still incomplete", peer, pivot
+
+    trace "Snap full sync -- not implemented yet", peer, pivot
     await sleepAsync(5.seconds)
+    return
 
-  else:
+  # Snapshot sync processing
-    # Snapshot sync processing. Note that *serialSync => accountsDone*.
+  # ------------------------
-    await buddy.rangeFetchAccounts()
-    if buddy.ctrl.stopped: return
 
-    await buddy.rangeFetchStorageSlots()
+  template runAsync(code: untyped) =
-    if buddy.ctrl.stopped: return
+    await code
+    if buddy.ctrl.stopped:
+      # To be disconnected from peer.
+      return
+    if env != ctx.data.pivotTable.lastValue.value:
+      # Pivot has changed, so restart with the latest one
+      return
 
-    # Pivot might have changed, so restart with the latest one
+  # If this is a new pivot, the previous one can be partially cleaned up.
-    if env != ctx.data.pivotTable.lastValue.value: return
+  # There is no point in keeping some older space consuming state data any
+  # longer.
+  block:
+    let rc = ctx.data.pivotTable.beforeLastValue
+    if rc.isOk:
+      let nFetchStorage = rc.value.fetchStorage.len
+      if 0 < nFetchStorage:
+        trace "Cleaning up previous pivot", peer, pivot, nFetchStorage
+        rc.value.fetchStorage.clear()
+        rc.value.fetchAccounts.checkNodes.setLen(0)
+        rc.value.fetchAccounts.missingNodes.setLen(0)
 
-    # If the current database is not complete yet
+  if env.accountsState != HealerDone:
-    if 0 < env.fetchAccounts.unprocessed[0].chunks or
+    runAsync buddy.rangeFetchAccounts()
-       0 < env.fetchAccounts.unprocessed[1].chunks:
+    runAsync buddy.rangeFetchStorageSlots()
 
-      await buddy.healAccounts()
+    # Can only run a single accounts healer instance at a time. This instance
-      if buddy.ctrl.stopped: return
+    # will clear the batch queue so there is nothing to do for another process.
+    if env.accountsState == HealerIdle:
+      env.accountsState = HealerRunning
+      runAsync buddy.healAccounts()
+      env.accountsState = HealerIdle
 
-      await buddy.healStorageSlots()
+      # Some additional storage slots might have been popped up
-      if buddy.ctrl.stopped: return
+      runAsync buddy.rangeFetchStorageSlots()
 
-      # Check whether accounts might be complete.
+  runAsync buddy.healStorageSlots()
+
+  # Debugging log: analyse pivot against database
+  discard buddy.checkAccountsListOk(env)
+  discard buddy.checkStorageSlotsTrieIsComplete(env)
+
+  # Check whether there are more accounts to fetch.
+  #
+  # Note that some other process might have temporarily borrowed from the
+  # `fetchAccounts.unprocessed` list. Whether we are done can only be decided
+  # if only a single buddy is active. S be it.
+  if env.fetchAccounts.unprocessed.isEmpty():
+
+    # Check whether pivot download is complete.
     if env.fetchStorage.len == 0:
-        # Possibly done but some buddies might wait for an account range to be
+      trace "Running pool mode for verifying completeness", peer, pivot
-        # received from the network. So we need to sync.
       buddy.ctx.poolMode = true
 
 # ------------------------------------------------------------------------------

nimbus/sync/snap/worker/com/com_error.nim

@@ -10,19 +10,15 @@
 
 import
   chronos,
-  ../../../sync_desc
+  ../../../sync_desc,
-
+  ../../constants
-const
-  comErrorsTimeoutMax* = 2
-    ## Maximal number of non-resonses accepted in a row. If there are more than
-    ## `comErrorsTimeoutMax` consecutive errors, the worker will be degraded
-    ## as zombie.
 
 type
   ComErrorStatsRef* = ref object
     ## particular error counters so connections will not be cut immediately
     ## after a particular error.
     nTimeouts*: uint
+    nNoData*: uint
     nNetwork*: uint
 
   ComError* = enum
@@ -37,7 +33,7 @@ type
     ComNoAccountsForStateRoot
     ComNoByteCodesAvailable
     ComNoDataForProof
-    ComNoHeaderAvailable
+    #ComNoHeaderAvailable -- unused, see get_block_header.nim
     ComNoStorageForAccounts
     ComNoTrieNodesAvailable
     ComResponseTimeout
@@ -46,10 +42,10 @@ type
     ComTooManyStorageSlots
     ComTooManyTrieNodes
 
-    # Other errors not directly related to communication
-    ComInspectDbFailed
-    ComImportAccountsFailed
 
+proc resetComError*(stats: ComErrorStatsRef) =
+  ## Reset error counts after successful network operation
+  stats[].reset
 
 proc stopAfterSeriousComError*(
     ctrl: BuddyCtrlRef;
@@ -57,42 +53,47 @@ proc stopAfterSeriousComError*(
     stats: ComErrorStatsRef;
       ): Future[bool]
       {.async.} =
-  ## Error handling after data protocol failed.
+  ## Error handling after data protocol failed. Returns `true` if the current
+  ## worker should be terminated as *zombie*.
   case error:
   of ComResponseTimeout:
     stats.nTimeouts.inc
     if comErrorsTimeoutMax < stats.nTimeouts:
       # Mark this peer dead, i.e. avoid fetching from this peer for a while
       ctrl.zombie = true
-    else:
-      # Otherwise try again some time later. Nevertheless, stop the
-      # current action.
-      await sleepAsync(5.seconds)
       return true
 
-  of ComNetworkProblem,
+    when 0 < comErrorsTimeoutSleepMSecs:
-     ComMissingProof,
+      # Otherwise try again some time later.
-     ComAccountsMinTooSmall,
+      await sleepAsync(comErrorsTimeoutSleepMSecs.milliseconds)
-     ComAccountsMaxTooLarge:
+
+  of ComNetworkProblem:
     stats.nNetwork.inc
-    # Mark this peer dead, i.e. avoid fetching from this peer for a while
+    if comErrorsNetworkMax < stats.nNetwork:
       ctrl.zombie = true
       return true
 
-  of ComEmptyAccountsArguments,
+    when 0 < comErrorsNetworkSleepMSecs:
-     ComEmptyRequestArguments,
+      # Otherwise try again some time later.
-     ComEmptyPartialRange,
+      await sleepAsync(comErrorsNetworkSleepMSecs.milliseconds)
-     ComInspectDbFailed,
-     ComImportAccountsFailed,
-     ComNoDataForProof,
-     ComNothingSerious:
-    discard
 
   of ComNoAccountsForStateRoot,
-     ComNoStorageForAccounts,
      ComNoByteCodesAvailable,
-     ComNoHeaderAvailable,
+     ComNoStorageForAccounts,
-     ComNoTrieNodesAvailable,
+     #ComNoHeaderAvailable,
+     ComNoTrieNodesAvailable:
+    stats.nNoData.inc
+    if comErrorsNoDataMax < stats.nNoData:
+      ctrl.zombie = true
+      return true
+
+    when 0 < comErrorsNoDataSleepMSecs:
+      # Otherwise try again some time later.
+      await sleepAsync(comErrorsNoDataSleepMSecs.milliseconds)
+
+  of ComMissingProof,
+     ComAccountsMinTooSmall,
+     ComAccountsMaxTooLarge,
      ComTooManyByteCodes,
      ComTooManyHeaders,
      ComTooManyStorageSlots,
@@ -101,4 +102,11 @@ proc stopAfterSeriousComError*(
     ctrl.zombie = true
     return true
 
+  of ComEmptyAccountsArguments,
+     ComEmptyRequestArguments,
+     ComEmptyPartialRange,
+     ComNoDataForProof,
+     ComNothingSerious:
+    discard
+
 # End

nimbus/sync/snap/worker/com/get_account_range.nim

@@ -18,7 +18,7 @@ import
   eth/[common, p2p, trie/trie_defs],
   stew/interval_set,
   "../../.."/[protocol, protocol/trace_config],
-  "../.."/[range_desc, worker_desc],
+  "../.."/[constants, range_desc, worker_desc],
   ./com_error
 
