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
* proposed structure for hf1
* refactor datatypes.nim into datatypes/{base, phase0, hf1}.nim
* hf1 is Altair
* some syncing with alpha 2
* adjust epoch processing to disambiguate access to RewardFlags
* relocate StateData to stay consistent with meaning phase 0 StateData
* passes v1.1.0 alpha 5 SSZ consensus object tests
* Altair block header test fixtures work
* fix slash_validator() so that Altair attester slashings, proposer slashings, and voluntary exit textures work
* deposit operation Altair test fixtures work
* slot sanity and all but a couple epoch transition tests switched to Altair
* attestation Altair test fixtures work
* Altair block sanity test fixtures work
* add working altair sync committee tests
* improve workarounds for sum-types-across-modules Nim bug; incorporate SignedBeaconBlock root reconstuction to SSZ byte reader
* 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
* 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
The `kvstore` design we're using now turns out to not be the best way to
use `sqlite` - in particular, there are some significant benefits to
using rowid in certain situations and to keep data in separate tables.
With this branch, there are massive improvements in startup time
(seconds instead of minutes) and state/block storage and pruning times
(milliseconds instead of seconds) - these improvements can in particular
be seen on slow drives and translate directly into better attestation
performance.
* update kvstore to new keyspace design
* remove `DirStoreRef` and the hidden `--state-db-kind` option - this
was an experiment to store large blobs in files, but with the new
kvstore, there's no compelling reason to do so
* remove `DbMap` - unused and would need updating for new keyspace
design
* introduce separate tables for each data type (blocks, states etc)
* remove "WITHOUT ROWID" pessimization for tables with large blobs
* close DbSeq statements explicitly (and earlier)
* store beacon block summaries in separate table, without SSZ
compression and load them all with single query on startup
* stop storing backwards compat full states
* mark genesis beacon block as trusted
* avoid faststreams when loading SSZ data
* remove `DisagreementBehavior` (unused)
* avoid creating indexed attestation just to check signatures - above
all, don't create it when not checking signatures ;)
* avoid pointer op when adding attestation to pool
* better iterator for yielding attestations
* add metric / log for attestation packing time
* Reset cached indices when resetting cache on SSZ read
When deserializing into an existing structure, the cache should be
cleared - goes for json also. Also improve error messages.
* use IntSet rather than HashSet[ValidatorIndex]
* add bounds check before uint64 -> int conversion
* use intsets in block transitions
* remove superfluous Nim issue explanation/reference
* performance fixes
* don't mark tree cache as dirty on read-only List accesses
* store only blob in memory for keys and signatures, parse blob lazily
* compare public keys by blob instead of parsing / converting to raw
* compare Eth2Digest using non-constant-time comparison
* avoid some unnecessary validator copying
This branch will in particular speed up deposit processing which has
been slowing down block replay.
Pre (mainnet, 1600 blocks):
```
All time are ms
Average, StdDev, Min, Max, Samples, Test
Validation is turned off meaning that no BLS operations are performed
3450.269, 0.000, 3450.269, 3450.269, 1, Initialize DB
0.417, 0.822, 0.036, 21.098, 1400, Load block from database
16.521, 0.000, 16.521, 16.521, 1, Load state from database
27.906, 50.846, 8.104, 1507.633, 1350, Apply block
52.617, 37.029, 20.640, 135.938, 50, Apply epoch block
```
Post:
```
3502.715, 0.000, 3502.715, 3502.715, 1, Initialize DB
0.080, 0.560, 0.035, 21.015, 1400, Load block from database
17.595, 0.000, 17.595, 17.595, 1, Load state from database
15.706, 11.028, 8.300, 107.537, 1350, Apply block
33.217, 12.622, 17.331, 60.580, 50, Apply epoch block
```
* more perf fixes
* load EpochRef cache into StateCache more aggressively
* point out security concern with public key cache
* reuse proposer index from state when processing block
* avoid genericAssign in a few more places
* don't parse key when signature is unparseable
* fix `==` overload for Eth2Digest
* preallocate validator list when getting active validators
* speed up proposer index calculation a little bit
* reuse cache when replaying blocks in ncli_db
* avoid a few more copying loops
```
Average, StdDev, Min, Max, Samples, Test
Validation is turned off meaning that no BLS operations are performed
3279.158, 0.000, 3279.158, 3279.158, 1, Initialize DB
0.072, 0.357, 0.035, 13.400, 1400, Load block from database
17.295, 0.000, 17.295, 17.295, 1, Load state from database
