346 lines
10 KiB
Nim
346 lines
10 KiB
Nim
# nimbus-eth1
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# Copyright (c) 2023 Status Research & Development GmbH
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# Licensed under either of
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# * Apache License, version 2.0, ([LICENSE-APACHE](LICENSE-APACHE) or
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# http://www.apache.org/licenses/LICENSE-2.0)
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# * MIT license ([LICENSE-MIT](LICENSE-MIT) or
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# http://opensource.org/licenses/MIT)
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# at your option. This file may not be copied, modified, or distributed
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# except according to those terms.
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## Aristo DB -- Transaction interface
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## ==================================
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##
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{.push raises: [].}
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import
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results,
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"."/[aristo_desc, aristo_filter, aristo_get, aristo_layers, aristo_hashify]
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func isTop*(tx: AristoTxRef): bool
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func level*(db: AristoDbRef): int
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# ------------------------------------------------------------------------------
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# Private helpers
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# ------------------------------------------------------------------------------
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func getDbDescFromTopTx(tx: AristoTxRef): Result[AristoDbRef,AristoError] =
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if not tx.isTop():
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return err(TxNotTopTx)
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let db = tx.db
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if tx.level != db.stack.len:
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return err(TxStackGarbled)
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ok db
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proc getTxUid(db: AristoDbRef): uint =
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if db.txUidGen == high(uint):
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db.txUidGen = 0
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db.txUidGen.inc
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db.txUidGen
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# ------------------------------------------------------------------------------
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# Public functions, getters
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# ------------------------------------------------------------------------------
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func txTop*(db: AristoDbRef): Result[AristoTxRef,AristoError] =
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## Getter, returns top level transaction if there is any.
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if db.txRef.isNil:
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err(TxNoPendingTx)
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else:
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ok(db.txRef)
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func isTop*(tx: AristoTxRef): bool =
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## Getter, returns `true` if the argument `tx` referes to the current top
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## level transaction.
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tx.db.txRef == tx and tx.db.top.txUid == tx.txUid
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func level*(tx: AristoTxRef): int =
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## Getter, positive nesting level of transaction argument `tx`
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tx.level
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func level*(db: AristoDbRef): int =
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## Getter, non-negative nesting level (i.e. number of pending transactions)
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if not db.txRef.isNil:
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result = db.txRef.level
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# ------------------------------------------------------------------------------
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# Public functions
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# ------------------------------------------------------------------------------
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func to*(tx: AristoTxRef; T: type[AristoDbRef]): T =
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## Getter, retrieves the parent database descriptor from argument `tx`
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tx.db
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proc forkTx*(
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tx: AristoTxRef; # Transaction descriptor
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dontHashify = false; # Process/fix MPT hashes
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): Result[AristoDbRef,AristoError] =
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## Clone a transaction into a new DB descriptor accessing the same backend
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## database (if any) as the argument `db`. The new descriptor is linked to
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## the transaction parent and is fully functional as a forked instance (see
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## comments on `aristo_desc.reCentre()` for details.)
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##
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## Input situation:
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## ::
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## tx -> db0 with tx is top transaction, tx.level > 0
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##
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## Output situation:
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## ::
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## tx -> db0 \
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## > share the same backend
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## tx1 -> db1 /
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##
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## where `tx.level > 0`, `db1.level == 1` and `db1` is returned. The
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## transaction `tx1` can be retrieved via `db1.txTop()`.
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##
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## The new DB descriptor will contain a copy of the argument transaction
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## `tx` as top layer of level 1 (i.e. this is he only transaction.) Rolling
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## back will end up at the backend layer (incl. backend filter.)
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##
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## If the arguent flag `dontHashify` is passed `true`, the clone descriptor
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## will *NOT* be hashified right after construction.
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##
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## Use `aristo_desc.forget()` to clean up this descriptor.
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##
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let db = tx.db
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# Verify `tx` argument
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if db.txRef == tx:
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if db.top.txUid != tx.txUid:
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return err(TxArgStaleTx)
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elif db.stack.len <= tx.level:
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return err(TxArgStaleTx)
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elif db.stack[tx.level].txUid != tx.txUid:
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return err(TxArgStaleTx)
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# Provide new empty stack layer
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let stackLayer = block:
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let rc = db.getIdgBE()
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if rc.isOk:
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LayerRef(final: LayerFinal(vGen: rc.value))
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elif rc.error == GetIdgNotFound:
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LayerRef()
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else:
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return err(rc.error)
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# Set up clone associated to `db`
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let txClone = ? db.fork(rawToplayer = true)
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txClone.top = db.layersCc tx.level # Provide tx level 1 stack
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txClone.stack = @[stackLayer] # Zero level stack
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txClone.roFilter = db.roFilter # No need to copy (done when updated)
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txClone.backend = db.backend
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txClone.top.txUid = 1
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txClone.txUidGen = 1
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# Install transaction similar to `tx` on clone
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txClone.txRef = AristoTxRef(
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db: txClone,
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txUid: 1,
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level: 1)
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if not dontHashify:
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discard txClone.hashify().valueOr:
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discard txClone.forget()
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return err(error[1])
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ok(txClone)
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proc forkTop*(
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db: AristoDbRef;
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dontHashify = false; # Process/fix MPT hashes
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): Result[AristoDbRef,AristoError] =
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## Variant of `forkTx()` for the top transaction if there is any. Otherwise
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## the top layer is cloned, only.
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##
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## Use `aristo_desc.forget()` to clean up this descriptor.
