387 lines
12 KiB
Nim
387 lines
12 KiB
Nim
# nimbus-eth1
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# Copyright (c) 2021 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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std/[options, sets],
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results,
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"."/[aristo_desc, aristo_filter, aristo_get, aristo_hashify]
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func isTop*(tx: AristoTxRef): bool
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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(TxStackUnderflow)
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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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proc linkClone(db: AristoDbRef; clone: AristoDbRef) =
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## Link clone to parent
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clone.dudes = AristoDudesRef(
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rwOk: false,
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rwDb: db)
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if db.dudes.isNil:
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db.dudes = AristoDudesRef(
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rwOk: true,
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roDudes: @[clone].toHashSet)
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else:
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db.dudes.roDudes.incl clone
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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 copyCat*(tx: AristoTxRef): Result[AristoDbRef,AristoError] =
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## Clone a transaction into a new DB descriptor. The new descriptor is linked
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## to the transaction parent and will be updated with functions like
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## `aristo_filter.resolveBE()` or `aristo_filter.ackqRwMode()`. The new
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## descriptor is fully functional apart from the fact that the physical
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## backend cannot be updated (but see `aristo_filter.ackqRwMode()`.)
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##
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## The new DB descriptor contains a copy of the argument transaction `tx` as
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## top layer of level 1 (i.e. this is he only transaction.) Rolling back will
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## end up at the backend layer (incl. backend filter.)
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##
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## Use `aristo_filter.dispose()` to clean up the new DB descriptor.
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##
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let db = tx.db
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# Provide new top layer
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var topLayer: AristoLayerRef
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if db.txRef == tx:
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topLayer = db.top.dup
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elif tx.level < db.stack.len:
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topLayer = db.stack[tx.level].dup
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else:
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return err(TxArgStaleTx)
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if topLayer.txUid != tx.txUid:
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return err(TxArgStaleTx)
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topLayer.txUid = 1
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# Empty stack
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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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AristoLayerRef(vGen: rc.value)
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elif rc.error == GetIdgNotFound:
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AristoLayerRef()
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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 = AristoDbRef(
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top: topLayer, # is a deep copy
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stack: @[stackLayer],
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roFilter: db.roFilter, # no need to copy contents (done when updated)
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backend: db.backend,
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txUidGen: 1,
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dudes: AristoDudesRef(
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rwOk: false,
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rwDb: db))
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# Link clone to parent
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db.linkClone txClone
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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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ok(txClone)
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proc copyCat*(db: AristoDbRef): Result[AristoDbRef,AristoError] =
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## Variant of `copyCat()`. If there is a transaction pending, then the
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## function returns `db.txTop.value.copyCat()`. Otherwise it returns a
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## clone of the top layer.
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##
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## Use `aristo_filter.dispose()` to clean up the copy cat descriptor.
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##
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if db.txRef.isNil:
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let dbClone = AristoDbRef(
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top: db.top.dup, # is a deep copy
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roFilter: db.roFilter, # no need to copy contents (done when updated)
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backend: db.backend)
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# Link clone to parent
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db.linkClone dbClone
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return ok(dbClone)
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db.txRef.copyCat()
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proc exec*(
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tx: AristoTxRef;
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action: AristoDbAction;
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): Result[void,AristoError]
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{.gcsafe, raises: [CatchableError].} =
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## Execute function argument `action()` on a temporary `tx.copyCat()`
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## transaction database. After return, the temporary database gets
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## destroyed.
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##
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let db = block:
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let rc = tx.copyCat()
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if rc.isErr:
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return err(rc.error)
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rc.value
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db.action()
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block:
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let rc = db.dispose()
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if rc.isErr:
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return err(rc.error)
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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,(VertexID,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((VertexID(0),TxStackGarbled))
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db.stack.add db.top.dup # push (save and use top later)
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db.top.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,(VertexID,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 = block:
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let rc = tx.getDbDescFromTopTx()
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if rc.isErr:
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return err((VertexID(0),rc.error))
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rc.value
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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 = tx.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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dontHashify = false; # Process/fix MPT hashes
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): Result[void,(VertexID,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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## Unless the argument `dontHashify` is set `true`, the function will process
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## Merkle Patricia Treee hashes unless there was no change to this layer.
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## This may produce additional errors (see `hashify()`.)
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let db = block:
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let rc = tx.getDbDescFromTopTx()
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if rc.isErr:
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return err((VertexID(0),rc.error))
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rc.value
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if db.top.dirty and not dontHashify:
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let rc = db.hashify()
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if rc.isErr:
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return err(rc.error)
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# Keep top and discard layer below
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db.top.txUid = db.stack[^1].txUid
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db.stack.setLen(db.stack.len-1)
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db.txRef = tx.parent
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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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dontHashify = false; # Process/fix MPT hashes
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): Result[void,(VertexID,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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## The `dontHashify` is treated as described for `commit()`
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let db = block:
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let rc = tx.getDbDescFromTopTx()
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if rc.isErr:
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return err((VertexID(0),rc.error))
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rc.value
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# If commit, then leave the current layer and clear the stack, oterwise
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# install the stack bottom.
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if not commit:
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db.stack[0].swap db.top
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if db.top.dirty and not dontHashify:
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let rc = db.hashify()
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if rc.isErr:
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if not commit:
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db.stack[0].swap db.top # restore
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return err(rc.error)
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db.top.txUid = 0
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db.stack.setLen(0)
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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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dontHashify = false; # Process/fix MPT hashes
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chunkedMpt = false; # Partial data (e.g. from `snap`)
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): Result[void,(VertexID,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 `dontHashify` is treated as described for `commit()`.
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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((VertexID(0),TxPendingTx))
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if 0 < db.stack.len:
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return err((VertexID(0),TxStackGarbled))
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if persistent and not db.canResolveBE():
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return err((VertexID(0),TxRoBackendOrMissing))
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if db.top.dirty and not dontHashify:
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let rc = db.hashify()
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if rc.isErr:
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return err(rc.error)
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let fwd = block:
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let rc = db.fwdFilter(db.top, chunkedMpt)
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if rc.isErr:
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return err(rc.error)
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rc.value
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if fwd.vGen.isSome: # Otherwise this layer is pointless
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block:
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# Merge `top` layer into `roFilter`
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let rc = db.merge fwd
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if rc.isErr:
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return err(rc.error)
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db.top = AristoLayerRef(vGen: db.roFilter.vGen.unsafeGet)
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if persistent:
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let rc = db.resolveBE()
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if rc.isErr:
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return err(rc.error)
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db.roFilter = AristoFilterRef(nil)
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# Delete or clear stack and clear top
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db.stack.setLen(0)
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db.top = AristoLayerRef(vGen: db.top.vGen, txUid: db.top.txUid)
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ok()
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proc stow*(
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db: AristoDbRef; # Database
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stageLimit: int; # Policy based persistent storage
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dontHashify = false; # Process/fix MPT hashes
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chunkedMpt = false; # Partial data (e.g. from `snap`)
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): Result[void,(VertexID,AristoError)] =
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## Variant of `stow()` with the `persistent` argument replaced by
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## `stageLimit < max(db.roFilter.bulk, db.top.bulk)`.
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db.stow(
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persistent = (stageLimit < max(db.roFilter.bulk, db.top.bulk)),
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dontHashify = dontHashify,
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chunkedMpt = chunkedMpt)
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# ------------------------------------------------------------------------------
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# End
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# ------------------------------------------------------------------------------
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