Commit Graph

119 Commits

Author SHA1 Message Date
Dustin Brody 6638476b5f discard putative blocks from invalid hardforks 2021-09-16 16:18:40 +03:00
tersec 43a976f89b
proc -> func in ncli/, research/, and test/ (#2818) 2021-08-25 14:51:52 +00:00
Jacek Sieka a7a65bce42
disentangle eth2 types from the ssz library (#2785)
* reorganize ssz dependencies

This PR continues the work in
https://github.com/status-im/nimbus-eth2/pull/2646,
https://github.com/status-im/nimbus-eth2/pull/2779 as well as past
issues with serialization and type, to disentangle SSZ from eth2 and at
the same time simplify imports and exports with a structured approach.

The principal idea here is that when a library wants to introduce SSZ
support, they do so via 3 files:

* `ssz_codecs` which imports and reexports `codecs` - this covers the
basic byte conversions and ensures no overloads get lost
* `xxx_merkleization` imports and exports `merkleization` to specialize
and get access to `hash_tree_root` and friends
* `xxx_ssz_serialization` imports and exports `ssz_serialization` to
specialize ssz for a specific library

Those that need to interact with SSZ always import the `xxx_` versions
of the modules and never `ssz` itself so as to keep imports simple and
safe.

This is similar to how the REST / JSON-RPC serializers are structured in
that someone wanting to serialize spec types to REST-JSON will import
`eth2_rest_serialization` and nothing else.

* split up ssz into a core library that is independendent of eth2 types
* rename `bytes_reader` to `codec` to highlight that it contains coding
and decoding of bytes and native ssz types
* remove tricky List init overload that causes compile issues
* get rid of top-level ssz import
* reenable merkleization tests
* move some "standard" json serializers to spec
* remove `ValidatorIndex` serialization for now
* remove test_ssz_merkleization
* add tests for over/underlong byte sequences
* fix broken seq[byte] test - seq[byte] is not an SSZ type

There are a few things this PR doesn't solve:

* like #2646 this PR is weak on how to handle root and other
dontSerialize fields that "sometimes" should be computed - the same
problem appears in REST / JSON-RPC etc

* Fix a build problem on macOS

* Another way to fix the macOS builds

Co-authored-by: Zahary Karadjov <zahary@gmail.com>
2021-08-18 20:57:58 +02:00
Jacek Sieka 7a622e8505
rework spec imports (#2779)
The spec imports are a mess to work with, so this branch cleans them up
a bit to ensure that we avoid generic sandwitches and that importing
stuff generally becomes easier.

* reexport crypto/digest/presets because these are part of the public
symbol set of the rest of the spec types
* don't export `merge` types from `base` - this causes circular deps
* fix circular deps in `ssz/spec_types` - this is the first step in
disentangling ssz from spec
* be explicit about phase0 vs altair - longer term, `altair` will become
the "natural" type set, then merge and so on, so no point in giving
`phase0` special preferential treatment
2021-08-12 13:08:20 +00:00
Jacek Sieka 9697b73e71
forkedbeaconstate_helpers -> forks (#2772)
Simpler module name for stuff that covers forks

* check that runtime config matches database state
* also include some assorted altair cleanups
* use "standard" genesis fork in local testnet to work around missing
runtime config support
2021-08-10 22:46:35 +02:00
Jacek Sieka 7bb76a6cd1
Merge remote-tracking branch 'origin/stable' into merge-stable 2021-08-09 13:14:28 +02:00
Jacek Sieka ee79c10a7d
update validator key cache on startup (#2760)
* update validator key cache on startup

Versions prior to 1.1.0 do not write a validator key cache at all.

Versions from 1.4.0 and upwards require an immutable validator key cache
to verify blocks - normally, block verification fills the cache but that
assumes that at least one block was verified by a version that has the
key cache.

Taken together, this breaks direct upgrades from anything <1.1.0 to
1.4.0.

The fix is simply to refresh fill the cache from an existing state on
startup.

* also log serious block validation failures at info level
2021-08-05 11:26:10 +03:00
tersec e4afc36d71
use ForkedTrustedSignedBeaconBlock (#2720)
* use ForkedTrustedSignedBeaconBlock

* remove --subscribe-all-subnets

* https://ethereum.github.io/eth2.0-APIs/#/Beacon/getBlock implementation was passing through forked beaconblocks
2021-07-14 12:18:52 +00:00
Jacek Sieka 23eea197f6
Implement split preset/config support (#2710)
* Implement split preset/config support

This is the initial bulk refactor to introduce runtime config values in
a number of places, somewhat replacing the existing mechanism of loading
network metadata.

