nimbus-eth1/nimbus/db/aristo/aristo_tx.nim
Jacek Sieka 06a544ac85
Remove forkTx and friends (#2951)
The forking facility has been replaced by ForkedChain - frames and
layers are two other mechanisms that mostly do the same thing at the
aristo level, without quite providing the functionality FC needs - this
cleanup will make that integration easier.
2024-12-18 11:56:46 +01:00

140 lines
5.1 KiB
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.
## Aristo DB -- Transaction interface
## ==================================
##
{.push raises: [].}
import
results,
./aristo_tx/[tx_frame, tx_stow],
./aristo_desc
# ------------------------------------------------------------------------------
# Public functions, getters
# ------------------------------------------------------------------------------
func txTop*(db: AristoDbRef): Result[AristoTxRef,AristoError] =
## Getter, returns top level transaction if there is any.
db.txFrameTop()
func isTop*(tx: AristoTxRef): bool =
## Getter, returns `true` if the argument `tx` referes to the current top
## level transaction.
tx.txFrameIsTop()
func txLevel*(tx: AristoTxRef): int =
## Getter, positive nesting level of transaction argument `tx`
tx.txFrameLevel()
func level*(db: AristoDbRef): int =
## Getter, non-negative nesting level (i.e. number of pending transactions)
db.txFrameLevel()
# ------------------------------------------------------------------------------
# Public functions
# ------------------------------------------------------------------------------
func to*(tx: AristoTxRef; T: type[AristoDbRef]): T =
## Getter, retrieves the parent database descriptor from argument `tx`
tx.db
# ------------------------------------------------------------------------------
# Public functions: Transaction frame
# ------------------------------------------------------------------------------
proc txBegin*(db: AristoDbRef): Result[AristoTxRef,AristoError] =
## Starts a new transaction.
##
## Example:
## ::
## proc doSomething(db: AristoDbRef) =
## let tx = db.begin
## defer: tx.rollback()
## ... continue using db ...
## tx.commit()
##
db.txFrameBegin()
proc rollback*(
tx: AristoTxRef; # Top transaction on database
): Result[void,AristoError] =
## Given a *top level* handle, this function discards all database operations
## performed for this transactio. The previous transaction is returned if
## there was any.
##
tx.txFrameRollback()
proc commit*(
tx: AristoTxRef; # Top transaction on database
): Result[void,AristoError] =
## 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.
##
tx.txFrameCommit()
proc collapse*(
tx: AristoTxRef; # Top transaction on database
commit: bool; # Commit if `true`, otherwise roll back
): Result[void,AristoError] =
## Iterated application of `commit()` or `rollback()` performing the
## something similar to
## ::
## while true:
## discard tx.commit() # ditto for rollback()
## if db.txTop.isErr: break
## tx = db.txTop.value
##
tx.txFrameCollapse commit
# ------------------------------------------------------------------------------
# Public functions: save to database
# ------------------------------------------------------------------------------
proc persist*(
db: AristoDbRef; # Database
nxtSid = 0u64; # Next state ID (aka block number)
): Result[void,AristoError] =
## Persistently store data onto backend database. If the system is running
## without a database backend, the function returns immediately with an
## error. The same happens if there is a pending transaction.
##
## The function merges all staged data from the top layer cache onto the
## backend stage area. After that, the top layer cache is cleared.
##
## Finally, the staged data are merged into the physical backend database
## and the staged data area is cleared. Wile performing this last step,
## the recovery journal is updated (if available.)
##
## If the argument `nxtSid` is passed non-zero, it will be the ID for the
## next recovery journal record. If non-zero, this ID must be greater than
## all previous IDs (e.g. block number when stowing after block execution.)
##
db.txStow(nxtSid, persistent=true)
proc stow*(
db: AristoDbRef; # Database
): Result[void,AristoError] =
## This function is similar to `persist()` stopping short of performing the
## final step storing on the persistent database. It fails if there is a
## pending transaction.
##
## The function merges all staged data from the top layer cache onto the
## backend stage area and leaves it there. This function can be seen as
## a sort of a bottom level transaction `commit()`.
##
db.txStow(nxtSid=0u64, persistent=false)
# ------------------------------------------------------------------------------
# End
# ------------------------------------------------------------------------------