 {.push raises: [Defect].}
@@ -40,6 +40,7 @@ proc getAccountRangeReq(
     buddy: SnapBuddyRef;
     root: Hash256;
     iv: NodeTagRange;
+    pivot: string;
       ): Future[Result[Option[SnapAccountRange],void]] {.async.} =
   let
     peer = buddy.peer
@@ -48,7 +49,7 @@ proc getAccountRangeReq(
       root, iv.minPt.to(Hash256), iv.maxPt.to(Hash256), snapRequestBytesLimit)
     return ok(reply)
   except CatchableError as e:
-    trace trSnapRecvError & "waiting for GetAccountRange reply", peer,
+    trace trSnapRecvError & "waiting for GetAccountRange reply", peer, pivot,
       error=e.msg
     return err()
 
@@ -58,22 +59,23 @@ proc getAccountRangeReq(
 
 proc getAccountRange*(
     buddy: SnapBuddyRef;
-    stateRoot: Hash256;
+    stateRoot: Hash256;         ## Current DB base (see `pivot` for logging)
-    iv: NodeTagRange;
+    iv: NodeTagRange;           ## Range to be fetched
+    pivot: string;              ## For logging, instead of `stateRoot`
       ): Future[Result[GetAccountRange,ComError]] {.async.} =
   ## Fetch data using the `snap#` protocol, returns the range covered.
   let
     peer = buddy.peer
   if trSnapTracePacketsOk:
-    trace trSnapSendSending & "GetAccountRange", peer,
+    trace trSnapSendSending & "GetAccountRange", peer, pivot,
-      accRange=iv, stateRoot, bytesLimit=snapRequestBytesLimit
+      accRange=iv, bytesLimit=snapRequestBytesLimit
 
   var dd = block:
-    let rc = await buddy.getAccountRangeReq(stateRoot, iv)
+    let rc = await buddy.getAccountRangeReq(stateRoot, iv, pivot)
     if rc.isErr:
       return err(ComNetworkProblem)
     if rc.value.isNone:
-      trace trSnapRecvTimeoutWaiting & "for reply to GetAccountRange", peer
+      trace trSnapRecvTimeoutWaiting & "for AccountRange", peer, pivot
       return err(ComResponseTimeout)
     let snAccRange = rc.value.get
     GetAccountRange(
@@ -108,15 +110,15 @@ proc getAccountRange*(
     #   any) account after limitHash must be provided.
     if nProof == 0:
       # Maybe try another peer
-      trace trSnapRecvReceived & "empty AccountRange", peer,
+      trace trSnapRecvReceived & "empty AccountRange", peer, pivot,
-        nAccounts, nProof, accRange="n/a", reqRange=iv, stateRoot
+        nAccounts, nProof, accRange="n/a", reqRange=iv
       return err(ComNoAccountsForStateRoot)
 
     # So there is no data, otherwise an account beyond the interval end
     # `iv.maxPt` would have been returned.
     dd.consumed = NodeTagRange.new(iv.minPt, high(NodeTag))
-    trace trSnapRecvReceived & "terminal AccountRange", peer,
+    trace trSnapRecvReceived & "terminal AccountRange", peer, pivot,
-      nAccounts, nProof, accRange=dd.consumed, reqRange=iv, stateRoot
+      nAccounts, nProof, accRange=dd.consumed, reqRange=iv
     return ok(dd)
 
   let (accMinPt, accMaxPt) = (
@@ -133,15 +135,15 @@ proc getAccountRange*(
     #   across both.
     if 0.to(NodeTag) < iv.minPt:
       trace trSnapRecvProtocolViolation & "proof-less AccountRange", peer,
-        nAccounts, nProof, accRange=NodeTagRange.new(iv.minPt, accMaxPt),
+        pivot, nAccounts, nProof, accRange=NodeTagRange.new(iv.minPt, accMaxPt),
-        reqRange=iv, stateRoot
+        reqRange=iv
       return err(ComMissingProof)
 
   if accMinPt < iv.minPt:
     # Not allowed
     trace trSnapRecvProtocolViolation & "min too small in AccountRange", peer,
-      nAccounts, nProof, accRange=NodeTagRange.new(accMinPt, accMaxPt),
+      pivot, nAccounts, nProof, accRange=NodeTagRange.new(accMinPt, accMaxPt),
-      reqRange=iv, stateRoot
+      reqRange=iv
     return err(ComAccountsMinTooSmall)
 
   if iv.maxPt < accMaxPt:
@@ -157,13 +159,13 @@ proc getAccountRange*(
       if iv.maxPt < dd.data.accounts[^2].accKey.to(NodeTag):
         # The segcond largest should not excceed the top one requested.
         trace trSnapRecvProtocolViolation & "AccountRange top exceeded", peer,
-          nAccounts, nProof, accRange=NodeTagRange.new(iv.minPt, accMaxPt),
+          pivot, nAccounts, nProof,
-          reqRange=iv, stateRoot
+          accRange=NodeTagRange.new(iv.minPt, accMaxPt), reqRange=iv
         return err(ComAccountsMaxTooLarge)
 
   dd.consumed = NodeTagRange.new(iv.minPt, max(iv.maxPt,accMaxPt))
-  trace trSnapRecvReceived & "AccountRange", peer,
+  trace trSnapRecvReceived & "AccountRange", peer, pivot,
-    nAccounts, nProof, accRange=dd.consumed, reqRange=iv, stateRoot
+    nAccounts, nProof, accRange=dd.consumed, reqRange=iv
 
   return ok(dd)
 

nimbus/sync/snap/worker/com/get_storage_ranges.nim

@@ -15,7 +15,7 @@ import
   eth/[common, p2p],
   stew/interval_set,
   "../../.."/[protocol, protocol/trace_config],
-  "../.."/[range_desc, worker_desc],
+  "../.."/[constants, range_desc, worker_desc],
   ./com_error
 
 {.push raises: [Defect].}
@@ -46,8 +46,9 @@ const
 proc getStorageRangesReq(
     buddy: SnapBuddyRef;
     root: Hash256;
-    accounts: seq[Hash256],
+    accounts: seq[Hash256];
-    iv: Option[NodeTagRange]
+    iv: Option[NodeTagRange];
+    pivot: string;
       ): Future[Result[Option[SnapStorageRanges],void]]
       {.async.} =
   let
@@ -70,7 +71,7 @@ proc getStorageRangesReq(
     return ok(reply)
 
   except CatchableError as e:
-    trace trSnapRecvError & "waiting for GetStorageRanges reply", peer,
+    trace trSnapRecvError & "waiting for GetStorageRanges reply", peer, pivot,
       error=e.msg
     return err()
 