It still needs more work, this is the initial refactor that introduces
runtime configuration in some of the places that need it.

The PR changes the way presets and constants work, to match the spec. In
particular, a "preset" now refers to the compile-time configuration
while a "cfg" or "RuntimeConfig" is the dynamic part.

A single binary can support either mainnet or minimal, but not both.
Support for other presets has been removed completely (can be readded,
in case there's need).

There's a number of outstanding tasks:

* `SECONDS_PER_SLOT` still needs fixing
* loading custom runtime configs needs redoing
* checking constants against YAML file

* yeerongpilly support

`build/nimbus_beacon_node --network=yeerongpilly --discv5:no --log-level=DEBUG`

* load fork epoch from config

* fix fork digest sent in status
* nicer error string for request failures
* fix tools

* one more

* fixup

* fixup

* fixup

* use "standard" network definition folder in local testnet

Files are loaded from their standard locations, including genesis etc,
to conform to the format used in the `eth2-networks` repo.

* fix launch scripts, allow unknown config values

* fix base config of rest test

* cleanups

* bundle mainnet config using common loader
* fix spec links and names
* only include supported preset in binary

* drop yeerongpilly, add altair-devnet-0, support boot_enr.yaml
2021-07-12 15:01:38 +02:00
tersec ae1abf24af
add Altair support to block quarantine/clearance and block_sim (#2662)
* add Altair support to the block quarantine

* switch some spec/datatypes imports to spec/datatypes/base

* add Altair support to block_clearance

* allow runtime configuration of Altair transition slot

* enable Altair in block_sim, including in CI
2021-06-23 14:43:18 +00:00
tersec b1d5609171
remove false OnBlockAdded dependency on phase0 HashedBeaconState (#2661)
* remove false OnBlockAdded dependency on phase.HashedBeaconState

* introduce altair data types into block_clearance; update some alpha.6 spec refs to alpha.7; add get_active_validator_indices_len ForkedHashedBeaconState wrapper

* switch many modules from using datatypes (with phase0 states/blocks) to datatypes/base (fork-independent); update spec refs from alpha.6 to alpha.7 and remove rm'd G2_POINT_AT_INFINITY

* switch more modules from using datatypes (with phase0 states/blocks) to datatypes/base (fork-independent); update spec refs from alpha.6 to alpha.7

* remove unnecessary phase0-only wrapper of get_attesting_indices(); allow signatures_batch to process either fork; remove O(n^2) nested loop in process_inactivity_updates(); add altair support to getAttestationsforTestBlock()

* add Altair versions of asSigVerified(), asTrusted(), and makeBeaconBlock()

* fix spec URL to be Altair for Altair makeBeaconBlock()
2021-06-21 08:35:24 +00:00
tersec 146fa48454
use ForkedHashedBeaconState in StateData (#2634)
* use ForkedHashedBeaconState in StateData

* fix FAR_FUTURE_EPOCH -> slot overflow; almost always use assign()

* avoid stack allocation in maybeUpgradeStateToAltair()

* create and use dispatch functions for check_attester_slashing(), check_proposer_slashing(), and check_voluntary_exit()

* use getStateRoot() instead of various state.data.hbsPhase0.root

* remove withStateVars.hashedState(), which doesn't work as a design anymore

* introduce spec/datatypes/altair into beacon_chain_db

* fix inefficient codegen for getStateField(largeStateField)

* state_transition_slots() doesn't either need/use blocks or runtime presets

* combine process_slots(HBS)/state_transition_slots(HBS) which differ only in last-slot htr optimization

* getStateField(StateData, ...) was replaced by getStateField(ForkedHashedBeaconState, ...)

* fix rollback

* switch some state_transition(), process_slots, makeTestBlocks(), etc to use ForkedHashedBeaconState

* remove state_transition(phase0.HashedBeaconState)

* remove process_slots(phase0.HashedBeaconState)

* remove state_transition_block(phase0.HashedBeaconState)

* remove unused callWithBS(); separate case expression from if statement

* switch back from nested-ref-object construction to (ref Foo)(Bar())
2021-06-11 20:51:46 +03:00
Jacek Sieka 9193be9b7b
fix epoch logging (fixes #2283) (#2642)
Also put epoch first to disambiguate vs slot
2021-06-11 01:07:16 +03:00
Jacek Sieka d859bc12f0
write uncompressed validator keys to database (#2639)
* write uncompressed validator keys to database

Loading 150k+ validator keys on startup in compressed format takes a lot
of time - better store them in uncompressed format which makes behaviour
just after startup faster / more predictable.

