nimbus-eth1/nimbus/db/kvt/kvt_delta.nim

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Nim

# nimbus-eth1
# Copyright (c) 2023-2024 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.
## Kvt DB -- Filter management
## ===========================
##
import
std/[sequtils, tables],
results,
./kvt_desc,
./kvt_desc/desc_backend,
./kvt_delta/[delta_merge, delta_reverse]
# ------------------------------------------------------------------------------
# Public functions
# ------------------------------------------------------------------------------
proc deltaPersistentOk*(db: KvtDbRef): bool =
## Check whether the balancer filter can be merged into the backend
not db.backend.isNil and db.isCentre
proc deltaPersistent*(
db: KvtDbRef, # Database
reCentreOk = false,
): Result[void, KvtError] =
## Resolve (i.e. move) the backend filter into the physical backend database.
##
## This needs write permission on the backend DB for the argument `db`
## descriptor (see the function `aristo_desc.isCentre()`.) With the argument
## flag `reCentreOk` passed `true`, write permission will be temporarily
## acquired when needed.
##
## Other non-centre descriptors are updated so there is no visible database
## change for these descriptors.
##
let be = db.backend
if be.isNil:
return err(FilBackendMissing)
# Blind or missing filter
if db.balancer.isNil:
return ok()
# Make sure that the argument `db` is at the centre so the backend is in
# read-write mode for this peer.
let parent = db.getCentre
if db != parent:
if not reCentreOk:
return err(FilBackendRoMode)
?db.reCentre()
# Always re-centre to `parent` (in case `reCentreOk` was set)
defer:
discard parent.reCentre()
# Update forked balancers here do that errors are detected early (if any.)
if 0 < db.nForked:
let rev = db.revFilter(db.balancer).valueOr:
return err(error[1])
if 0 < rev.sTab.len: # Can an empty `rev` happen at all?
var unsharedRevOk = true
for w in db.forked:
if not w.db.balancer.isValid:
unsharedRevOk = false
# The `rev` filter can be modified if one can make sure that it is
# not shared (i.e. only previously merged into the w.db.balancer.)
# Note that it is trivially true for a single fork.
let modLowerOk = w.isLast and unsharedRevOk
w.db.balancer =
deltaMerge(w.db.balancer, modUpperOk = false, rev, modLowerOk = modLowerOk)
# Store structural single trie entries
let writeBatch = ?be.putBegFn()
be.putKvpFn(writeBatch, db.balancer.sTab.pairs.toSeq)
?be.putEndFn writeBatch
# Done with balancer, all saved to backend
db.balancer = LayerRef(nil)
ok()
# ------------------------------------------------------------------------------
# End
# ------------------------------------------------------------------------------