5.918, 9.896, 0.198, 98.028, 1350, Apply block
15.888, 10.951, 7.902, 39.535, 50, Apply epoch block
0.000, 0.000, 0.000, 0.000, 0, Database block store
```
* clear full balance cache before processing rewards and penalties
```
All time are ms
Average, StdDev, Min, Max, Samples, Test
Validation is turned off meaning that no BLS operations are performed
3947.901, 0.000, 3947.901, 3947.901, 1, Initialize DB
0.124, 0.506, 0.026, 202.370, 363345, Load block from database
97.614, 0.000, 97.614, 97.614, 1, Load state from database
0.186, 0.188, 0.012, 99.561, 357262, Advance slot, non-epoch
14.161, 5.966, 1.099, 395.511, 11524, Advance slot, epoch
1.372, 4.170, 0.017, 276.401, 363345, Apply block, no slot processing
0.000, 0.000, 0.000, 0.000, 0, Database block store
```
Validators exiting is normal, no need to scream about it
* avoid reallocating seq on big exit queue
* avoid fetching state cache when updating head (it's rarely needed)
* remove incorrectly implemented live validator counts (avoids memory
allocs)
Calculating rewards/penalties is slow due to how we compute sets of
attestations validators then use the sets for inclusion checks, to see
who attested. The dominant function during validated block processing /
epoch processing is hash set building and lookup.
This PR inverts the flow by removing the sets and creating a single
large validator status list, then applying all relevant state
attestations, then updating rewards and penalties.
This provides a 10x speedup to epoch processing which in turn speeds up
both empty slot and block processing - for example, on startup, we
replay all non-finalized blocks to prime fork choice - the same when
validating attestations or replaying states on reorg.
* misc memory and perf fixes
* use EpochRef for attestation aggregation
* compress effective balances in memory (medalla unfinalized: 4gb ->
1gb)
* avoid hitting db when rewinding to head or clearance state
* avoid hitting db when blocks can be applied to in-memory state -
speeds up startup considerably
* avoid storing epochref in fork choice
* simplify and speed up beacon block creation flow - avoids state reload
thanks to head rewind optimization
* iterator-based committee and attestation participation help avoid lots
of small memory allocations throughout epoch transition (40% speedup on
epoch processing, for example during startup)
* add constant for threshold
* evaluate block attestations under the epochref of the block - this is
what the state transition function does
* avoid copying attestation seq unnecessarily
* avoid unnecessary hashset for unslashed indices
* Lazy loading of crypto objects
* Try to fix incorrect field access by hiding fields but no luck. SSZ/Chronicles/macro bug?
* Fix incorrect blsValue access. was "aggregate" not "chronicles"
* Fix tests that rely on the internal BLSValue representation
* 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
* add helper for beacon committee length (used for quickly validating
attestations)
* refactor some attestation checks to do cheap checks early
* validate attestation epoch before computing active validator set
* clean up documentation / comments
* fill state cache on demand
* avoid converting from uint64 to int, and where most feasible, int type conversion at all
* .len.uint64 -> .len64
* fix 32-bit compilation
* try keeping state_sim loop variable/bounds as int for 32-bit Azure
* len64 -> lenu64
* cache beacon committee size calculation
this fixes a bug in get_validator_churn_limit as well
* fix
* make committee counts consistently uint64
mixing feels like the worst of the two worlds
hash_tree_root was turning up when running beacon_node, turns out to be
repeated hash_tree_root invocations - this pr brings them back down to
normal.
this PR caches the root of a block in the SignedBeaconBlock object -
this has the potential downside that even invalid blocks will be hashed
(as part of deserialization) - later, one could imagine delaying this
until checks have passed
there's also some cleanup of the `cat=` logs which were applied randomly
and haphazardly, and to a large degree are duplicated by other
information in the log statements - in particular, topics fulfill the
same role
* restore EpochRef and flush statecaches on epoch transitions
* more targeted cache invalidation
* remove get_empty_per_epoch_cache(); implement simpler but still faster get_beacon_proposer_index()/compute_proposer_index() approach; add some abstraction layer for accessing the shuffled validator indices cache
* reduce integer type conversions
* remove most of rest of integer type conversion in compute_proposer_index()
This also assigns precise types to the constants in the minimal
and mainnet presets in order to reduce the chance of compilation
errors when custom presets are used (previously, only the custom
presets have precisely assigned types for the constants).
