271 lines
7.7 KiB
Nim
271 lines
7.7 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.
|
|
|
|
## Kvt DB -- Transaction interface
|
|
## ===============================
|
|
##
|
|
{.push raises: [].}
|
|
|
|
import
|
|
std/[sequtils, tables],
|
|
eth/common,
|
|
results,
|
|
./kvt_desc/desc_backend,
|
|
"."/[kvt_desc, kvt_layers]
|
|
|
|
func isTop*(tx: KvtTxRef): bool
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# Private helpers
|
|
# ------------------------------------------------------------------------------
|
|
|
|
func getDbDescFromTopTx(tx: KvtTxRef): Result[KvtDbRef,KvtError] =
|
|
if not tx.isTop():
|
|
return err(TxNotTopTx)
|
|
let db = tx.db
|
|
if tx.level != db.stack.len:
|
|
return err(TxStackUnderflow)
|
|
ok db
|
|
|
|
proc getTxUid(db: KvtDbRef): uint =
|
|
if db.txUidGen == high(uint):
|
|
db.txUidGen = 0
|
|
db.txUidGen.inc
|
|
db.txUidGen
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# Public functions, getters
|
|
# ------------------------------------------------------------------------------
|
|
|
|
func txTop*(db: KvtDbRef): Result[KvtTxRef,KvtError] =
|
|
## Getter, returns top level transaction if there is any.
|
|
if db.txRef.isNil:
|
|
err(TxNoPendingTx)
|
|
else:
|
|
ok(db.txRef)
|
|
|
|
func isTop*(tx: KvtTxRef): bool =
|
|
## Getter, returns `true` if the argument `tx` referes to the current top
|
|
## level transaction.
|
|
tx.db.txRef == tx and tx.db.top.txUid == tx.txUid
|
|
|
|
func level*(tx: KvtTxRef): int =
|
|
## Getter, positive nesting level of transaction argument `tx`
|
|
tx.level
|
|
|
|
func level*(db: KvtDbRef): int =
|
|
## Getter, non-negative nesting level (i.e. number of pending transactions)
|
|
if not db.txRef.isNil:
|
|
result = db.txRef.level
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# Public functions
|
|
# ------------------------------------------------------------------------------
|
|
|
|
func to*(tx: KvtTxRef; T: type[KvtDbRef]): T =
|
|
## Getter, retrieves the parent database descriptor from argument `tx`
|
|
tx.db
|
|
|
|
proc forkTx*(tx: KvtTxRef): Result[KvtDbRef,KvtError] =
|
|
## Clone a transaction into a new DB descriptor accessing the same backend
|
|
## (if any) database as the argument `db`. The new descriptor is linked to
|
|
## the transaction parent and is fully functional as a forked instance (see
|
|
## comments on `kvt_desc.reCentre()` for details.)
|
|
##
|
|
## The new DB descriptor will contain a copy of the argument transaction
|
|
## `tx` as top layer of level 1 (i.e. this is he only transaction.) Rolling
|
|
## back will end up at the backend layer (incl. backend filter.)
|
|
##
|
|
## Use `kvt_desc.forget()` to clean up this descriptor.
|
|
##
|
|
let db = tx.db
|
|
|
|
# Verify `tx` argument
|
|
if db.txRef == tx:
|
|
if db.top.txUid != tx.txUid:
|
|
return err(TxArgStaleTx)
|
|
elif db.stack.len <= tx.level:
|
|
return err(TxArgStaleTx)
|
|
elif db.stack[tx.level].txUid != tx.txUid:
|
|
return err(TxArgStaleTx)
|
|
|
|
# Set up clone associated to `db`
|
|
let txClone = ? db.fork()
|
|
txClone.top = db.layersCc tx.level
|
|
txClone.stack = @[LayerRef()] # Provide tx level 1 stack
|
|
txClone.top.txUid = 1
|
|
txClone.txUidGen = 1 # Used value of `txClone.top.txUid`
|
|
|
|
# Install transaction similar to `tx` on clone
|
|
txClone.txRef = KvtTxRef(
|
|
db: txClone,
|
|
txUid: 1,
|
|
level: 1)
|
|
|
|
ok(txClone)
|
|
|
|
proc forkTop*(db: KvtDbRef): Result[KvtDbRef,KvtError] =
|
|
## Variant of `forkTx()` for the top transaction if there is any. Otherwise
|
|
## the top layer is cloned, only.
|
|
##
|
|
## Use `kvt_desc.forget()` to clean up this descriptor.
|
|
##
|
|
if db.txRef.isNil:
|
|
let dbClone = ? db.fork()
|
|
dbClone.top = db.layersCc
|
|
return ok(dbClone)
|
|
|
|
db.txRef.forkTx()
|
|
|
|
|
|
proc exec*(
|
|
tx: KvtTxRef;
|
|
action: KvtDbAction;
