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.
Compared to `keyed_queue`, `minilru` uses significantly less memory, in
particular for the 32-byte hash keys where `kq` stores several copies of
the key redundantly.
* replace rocksdb row cache with larger rdb lru caches - these serve the
same purpose but are more efficient because they skips serialization,
locking and rocksdb layering
* don't append fresh items to cache - this has the effect of evicting
the existing items and replacing them with low-value entries that might
never be read - during write-heavy periods of processing, the
newly-added entries were evicted during the store loop
* allow tuning rdb lru size at runtime
* add (hidden) option to print lru stats at exit (replacing the
compile-time flag)
pre:
```
INF 2024-09-03 15:07:01.136+02:00 Imported blocks
blockNumber=20012001 blocks=12000 importedSlot=9216851 txs=1837042
mgas=181911.265 bps=11.675 tps=1870.397 mgps=176.819 avgBps=10.288
avgTps=1574.889 avgMGps=155.952 elapsed=19m26s458ms
```
post:
```
INF 2024-09-03 13:54:26.730+02:00 Imported blocks
blockNumber=20012001 blocks=12000 importedSlot=9216851 txs=1837042
mgas=181911.265 bps=11.637 tps=1864.384 mgps=176.250 avgBps=11.202
avgTps=1714.920 avgMGps=169.818 elapsed=17m51s211ms
```
9%:ish import perf improvement on similar mem usage :)
For the block cache to be shared between column families, the options
instance must be shared between the various column families being
created. This also ensures that there is only one source of truth for
configuration options instead of having two different sets depending on
how the tables were initialized.
This PR also removes the re-opening mechanism which can double startup
time - every time the database is opened, the log is replayed - a large
log file will take a long time to open.
Finally, several options got correclty implemented as column family
options, including an one that puts a hash index in the SST files.
* Fix initialiser
why:
Possible crash (app profiling, tracer etc.)
* Update column family options processing
why:
Same for kvt as for aristo
* Move `AristoDbDualRocks` backend type to the test suite
why:
So it is not available for production
* Fix typos in API jump table
why:
Used for tracing and app profiling only. Needed some update
* Purged CoreDb legacy API
why:
Not needed anymore, was transitionary and disabled.
* Rename `flush` argument to `eradicate` in a DB close context
why:
The word `eradicate` leaves no doubt what is meant
* Rename `stoFlush()` -> `stoDelete()`
* Rename `core_apps_newapi` -> `core_apps` (not so new anymore)
* bump rockdb
* Rename `KVT` objects related to filters according to `Aristo` naming
details:
filter* => delta*
roFilter => balancer
* Compulsory error handling if `persistent()` fails
* Add return code to `reCentre()`
why:
Might eventually fail if re-centring is blocked. Some logic will be
added in subsequent patch sets.
* Add column families from earlier session to rocksdb in opening procedure
why:
All previously used CFs must be declared when re-opening an existing
database.
* Update `init()` and add rocksdb `reinit()` methods for changing parameters
why:
Opening a set column families (with different open options) must span
at least the ones that are already on disk.
* Provide write-trigger-event interface into `Aristo` backend
why:
This allows to save data from a guest application (think `KVT`) to
get synced with the write cycle so the guest and `Aristo` save all
atomically.
* Use `KVT` with new column family interface from `Aristo`
* Remove obsolete guest interface
* Implement `KVT` piggyback on `Aristo` backend
* CoreDb: Add separate `KVT`/`Aristo` backend mode for debugging
* Remove `rocks_db` import from `persist()` function
why:
Some systems (i.p `fluffy` and friends) use the `Aristo` memory
backend emulation and do not link against rocksdb when building the
application. So this should fix that problem.
These options, inspired by Nethermind and general internet wisdom, bring
the database size down to 2/3 without affecting throughput. In theory,
they should also bring down memory usage and/or make more efficient use
of whatever memory is already assigned to rocksdb but this needs
verification in a longer test at synced-mainnet sizes.
In the meantime, they make testing easier by removing some noise that
the profiler says are bad, such as excessive SkipList access (countered
by bloom filters).