@@ -80,8 +81,9 @@ proc getStorageRangesReq(
 
 proc getStorageRanges*(
     buddy: SnapBuddyRef;
-    stateRoot: Hash256;
+    stateRoot: Hash256;                ## Current DB base (`pivot` for logging)
-    accounts: seq[AccountSlotsHeader],
+    accounts: seq[AccountSlotsHeader]; ## List of per-account storage slots
+    pivot: string;                     ## For logging, instead of `stateRoot`
       ): Future[Result[GetStorageRanges,ComError]]
       {.async.} =
   ## Fetch data using the `snap#` protocol, returns the range covered.
@@ -99,16 +101,16 @@ proc getStorageRanges*(
     return err(ComEmptyAccountsArguments)
 
   if trSnapTracePacketsOk:
-    trace trSnapSendSending & "GetStorageRanges", peer,
+    trace trSnapSendSending & "GetStorageRanges", peer, pivot,
-      nAccounts, stateRoot, bytesLimit=snapRequestBytesLimit
+      nAccounts, bytesLimit=snapRequestBytesLimit
 
   let snStoRanges = block:
-    let rc = await buddy.getStorageRangesReq(
+    let rc = await buddy.getStorageRangesReq(stateRoot,
-      stateRoot, accounts.mapIt(it.accKey.to(Hash256)), accounts[0].subRange)
+      accounts.mapIt(it.accKey.to(Hash256)), accounts[0].subRange, pivot)
     if rc.isErr:
       return err(ComNetworkProblem)
     if rc.value.isNone:
-      trace trSnapRecvTimeoutWaiting & "for reply to GetStorageRanges", peer,
+      trace trSnapRecvTimeoutWaiting & "for StorageRanges", peer, pivot,
         nAccounts
       return err(ComResponseTimeout)
     if nAccounts < rc.value.get.slotLists.len:
@@ -129,8 +131,8 @@ proc getStorageRanges*(
     #   for any requested account hash, it must return an empty reply. It is
     #   the responsibility of the caller to query an state not older than 128
     #   blocks; and the caller is expected to only ever query existing accounts.
-    trace trSnapRecvReceived & "empty StorageRanges", peer,
+    trace trSnapRecvReceived & "empty StorageRanges", peer, pivot,
-      nAccounts, nSlotLists, nProof, stateRoot, firstAccount=accounts[0].accKey
+      nAccounts, nSlotLists, nProof, firstAccount=accounts[0].accKey
     return err(ComNoStorageForAccounts)
 
   # Assemble return structure for given peer response
@@ -171,8 +173,8 @@ proc getStorageRanges*(
     # assigning empty slice isa ok
     dd.leftOver = dd.leftOver & accounts[nSlotLists ..< nAccounts]
 
-  trace trSnapRecvReceived & "StorageRanges", peer, nAccounts, nSlotLists,
+  trace trSnapRecvReceived & "StorageRanges", peer, pivot, nAccounts,
-    nProof, nLeftOver=dd.leftOver.len, stateRoot
+    nSlotLists, nProof, nLeftOver=dd.leftOver.len
 
   return ok(dd)
 

nimbus/sync/snap/worker/com/get_trie_nodes.nim

@@ -13,7 +13,7 @@ import
   chronos,
   eth/[common, p2p],
   "../../.."/[protocol, protocol/trace_config],
-  "../.."/[range_desc, worker_desc],
+  "../.."/[constants, range_desc, worker_desc],
   ./com_error
 
 {.push raises: [Defect].}
@@ -37,6 +37,7 @@ proc getTrieNodesReq(
     buddy: SnapBuddyRef;
     stateRoot: Hash256;
     paths: seq[seq[Blob]];
+    pivot: string;
       ): Future[Result[Option[SnapTrieNodes],void]]
       {.async.} =
   let
@@ -46,7 +47,7 @@ proc getTrieNodesReq(
     return ok(reply)
 
   except CatchableError as e:
-    trace trSnapRecvError & "waiting for GetByteCodes reply", peer,
+    trace trSnapRecvError & "waiting for GetByteCodes reply", peer, pivot,
       error=e.msg
     return err()
 
@@ -56,8 +57,9 @@ proc getTrieNodesReq(
 
 proc getTrieNodes*(
     buddy: SnapBuddyRef;
-    stateRoot: Hash256;
+    stateRoot: Hash256;         ## Current DB base (see `pivot` for logging)
-    paths: seq[seq[Blob]],
+    paths: seq[seq[Blob]];      ## Nodes to fetch
+    pivot: string;              ## For logging, instead of `stateRoot`
       ): Future[Result[GetTrieNodes,ComError]]
       {.async.} =
   ## Fetch data using the `snap#` protocol, returns the trie nodes requested
@@ -72,15 +74,15 @@ proc getTrieNodes*(
   let nTotal = paths.mapIt(it.len).foldl(a+b, 0)
 
   if trSnapTracePacketsOk:
-    trace trSnapSendSending & "GetTrieNodes", peer,
+    trace trSnapSendSending & "GetTrieNodes", peer, pivot,
       nPaths, nTotal, bytesLimit=snapRequestBytesLimit
 
   let trieNodes = block:
-    let rc = await buddy.getTrieNodesReq(stateRoot, paths)
+    let rc = await buddy.getTrieNodesReq(stateRoot, paths, pivot)
     if rc.isErr:
       return err(ComNetworkProblem)
     if rc.value.isNone:
-      trace trSnapRecvTimeoutWaiting & "for reply to GetTrieNodes", peer, nPaths
+      trace trSnapRecvTimeoutWaiting & "for TrieNodes", peer, pivot, nPaths
       return err(ComResponseTimeout)
     let blobs = rc.value.get.nodes
     if nTotal < blobs.len:
@@ -104,7 +106,7 @@ proc getTrieNodes*(
     #   nodes.
     # * The responding node is allowed to return less data than requested
     #   (serving QoS limits), but the node must return at least one trie node.
-    trace trSnapRecvReceived & "empty TrieNodes", peer, nPaths, nNodes
+    trace trSnapRecvReceived & "empty TrieNodes", peer, pivot, nPaths, nNodes
     return err(ComNoByteCodesAvailable)
 
   # Assemble return value
@@ -153,7 +155,7 @@ proc getTrieNodes*(
         if 0 < pushBack.len:
           dd.leftOver.add paths[n][0] & pushBack
 
-  trace trSnapRecvReceived & "TrieNodes", peer,
+  trace trSnapRecvReceived & "TrieNodes", peer, pivot,
     nPaths, nNodes, nLeftOver=dd.leftOver.len
 
   return ok(dd)

nimbus/sync/snap/worker/db/snapdb_accounts.nim

@@ -216,10 +216,10 @@ proc importAccounts*(
     error "Import Accounts exception", peer=ps.peer, name=($e.name), msg=e.msg
     return err(OSErrorException)
 
-  when extraTraceMessages:
+  #when extraTraceMessages:
-    trace "Accounts and proofs ok", peer=ps.peer,
+  #  trace "Accounts imported", peer=ps.peer,
-      root=ps.root.ByteArray32.toHex,
+  #    root=ps.root.ByteArray32.toHex,
-      proof=data.proof.len, base, accounts=data.accounts.len
+  #    proof=data.proof.len, base, accounts=data.accounts.len
   ok()
 