* refactor cached validator key access
* fix isomorphic cast to work with non-var instances
* remove cooked pubkey cache - directly use database cache in chaindag
as well (one less cache to keep in sync)
* bump blscurve, introduce loadValid for known-to-be-valid keys
2021-06-10 10:37:02 +03:00
Jacek Sieka b11da2cb34 fix state cache loading
* load the cache of the current state epoch instead of the target state
epoch, when applying states and slots
* load state cache for each slot/block (for longer slot jumps)
* load state cache after full updateStateData
* look up two state cache epochs, instead of the same epoch twice :)
2021-06-03 21:37:52 +03:00
Jacek Sieka abe0d7b4ae singe validator key cache
Instead of keeping a validator key list per EpochRef, this PR introduces
a single shared validator key list in ChainDAG, and cleans up some other
ChainDAG and key-related issues.

The PR does not introduce the validator key list in the state transition
- this is because we batch-check all signatures before entering the spec
code, thus the spec code never hits the cache.

A future refactor should _probably_ remove the threadvar altogether.

There's a few other small fixes in here that make the flow easier to
read:

* fix `var ChainDAGRef` -> `ChainDAGRef`
* fix `var QuarantineRef` -> `QuarantineRef`
* consistent `dag` variable name
* avoid using threadvar pubkey cache in most cases
* better error messages in batch signature checking
2021-06-01 20:43:44 +03:00
tersec 0b0bfd1de0
use StateData in place of BeaconState outside state transition code (#2551)
* use StateData in place of BeaconState outside state transition code

* propagate more StateData usage

* remove withStateVars().state

* wrap get_beacon_committee(BeaconState, ...) as gbc(StateData, ...)

* switch makeAttestation() to use StateData

* use StateData wrapper/dispatcher for get_committee_count_per_slot()

* convert AttestationCache.init(), weak subjectivity functions, and updateValidatorMetrics()

* add get_shuffled_active_validator_indices(StateData) and get_block_root_at_slot(StateData)

* switch makeAttestationData() to StateData

* sync AllTests-mainnet.md after rebase
2021-05-21 09:23:28 +00:00
Jacek Sieka 97f4e1fffe
Db1 cont (#2573)
* Revert "Revert "Upgrade database schema" (#2570)"

This reverts commit 6057c2ffb4.

* ssz: fix loading empty lists into existing instances

Not a problem earlier because we didn't reuse instances

* bump nim-eth

* bump nim-web3
2021-05-17 18:37:26 +02:00
Jacek Sieka 646923c3dd
add attestation stats tool to ncli_db (#2539)
This also makes future efforts to provide metrics and logs for
attestation efficiency easier

* Export rewards from epoch transition
* Use less memory for reward calculation (bool -> set[enum], field
alignment)
* Reuse reward memory when replaying, avoiding spike
* Allow replaying any range in ncli_db benchmark
2021-05-07 13:36:21 +02:00
Jacek Sieka ce49da6c0a
Introduce unittest2 and junit reports (#2522)
* Introduce unittest2 and junit reports

* fix XML path

* don't combine multiple CI runs

* fixup

* public combined report also

Co-authored-by: Ștefan Talpalaru <stefantalpalaru@yahoo.com>
2021-04-28 18:41:02 +02:00
tersec 99fccaee6e
more abstraction over BeaconState (#2509)
* more abstraction over BeaconState

* use HashedBeaconState copy of htr
2021-04-16 08:49:37 +00:00
Jacek Sieka 4ed2e34a9e Revamp attestation pool
This is a revamp of the attestation pool that cleans up several aspects
of attestation processing as the network grows larger and block space
becomes more precious.

The aim is to better exploit the divide between attestation subnets and
aggregations by keeping the two kinds separate until it's time to either
produce a block or aggregate. This means we're no longer eagerly
combining single-vote attestations, but rather wait until the last
moment, and then try to add singles to all aggregates, including those
coming from the network.