* Use RocksDb column families instead of a prefixed single column
why:
Better performance
* Use structural objects `VertexRef` and `HashKey` in LRU cache for RocksDb
why:
Avoids repeated de/serialisation
These options are there mainly to drive experiments, and are therefore
hidden.
One thing that this PR brings in is an initial set of caches and buffers for rocksdb - the set that I've been using during various performance tests to get to a viable baseline performance level.
* Aristo: Generalise alien/guest interface for piggiback on database
* Aristo: Code cosmetics
* CoreDb+Kvt: Update transaction API
why:
Use single addressable function `forkTx(backLevel: int)` as used
in `Aristo`. So `Kvt` can be synced simultaneously to `Aristo`.
also:
Refactored `kvt_tx.nim` in a similar fashion to `Aristo`.
* Kvt: Replace `LayerDelta` object by reference
why:
Will be needed when introducing filters
* Kvt: Remodel backend filter facility similar to `Aristo`
why:
This allows to operate on several KVT instances simultaneously.
* CoreDb+Kvt: Fix on-disk storage
why:
Overlooked name change: `stow()` => `persist()` for permanent storage
* Fix copyright headers
* Aristo+RocksDB: Update backend drivers
why:
RocksDB update allows use some of the newly provided methods which
were previously implemented by using the very C backend (for the lack
of NIM methods.)
* Aristo+RocksDB: Simplify drivers wrapper
* Kvt: Update backend drivers and wrappers similar to `Aristo`
* Aristo+Kvm: Use column families for RocksDB
* Aristo+MemoryDB: Code cosmetics
* Aristo: Provide guest column family for export
why:
So `Kvt` can piggyback on `Aristo` so there avoiding to run a second
DBMS system in parallel.
* Kvt: Provide import mechanism for RoksDB guest column family
why:
So `Kvt` can piggyback on `Aristo` so there avoiding to run a second
DBMS system in parallel.
* CoreDb+Aristo: Run persistent `Kvt` DB piggybacked on `Aristo`
why:
Avoiding to run two DBMS systems in parallel.
* Fix copyright year
* Ditto
* Add new RocksNamespaceRef type and remove backups and readonly support from RocksDb KvStore.
* Bump nim-rocksdb to fc2ba4a836b6b47ae1b17d1c45801c7e06585e19
* Fix tests.
* Fix copyright notice.
* Using different `tmp` directories for `Kvt` and `Aristo`
why:
Closing one database would leave the other set of directories
incomplete.
* Code cosmetics, silence compiler
* Fix typo `EMPTY_ROOT_HASH` vs. `EMPTY_CODE_HASH`
* Fix copyright years
* Fix debug noise in `hashify()` for perfectly normal situation
why:
Was previously considered a fixable error
* Fix test sample file names
why:
The larger test file `goerli68161.txt.gz` is already in the local
archive. So there is no need to use the smaller one from the external
repo.
* Activate `accounts_cache` module from `db/ledger`
why:
A copy of the original `accounts_cache.nim` source to be integrated
into the `Ledger` module wrapper which allows to switch between
different `accounts_cache` implementations unser tha same API.
details:
At a later state, the `db/accounts_cache.nim` wrapper will be
removed so that there is only one access to that module via
`db/ledger/accounts_cache.nim`.
* Fix copyright headers in source code
* Rewrite remaining `AristoError` return code into `Result[void,AristoError]`
why:
Better code maintenance
* Update import sections
* Update Aristo DB paths
why:
More systematic so directory can be shared with other DB types
* More cosmetcs
* Update unit tests runners
why:
Proper handling of persistent and mem-only DB. The latter can be
consistently triggered by an empty DB path.
* Rename FilterID => QueueID
why:
The current usage does not identify a particular filter but uses it as
storage tag to manage it on the database (to be organised in a set of
FIFOs or queues.)
* Split `aristo_filter` source into sub-files
why:
Make space for filter management API
* Store filter queue IDs in pairs on the backend
why:
Any pair will will describe a FIFO accessed by bottom/top IDs
* Reorg some source file names
why:
The "aristo_" prefix for make local/private files is tedious to
use, so removed.
* Implement filter slot scheduler
details:
Filters will be stored on the database on cascaded FIFOs. When a FIFO
queue is full, some filter items are bundled together and stored on the
next FIFO.