 proc importAccounts*(

nimbus/sync/snap/worker/db/snapdb_check.nim

@@ -0,0 +1,266 @@
+# 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.
+
+## Check/analyse DB completeness
+## =============================
+
+import
+  chronicles,
+  eth/[common, p2p, trie/trie_defs],
+  stew/keyed_queue,
+  ../../../../utils/prettify,
+  ../../../sync_desc,
+  "../.."/[range_desc, worker_desc],
+  "."/[hexary_desc, hexary_error, snapdb_accounts, snapdb_storage_slots]
+
+{.push raises: [Defect].}
+
+logScope:
+  topics = "snap-db"
+
+const
+  extraTraceMessages = false or true
+    ## Enabled additional logging noise
+
+# ------------------------------------------------------------------------------
+# Private logging helpers
+# ------------------------------------------------------------------------------
+
+template logTxt(info: static[string]): static[string] =
+  "Check DB " & info
+
+proc accountsCtx(
+    buddy: SnapBuddyRef;
+    env: SnapPivotRef;
+      ): string =
+  let
+    ctx = buddy.ctx
+  "{" &
+    "pivot=" & "#" & $env.stateHeader.blockNumber & "," &
+    "nAccounts=" & $env.nAccounts & "," &
+    ("covered=" & env.fetchAccounts.unprocessed.emptyFactor.toPC(0) & "/" &
+        ctx.data.coveredAccounts.fullFactor.toPC(0)) & "," &
+    "nCheckNodes=" & $env.fetchAccounts.checkNodes.len & "," &
+    "nMissingNodes=" & $env.fetchAccounts.missingNodes.len & "}"
+
+# ------------------------------------------------------------------------------
+# Private helpers
+# ------------------------------------------------------------------------------
+
+proc storageSlotsCtx(
+    buddy: SnapBuddyRef;
+    storageRoot: Hash256;
+    env: SnapPivotRef;
+      ): string =
+  let
+    ctx = buddy.ctx
+    rc = env.fetchStorage.eq(storageRoot)
+  if rc.isErr:
+    return "n/a"
+  let
+    data = rc.value
+    slots = data.slots
+  result = "{" &
+    "inherit=" & (if data.inherit: "t" else: "f") & ","
+  if not slots.isNil:
+    result &= "" &
+      "covered=" & slots.unprocessed.emptyFactor.toPC(0) &
+      "nCheckNodes=" & $slots.checkNodes.len & "," &
+      "nMissingNodes=" & $slots.missingNodes.len
+  result &= "}"
+
+# ------------------------------------------------------------------------------
+# Private functions
+# ------------------------------------------------------------------------------
+
+proc checkStorageSlotsTrie(
+    buddy: SnapBuddyRef;
+    accKey: NodeKey;
+    storageRoot: Hash256;
+    env: SnapPivotRef;
+      ): Result[bool,HexaryDbError] =
+  ## Check whether a storage slots hexary trie is complete.
+  let
+    ctx = buddy.ctx
+    db = ctx.data.snapDb
+    peer = buddy.peer
+
+    rc = db.inspectStorageSlotsTrie(peer, accKey, storageRoot)
+
+  if rc.isErr:
+    return err(rc.error)
+
+  ok(rc.value.dangling.len == 0)
+
+
+iterator accountsWalk(
+    buddy: SnapBuddyRef;
+    env: SnapPivotRef;
+      ): (NodeKey,Account,HexaryDbError) =
+  let
+    ctx = buddy.ctx
+    db = ctx.data.snapDb
+    peer = buddy.peer
+    stateRoot = env.stateHeader.stateRoot
+    walk = SnapDbAccountsRef.init(db, stateRoot, peer)
+
+  var
+    accKey = NodeKey.default
+    count = 0
+    runOk = true
+
+  while runOk:
+    count.inc
+
+    let nextKey = block:
+      let rc = walk.nextAccountsChainDbKey(accKey)
+      if rc.isErr:
+        if rc.error != AccountNotFound:
+          error logTxt "accounts walk stopped", peer,
+            account=accKey.to(NodeTag),
+            ctx=buddy.accountsCtx(env), count, reason=rc.error
+        runOk = false
+        continue
+      rc.value
+
+    accKey = nextKey
+
+    let accData = block:
+      let rc = walk.getAccountsData(accKey, persistent = true)
+      if rc.isErr:
+        error logTxt "accounts walk error", peer, account=accKey,
+          ctx=buddy.accountsCtx(env), count, error=rc.error
+        runOk = false
+        continue
+      rc.value
+
+    yield (accKey, accData, NothingSerious)
+
+# ------------------------------------------------------------------------------
+# Public functions
+# ------------------------------------------------------------------------------
+
+proc checkAccountsTrieIsComplete*(
+    buddy: SnapBuddyRef;
+    env: SnapPivotRef;
+      ): bool =
+  ## Check whether accounts hexary trie is complete
+  let
+    ctx = buddy.ctx
+    db = ctx.data.snapDb
+    peer = buddy.peer
+    stateRoot = env.stateHeader.stateRoot
+
+    rc = db.inspectAccountsTrie(peer, stateRoot)
+
+  if rc.isErr:
+    error logTxt "accounts health check failed", peer,
+      ctx=buddy.accountsCtx(env), error=rc.error
+    return false
+
+  rc.value.dangling.len == 0
+
+
+proc checkAccountsListOk*(
+    buddy: SnapBuddyRef;
+    env: SnapPivotRef;
+    noisy = false;
+      ): bool =
+  ## Loop over accounts, returns `false` for some error.
+  let
+    ctx = buddy.ctx
+    peer = buddy.peer
+  var
+    accounts = 0
+    storage = 0
+    nextMsgThresh = 1
+
+  for (key,accData,error) in buddy.accountsWalk(env):
+
+    if error != NothingSerious:
+      error logTxt "accounts loop stopped", peer, ctx=buddy.accountsCtx(env),
+        accounts, storage, error
+      return false
+
+    accounts.inc
+    if accData.storageRoot != emptyRlpHash:
+      storage.inc
+
+    when extraTraceMessages:
+      if noisy and nextMsgThresh <= accounts:
+        debug logTxt "accounts loop check point", peer,
+          ctx=buddy.accountsCtx(env), accounts, storage
+        nextMsgThresh *= 2
+
+  when extraTraceMessages:
+    let isComplete = buddy.checkAccountsTrieIsComplete(env)
+    debug logTxt "accounts list report", peer, ctx=buddy.accountsCtx(env),
+      accounts, storage, isComplete
+
+  true
+
+
+proc checkStorageSlotsTrieIsComplete*(
+    buddy: SnapBuddyRef;
+    accKey: NodeKey;
+    storageRoot: Hash256;
+    env: SnapPivotRef;
+      ): bool =
+  ## Check whether a storage slots hexary trie is complete.
+  let
+    peer = buddy.peer
+    rc = buddy.checkStorageSlotsTrie(accKey, storageRoot, env)
+  if rc.isOk:
+    return rc.value
+
+  when extraTraceMessages:
+    debug logTxt "atorage slots health check failed", peer,
+      nStoQueue=env.fetchStorage.len,
+      ctx=buddy.storageSlotsCtx(storageRoot, env), error=rc.error
+
+proc checkStorageSlotsTrieIsComplete*(
+    buddy: SnapBuddyRef;
+    env: SnapPivotRef;
+      ): bool =
+  ## Check for all accounts thye whether storage slot hexary tries are complete.
+  let
+    ctx = buddy.ctx
+    peer = buddy.peer
+  var
+    accounts = 0
+    incomplete = 0
+    complete = 0
+
+  for (accKey,accData,error) in buddy.accountsWalk(env):
+    if error != NothingSerious:
+      error logTxt "atorage slots accounts loop stopped", peer,
+        nStoQueue=env.fetchStorage.len, accounts, incomplete, complete, error
+      return false
+
+    accounts.inc
+    let storageRoot = accData.storageRoot
+    if storageRoot == emptyRlpHash:
+      continue
+
+    let rc = buddy.checkStorageSlotsTrie(accKey, storageRoot, env)
+    if rc.isOk and rc.value:
+      complete.inc
+    else:
+      incomplete.inc
+
+  when extraTraceMessages:
+    debug logTxt "storage slots report", peer, ctx=buddy.accountsCtx(env),
+      nStoQueue=env.fetchStorage.len, accounts, incomplete, complete
+
+  0 < accounts and incomplete == 0
+
+# ------------------------------------------------------------------------------
+# End
+# ------------------------------------------------------------------------------

nimbus/sync/snap/worker/db/snapdb_storage_slots.nim

@@ -251,10 +251,10 @@ proc importStorageSlots*(
       error "Import storage slots exception", peer, itemInx, nItems,
         name=($e.name), msg=e.msg, nErrors=result.len
 
-  when extraTraceMessages:
+  #when extraTraceMessages:
-    if result.len == 0:
+  #  if result.len == 0:
-      trace "Storage slots imported", peer, nItems,
+  #    trace "Storage slots imported", peer, nItems,
-        nSlotLists=data.storages.len, proofs=data.proof.len
+  #      nSlotLists=data.storages.len, proofs=data.proof.len
 
 proc importStorageSlots*(
     pv: SnapDbRef;             ## Base descriptor on `BaseChainDB`

nimbus/sync/snap/worker/heal_accounts.nim

@@ -112,7 +112,7 @@ import
   stew/[interval_set, keyed_queue],
   ../../../utils/prettify,
   ../../sync_desc,
-  ".."/[range_desc, worker_desc],
+  ".."/[constants, range_desc, worker_desc],
   ./com/[com_error, get_trie_nodes],
   ./db/[hexary_desc, hexary_error, snapdb_accounts]
 