* update most of the remaining non-fork-choice spec refs, updating code where necessary
* revert presumably harmless compute_signing_root() change, but this way, keep things really unchanged outside inspector
* Dual headed fork choice
* fix finalizedEpoch not moving
* reduce fork choice verbosity
* Add failing tests due to pruning
* Properly handle duplicate blocks in sync
* test_block_pool also add a test for duplicate blocks
* comments addressing review
* Fix fork choice v2, was missing integrating block proposed
* remove a spurious debug writeStackTrace
* update block_sim
* Use OrderedTable to ensure that we always load parents before children in fork choice
* Load the DAG data in fork choice at init if there is some (can sync witti)
* Cluster of quarantined blocks were not properly added to the fork choice
* Workaround async gcsafe warnings
* Update blockpoool tests
* Do the callback before clearing the quarantine
* Revert OrderedTable, implement topological sort of DAG, allow forkChoice to be initialized from arbitrary finalized heads
* Make it work with latest devel - Altona readyness
* Add a recovery mechanism when forkchoice desyncs with blockpool
* add the current problematic node to the stack
* Fix rebase indentation bug (but still producing invalid block)
* Fix cache at epoch boundaries and lateBlock addition
* adopt Result[void, string] in place of some bool return signatures
* string -> cstring to reduce memory allocations; ensure all err() strings are constants, with contextual information from higher-level callers
* logScope usage fixes
* homogenize err() reporting convention
* invalid signature in deposit isn't an error
* cleanups
* fix ncli state root check flag
* add block dump to ncli_db
* limit ncli_db benchmark length
* tone down finalization logs
* introduce trusted blocks
We only store blocks whose signature we've verified in the database - as
such, there's no need to check it again, and most importantly, no need
to deserialize the signature when loading from database.
50x startup time improvement, 200x block load time improvement.
* fix rewinding when deposits have invalid signature
* speed up ancestor iteration by avoiding copy
* avoid deserializing signatures for trusted data
* load blocks lazily when rewinding (less memory used)
* chronicles workarounds
* document trustedbeaconblock
* collect signature production and verificaiton in one place
Signatures are made over data and domain - here we collect all such
activities in one place.
Also:
* security: fix cast-before-range-check
* log block/attestation verification consistently
* run block verification based on `getProposer` in its own history
* clean up some unused stuff
* import
* missing raises
* random fixes
* create dump dir on startup
* don't crash on failure to write dump
* fix a few `uint64` instances being used when indexing arrays - this
should be a compile error but isn't due to compiler bugs
* fix standalone test_block_pool compilation
* add signed block processing in ncli
* reuse cache entry instead of allocating a new one
* allow for small clock disparities when validating blocks
* reorder ssz
* split into hash_trees and ssz_serialization, roughly, for hashing and
IO
* move bitseqs into ssz (from stew)
* clean up imports
* docs, imports
* sync fixes
* fix Status message finalized info
* work around sync starting before initial status exchange
* don't fail block on deposit signature check failure (fixes#989)
* print ForkDigest and Version nicely
* dump incoming blocks
* fix crash when libp2p peer connection is closed
* update chunk size to 16 to work around missing blocks when syncing
* bump libp2p
* bump libp2p
* better deposit skip message
* fix some warnings related to beacon_node splitting; reimplement finalization verification more robustly; improve attestation pool block selection logic
* re-add missing import
* whitelist allowed state transition flags and make rollback/restore naming more consistent
* restore usage of update flags passed into skipAndUpdateState(...) in addition to the potential verifyFinalization flag
* switch rest of rollback -> restore
* remove near-duplicate code paths: process_slot(), process_slots(), and state_transition() for BeaconState are now wrappers around the HashedBeaconState versions
* convert tests/test_state_transition.nim to use HashedBeaconState
* convert mocking infrastructure and spec_block/epoch_processing tests to use HashedBeaconBlock, and remove thus unused process_slot*(state: var BeaconState)
* add another check for inconsistent aggregation and committee length, since ncli_transition bypasses process_attestation(...)/check_attestation(...) and calls almost directly into process_epoch(...)
