mirror of
https://github.com/status-im/nimbus-eth1.git
synced 2025-01-10 04:15:54 +00:00
71c91e2280
* Better error handling why: Bail out on some error as early as possible before any changes. * Implement `fetch()` as opposite of `merge()` rationale: In the `Aristo` realm, the action named `fetch()` and `merge()` indicate leaf value related actions on the MPT, while actions `get()` and `put()` handle vertex or hash key related operations that constitute the MPT. * Re-factor `merge()` prototypes why: The most used variant of `merge()` should have the simplest prototype. * Persistent DB constructor needs to import `aristo/aristo_init/persistent` why: Most applications use memory DB anyway. This avoids linking `-lrocksdb` or any other back end libraries by default. * Re-factor transaction module why: Got the paradigm wrong. The transaction descriptor did replace the database one but should be handled separately.
290 lines
8.7 KiB
Nim
290 lines
8.7 KiB
Nim
# nimbus-eth1
|
|
# Copyright (c) 2021 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_desc, aristo_layer]
|
|
|
|
type
|
|
AristoTxAction* = proc() {.gcsafe, raises: [CatchableError].}
|
|
|
|
const
|
|
TxUidLocked = high(uint) div 2
|
|
## The range of valid transactions of is roughly `high(int)`. For
|
|
## normal transactions, the lower range is applied while for restricted
|
|
## transactions used with `execute()` below, the higher range is used.
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# Private helpers
|
|
# ------------------------------------------------------------------------------
|
|
|
|
proc backup(db: AristoDbRef): AristoDbRef =
|
|
AristoDbRef(
|
|
top: db.top, # ref
|
|
stack: db.stack, # sequence of refs
|
|
history: db.history, # sequence of refs
|
|
txRef: db.txRef, # ref
|
|
txUidGen: db.txUidGen) # number
|
|
|
|
proc restore(db: AristoDbRef, backup: AristoDbRef) =
|
|
db.top = backup.top
|
|
db.stack = backup.stack
|
|
db.history = backup.history
|
|
db.txRef = backup.txRef
|
|
db.txUidGen = backup.txUidGen
|
|
|
|
proc cpy(layer: AristoLayerRef): AristoLayerRef =
|
|
new result
|
|
result[] = layer[]
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# Private functions
|
|
# ------------------------------------------------------------------------------
|
|
|
|
proc getTxUid(db: AristoDbRef): uint =
|
|
if db.txUidGen < TxUidLocked:
|
|
if db.txUidGen == TxUidLocked - 1:
|
|
db.txUidGen = 0
|
|
else:
|
|
if db.txUidGen == high(uint):
|
|
db.txUidGen = TxUidLocked
|
|
db.txUidGen.inc
|
|
db.txUidGen
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# Public functions, getters
|
|
# ------------------------------------------------------------------------------
|
|
|
|
proc txTop*(db: AristoDbRef): Result[AristoTxRef,AristoError] =
|
|
## Getter, returns top level transaction if there is any.
|
|
if db.txRef.isNil:
|
|
err(TxNoPendingTx)
|
|
else:
|
|
ok(db.txRef)
|
|
|
|
proc isTop*(tx: AristoTxRef): 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
|
|
|
|
proc level*(tx: AristoTxRef): int =
|
|
## Getter, non-negaitve transaction nesting level
|
|
var tx = tx
|
|
while tx.parent != AristoTxRef(nil):
|
|
tx = tx.parent
|
|
result.inc
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# Public functions
|
|
# ------------------------------------------------------------------------------
|
|
|
|
proc to*(tx: AristoTxRef; T: type[AristoDbRef]): T =
|
|
## Getter, retrieves the parent database descriptor
|
|
tx.db
|
|
|
|
proc rebase*(tx: AristoTxRef): Result[void,AristoError] =
|
|
## Revert transaction stack to an earlier point in time.
|
|
if not tx.isTop():
|
|
let
|
|
db = tx.db
|
|
inx = tx.stackInx
|
|
if db.stack.len <= inx or db.stack[inx].txUid != tx.txUid:
|
|
return err(TxArgStaleTx)
|
|
# Roll back to some earlier layer.
|
|
db.top = db.stack[inx]
|
|
db.stack.setLen(inx)
|
|
ok()
|
|
|
|
proc exec*(
|
|
tx: AristoTxRef;
|
|
action: AristoTxAction;
|
|
): Result[void,AristoError]
