The optimistic sync spec was updated since the LC based optsync module
was introduced. It is no longer necessary to wait for the justified
checkpoint to have execution enabled; instead, any block is okay to be
optimistically imported to the EL client, as long as its parent block
has execution enabled. Complex syncing logic has been removed, and the
LC optsync module will now follow gossip directly, reducing the latency
when using this module. Note that because this is now based on gossip
instead of using sync manager / request manager, that individual blocks
may be missed. However, EL clients should recover from this by fetching
missing blocks themselves.
* Use final `v1` version for light client protocols
* Unhide LC data collection options
* Default enable LC data serving
* rm unneeded import
* Connect to EL on startup
* Add docs for LC based EL sync
Adds the `--web3-url` launch argument to `nimbus_light_client` to enable
driving the EL with the optimistic head obtained from LC sync protocol.
This will keep issuing `newPayload` / `forkChoiceUpdated` requests for
new blocks, marking them as optimistic. `ZERO_HASH` is reported as the
finalized block for now.
* optimistic sync
* flag that initially loaded blocks from database might need execution block root filled in
* return optimistic status in REST calls
* refactor blockslot pruning
* ensure beacon_blocks_by_{root,range} do not provide optimistic blocks
* handle forkchoice head being pre-merge with block being postmerge
* re-enable blocking head updates on validator duties
* fix is_optimistic_candidate_block per spec; don't crash with nil future
* fix is_optimistic_candidate_block per spec; don't crash with nil future
* mark blocks sans execution payloads valid during head update
Combines the LC data configuration options (serve / importMode), the
callbacks (finality / optimistic LC update) as well as the cache storing
light client data, into a new `LightClientDataStore` structure.
Also moves the structure into a light client specific file.
* adopt LC REST API with v0 suffix (without proofs)
Adopts the light client data REST API used by Lodestar as defined in
https://github.com/ethereum/beacon-APIs/pull/181 with a v0 suffix.
Requests:
- `/eth/v0/beacon/light_client/bootstrap/{block_root}`
- `/eth/v0/beacon/light_client/updates?start_period={start_period}&count={count}`
- `/eth/v0/beacon/light_client/finality_update`
- `/eth/v0/beacon/light_client/optimistic_update`
HTTP Server-Sent Events (SSE):
- `light_client_finality_update_v0`
- `light_client_optimistic_update_v0`
More work is needed to adopt the proofs endpoint, it is not included.
* initialize event queues
* register event topics
Ensures that all intermediate blocks are reported if a small gap is
encountered when downloading optimistic blocks. Gaps may occur when
a block is missed and still downloading, or when EL processing is slow.
If the gap exceeds 1 epoch, optimistic block stream jumps to latest.
For consistency with other options, use a common prefix for light client
data configuration options.
* `--serve-light-client-data` --> `--light-client-data-serve`
* `--import-light-client-data` --> `--light-client-data-import-mode`
No deprecation of the old identifiers as they were only sparingly used
and all usage can be easily updated without interferance.
Corrects an off-by-1 in the reported sync percentage computation.
New logic is based on `SyncQueue.total` and `SyncQueue.progress`
with `pivot` instead of `sq.startSlot`.
When launched with `--light-client-enable` the latest blocks are fetched
and optimistic candidate blocks are passed to a callback (log for now).
This helps accelerate syncing in the future (optimistic sync).
Introduces a new library for syncing using libp2p based light client
sync protocol, and adds a new `nimbus_light_client` executable that uses
this library for syncing. The new executable emits log messages when
new beacon block headers are received, and is integrated into testing.
Incorporates the latest changes to the light client sync protocol based
on Devconnect AMS feedback. Note that this breaks compatibility with the
previous prototype, due to changes to data structures and endpoints.
See https://github.com/ethereum/consensus-specs/pull/2802
Follows up on https://github.com/status-im/nimbus-eth2/pull/3461 which
ensured that repeated `beaconBlocksByRange` requests get shrinked to
account for potential out-of-band advancements to `safeSlot`, with
similar logic for the initial request.
* use MAX_CHUNK_SIZE_BELLATRIX for signed Bellatrix blocks
* Update beacon_chain/networking/eth2_network.nim
Co-authored-by: Etan Kissling <etan@status.im>
* localPassC to localPassc
* check against maxChunkSize rather than constant
Co-authored-by: Etan Kissling <etan@status.im>
* Add `NoMonitor` flag to stop SyncManager from monitoring sync situation.
* Remove `toleranceValue` and `PeerScoreHeadTooNew`.
Co-authored-by: Etan Kissling <etan@status.im>
Some upstream repos still need fixes, but this gets us close enough that
style hints can be enabled by default.
In general, "canonical" spellings are preferred even if they violate
nep-1 - this applies in particular to spec-related stuff like
`genesis_validators_root` which appears throughout the codebase.