* bump validator functions to v0.11.1 spec references
* bump some spec references to v0.11.1
* poke
* initial extended validation setup
* flesh out all TODO items for attestation and beaconblock verification
* fix finalization and add chronicles debugging messages
* directly use blockPool.headState rather than pointlessly updating it and document this constraint
* fix logic relating to first-attestation checking; support validating blocks across multiple forks
* initial 0.11.1 spec commit; no test regressions and finalizes in eth2_network_simulation
* with BLS 0.10/0.11 available, stop skipping attester slashing, proposer slashing, and voluntary exist operations fixture tests
* switch param orders to group state.{fork, genesis_validators_root}; bump spec/datatypes spec version for network purposes
* mark attestation construction and broadcast and some minimal/mainnet constants as 0.11.1-compatible; remove phase 1 sharding constants from minimal which don't exist in that preset
* Initial implementation of runtime bls skipping.
Add libnfuzz skipBLSValidation handling, check that it propagates.
* Rename skipBLSValidation -> skipBlsValidation, start skipStateRootValidation
* Replace skipValidation flags with more granular flags.
Also added skipBlockParentRootValidation flag
Mainly replaced with skipBlsValidation but also StateRoot or
BlockParentRootValidation flags where appropriate.
* Adjust interop test to pass when skipping merkle validation.
* Stop skipping validation for mainchain_monitor.
* Remove comment.
* Also skipMerkleValidation for test_beacon_chain_db.
* update to 0.10.1
* SSZ Generic and nbench uses the v0.10.1 fixtures
* Tests + spec links: v0.10.0 -> v0.10.1
* Add v0.10.1 TODO in get_latest_attesting_balance (forkchoice)
* SSZ Bytes are now ByteList
* Remove nim-result submodules that was leftover/added by mistake in the branch
* nbench PoC
* Remove the yaml files from the example scenarios
* update README with current status
* Add an alternative implementation that uses defer
* Forgot to add the old proc body
* slots-processing
* allow benching state_transition failures
* Add Attestations processing (workaround confutils bug:
- https://github.com/status-im/nim-confutils/issues/10
- https://github.com/status-im/nim-confutils/issues/11
- https://github.com/status-im/nim-confutils/issues/12
* Add CLI command in the readme
* Filter report and add notes about CPU cycles
* Report averages
* Add debugecho style time/cycle print
* Report when we skip BLS and state root verification
* Update to 0.9.3
* Generalize scenario parsing
* Support all block processing scenarios
* parallel bench runner PoC
* gitBetter load issues reporting (the load issues were invalid signature and expected to fail)
* re-enable test_interop based on zcli with 0.9.1 specs and update initialize_beacon_state_from_eth1(...) to 0.9.1
* switch many procs to funcs
* fix import os.nim instead; ospaths is deprecated [Deprecated] warnings
* transition deposit operations fixture to 0.9.0
* mark slash_validator(...) as 0.9.0
* switch remaining non-ref objects to ref objects to maybe avoid crashes in CI
* remove unused helpers/debug_state imports
* rename compute_epoch_of_slot(...) to compute_epoch_at_slot(...)
* remove some unnecessary imports; remove some crosslink-related code and tests; complete renaming of compute_epoch_of_slot(...) to compute_epoch_at_slot(...)
* rm more transfer-related code and tests; rm more unnecessary strutils imports
* rm remaining unused imports
* remove useless get_empty_per_epoch_cache(...)/compute_start_slot_of_epoch(...) calls
* rename compute_start_slot_of_epoch(...) to compute_start_slot_at_epoch(...)