@@ -137,6 +137,7 @@ proc healingCtx(buddy: SnapBuddyRef): string =
     ctx = buddy.ctx
     env = buddy.data.pivotEnv
   "{" &
+    "pivot=" & "#" & $env.stateHeader.blockNumber & "," &
     "nAccounts=" & $env.nAccounts & "," &
     ("covered=" & env.fetchAccounts.unprocessed.emptyFactor.toPC(0) & "/" &
         ctx.data.coveredAccounts.fullFactor.toPC(0)) & "," &
@@ -212,9 +213,10 @@ proc getMissingNodesFromNetwork(
     peer = buddy.peer
     env = buddy.data.pivotEnv
     stateRoot = env.stateHeader.stateRoot
+    pivot = "#" & $env.stateHeader.blockNumber # for logging
 
     nMissingNodes = env.fetchAccounts.missingNodes.len
-    inxLeft = max(0, nMissingNodes - maxTrieNodeFetch)
+    inxLeft = max(0, nMissingNodes - snapTrieNodeFetchMax)
 
   # There is no point in processing too many nodes at the same time. So leave
   # the rest on the `missingNodes` queue to be handled later.
@@ -231,8 +233,11 @@ proc getMissingNodesFromNetwork(
 
   # Fetch nodes from the network. Note that the remainder of the `missingNodes`
   # list might be used by another process that runs semi-parallel.
-  let rc = await buddy.getTrieNodes(stateRoot, pathList)
+  let rc = await buddy.getTrieNodes(stateRoot, pathList, pivot)
   if rc.isOk:
+    # Reset error counts for detecting repeated timeouts, network errors, etc.
+    buddy.data.errors.resetComError()
+
     # Register unfetched missing nodes for the next pass
     for w in rc.value.leftOver:
       env.fetchAccounts.missingNodes.add NodeSpecs(
@@ -316,35 +321,18 @@ proc registerAccountLeaf(
       storageRoot: acc.storageRoot)
 
 # ------------------------------------------------------------------------------
-# Public functions
+# Private functions: do the healing for one round
 # ------------------------------------------------------------------------------
 
-proc healAccounts*(buddy: SnapBuddyRef) {.async.} =
+proc accountsHealingImpl(buddy: SnapBuddyRef): Future[int] {.async.} =
-  ## Fetching and merging missing account trie database nodes.
+  ## Fetching and merging missing account trie database nodes. It returns the
+  ## number of nodes fetched from the network, and -1 upon error.
   let
     ctx = buddy.ctx
     db = ctx.data.snapDb
     peer = buddy.peer
     env = buddy.data.pivotEnv
 
-  # Only start healing if there is some completion level, already.
-  #
-  # We check against the global coverage factor, i.e. a measure for how
-  # much of the total of all accounts have been processed. Even if the trie
-  # database for the current pivot state root is sparsely filled, there
-  # is a good chance that it can inherit some unchanged sub-trie from an
-  # earlier pivor state root download. The healing process then works like
-  # sort of glue.
-  #
-  if env.nAccounts == 0 or
-     ctx.data.coveredAccounts.fullFactor < healAccountsTrigger:
-    #when extraTraceMessages:
-    #  trace logTxt "postponed", peer, ctx=buddy.healingCtx()
-    return
-
-  when extraTraceMessages:
-    trace logTxt "started", peer, ctx=buddy.healingCtx()
-
   # Update for changes since last visit
   buddy.updateMissingNodesList()
 
@@ -353,17 +341,17 @@ proc healAccounts*(buddy: SnapBuddyRef) {.async.} =
   if env.fetchAccounts.checkNodes.len != 0 or
      env.fetchAccounts.missingNodes.len == 0:
     if not buddy.appendMoreDanglingNodesToMissingNodesList():
-      return
+      return 0
 
   # Check whether the trie is complete.
   if env.fetchAccounts.missingNodes.len == 0:
     trace logTxt "complete", peer, ctx=buddy.healingCtx()
-    return # nothing to do
+    return 0 # nothing to do
 
   # Get next batch of nodes that need to be merged it into the database
   let nodeSpecs = await buddy.getMissingNodesFromNetwork()
   if nodeSpecs.len == 0:
-    return
+    return 0
 
   # Store nodes onto disk
   let report = db.importRawAccountsNodes(peer, nodeSpecs)
@@ -372,11 +360,7 @@ proc healAccounts*(buddy: SnapBuddyRef) {.async.} =
     error logTxt "error updating persistent database", peer,
       ctx=buddy.healingCtx(), nNodes=nodeSpecs.len, error=report[^1].error
     env.fetchAccounts.missingNodes = env.fetchAccounts.missingNodes & nodeSpecs
-    return
+    return -1
-
-  when extraTraceMessages:
-    trace logTxt "merged into database", peer,
-      ctx=buddy.healingCtx(), nNodes=nodeSpecs.len
 
   # Filter out error and leaf nodes
   var nLeafNodes = 0 # for logging
@@ -405,7 +389,54 @@ proc healAccounts*(buddy: SnapBuddyRef) {.async.} =
           env.fetchAccounts.checkNodes.add nodePath
 
   when extraTraceMessages:
-    trace logTxt "job done", peer, ctx=buddy.healingCtx(), nLeafNodes
+    trace logTxt "merged into database", peer,
+      ctx=buddy.healingCtx(), nNodes=nodeSpecs.len, nLeafNodes
+
+  return nodeSpecs.len
+
+# ------------------------------------------------------------------------------
+# Public functions
+# ------------------------------------------------------------------------------
+
+proc healAccounts*(buddy: SnapBuddyRef) {.async.} =
+  ## Fetching and merging missing account trie database nodes.
+  let
+    ctx = buddy.ctx
+    peer = buddy.peer
+    env = buddy.data.pivotEnv
+
+  # Only start healing if there is some completion level, already.
+  #
+  # We check against the global coverage factor, i.e. a measure for how
+  # much of the total of all accounts have been processed. Even if the trie
+  # database for the current pivot state root is sparsely filled, there
+  # is a good chance that it can inherit some unchanged sub-trie from an
+  # earlier pivor state root download. The healing process then works like
+  # sort of glue.
+  #
+  if env.nAccounts == 0 or
+     ctx.data.coveredAccounts.fullFactor < healAccountsTrigger:
+    #when extraTraceMessages:
+    #  trace logTxt "postponed", peer, ctx=buddy.healingCtx()
+    return
+
+  when extraTraceMessages:
+    trace logTxt "started", peer, ctx=buddy.healingCtx()
+
+  var
+    nNodesFetched = 0
+    nFetchLoop = 0
+  # Stop after `snapAccountsHealBatchFetchMax` nodes have been fetched
+  while nNodesFetched < snapAccountsHealBatchFetchMax:
+    var nNodes = await buddy.accountsHealingImpl()
+    if nNodes <= 0:
+      break
+    nNodesFetched.inc(nNodes)
+    nFetchLoop.inc
+
+  when extraTraceMessages:
+    trace logTxt "job done", peer, ctx=buddy.healingCtx(),
+      nNodesFetched, nFetchLoop
 
