131 lines
4.0 KiB
Nim
131 lines
4.0 KiB
Nim
# nimbus-eth1
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# Copyright (c) 2023-2024 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 fork helpers
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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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./tx_frame,
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".."/[aristo_desc, aristo_get, aristo_layers]
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# ------------------------------------------------------------------------------
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# Public functions
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# ------------------------------------------------------------------------------
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proc txFork*(
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tx: AristoTxRef; # Transaction descriptor
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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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## 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.getTuvBE()
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if rc.isOk:
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LayerRef(
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delta: LayerDeltaRef(vTop: rc.value))
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elif rc.error == GetTuvNotFound:
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LayerRef.init()
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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(noToplayer = true, noFilter = false)
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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.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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ok(txClone)
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proc txForkTop*(
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db: AristoDbRef;
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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, and an empty transaction is set up. After
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## successful fork the returned descriptor has transaction level 1.
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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 txClone = ? db.fork(noToplayer=true, noFilter=false)
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txClone.top = db.layersCc # Is a deep copy
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discard txClone.txFrameBegin()
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return ok(txClone)
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# End if()
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db.txRef.txFork()
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proc txForkBase*(
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db: AristoDbRef;
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): Result[AristoDbRef,AristoError] =
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## Variant of `forkTx()`, sort of the opposite of `forkTop()`. This is the
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## equivalent of top layer forking after all tranactions have been rolled
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## back.
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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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return db.txForkTop()
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let txClone = ? db.fork(noToplayer=true, noFilter=false)
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txClone.top = db.layersCc 0
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discard txClone.txFrameBegin()
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ok(txClone)
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# ------------------------------------------------------------------------------
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# End
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# ------------------------------------------------------------------------------
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