* era: load blocks and states
Era files contain finalized history and can be thought of as an
alternative source for block and state data that allows clients to avoid
syncing this information from the P2P network - the P2P network is then
used to "top up" the client with the most recent data. They can be
freely shared in the community via whatever means (http, torrent, etc)
and serve as a permanent cold store of consensus data (and, after the
merge, execution data) for history buffs and bean counters alike.
This PR gently introduces support for loading blocks and states in two
cases: block requests from rest/p2p and frontfilling when doing
checkpoint sync.
The era files are used as a secondary source if the information is not
found in the database - compared to the database, there are a few key
differences:
* the database stores the block indexed by block root while the era file
indexes by slot - the former is used only in rest, while the latter is
used both by p2p and rest.
* when loading blocks from era files, the root is no longer trivially
available - if it is needed, it must either be computed (slow) or cached
(messy) - the good news is that for p2p requests, it is not needed
* in era files, "framed" snappy encoding is used while in the database
we store unframed snappy - for p2p2 requests, the latter requires
recompression while the former could avoid it
* front-filling is the process of using era files to replace backfilling
- in theory this front-filling could happen from any block and
front-fills with gaps could also be entertained, but our backfilling
algorithm cannot take advantage of this because there's no (simple) way
to tell it to "skip" a range.
* front-filling, as implemented, is a bit slow (10s to load mainnet): we
load the full BeaconState for every era to grab the roots of the blocks
- it would be better to partially load the state - as such, it would
also be good to be able to partially decompress snappy blobs
* lookups from REST via root are served by first looking up a block
summary in the database, then using the slot to load the block data from
the era file - however, there needs to be an option to create the
summary table from era files to fully support historical queries
To test this, `ncli_db` has an era file exporter: the files it creates
should be placed in an `era` folder next to `db` in the data directory.
What's interesting in particular about this setup is that `db` remains
as the source of truth for security purposes - it stores the latest
synced head root which in turn determines where a node "starts" its
consensus participation - the era directory however can be freely shared
between nodes / people without any (significant) security implications,
assuming the era files are consistent / not broken.
There's lots of future improvements to be had:
* we can drop the in-memory `BlockRef` index almost entirely - at this
point, resident memory usage of Nimbus should drop to a cool 500-600 mb
* we could serve era files via REST trivially: this would drop backfill
times to whatever time it takes to download the files - unlike the
current implementation that downloads block by block, downloading an era
at a time almost entirely cuts out request overhead
* we can "reasonably" recreate detailed state history from almost any
point in time, turning an O(slot) process into O(1) effectively - we'll
still need caches and indices to do this with sufficient efficiency for
the rest api, but at least it cuts the whole process down to minutes
instead of hours, for arbitrary points in time
* CI: ignore failures with Nim-1.6 (temporary)
* test fixes
Co-authored-by: Ștefan Talpalaru <stefantalpalaru@yahoo.com>
This extends the `--serve-light-client-data` launch option to serve
locally collected light client data via libp2p.
Backfill of historic best `LightClientUpdate` is not yet implemented.
See https://github.com/ethereum/consensus-specs/pull/2802
When a `beaconBlocksByRange` response advances the `safeSlot`, but later
has errors, the sync queue keeps repeating that same request until it is
fulfilled without errors. Data up through `safeSlot` is considered to be
immutable, i.e., finalized, so re-requesting that data is not useful.
By advancing the sync progress in that scenario, those redundant query
portions can be avoided. Note, the finalized block _itself_ is always
requested, even in the initial request. This behaviour is kept same.
* fewer deps on `BlockRef` traversal in anticipation of pruning
* allows identifying EpochRef:s by their shuffling as a first step of
* tighten error handling around missing blocks
using the zero hash for signalling "missing block" is fragile and easy
to miss - with checkpoint sync now, and pruning in the future, missing
blocks become "normal".
* Refactor and optimize logs.
* Introduce shortLog(SyncRequest).
* Address review comment.
* make sync queue logs more consistent
Adds a few minor logging improvements:
- Fixes a typo (`was happened` -> `has happened`)
- Avoids passing `reset_slot` argument to log statement multiple times
- Uses same `rewind_to_slot` label when logging in both sync directions
- Consistent rewind point logging
Co-authored-by: cheatfate <eugene.kabanov@status.im>
When initializing backfill sync, the implementation intends to start at
the first unknown slot (`1` before tail). However, an incorrect variable
is passed, and backfill sync actually starts at the tail slot instead.
This patch corrects this by passing the intended variable. The problem
was introduced with the original backfill implementation at #3263.
The `SyncManager` has a leftover optional `sleepTime` parameter in
its constructor that used to configure the sync loop polling rate.
This parameter was replaced with a constant in #1602 and is no longer
functional. This patch removes the `sleepTime` leftovers.
#3304 introduced a regression to the sync status string displayed in the
status bar; during the main forward sync, the current slot is no longer
reported and always displays as `0`. This patch corrects the computation
to accurately report the current slot once more.