 # ------------------------------------------------------------------------------
 # End

nimbus/sync/snap/worker/heal_storage_slots.nim

@@ -11,8 +11,18 @@
 ## Heal storage DB:
 ## ================
 ##
-## This module works similar to `heal_accounts` applied to each
+## This module works similar to `heal_accounts` applied to each per-account
-## per-account storage slots hexary trie.
+## storage slots hexary trie. These per-account trie work items  are stored in
+## the list `env.fetchStorage`.
+##
+## There is one additional short cut for speeding up processing. If a
+## per-account storage slots hexary trie is marked inheritable, it will be
+## checked whether it is complete and can be used wholesale.
+##
+## Inheritable tries appear after a pivot state root change. Typically, not all
+## account data have changed and so the same  per-account storage slots are
+## valid.
+##
 
 import
   std/sequtils,
@@ -22,7 +32,7 @@ import
   stew/[interval_set, keyed_queue],
   ../../../utils/prettify,
   ../../sync_desc,
-  ".."/[range_desc, worker_desc],
+  ".."/[constants, range_desc, worker_desc],
   ./com/[com_error, get_trie_nodes],
   ./db/[hexary_desc, hexary_error, snapdb_storage_slots]
 
@@ -47,8 +57,10 @@ proc healingCtx(
     kvp: SnapSlotsQueuePair;
       ): string =
   let
+    env = buddy.data.pivotEnv
     slots = kvp.data.slots
   "{" &
+    "pivot=" & "#" & $env.stateHeader.blockNumber & "," &
     "covered=" & slots.unprocessed.emptyFactor.toPC(0) & "," &
     "nCheckNodes=" & $slots.checkNodes.len & "," &
     "nMissingNodes=" & $slots.missingNodes.len & "}"
@@ -158,10 +170,11 @@ proc getMissingNodesFromNetwork(
     env = buddy.data.pivotEnv
     accKey = kvp.data.accKey
     storageRoot = kvp.key
+    pivot = "#" & $env.stateHeader.blockNumber # for logging
     slots = kvp.data.slots
 
     nMissingNodes = slots.missingNodes.len
-    inxLeft = max(0, nMissingNodes - maxTrieNodeFetch)
+    inxLeft = max(0, nMissingNodes - snapTrieNodeFetchMax)
 
   # There is no point in processing too many nodes at the same time. So leave
   # the rest on the `missingNodes` queue to be handled later.
@@ -180,8 +193,11 @@ proc getMissingNodesFromNetwork(
   # list might be used by another process that runs semi-parallel.
   let
     req = @[accKey.to(Blob)] & fetchNodes.mapIt(it.partialPath)
-    rc = await buddy.getTrieNodes(storageRoot, @[req])
+    rc = await buddy.getTrieNodes(storageRoot, @[req], pivot)
   if rc.isOk:
+    # Reset error counts for detecting repeated timeouts, network errors, etc.
+    buddy.data.errors.resetComError()
+
     # Register unfetched missing nodes for the next pass
     for w in rc.value.leftOver:
       for n in 1 ..< w.len:
@@ -418,7 +434,7 @@ proc healStorageSlots*(buddy: SnapBuddyRef) {.async.} =
   for kvp in env.fetchStorage.nextPairs:
 
     # Marked items indicate that a partial sub-trie existsts which might have
-    # been inherited from an earlier state root.
+    # been inherited from an earlier storage root.
     if not kvp.data.inherit:
       let slots = kvp.data.slots
 
@@ -442,7 +458,7 @@ proc healStorageSlots*(buddy: SnapBuddyRef) {.async.} =
 
     # Add to local batch to be processed, below
     toBeHealed.add kvp
-    if maxStoragesHeal <= toBeHealed.len:
+    if healStoragesSlotsBatchMax <= toBeHealed.len:
       break
 
   # Run against local batch

nimbus/sync/snap/worker/range_fetch_accounts.nim

@@ -8,24 +8,26 @@
 # at your option. This file may not be copied, modified, or distributed
 # except according to those terms.
 
-## Fetch accounts stapshot
+## Fetch account ranges
-## =======================
+## ====================
 ##
-## Worker items state diagram:
+## Acccount ranges not on the database yet are organised in the set
-## ::
+## `env.fetchAccounts.unprocessed` of intervals (of account hashes.)
-##   unprocessed        | peer workers +          |
-##   account ranges     | account database update | unprocessed storage slots
-##   ========================================================================
 ##
-##        +---------------------------------------+
+## When processing, the followin happens.
-##        |                                       |
+##
-##        v                                       |
+## * Some interval `iv` is removed from the `env.fetchAccounts.unprocessed`
-##   <unprocessed> -----+------> <worker-0> ------+-----> OUTPUT
+##   set. This interval set might then be safely accessed and manipulated by
-##                      |                         |
+##   other worker instances.
-##                      +------> <worker-1> ------+
+##
-##                      |                         |
+## * The data points in the interval `iv` (aka ccount hashes) are fetched from
-##                      +------> <worker-2> ------+
+##   another peer over the network.
-##                      :                         :
+##
+## * The received data points of the interval `iv` are verified and merged
+##   into the persistent database.
+##
+## * Data points in `iv` that were invalid or not recevied from the network
+##   are merged back it the set `env.fetchAccounts.unprocessed`.
 ##
 
 import
@@ -48,6 +50,12 @@ const
   extraTraceMessages = false or true
     ## Enabled additional logging noise
 
+  numChunksMax = 2000
+    ## Bound for `numChunks()` (some fancy number)
+
+  addToFetchLoopMax = 4
+    ## Add some extra when calculating number of fetch/store rounds
+
 # ------------------------------------------------------------------------------
 # Private logging helpers
 # ------------------------------------------------------------------------------
@@ -59,6 +67,12 @@ template logTxt(info: static[string]): static[string] =
 # Private helpers
 # ------------------------------------------------------------------------------
 
+proc numChunks(buddy: SnapBuddyRef): int =
+  var total = 0u64
+  for ivSet in buddy.data.pivotEnv.fetchAccounts.unprocessed:
+    total += ivSet.chunks.uint64
+  min(numChunksMax.uint64, total).int
+
 proc withMaxLen(
     buddy: SnapBuddyRef;
     iv: NodeTagRange;
@@ -102,48 +116,50 @@ proc markGloballyProcessed(buddy: SnapBuddyRef; iv: NodeTagRange) =
   discard buddy.ctx.data.coveredAccounts.merge(iv)
 
 # ------------------------------------------------------------------------------
-# Public functions
+#  Private functions: do the account fetching for one round
 # ------------------------------------------------------------------------------
 
-proc rangeFetchAccounts*(buddy: SnapBuddyRef) {.async.} =
+proc accountsRagefetchImpl(buddy: SnapBuddyRef): Future[bool] {.async.} =
-  ## Fetch accounts and store them in the database.
+  ## Fetch accounts and store them in the database. Returns true while more
+  ## data can probably be fetched.
   let
     ctx = buddy.ctx
     peer = buddy.peer
     env = buddy.data.pivotEnv
     stateRoot = env.stateHeader.stateRoot
+    pivot = "#" & $env.stateHeader.blockNumber # for logging
 
   # Get a range of accounts to fetch from
   let iv = block:
     let rc = buddy.getUnprocessed()
     if rc.isErr:
       when extraTraceMessages:
-        trace logTxt "currently all processed", peer, stateRoot
+        trace logTxt "currently all processed", peer, pivot
       return
     rc.value
 
   # Process received accounts and stash storage slots to fetch later
   let dd = block:
-    let rc = await buddy.getAccountRange(stateRoot, iv)
+    let rc = await buddy.getAccountRange(stateRoot, iv, pivot)
     if rc.isErr:
       buddy.putUnprocessed(iv) # fail => interval back to pool
       let error = rc.error
       if await buddy.ctrl.stopAfterSeriousComError(error, buddy.data.errors):
         when extraTraceMessages:
-          trace logTxt "fetch error => stop", peer,
+          trace logTxt "fetch error => stop", peer, pivot, reqLen=iv.len, error
-            stateRoot, req=iv.len, error
       return
-    # Reset error counts for detecting repeated timeouts
-    buddy.data.errors.nTimeouts = 0
     rc.value
 