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##
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if db.txRef.isNil:
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let dbClone = ? db.fork(rawToplayer = true)
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dbClone.top = db.layersCc # Is a deep copy
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dbClone.roFilter = db.roFilter # No need to copy contents when updated
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dbClone.backend = db.backend
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if not dontHashify:
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discard dbClone.hashify().valueOr:
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discard dbClone.forget()
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return err(error[1])
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return ok(dbClone)
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db.txRef.forkTx dontHashify
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proc exec*(
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tx: AristoTxRef;
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action: AristoDbAction;
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dontHashify = false; # Process/fix MPT hashes
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): Result[void,AristoError] =
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## Execute function argument `action()` on a temporary `tx.forkTx()`
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## transaction clone database. After return, the temporary database gets
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## destroyed.
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##
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## If the arguent flag `dontHashify` is passed `true`, the clone database
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## will *NOT* be hashified right after construction.
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##
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let db = ? tx.forkTx dontHashify
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db.action()
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? db.forget()
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ok()
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# ------------------------------------------------------------------------------
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# Public functions: Transaction frame
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# ------------------------------------------------------------------------------
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proc txBegin*(db: AristoDbRef): Result[AristoTxRef,AristoError] =
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## Starts a new transaction.
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##
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## Example:
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## ::
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## proc doSomething(db: AristoDbRef) =
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## let tx = db.begin
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## defer: tx.rollback()
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## ... continue using db ...
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## tx.commit()
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##
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if db.level != db.stack.len:
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return err(TxStackGarbled)
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db.stack.add db.top
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db.top = LayerRef(
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final: db.top.final,
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txUid: db.getTxUid)
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db.txRef = AristoTxRef(
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db: db,
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txUid: db.top.txUid,
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parent: db.txRef,
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level: db.stack.len)
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ok db.txRef
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proc rollback*(
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tx: AristoTxRef; # Top transaction on database
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): Result[void,AristoError] =
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## Given a *top level* handle, this function discards all database operations
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## performed for this transactio. The previous transaction is returned if
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## there was any.
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##
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let db = ? tx.getDbDescFromTopTx()
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# Roll back to previous layer.
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db.top = db.stack[^1]
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db.stack.setLen(db.stack.len-1)
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db.txRef = db.txRef.parent
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ok()
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proc commit*(
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tx: AristoTxRef; # Top transaction on database
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): Result[void,AristoError] =
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## Given a *top level* handle, this function accepts all database operations
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## performed through this handle and merges it to the previous layer. The
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## previous transaction is returned if there was any.
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##
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let db = ? tx.getDbDescFromTopTx()
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discard db.hashify().valueOr:
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return err(error[1])
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# Replace the top two layers by its merged version
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let merged = db.top.layersMergeOnto db.stack[^1]
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# Install `merged` layer
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db.top = merged
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db.stack.setLen(db.stack.len-1)
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db.txRef = tx.parent
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if 0 < db.stack.len:
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db.txRef.txUid = db.getTxUid
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db.top.txUid = db.txRef.txUid
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ok()
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proc collapse*(
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tx: AristoTxRef; # Top transaction on database
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commit: bool; # Commit if `true`, otherwise roll back
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): Result[void,AristoError] =
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## Iterated application of `commit()` or `rollback()` performing the
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## something similar to
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## ::
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## while true:
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## discard tx.commit() # ditto for rollback()
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## if db.topTx.isErr: break
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## tx = db.topTx.value
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##
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let db = ? tx.getDbDescFromTopTx()
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if commit:
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# For commit, hashify the current layer if requested and install it
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discard db.hashify().valueOr:
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return err(error[1])
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db.top.txUid = 0
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db.stack.setLen(0)
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db.txRef = AristoTxRef(nil)
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ok()
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# ------------------------------------------------------------------------------
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# Public functions: save database
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# ------------------------------------------------------------------------------
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proc stow*(
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db: AristoDbRef; # Database
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persistent = false; # Stage only unless `true`
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chunkedMpt = false; # Partial data (e.g. from `snap`)
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): Result[void,AristoError] =
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## If there is no backend while the `persistent` argument is set `true`,
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## the function returns immediately with an error. The same happens if there
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## is a pending transaction.
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##
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## The function then merges the data from the top layer cache into the
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## backend stage area. After that, the top layer cache is cleared.
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##
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## Staging the top layer cache might fail withh a partial MPT when it is
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## set up from partial MPT chunks as it happens with `snap` sync processing.
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## In this case, the `chunkedMpt` argument must be set `true` (see alse
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## `fwdFilter`.)
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##
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## If the argument `persistent` is set `true`, all the staged data are merged
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## into the physical backend database and the staged data area is cleared.
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##
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if not db.txRef.isNil:
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return err(TxPendingTx)
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if 0 < db.stack.len:
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return err(TxStackGarbled)
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if persistent and not db.canResolveBackendFilter():
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return err(TxBackendNotWritable)
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discard db.hashify().valueOr:
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return err(error[1])
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let fwd = db.fwdFilter(db.top, chunkedMpt).valueOr:
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return err(error[1])
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if fwd.isValid:
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# Merge `top` layer into `roFilter`
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db.merge(fwd).isOkOr:
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return err(error[1])
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db.top = LayerRef(final: LayerFinal(vGen: db.roFilter.vGen))
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if persistent:
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? db.resolveBackendFilter()
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db.roFilter = FilterRef(nil)
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# Delete/clear top
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db.top = LayerRef(
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final: LayerFinal(vGen: db.vGen),
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txUid: db.top.txUid)
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ok()
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# ------------------------------------------------------------------------------
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# End
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# ------------------------------------------------------------------------------
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