|
|
): Result[void,KvtError] =
|
|
## Execute function argument `action()` on a temporary `tx.forkTx()`
|
|
## transaction database. After return, the temporary database gets
|
|
## destroyed.
|
|
##
|
|
let db = ? tx.forkTx()
|
|
db.action()
|
|
? db.forget()
|
|
ok()
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# Public functions: Transaction frame
|
|
# ------------------------------------------------------------------------------
|
|
|
|
proc txBegin*(db: KvtDbRef): Result[KvtTxRef,KvtError] =
|
|
## Starts a new transaction.
|
|
##
|
|
## Example:
|
|
## ::
|
|
## proc doSomething(db: KvtDbRef) =
|
|
## let tx = db.begin
|
|
## defer: tx.rollback()
|
|
## ... continue using db ...
|
|
## tx.commit()
|
|
##
|
|
if db.level != db.stack.len:
|
|
return err(TxStackGarbled)
|
|
|
|
db.stack.add db.top
|
|
db.top = LayerRef(txUid: db.getTxUid)
|
|
db.txRef = KvtTxRef(
|
|
db: db,
|
|
txUid: db.top.txUid,
|
|
parent: db.txRef,
|
|
level: db.stack.len)
|
|
|
|
ok db.txRef
|
|
|
|
proc rollback*(
|
|
tx: KvtTxRef; # Top transaction on database
|
|
): Result[void,KvtError] =
|
|
## Given a *top level* handle, this function discards all database operations
|
|
## performed for this transactio. The previous transaction is returned if
|
|
## there was any.
|
|
##
|
|
let db = ? tx.getDbDescFromTopTx()
|
|
|
|
# Roll back to previous layer.
|
|
db.top = db.stack[^1]
|
|
db.stack.setLen(db.stack.len-1)
|
|
|
|
db.txRef = tx.parent
|
|
ok()
|
|
|
|
|
|
proc commit*(
|
|
tx: KvtTxRef; # Top transaction on database
|
|
): Result[void,KvtError] =
|
|
## Given a *top level* handle, this function accepts all database operations
|
|
## performed through this handle and merges it to the previous layer. The
|
|
## previous transaction is returned if there was any.
|
|
##
|
|
let db = ? tx.getDbDescFromTopTx()
|
|
|
|
# Replace the top two layers by its merged version
|
|
let merged = db.stack[^1]
|
|
for (key,val) in db.top.delta.sTab.pairs:
|
|
merged.delta.sTab[key] = val
|
|
|
|
# Install `merged` layer
|
|
db.top = merged
|
|
db.stack.setLen(db.stack.len-1)
|
|
db.txRef = tx.parent
|
|
if 0 < db.stack.len:
|
|
db.txRef.txUid = db.getTxUid
|
|
db.top.txUid = db.txRef.txUid
|
|
|
|
ok()
|
|
|
|
|
|
proc collapse*(
|
|
tx: KvtTxRef; # Top transaction on database
|
|
commit: bool; # Commit if `true`, otherwise roll back
|
|
): Result[void,KvtError] =
|
|
## Iterated application of `commit()` or `rollback()` performing the
|
|
## something similar to
|
|
## ::
|
|
## while true:
|
|
## discard tx.commit() # ditto for rollback()
|
|
## if db.topTx.isErr: break
|
|
## tx = db.topTx.value
|
|
##
|
|
let db = ? tx.getDbDescFromTopTx()
|
|
|
|
if commit:
|
|
db.top = db.layersCc
|
|
else:
|
|
db.top = db.stack[0]
|
|
db.top.txUid = 0
|
|
|
|
# Clean up
|
|
db.stack.setLen(0)
|
|
db.txRef = KvtTxRef(nil)
|
|
ok()
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# Public functions: save database
|
|
# ------------------------------------------------------------------------------
|
|
|
|
proc stow*(
|
|
db: KvtDbRef; # Database
|
|
): Result[void,KvtError] =
|
|
## The function saves the data from the top layer cache into the
|
|
## backend database.
|
|
##
|
|
## If there is no backend the function returns immediately with an error.
|
|
## The same happens if there is a pending transaction.
|
|
##
|
|
if not db.txRef.isNil:
|
|
return err(TxPendingTx)
|
|
if 0 < db.stack.len:
|
|
return err(TxStackGarbled)
|
|
|
|
let be = db.backend
|
|
if be.isNil:
|
|
return err(TxBackendNotWritable)
|
|
|
|
# Save structural and other table entries
|
|
let txFrame = be.putBegFn()
|
|
be.putKvpFn(txFrame, db.top.delta.sTab.pairs.toSeq)
|
|
? be.putEndFn txFrame
|
|
|
|
# Clean up
|
|
db.top.delta.sTab.clear
|
|
|
|
ok()
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# End
|
|
# ------------------------------------------------------------------------------
|