|
|
{.gcsafe, raises: [CatchableError].} =
|
|
## Execute function argument `action()` on a transaction `tx` which might
|
|
## refer to an earlier one. There are some restrictions on the database
|
|
## `tx` referres to which might have been captured by the `action` closure.
|
|
##
|
|
## Restrictions:
|
|
## * For the argument transaction `tx`, the expressions `tx.commit()` or
|
|
## `tx.rollack()` will throw an `AssertDefect` error.
|
|
## * The `ececute()` call must not be nested. Doing otherwise will throw an
|
|
## `AssertDefect` error.
|
|
## * Changes on the database referred to by `tx` cannot be saved on disk with
|
|
## the `persistent()` directive.
|
|
##
|
|
## After return, the state of the underlying database will not have changed.
|
|
## Any transactions left open by the `action()` call will have been discarded.
|
|
##
|
|
## So these restrictions amount to sort of a temporary *read-only* mode for
|
|
## the underlying database.
|
|
##
|
|
if TxUidLocked <= tx.txUid:
|
|
return err(TxExecNestingAttempt)
|
|
|
|
# Move current DB to a backup copy
|
|
let
|
|
db = tx.db
|
|
saved = db.backup
|
|
|
|
# Install transaction layer
|
|
if not tx.isTop():
|
|
if db.stack.len <= tx.stackInx:
|
|
return err(TxArgStaleTx)
|
|
db.top[] = db.stack[tx.stackInx][] # deep copy
|
|
|
|
db.top.txUid = TxUidLocked
|
|
db.stack = @[AristoLayerRef()]
|
|
db.txUidGen = TxUidLocked
|
|
db.txRef = AristoTxRef(db: db, txUid: TxUidLocked, stackInx: 1)
|
|
|
|
# execute action
|
|
action()
|
|
|
|
# restore
|
|
db.restore saved
|
|
ok()
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# Public functions: Transaction frame
|
|
# ------------------------------------------------------------------------------
|
|
|
|
proc txBegin*(db: AristoDbRef): AristoTxRef =
|
|
## Starts a new transaction.
|
|
##
|
|
## Example:
|
|
## ::
|
|
## proc doSomething(db: AristoDbRef) =
|
|
## let tx = db.begin
|
|
## defer: tx.rollback()
|
|
## ... continue using db ...
|
|
## tx.commit()
|
|
##
|
|
db.stack.add db.top.cpy # push (save and use top later)
|
|
db.top.txUid = db.getTxUid()
|
|
|
|
db.txRef = AristoTxRef(
|
|
db: db,
|
|
txUid: db.top.txUid,
|
|
parent: db.txRef,
|
|
stackInx: db.stack.len)
|
|
db.txRef
|
|
|
|
|
|
proc rollback*(tx: AristoTxRef): 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.
|
|
##
|
|
## This function will throw a `AssertionDefect` exception unless `tx` is the
|
|
## top level transaction descriptor and the layer stack was not maipulated
|
|
## externally.
|
|
if not tx.isTop():
|
|
return err(TxNotTopTx)
|
|
if tx.txUid == TxUidLocked:
|
|
return err(TxExecBaseTxLocked)
|
|
|
|
let db = tx.db
|
|
if db.stack.len == 0:
|
|
return err(TxStackUnderflow)
|
|
|
|
# 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: AristoTxRef): 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.
|
|
##
|
|
## This function will throw a `AssertionDefect` exception unless `tx` is the
|
|
## top level transaction descriptor and the layer stack was not maipulated
|
|
## externally.
|
|
if not tx.isTop():
|
|
return err(TxNotTopTx)
|
|
if tx.txUid == TxUidLocked:
|
|
return err(TxExecBaseTxLocked)
|
|
|
|
let db = tx.db
|
|
if db.stack.len == 0:
|
|
return err(TxStackUnderflow)
|
|
|
|
# Keep top and discard layer below
|
|
db.top.txUid = db.stack[^1].txUid
|
|
db.stack.setLen(db.stack.len-1)
|
|
|
|
db.txRef = tx.parent
|
|
ok()
|
|
|
|
|
|
proc collapse*(
|
|
tx: AristoTxRef; # Database, transaction wrapper
|
|
commit: bool; # Commit is `true`, otherwise roll back
|
|
): Result[void,AristoError] =
|
|
## Iterated application of `commit()` or `rollback()` performing the
|
|
## something similar to
|
|
## ::
|
|
## if tx.isTop():
|
|
## while true:
|
|
## discard tx.commit() # ditto for rollback()
|
|
## if db.topTx.isErr: break
|
|
## tx = db.topTx.value
|
|
##
|
|
if not tx.isTop():
|
|
return err(TxNotTopTx)
|
|
if tx.txUid == TxUidLocked:
|
|
return err(TxExecBaseTxLocked)
|
|
|
|
# Get the first transaction
|
|
var txBase = tx
|
|
while txBase.parent != AristoTxRef(nil):
|
|
txBase = txBase.parent
|
|
|
|
let
|
|
db = tx.db
|
|
inx = txBase.stackInx-1
|
|
|
|
if commit:
|
|
# If commit, then leave the current layer and clear the stack
|
|
db.top.txUid = 0
|
|
else:
|
|
# Otherwise revert to previous layer from stack
|
|
db.top = db.stack[inx]
|
|
|
|
db.stack.setLen(inx)
|
|
ok()
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# Public functions: save database
|
|
# ------------------------------------------------------------------------------
|
|
|
|
proc persistent*(db: AristoDbRef): Result[void,AristoError] =
|
|
## ...
|
|
let noTxPending = db.txRef.isNil
|
|
if not noTxPending and TxUidLocked <= db.txRef.txUid:
|
|
return err(TxExecDirectiveLocked)
|
|
|
|
let rc = db.save()
|
|
if rc.isErr:
|
|
return err(rc.error[1])
|
|
|
|
ok()
|
|
|
|
# ------------------------------------------------------------------------------
|
|
# End
|
|
# ------------------------------------------------------------------------------
|