+  # Reset error counts for detecting repeated timeouts, network errors, etc.
+  buddy.data.errors.resetComError()
+
   let
     gotAccounts = dd.data.accounts.len
     gotStorage = dd.withStorage.len
 
-  when extraTraceMessages:
+  #when extraTraceMessages:
-    trace logTxt "fetched", peer, gotAccounts, gotStorage,
+  #  trace logTxt "fetched", peer, gotAccounts, gotStorage,
-      stateRoot, req=iv.len, got=dd.consumed
+  #    pivot, reqLen=iv.len, gotLen=dd.consumed.len
 
   block:
     let rc = ctx.data.snapDb.importAccounts(peer, stateRoot, iv.minPt, dd.data)
@@ -153,7 +169,7 @@ proc rangeFetchAccounts*(buddy: SnapBuddyRef) {.async.} =
       buddy.ctrl.zombie = true
       when extraTraceMessages:
         trace logTxt "import failed => stop", peer, gotAccounts, gotStorage,
-          stateRoot, req=iv.len, got=dd.consumed, error=rc.error
+          pivot, reqLen=iv.len, gotLen=dd.consumed.len, error=rc.error
       return
 
   # Statistics
@@ -184,9 +200,35 @@ proc rangeFetchAccounts*(buddy: SnapBuddyRef) {.async.} =
   # Store accounts on the storage TODO list.
   env.fetchStorage.merge dd.withStorage
 
+  return true
+
+# ------------------------------------------------------------------------------
+# Public functions
+# ------------------------------------------------------------------------------
+
+proc rangeFetchAccounts*(buddy: SnapBuddyRef) {.async.} =
+  ## Fetch accounts and store them in the database.
+  let numChunks = buddy.numChunks()
+  if 0 < numChunks:
+    let
+      ctx = buddy.ctx
+      peer = buddy.peer
+      env = buddy.data.pivotEnv
+      pivot = "#" & $env.stateHeader.blockNumber # for logging
+
+      nFetchLoopMax = max(ctx.buddiesMax + 1, numChunks) + addToFetchLoopMax
+
     when extraTraceMessages:
-    trace logTxt "done", peer, gotAccounts, gotStorage,
+      trace logTxt "start", peer, pivot, nFetchLoopMax
-      stateRoot, req=iv.len, got=dd.consumed
+
+    var nFetchAccounts = 0
+    while nFetchAccounts < nFetchLoopMax:
+      if not await buddy.accountsRagefetchImpl():
+        break
+      nFetchAccounts.inc
+
+    when extraTraceMessages:
+      trace logTxt "done", peer, pivot, nFetchAccounts, nFetchLoopMax
 
 # ------------------------------------------------------------------------------
 # End

nimbus/sync/snap/worker/range_fetch_storage_slots.nim

@@ -8,8 +8,8 @@
 # at your option. This file may not be copied, modified, or distributed
 # except according to those terms.
 
-## Fetch accounts stapshot
+## Fetch storage slots
-## =======================
+## ===================
 ##
 ## Flow chart for storage slots download
 ## -------------------------------------
@@ -39,6 +39,17 @@
 ## * `{completed}`: list is optimised out
 ## * `{partial}`: list is optimised out
 ##
+## Discussion
+## ----------
+## Handling storage slots can be seen as an generalisation of handling account
+## ranges (see `range_fetch_accounts` module.) Contrary to the situation with
+## accounts, storage slots are typically downloaded in the size of a full list
+## that can be expanded to a full hexary trie for the given storage root.
+##
+## Only in rare cases a storage slots list is incomplete, a partial hexary
+## trie. In that case, the list of storage slots is processed as described
+## for accounts (see `range_fetch_accounts` module.)
+##
 
 import
   chronicles,
@@ -47,7 +58,7 @@ import
   stew/[interval_set, keyed_queue],
   stint,
   ../../sync_desc,
-  ".."/[range_desc, worker_desc],
+  ".."/[constants, range_desc, worker_desc],
   ./com/[com_error, get_storage_ranges],
   ./db/snapdb_storage_slots
 
@@ -81,10 +92,10 @@ proc getNextSlotItems(
   ##   item. An explicit list of slots is only calculated if there was a queue
   ##   item with a partially completed slots download.
   ##
-  ## * Otherwise, a list of at most `maxStoragesFetch` work items is returned.
+  ## * Otherwise, a list of at most `snapStoragesSlotsFetchMax` work items is
-  ##   These work items were checked for that there was no trace of a previously
+  ##   returned. These work items were checked for that there was no trace of a
-  ##   installed (probably partial) storage trie on the database (e.g. inherited
+  ##   previously installed (probably partial) storage trie on the database
-  ##   from an earlier state root pivot.)
+  ##   (e.g. inherited from an earlier state root pivot.)
   ##
   ##   If there is an indication that the storage trie may have some data
   ##   already it is ignored here and marked `inherit` so that it will be
@@ -152,7 +163,7 @@ proc getNextSlotItems(
     env.fetchStorage.del(kvp.key) # ok to delete this item from batch queue
 
     # Maximal number of items to fetch
-    if maxStoragesFetch <= result.len:
+    if snapStoragesSlotsFetchMax <= result.len:
       break
 
   when extraTraceMessages:
@@ -170,6 +181,7 @@ proc storeStoragesSingleBatch(
     peer = buddy.peer
     env = buddy.data.pivotEnv
     stateRoot = env.stateHeader.stateRoot
+    pivot = "#" & $env.stateHeader.blockNumber # for logging
 
   # Fetch storage data and save it on disk. Storage requests are managed by
   # a request queue for handling partioal replies and re-fetch issues. For
@@ -182,26 +194,26 @@ proc storeStoragesSingleBatch(
 
   # Get storages slots data from the network
   var stoRange = block:
-    let rc = await buddy.getStorageRanges(stateRoot, req)
+    let rc = await buddy.getStorageRanges(stateRoot, req, pivot)
     if rc.isErr:
       env.fetchStorage.merge req
 
       let error = rc.error
       if await buddy.ctrl.stopAfterSeriousComError(error, buddy.data.errors):
         discard
-        trace logTxt "fetch error => stop", peer,
+        trace logTxt "fetch error => stop", peer, pivot,
           nSlotLists=env.nSlotLists, nReq=req.len,
           nStorageQueue=env.fetchStorage.len, error
       return
     rc.value
 
-  # Reset error counts for detecting repeated timeouts
+  # Reset error counts for detecting repeated timeouts, network errors, etc.
-  buddy.data.errors.nTimeouts = 0
+  buddy.data.errors.resetComError()
 
   var gotSlotLists = stoRange.data.storages.len
 
   #when extraTraceMessages:
-  #  trace logTxt "fetched", peer,
+  #  trace logTxt "fetched", peer, pivot,
   #    nSlotLists=env.nSlotLists, nSlotLists=gotSlotLists, nReq=req.len,
   #    nStorageQueue=env.fetchStorage.len, nLeftOvers=stoRange.leftOver.len
 
@@ -217,7 +229,7 @@ proc storeStoragesSingleBatch(
         env.fetchStorage.merge req
         gotSlotLists.dec(report.len - 1) # for logging only
 
-        error logTxt "import failed", peer,
+        error logTxt "import failed", peer, pivot,
           nSlotLists=env.nSlotLists, nSlotLists=gotSlotLists, nReq=req.len,
           nStorageQueue=env.fetchStorage.len, error=report[^1].error
         return
@@ -246,7 +258,7 @@ proc storeStoragesSingleBatch(
         # Update local statistics counter for `nSlotLists` counter update
         gotSlotLists.dec
 
-        trace logTxt "processing error", peer, nSlotLists=env.nSlotLists,
+        trace logTxt "processing error", peer, pivot, nSlotLists=env.nSlotLists,
           nSlotLists=gotSlotLists, nReqInx=inx, nReq=req.len,
           nStorageQueue=env.fetchStorage.len, error=report[inx].error
 