The `SyncManager` has a leftover optional `maxStatusAge` parameter in
its constructor that used to configure the libp2p `Status` polling rate.
This parameter was replaced with a constant in #1827 and is no longer
functional. This patch removes the `maxStatusAge` leftovers.
* harden and speed up block sync
The `GetBlockBy*` server implementation currently reads SSZ bytes from
database, deserializes them into a Nim object then serializes them right
back to SSZ - here, we eliminate the deser/ser steps and send the bytes
straight to the network. Unfortunately, the snappy recoding must still
be done because of differences in framing.
Also, the quota system makes one giant request for quota right before
sending all blocks - this means that a 1024 block request will be
"paused" for a long time, then all blocks will be sent at once causing a
spike in database reads which potentially will see the reading client
time out before any block is sent.
Finally, on the reading side we make several copies of blocks as they
travel through various queues - this was not noticeable before but
becomes a problem in two cases: bellatrix blocks are up to 10mb (instead
of .. 30-40kb) and when backfilling, we process a lot more of them a lot
faster.
* fix status comparisons for nodes syncing from genesis (#3327 was a bit
too hard)
* don't hit database at all for post-altair slots in GetBlock v1
requests
Additional sanity checking of the status message exchanged during a
fresh connection:
* check that head and finalized make sense, slot-wise
* verify that finalized root lies on the canonical chain, when possible
* re-check these things for every status message during sync
* Harden handling of unviable forks
In our current handling of unviable forks, we allow peers to send us
blocks that come from a different fork - this is not necessarily an
error as it can happen naturally, but it does open up the client to a
case where the same unviable fork keeps getting requested - rather than
allowing this to happen, we'll now give these peers a small negative
score - if it keeps happening, we'll disconnect them.
* keep track of unviable forks in quarantine, to avoid filling it with
known junk
* collect peer scores in single module
* descore peers when they send unviable blocks during sync
* don't give score for duplicate blocks
* increase quarantine size to a level that allows finality to happen
under optimal conditions - this helps avoid downloading the same blocks
over and over in case of an unviable fork
* increase initial score for new peers to make room for one more failure
before disconnection
* log and score invalid/unviable blocks in requestmanager too
* avoid ChainDAG dependency in quarantine
* reject gossip blocks with unviable parent
* continue processing unviable sync blocks in order to build unviable
dag
* docs
* Update beacon_chain/consensus_object_pools/block_pools_types.nim
* add unviable queue test
* limit by-root requests to non-finalized blocks
Presently, we keep a mapping from block root to `BlockRef` in memory -
this has simplified reasoning about the dag, but is not sustainable with
the chain growing.
We can distinguish between two cases where by-root access is useful:
* unfinalized blocks - this is where the beacon chain is operating
generally, by validating incoming data as interesting for future fork
choice decisions - bounded by the length of the unfinalized period
* finalized blocks - historical access in the REST API etc - no bounds,
really
In this PR, we limit the by-root block index to the first use case:
finalized chain data can more efficiently be addressed by slot number.
Future work includes:
* limiting the `BlockRef` horizon in general - each instance is 40
bytes+overhead which adds up - this needs further refactoring to deal
with the tail vs state problem
* persisting the finalized slot-to-hash index - this one also keeps
growing unbounded (albeit slowly)
Anyway, this PR easily shaves ~128mb of memory usage at the time of
writing.
* No longer honor `BeaconBlocksByRoot` requests outside of the
non-finalized period - previously, Nimbus would generously return any
block through this libp2p request - per the spec, finalized blocks
should be fetched via `BeaconBlocksByRange` instead.
* return `Opt[BlockRef]` instead of `nil` when blocks can't be found -
this becomes a lot more common now and thus deserves more attention
* `dag.blocks` -> `dag.forkBlocks` - this index only carries unfinalized
blocks from now - `finalizedBlocks` covers the other `BlockRef`
instances
* in backfill, verify that the last backfilled block leads back to
genesis, or panic
* add backfill timings to log
* fix missing check that `BlockRef` block can be fetched with
`getForkedBlock` reliably
* shortcut doppelganger check when feature is not enabled
* in REST/JSON-RPC, fetch blocks without involving `BlockRef`
* fix dag.blocks ref
Backfilling is the process of downloading historical blocks via P2P that
are required to fulfill `GetBlocksByRange` duties - this happens during
both trusted node and finalized checkpoint syncs.
In particular, backfilling happens after syncing to head, such that
attestation work can start as soon as possible.
* Fix SyncQueue initialization procedure.
Remove usage of `awaitne`.
Add cancellation support.
Remove unneeded `sleepAsync()` if peer's head is older than needed.
Add `direction` field to all logs.
Fix syncmanager wedge issue.
Add proper resource cleaning procedure on backward sync finish.
Co-authored-by: cheatfate <eugene.kabanov@status.im>
Etan Kissling
tersec
Miran
Jacek Sieka
Eugene Kabanov