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01ca415721
Currently, computed hash keys are stored in a separate column family with respect to the MPT data they're generated from - this has several disadvantages: * A lot of space is wasted because the lookup key (`RootedVertexID`) is repeated in both tables - this is 30% of the `AriKey` content! * rocksdb must maintain in-memory bloom filters and LRU caches for said keys, doubling its "minimal efficient cache size" * An extra disk traversal must be made to check for existence of cached hash key * Doubles the amount of files on disk due to each column family being its own set of files Here, the two CFs are joined such that both key and data is stored in `AriVtx`. This means: * we save ~30% disk space on repeated lookup keys * we save ~2gb of memory overhead that can be used to cache data instead of indices * we can skip storing hash keys for MPT leaf nodes - these are trivial to compute and waste a lot of space - previously they had to present in the `AriKey` CF to avoid having to look in two tables on the happy path. * There is a small increase in write amplification because when a hash value is updated for a branch node, we must write both key and branch data - previously we would write only the key * There's a small shift in CPU usage - instead of performing lookups in the database, hashes for leaf nodes are (re)-computed on the fly * We can return to slightly smaller on-disk SST files since there's fewer of them, which should reduce disk traffic a bit Internally, there are also other advantages: * when clearing keys, we no longer have to store a zero hash in memory - instead, we deduce staleness of the cached key from the presence of an updated VertexRef - this saves ~1gb of mem overhead during import * hash key cache becomes dedicated to branch keys since leaf keys are no longer stored in memory, reducing churn * key computation is a lot faster thanks to the skipped second disk traversal - a key computation for mainnet can be completed in 11 hours instead of ~2 days (!) thanks to better cache usage and less read amplification - with additional improvements to the on-disk format, we can probably get rid of the initial full traversal method of seeding the key cache on first start after import All in all, this PR reduces the size of a mainnet database from 160gb to 110gb and the peak memory footprint during import by ~1-2gb.
120 lines
4.2 KiB
Nim
120 lines
4.2 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 -- Patricia Trie backend data access
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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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"."/[desc_error, desc_identifiers, desc_structural]
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type
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GetVtxFn* =
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proc(rvid: RootedVertexID, flags: set[GetVtxFlag]): Result[VertexRef,AristoError] {.gcsafe, raises: [].}
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## Generic backend database retrieval function for a single structural
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## `Aristo DB` data record.
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GetKeyFn* =
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proc(rvid: RootedVertexID): Result[HashKey,AristoError] {.gcsafe, raises: [].}
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## Generic backend database retrieval function for a single
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## `Aristo DB` hash lookup value.
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GetTuvFn* =
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proc(): Result[VertexID,AristoError] {.gcsafe, raises: [].}
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## Generic backend database retrieval function for the top used
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## vertex ID.
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GetLstFn* =
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proc(): Result[SavedState,AristoError]
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{.gcsafe, raises: [].}
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## Generic last recorded state stamp retrieval function
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# -------------
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PutHdlRef* = ref object of RootRef
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## Persistent database transaction frame handle. This handle is used to
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## wrap any of `PutVtxFn`, `PutKeyFn`, and `PutIdgFn` into and atomic
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## transaction frame. These transaction frames must not be interleaved
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## by any library function using the backend.
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PutBegFn* =
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proc(): Result[PutHdlRef,AristoError] {.gcsafe, raises: [].}
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## Generic transaction initialisation function
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PutVtxFn* =
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proc(hdl: PutHdlRef; rvid: RootedVertexID; vtx: VertexRef, key: HashKey)
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{.gcsafe, raises: [].}
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## Generic backend database bulk storage function, `VertexRef(nil)`
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## values indicate that records should be deleted.
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PutTuvFn* =
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proc(hdl: PutHdlRef; vs: VertexID)
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{.gcsafe, raises: [].}
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## Generic backend database ID generator storage function for the
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## top used vertex ID.
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PutLstFn* =
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proc(hdl: PutHdlRef; lst: SavedState)
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{.gcsafe, raises: [].}
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## Generic last recorded state stamp storage function. This
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## function replaces the currentlt saved state.
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PutEndFn* =
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proc(hdl: PutHdlRef): Result[void,AristoError] {.gcsafe, raises: [].}
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## Generic transaction termination function
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# -------------
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CloseFn* =
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proc(eradicate: bool) {.gcsafe, raises: [].}
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## Generic destructor for the `Aristo DB` backend. The argument
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## `eradicate` indicates that a full database deletion is requested. If
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## passed `false` the outcome might differ depending on the type of
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## backend (e.g. in-memory backends will always eradicate on close.)
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# -------------
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BackendRef* = ref BackendObj
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BackendObj* = object of RootObj
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## Backend interface.
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getVtxFn*: GetVtxFn ## Read vertex record
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getKeyFn*: GetKeyFn ## Read Merkle hash/key
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getTuvFn*: GetTuvFn ## Read top used vertex ID
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getLstFn*: GetLstFn ## Read saved state
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putBegFn*: PutBegFn ## Start bulk store session
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putVtxFn*: PutVtxFn ## Bulk store vertex records
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putTuvFn*: PutTuvFn ## Store top used vertex ID
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putLstFn*: PutLstFn ## Store saved state
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putEndFn*: PutEndFn ## Commit bulk store session
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closeFn*: CloseFn ## Generic destructor
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proc init*(trg: var BackendObj; src: BackendObj) =
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trg.getVtxFn = src.getVtxFn
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trg.getKeyFn = src.getKeyFn
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trg.getTuvFn = src.getTuvFn
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trg.getLstFn = src.getLstFn
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trg.putBegFn = src.putBegFn
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trg.putVtxFn = src.putVtxFn
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trg.putTuvFn = src.putTuvFn
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trg.putLstFn = src.putLstFn
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trg.putEndFn = src.putEndFn
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trg.closeFn = src.closeFn
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# ------------------------------------------------------------------------------
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# End
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# ------------------------------------------------------------------------------
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