Importantly, the branch improves on poor aggregate quality and poor
attestation packing in cases where block space is running out.

A basic greed scoring mechanism is used to select attestations for
blocks - attestations are added based on how much many new votes they
bring to the table.

* Collect single-vote attestations separately and store these until it's
time to make aggregates
* Create aggregates based on single-vote attestations
* Select _best_ aggregate rather than _first_ aggregate when on
aggregation duty
* Top up all aggregates with singles when it's time make the attestation
cut, thus improving the chances of grabbing the best aggregates out
there
* Improve aggregation test coverage
* Improve bitseq operations
* Simplify aggregate signature creation
* Make attestation cache temporary instead of storing it in attestation
pool - most of the time, blocks are not being produced, no need to keep
the data around
* Remove redundant aggregate storage that was used only for RPC
* Use tables to avoid some linear seeks when looking up attestation data
* Fix long cleanup on large slot jumps
* Avoid some pointers
* Speed up iterating all attestations for a slot (fixes #2490)
2021-04-13 20:24:02 +03:00
Jacek Sieka 3cb31e66b4
set upper bound on EpochRef cache (#2403)
* set upper bound on EpochRef cache

* max 32 EpochRef instances
* less memory waste in BlockRef by removing EpochRef seq that is mostly
unused (~20mb)
* less memory waste in dag block lookup by not keeping an extra copy of
digest (~70mb)
* fix `==` and `$` for Eth2Digest
* remove `ChainDAG.tmpState` (~50mb?)

all in all, this branch cuts mainnet memory usage by ~160-180mb and puts
limits on EpochRef cache usage - where normally it hovered around 950mb
before, it's now sitting at 600-700mb on my machine.

* docs
2021-03-17 11:17:15 +01:00
Mamy Ratsimbazafy 8e28a05cea
Move pruning out of latency critical path (#2384)
* Deferred DAG and fork choice pruning

* fixup

* Address https://github.com/status-im/nimbus-eth2/pull/2384/files#r589448448, rely only on onSLotEnd for state pruning

* no need to store needPruning in the data structure

* lastPrunePoint is updated in pruning proc

* Split eager and LazyPruning

* enforce pruning in updateHead
2021-03-09 15:36:17 +01:00
Mamy Ratsimbazafy 5d7f9c3a04
Consensus object pools [reorg 4/5] (#2374)
* Add documentation

* make test doesn't try to build the beacon node :/
2021-03-04 10:13:44 +01:00
Mamy Ratsimbazafy 2f17ac7b64
Move SSZ, deposit_contracts & eth1_monitor [reorg files 3/5] (#2371)
* move deposit_contract

* Move SSZ

* fix ssz import in tests

* move also eth1_monitor

* forgot to delete the original

* fix comma [skip ci]

* Fix "make" & tools imports

* Fix import

* Fix import again

* rename deposit_contract -> eth1

* Revert ssz move to subfolder

* path fixes [skip ci]
2021-03-03 07:23:05 +01:00
Jacek Sieka 3f8764ee61
fix replays stalling processing (#2361)
* fix replays stalling processing

Occasionally, attestations will arrive that vote for a target derived
either from the finalized block or earlier. In these cases, Nimbus would
replay the state transition of up to 32 epochs worth of blocks because
the finalized state has been pruned, delaying other processing and
leading to poor inclusion distance.

* put cheap attestation checks before forming EpochRef
* check that attestation target is not from an unviable history with
regards to finalization
* fix overly aggressive state pruning removing the state close to the
finalized checkpoint resulting in rare long replays for valid
attestations
* log long replays
* harden logging and traversal of nil BlockSlot

* simplify target check

no need to lookup target in chain dag again

* fixup

* fixup
2021-03-01 20:50:43 +01:00
Mamy Ratsimbazafy 70a03658e3
Block validation flow v2 + Batch (serial) sig verification (#2250)
* bump nim-blscurve

* Outline the block validation flow

* introduce the SigVerified types, pass the tests

* Split clearance/quarantine to prepare for batch crypto verif

* Add a batch signature collector

* Make clearance use SigVerified block and split verification between crypto and state transition

* Always use signedBeaconBlock for the onBlockAdded callback

* RANDAO signing_root is the epoch instead of the full block

* Support skipping BLS for testing

* Fix compilation of the validator client

* Try to fix strange errors MacOS and Jenkins (Clang, unknown type name br_hmac_drbg_context in stdlib_assertions.nim.c)