@@ -279,7 +291,8 @@ proc rangeFetchStorageSlots*(buddy: SnapBuddyRef) {.async.} =
   if 0 < env.fetchStorage.len:
     # Run at most the minimum number of times to get the batch queue cleaned up.
     var
-      fullRangeLoopCount = 1 + (env.fetchStorage.len - 1) div maxStoragesFetch
+      fullRangeLoopCount =
+        1 + (env.fetchStorage.len - 1) div snapStoragesSlotsFetchMax
       subRangeLoopCount = 0
 
     # Add additional counts for partial slot range items

nimbus/sync/snap/worker/ticker.nim

@@ -39,15 +39,15 @@ type
     ## Account fetching state that is shared among all peers.
     nBuddies:  int
     lastStats: TickerStats
-    lastTick:  uint64
     statsCb:   TickerStatsUpdater
     logTicker: TimerCallback
-    tick:      uint64 # more than 5*10^11y before wrap when ticking every sec
+    started:   Time
+    visited:   Time
 
 const
   tickerStartDelay = chronos.milliseconds(100)
   tickerLogInterval = chronos.seconds(1)
-  tickerLogSuppressMax = 100
+  tickerLogSuppressMax = initDuration(seconds = 100)
 
 # ------------------------------------------------------------------------------
 # Private functions: pretty printing
@@ -105,11 +105,13 @@ template noFmtError(info: static[string]; code: untyped) =
 proc setLogTicker(t: TickerRef; at: Moment) {.gcsafe.}
 
 proc runLogTicker(t: TickerRef) {.gcsafe.} =
-  let data = t.statsCb()
+  let
+    data = t.statsCb()
+    now = getTime().utc.toTime
 
-  if data != t.lastStats or t.lastTick + tickerLogSuppressMax < t.tick:
+  if data != t.lastStats or tickerLogSuppressMax < (now - t.visited):
     t.lastStats = data
-    t.lastTick = t.tick
+    t.visited = now
     var
       nAcc, nSto, bulk: string
       pivot = "n/a"
@@ -119,7 +121,9 @@ proc runLogTicker(t: TickerRef) {.gcsafe.} =
          "(" & data.accountsFill[1].toPC(0) & ")" &
          "/" & data.accountsFill[2].toPC(0)
       buddies = t.nBuddies
-      tick = t.tick.toSI
+
+      # With `int64`, there are more than 29*10^10 years range for seconds
+      up = (now - t.started).inSeconds.uint64.toSI
       mem = getTotalMem().uint.toSI
 
     noFmtError("runLogTicker"):
@@ -134,9 +138,8 @@ proc runLogTicker(t: TickerRef) {.gcsafe.} =
       nStoQue = $data.nStorageQueue.unsafeGet
 
     info "Snap sync statistics",
-      tick, buddies, pivot, nAcc, accCov, nSto, nStoQue, mem
+      up, buddies, pivot, nAcc, accCov, nSto, nStoQue, mem
 
-  t.tick.inc
   t.setLogTicker(Moment.fromNow(tickerLogInterval))
 
 
@@ -156,6 +159,8 @@ proc start*(t: TickerRef) =
   ## Re/start ticker unconditionally
   #debug "Started ticker"
   t.logTicker = safeSetTimer(Moment.fromNow(tickerStartDelay), runLogTicker, t)
+  if t.started == Time.default:
+    t.started = getTime().utc.toTime
 
 proc stop*(t: TickerRef) =
   ## Stop ticker unconditionally

nimbus/sync/snap/worker_desc.nim

@@ -19,60 +19,6 @@ import
 
 {.push raises: [Defect].}
 
-const
-  snapRequestBytesLimit* = 2 * 1024 * 1024
-    ## Soft bytes limit to request in `snap` protocol calls.
-
-  minPivotBlockDistance* = 128
-    ## The minimal depth of two block headers needed to activate a new state
-    ## root pivot.
-    ##
-    ## Effects on assembling the state via `snap/1` protocol:
-    ##
-    ## * A small value of this constant increases the propensity to update the
-    ##   pivot header more often. This is so because each new peer negoiates a
-    ##   pivot block number at least the current one.
-    ##
-    ## * A large value keeps the current pivot more stable but some experiments
-    ##   suggest that the `snap/1` protocol is answered only for later block
-    ##   numbers (aka pivot blocks.) So a large value tends to keep the pivot
-    ##   farther away from the chain head.
-    ##
-    ##   Note that 128 is the magic distance for snapshots used by *Geth*.
-
-  healAccountsTrigger* = 0.95
-    ## Apply accounts healing if the global snap download coverage factor
-    ## exceeds this setting. The global coverage factor is derived by merging
-    ## all account ranges retrieved for all pivot state roots (see
-    ## `coveredAccounts` in `CtxData`.)
-
-  healSlorageSlotsTrigger* = 0.70
-    ## Consider per account storage slost healing if this particular sub-trie
-    ## has reached this factor of completeness
-
-  maxStoragesFetch* = 5 * 1024
-    ## Maximal number of storage tries to fetch with a single message.
-
-  maxStoragesHeal* = 32
-    ## Maximal number of storage tries to to heal in a single batch run.
-
-  maxTrieNodeFetch* = 1024
-    ## Informal maximal number of trie nodes to fetch at once. This is nor
-    ## an official limit but found on several implementations (e.g. geth.)
-    ##
-    ## Resticting the fetch list length early allows to better paralellise
-    ## healing.
-
-  maxHealingLeafPaths* = 1024
-    ## Retrieve this many leave nodes with proper 32 bytes path when inspecting
-    ## for dangling nodes. This allows to run healing paralell to accounts or
-    ## storage download without requestinng an account/storage slot found by
-    ## healing again with the download.
-
-  noPivotEnvChangeIfComplete* = true
-    ## If set `true`, new peers will not change the pivot even if the
-    ## negotiated pivot would be newer. This should be the default.
-
 type
   SnapSlotsQueue* = KeyedQueue[Hash256,SnapSlotsQueueItemRef]
     ## Handles list of storage slots data for fetch indexed by storage root.
@@ -110,6 +56,13 @@ type
     ## Referenced object, so it can be made optional for the storage
     ## batch list
 
+  SnapHealingState* = enum
+    ## State of healing process. The `HealerRunning` state indicates that
+    ## dangling and/or missing nodes have been temprarily removed from the
+    ## batch queue while processing.
+    HealerIdle
+    HealerRunning
+    HealerDone
 
   SnapPivotRef* = ref object
     ## Per-state root cache for particular snap data environment
@@ -117,11 +70,11 @@ type
 
     # Accounts download
     fetchAccounts*: SnapTrieRangeBatch ## Set of accounts ranges to fetch
-    accountsDone*: bool                ## All accounts have been processed
+    accountsState*: SnapHealingState   ## All accounts have been processed
 
     # Storage slots download
     fetchStorage*: SnapSlotsQueue      ## Fetch storage for these accounts
-    serialSync*: bool                  ## Done with storage, block sync next
+    storageDone*: bool                 ## Done with storage, block sync next
 
     # Info
     nAccounts*: uint64                 ## Imported # of accounts
@@ -155,9 +108,6 @@ type
   SnapCtxRef* = CtxRef[CtxData]
     ## Extended global descriptor
 
-static:
-  doAssert healAccountsTrigger < 1.0 # larger values make no sense
-
 # ------------------------------------------------------------------------------
 # Public functions
 # ------------------------------------------------------------------------------

nimbus/sync/sync_sched.nim

@@ -161,7 +161,7 @@ proc workerLoop[S,W](buddy: RunnerBuddyRef[S,W]) {.async.} =
     discard dsc.buddies.lruFetch(peer.hash)
 
     # Allow task switch
-    await sleepAsync(50.milliseconds)
+    await sleepAsync(1.milliseconds)
     if worker.ctrl.stopped:
       break