This PR names and documents the concept of the archive: a range of slots
for which we have degraded functionality in terms of historical access -
in particular:
* we don't support rewinding to states in this range
* we don't keep an in-memory representation of the block dag
The archive de-facto exists in a trusted-node-synced node, but this PR
gives it a name and drops the in-memory digest index.
In order to satisfy `GetBlocksByRange` requests, we ensure that we have
blocks for the entire archive period via backfill. Future versions may
relax this further, adding a "pre-archive" period that is fully pruned.
During by-slot searches in the archive (both for libp2p and rest
requests), an extra database lookup is used to covert the given `slot`
to a `root` - future versions will avoid this using era files which
natively are indexed by `slot`. That said, the lookup is quite
fast compared to the actual block loading given how trivial the table
is - it's hard to measure, even.
A collateral benefit of this PR is that checkpoint-synced nodes will see
100-200MB memory usage savings, thanks to the dropped in-memory cache -
future pruning work will bring this benefit to full nodes as well.
* document chaindag storage architecture and assumptions
* look up parent using block id instead of full block in clearance
(future-proofing the code against a future in which blocks come from era
files)
* simplify finalized block init, always writing the backfill portion to
db at startup (to ensure lookups work as expected)
* preallocate some extra memory for finalized blocks, to avoid immediate
realloc
When node is restarted before backfill has started but after some blocks
have finalized with forward sync, we would not start the backfill.
* also clean up one last `SomeSome`
* Store finalized block roots in database (3s startup)
When the chain has finalized a checkpoint, the history from that point
onwards becomes linear - this is exploited in `.era` files to allow
constant-time by-slot lookups.
In the database, we can do the same by storing finalized block roots in
a simple sparse table indexed by slot, bringing the two representations
closer to each other in terms of conceptual layout and performance.
Doing so has a number of interesting effects:
* mainnet startup time is improved 3-5x (3s on my laptop)
* the _first_ startup might take slightly longer as the new index is
being built - ~10s on the same laptop
* we no longer rely on the beacon block summaries to load the full dag -
this is a lot faster because we no longer have to look up each block by
parent root
* a collateral benefit is that we no longer need to load the full
summaries table into memory - we get the RSS benefits of #3164 without
the CPU hit.
Other random stuff:
* simplify forky block generics
* fix withManyWrites multiple evaluation
* fix validator key cache not being updated properly in chaindag
read-only mode
* drop pre-altair summaries from `kvstore`
* recreate missing summaries from altair+ blocks as well (in case
database has lost some to an involuntary restart)
* print database startup timings in chaindag load log
* avoid allocating superfluos state at startup
* use a recursive sql query to load the summaries of the unfinalized
blocks
Time in the beacon chain is expressed relative to the genesis time -
this PR creates a `beacon_time` module that collects helpers and
utilities for dealing the time units - the new module does not deal with
actual wall time (that's remains in `beacon_clock`).
Collecting the time related stuff in one place makes it easier to find,
avoids some circular imports and allows more easily identifying the code
actually needs wall time to operate.
* move genesis-time-related functionality into `spec/beacon_time`
* avoid using `chronos.Duration` for time differences - it does not
support negative values (such as when something happens earlier than it
should)
* saturate conversions between `FAR_FUTURE_XXX`, so as to avoid
overflows
* fix delay reporting in validator client so it uses the expected
deadline of the slot, not "closest wall slot"
* simplify looping over the slots of an epoch
* `compute_start_slot_at_epoch` -> `start_slot`
* `compute_epoch_at_slot` -> `epoch`
A follow-up PR will (likely) introduce saturating arithmetic for the
time units - this is merely code moves, renames and fixing of small
bugs.
* REST cleanups
* reject out-of-range committee requests
* print all hex values as lower-case
* allow requesting state information by head state root
* turn `DomainType` into array (follow spec)
* `uint_to_bytesXX` -> `uint_to_bytes` (follow spec)
* fix wrong dependent root in `/eth/v1/validator/duties/proposer/`
* update documentation - `--subscribe-all-subnets` is no longer needed
when using the REST interface with validator clients
* more fixes
* common helpers for dependent block
* remove test rules obsoleted by more strict epoch tests
* fix trailing commas
* Update docs/the_nimbus_book/src/rest-api.md
* Update docs/the_nimbus_book/src/rest-api.md
Co-authored-by: sacha <sacha@status.im>
With the right sequence of events (for example a REST request or a
validation), it can happen that the first traversal across a state
checkpoint boundary is done without storing that state on disk - this
causes problens when replaying states, because now states may be missing
from the database.
Here, we simply avoid using the caches when advancing a state that will
go into the database, ensuring that the information lost during caching
always is permanently stored.
* fix recursion bug in `isProposed`
* BlockId reform
Introduce `BlockId` that helps track a root/slot pair - this prepares
the codebase for backfilling and handling out-of-dag blocks
* move block dag code to separate module
* fix finalised state root in REST event stream
* fix finalised head computation on head update, when starting from
checkpoint
* clean up chaindag init
* revert `epochAncestor` change in introduced in #3144 that would return
an epoch ancestor from the canoncial history instead of the given
history, causing `EpochRef` keys to point to the wrong block
tersec
Jacek Sieka