* address https://github.com/status-im/nimbus-eth2/pull/2250#discussion_r561819858

* address https://github.com/status-im/nimbus-eth2/pull/2250#discussion_r561828025

* onBlockAdded callback should use TrustedSignedBeaconBlock https://github.com/status-im/nimbus-eth2/pull/2250#discussion_r561837261

* address https://github.com/status-im/nimbus-eth2/pull/2250#discussion_r561828946

* Use the application RNG: https://github.com/status-im/nimbus-eth2/pull/2250#discussion_r561815336

* Improve codegen of conversion zero-cost)

* Quick fixes with loadWithCache after #2259 (TODO: graceful error since pubkey validations is now done first in signatures_batch)

* Graceful handle rogue pubkeys and signatures now that those are lazy-loaded
2021-01-25 20:45:48 +02:00
Jacek Sieka 7d5edb4353
use new stew helpers for assignment (#2172)
* bump libp2p (reduces libp2p gossip memory usage to ~1/3)
* use "generic" assign version
2020-12-16 09:37:22 +01:00
Jacek Sieka dbcc0686ff delay pruning of cache for finalized epoch (fixes #2049) 2020-11-20 20:57:50 +02:00
tersec a136c2e95a
bump libp2p; integrate pubsub.ValidationResult into extended validation (#1893) 2020-10-20 12:31:20 +00:00
Jacek Sieka df43b8aa8b
save some more states after all (#1887)
Don't save states when replaying history, but do save states when
applying new blocks (!)
2020-10-18 15:47:39 +00:00
Zahary Karadjov 7a577b2cef More tests for getBlockRange 2020-10-15 20:15:51 +03:00
Jacek Sieka 6b9419e547
fix db growth on attestation processing (#1860)
It turns out that we often save lots of states in the database that are
the result of empty slot processing only - here, we make sure to only
save a state if a block follows - this fixes several issues:

* empty slot states are not always pruned leading to state database size
explosion
* storing states is (very) slow which slows down processing in general,
so we should only do it when it's likely to be useful
* attestation processing doesn't get stuck on saving random states that
won't appear in the chain history
2020-10-15 14:28:44 +02:00
tersec e106549efe
keep REJECT/IGNORE of messages failing validation for libp2p scoring (#1676)
* keep REJECT/IGNORE status of messages failing validation for libp2p scoring

* fix test suite
2020-09-18 13:53:09 +02:00
Jacek Sieka c76305f824
fix some todo (#1645)
* remove some superfluous gcsafes
* remove getTailState (unused)
* don't store old epochrefs in blocks
* document attestation pool a bit
* remove `pcs =` cruft from log
2020-09-14 14:50:03 +00:00
Jacek Sieka 8a5a261fcd
Quick fix to prune some states, pending smarter state storage (#1624)
* Quick fix to prune some states, pending smarter state storage

Adverse effects might include slow rewinds - typically the protocol
doesn't ask for pre-finalized states but RPC might

* document issue, add test

* fix cache miss log
2020-09-11 10:03:50 +02:00
tersec 3d5f24f14c
stop discarding future epochs; remove a StateCache() construction (#1610)
* stop discarding non-existent future epochs during epoch state transitions; remove a pointless StateCache() construction in advance_slots()

* update nbench to pass StateCache to process_slots()
2020-09-07 15:04:33 +00:00
tersec ab255662df
bound block quarantine size (#1564)
* bound block quarantine size

* add additional logging for block quarantining

* re-add quarantine.add() call

* remove pre-finalization blocks; add logging for full quarantine

* clear quarantine on chain reorganization

* update block_sim and tests

* update test_attestation_pool
2020-08-31 11:00:38 +02:00
Jacek Sieka fa1621db46
implement clock disparity for attestation validation (#1568)
This implements disparity, resolving a part of
https://github.com/status-im/nim-beacon-chain/issues/1367

* make BeaconTime a duration for fractional seconds
* factor out attestation/aggregate validation
* simplify recording of queued attestations
* simplify attestation signature check
* fix blocks_received metric
* add some trivial validation tests
* remove unresolved attestation table - attestations for unknown blocks
are dropped instead (cannot verify their signature)
2020-08-27 09:34:12 +02:00
Mamy Ratsimbazafy 81788becfc
Fork choice - almost free pruning - fix #1534 (#1535)
* initial - cheaper pruning - addresses  #1534

