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

121 lines
4.3 KiB
Nim

# nimbus-eth1
# Copyright (c) 2023 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: [].}
import
std/[algorithm, sequtils, sets, tables],
eth/common,
results,
./kvt_desc
# ------------------------------------------------------------------------------
# Public getters/helpers
# ------------------------------------------------------------------------------
func nLayersKeys*(db: KvtDbRef): int =
## Maximum number of ley/value entries on the cache layers. This is an upper
## bound for the number of effective key/value mappings held on the cache
## layers as there might be duplicate entries for the same key on different
## layers.
db.stack.mapIt(it.delta.sTab.len).foldl(a + b, db.top.delta.sTab.len)
# ------------------------------------------------------------------------------
# Public functions: get function
# ------------------------------------------------------------------------------
proc layersHasKey*(db: KvtDbRef; key: openArray[byte]): bool =
## Return `true` id the argument key is cached.
##
if db.top.delta.sTab.hasKey @key:
return true
for w in db.stack.reversed:
if w.delta.sTab.hasKey @key:
return true
proc layersGet*(db: KvtDbRef; key: openArray[byte]): Result[Blob,void] =
## Find an item on the cache layers. An `ok()` result might contain an
## empty value if it is stored on the cache that way.
##
if db.top.delta.sTab.hasKey @key:
return ok(db.top.delta.sTab.getOrVoid @key)
for w in db.stack.reversed:
if w.delta.sTab.hasKey @key:
return ok(w.delta.sTab.getOrVoid @key)
err()
# ------------------------------------------------------------------------------
# Public functions: put function
# ------------------------------------------------------------------------------
proc layersPut*(db: KvtDbRef; key: openArray[byte]; data: openArray[byte]) =
## Store a (potentally empty) value on the top layer
db.top.delta.sTab[@key] = @data
# ------------------------------------------------------------------------------
# Public functions
# ------------------------------------------------------------------------------
proc layersCc*(db: KvtDbRef; level = high(int)): LayerRef =
## Provide a collapsed copy of layers up to a particular transaction level.
## If the `level` argument is too large, the maximum transaction level is
## returned. For the result layer, the `txUid` value set to `0`.
let layers = if db.stack.len <= level: db.stack & @[db.top]
else: db.stack[0 .. level]
# Set up initial layer (bottom layer)
result = LayerRef(delta: LayerDelta(sTab: layers[0].delta.sTab))
# Consecutively merge other layers on top
for n in 1 ..< layers.len:
for (key,val) in layers[n].delta.sTab.pairs:
result.delta.sTab[key] = val
# ------------------------------------------------------------------------------
# Public iterators
# ------------------------------------------------------------------------------
iterator layersWalk*(
db: KvtDbRef;
seen: var HashSet[Blob];
): tuple[key: Blob, data: Blob] =
## Walk over all key-value pairs on the cache layers. Note that
## entries are unsorted.
##
## The argument `seen` collects a set of all visited vertex IDs including
## the one with a zero vertex which are othewise skipped by the iterator.
## The `seen` argument must not be modified while the iterator is active.
##
for (key,val) in db.top.delta.sTab.pairs:
yield (key,val)
seen.incl key
for w in db.stack.reversed:
for (key,val) in w.delta.sTab.pairs:
if key notin seen:
yield (key,val)
seen.incl key
iterator layersWalk*(
db: KvtDbRef;
): tuple[key: Blob, data: Blob] =
## Variant of `layersWalk()`.
var seen: HashSet[Blob]
for (key,val) in db.layersWalk seen:
yield (key,val)
# ------------------------------------------------------------------------------
# End
# ------------------------------------------------------------------------------