nimbus-eth2/beacon_chain/kvstore.nim

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# Simple Key-Value store database interface
import
tables, hashes, sets
type
MemoryStoreRef* = ref object of RootObj
records: Table[seq[byte], seq[byte]]
DataProc* = proc(val: openArray[byte])
PutProc = proc (db: RootRef, key, val: openArray[byte]) {.gcsafe.}
GetProc = proc (db: RootRef, key: openArray[byte], onData: DataProc): bool {.gcsafe.}
DelProc = proc (db: RootRef, key: openArray[byte]) {.gcsafe.}
ContainsProc = proc (db: RootRef, key: openArray[byte]): bool {.gcsafe.}
KVStoreRef* = ref object
## Key-Value store virtual interface
obj: RootRef
putProc: PutProc
getProc: GetProc
delProc: DelProc
containsProc: ContainsProc
template put*(db: KVStoreRef, key, val: openArray[byte]) =
## Store ``value`` at ``key`` - overwrites existing value if already present
db.putProc(db.obj, key, val)
template get*(db: KVStoreRef, key: openArray[byte], onData: untyped): bool =
## Retrive value at ``key`` and call ``onData`` with the value. The data is
## valid for the duration of the callback.
## ``onData``: ``proc(data: openArray[byte])``
## returns true if found and false otherwise.
db.getProc(db.obj, key, onData)
template del*(db: KVStoreRef, key: openArray[byte]) =
## Remove value at ``key`` from store - do nothing if the value is not present
db.delProc(db.obj, key)
template contains*(db: KVStoreRef, key: openArray[byte]): bool =
## Return true iff ``key`` has a value in store
db.containsProc(db.obj, key)
proc get*(db: MemoryStoreRef, key: openArray[byte], onData: DataProc): bool =
let key = @key
db.records.withValue(key, v):
onData(v[])
return true
proc del*(db: MemoryStoreRef, key: openArray[byte]) =
# TODO: This is quite inefficient and it won't be necessary once
# https://github.com/nim-lang/Nim/issues/7457 is developed.
let key = @key
db.records.del(key)
proc contains*(db: MemoryStoreRef, key: openArray[byte]): bool =
db.records.contains(@key)
proc put*(db: MemoryStoreRef, key, val: openArray[byte]) =
# TODO: This is quite inefficient and it won't be necessary once
# https://github.com/nim-lang/Nim/issues/7457 is developed.
let key = @key
db.records[key] = @val
proc init*(T: type MemoryStoreRef): T =
T(
records: initTable[seq[byte], seq[byte]]()
)
proc putImpl[T](db: RootRef, key, val: openArray[byte]) =
mixin put
put(T(db), key, val)
proc getImpl[T](db: RootRef, key: openArray[byte], onData: DataProc): bool =
mixin get
get(T(db), key, onData)
proc delImpl[T](db: RootRef, key: openArray[byte]) =
mixin del
del(T(db), key)
proc containsImpl[T](db: RootRef, key: openArray[byte]): bool =
mixin contains
contains(T(db), key)
func kvStore*[T: RootRef](x: T): KVStoreRef =
mixin del, get, put, contains
KVStoreRef(
obj: x,
putProc: putImpl[T],
getProc: getImpl[T],
delProc: delImpl[T],
containsProc: containsImpl[T]
)