* Pass tests: update offset when pruning, proper handling of pruned parents

* Use options instead of nil for nilable newHead (finalization passing but rootcause not solved)

* First line of defense against stackoverflow in tests

* Fix compute_delta offset after pruning

* Rebase fix - medalla ready

* Remove Option[BlockRef]
2020-08-26 17:23:34 +02:00
Jacek Sieka f26d6a4fd3
reuse validator key cache better (#1562)
new key cache can be used for old epochs in the same tree
2020-08-26 17:06:40 +02:00
Jacek Sieka 46c94a18ba rework epoch cache referencing
* collect all epochrefs in specific blocks to make them easier to find
and to avoid lots of small seqs
* reuse validator key databases more aggressively by comparing keys
* make state cache available from within `withState`
* make epochRef available from within onBlockAdded callback
* integrate getEpochInfo into block resolution and epoch ref logic such
that epochrefs are created when blocks are added to pool or lazily when
needed by a getEpochRef
* fill state cache better from EpochRef, speeding up replay and
validation
* store epochRef in specific blocks to make them easier to find and
reuse
* fix database corruption when state is saved while replaying quarantine
* replay slots fully from block pool before processing state
* compare bls values more smartly
* store epoch state without block applied in database - it's recommended
to resync the node!

this branch will drastically speed up processing in times of long
non-finality, as well as cut memory usage by 10x during the recent
medalla madness.
2020-08-19 10:09:06 +03:00
Jacek Sieka 58d77153fc
fix invalid state root being written to database (#1493)
* fix invalid state root being written to database

When rewinding state data, the wrong block reference would be used when
saving the state root - this would cause state loading to fail by
loading a different state than expected, preventing blocks to be
applied.

* refactor state loading and saving to consistently use and set
StateData block
* avoid rollback when state is missing from database (as opposed to
being partially overwritten and therefore in need of rollback)
* don't store state roots for empty slots - previously, these were used
as a cache to avoid recalculating them in state transition, but this has
been superceded by hash tree root caching
* don't attempt loading states / state roots for non-epoch slots, these
are not saved to the database
* simplify rewinder and clean up funcitions after caches have been
reworked
* fix chaindag logscope
* add database reload metric
* re-enable clearance epoch tests

* names
2020-08-13 11:50:05 +02:00
Jacek Sieka 8b0f2cc96f
share validator keys in EpochRef (#1486) 2020-08-11 21:39:53 +02:00
Zahary Karadjov 30a8ec410d More spec compliant blocksByRange requests
* Eliminate possibilities for range errors and overflows
* Handle more properly invalid requests for furute slots
* Eliminate the confusing surrounding the MAX_REQUEST_BLOCKS constant

Addresses https://github.com/status-im/nim-beacon-chain/issues/1366
2020-08-10 22:09:13 +03:00
tersec df80071bcf
update attestation and block validation to v0.12.2; clean up getAncestorAt()/get_ancestor() (#1417)
* update attestation validation to v0.12.2; clean up getAncestorAt()/get_ancestor()

* update beacon block validation to v0.12.2
2020-08-03 19:47:42 +00:00
Viktor Kirilov 0a96e5f564
renamed CandidateChains to ChainDagRef and made the Quarantine type a ref type so there is a single instance in the beacon node (#1407) 2020-07-31 14:49:06 +00:00
Viktor Kirilov c032366547
removed the BlockPool type and all of the proxy functions around it (#1401)
* removed the BlockPool type and all of the proxy functions around it - passing the chain DAG and the quarantine explicitly where appropriately - they don't need to be bundled in a type

* fixed the build after the rebase
2020-07-30 21:18:17 +02:00
Jacek Sieka 157ddd2ac4
Fork choice fixes 5 (#1381)
* limit attestations kept in attestation pool

With fork choice updated, the attestation pool only needs to keep track
of attestations that will eventually end up in blocks - we can thus
limit the horizon of attestations that we keep more aggressively.

To get here, we expose getEpochRef which gets metadata about a
particular epochref, and make sure to populate it when a block is added
- this ensures that state rewinds during block addition are minimized.

In addition, we'll use the target root/epoch when validating
attestations - this helps minimize the number of different states that
we need to rewind to, in general.

* remove CandidateChains.justifiedState

unused

* remove BlockPools.Head object

* avoid quadratic quarantine loop

* fix
2020-07-28 13:54:32 +00:00