* rename ACTIVATION_EXIT_DELAY to MAX_SEED_LOOKAHEAD
* update domain types to 0.9.0
* mark AttesterSlashing, IndexedAttestation, AttestationDataAndCustodyBit, DepositData, BeaconBlockHeader, Fork, integer_squareroot(...), and process_voluntary_exit(...) as 0.9.0
* mark increase_balance(...), decrease_balance(...), get_block_root(...), CheckPoint, Deposit, PendingAttestation, HistoricalBatch, is_active_validator(...), and is_slashable_attestation_data(...) as 0.9.0
* mark compute_activation_exit_epoch(...), bls_verify(...), Validator, get_active_validator_indices(...), get_current_epoch(...), get_total_active_balance(...), and get_previous_epoch(...) as 0.9.0
* mark get_block_root_at_slot(...), ProposerSlashing, get_domain(...), VoluntaryExit, mainnet preset Gwei values, minimal preset max operations, process_block_header(...), and is_slashable_validator(...) as 0.9.0
* mark makeWithdrawalCredentials(...), get_validator_churn_limit(...), get_total_balance(...), is_valid_indexed_attestation(...), bls_aggregate_pubkeys(...), initial genesis value/constants, Attestation, get_randao_mix(...), mainnet preset max operations per block constants, minimal preset Gwei values and time parameters, process_eth1_data(...), get_shuffled_seq(...), compute_committee(...), and process_slots(...) as 0.9.0; partially update get_indexed_attestation(...) to 0.9.0 by removing crosslink refs and associated tests
* mark initiate_validator_exit(...), process_registry_updates(...), BeaconBlock, Eth1Data, compute_domain(...), process_randao(...), process_attester_slashing(...), get_base_reward(...), and process_slot(...) as 0.9.0
* Add attestation unit test
* process_attestation doesn't throw exceptions
* Allow SSZ deserialization of both real and invalid signatures
* Add new process_attestation checks - pass all process_attestation tests
* Add sanity check for #361
* Fix SSZ testing after fromBytes/fromSSZBytes changes
* Add sanity check for slot processing (also impacted by https://github.com/status-im/nim-beacon-chain/issues/373)
* use reportDiff also for all state tests vs EF
* initial sanity checks for blocks - workaround zero signature in block headers: https://github.com/status-im/nim-beacon-chain/issues/374
* Remove generic object variant compare commented code
* Add the one block state transition sanity checks
* generalize blocks test to multiple blocks
* simplify slots test runner
* Add official epoch transitions, sanity blocks, sanity slots to the test suite
* Fix index out-of-bounds in initiate_validator_exit - enable proposer slashings unittest
* Update BLS fixtures to 0.8.3
* Bump fixtures with shuffling with minimal preset
* Update shuffling tests
* parseTest generic over file format (Json or SSZ)
* Initial crosslink parsing commit for debugging Nim crash
* Workaround https://github.com/status-im/nim-beacon-chain/issues/369
* Crosslink test works for minimal - https://github.com/status-im/nim-beacon-chain/issues/369 is back on mainnet
* Use ref objects to workaround https://github.com/status-im/nim-beacon-chain/issues/369
* Generalize state transition epoch test to all epoch tests
* Fix slashing (potential uint64 overflow in previous spec)
* Add a state debugging macro to deeply inspect the wrong fields
* make reportDiff visible
* Improve the debug state macro for containers
* add interop launcher scripts
* stick validator_keygen into beacon_node
* fix lmd ghost slot number on missing block
* use mocked eth1data when producing blocks
* use bls public key method for withdrawal credentials
* fix deposit domain
* prefer lowercase for a bunch of toHex
* build simulation binary in data folder to avoid data types confusion
* Introduce new mocking proc to replace:
- makeFakeValidatorPrivKey
- hackPrivKey
- getNextBeaconProposerIndex
- addBlock
- makeBlock
* Add comments on datastructure unsynced with the spec
* Add merkle tree constructor and initial mocking for deposits (missing merkle proofs)
* [Mock] Implement sparse merkle tree and merkle proof builder
* [Mocking] Genesis deposits
* Add compact_committees_roots init + mock genesis state
* [Tests] Add first deposit test using the new mocking procedures
* [Tests -deposits] add at and over 32 ETH deposit tests
* [Tests - deposits] Add test for validator top-up
* [Tests -deposits] Mention the TODO to test for invalid conditions
* [Tests] Add stub to test "is_valid_genesis_state"
* [Merkle proofs] Implement round-trip checks
* Deactivate roundtrips test
* SSZ - use EF convention for hash_tree_root / hashTreeRoot
* [Tests - Attestation] Attestation mocking + initial test
* Add mocking + 3 new tests for valid attestations + mention future invalid attestation tests
* Add crosslinks test (1 failing to attestations in block being duplicated in state transition)
* Single attestation crosslink test - workaround https://github.com/status-im/nim-beacon-chain/issues/361
* Add test for failed crosslink penalty
* Rebase fixes + add refactored tests to test suite
* justif-finalization helpers first batch
* Add 234 finalization tests
* Fix justif test, Rule I 234 finalization does not happen with sufficient support.
(Also unittest check template does not fail properly in some cases)
* Add tests for all finalization rules
* Properly delete nim-byteutils following c91727e7e5 (diff-7c3613dba5171cb6027c67835dd3b9d4)
* use digest helper for deposit root
* relax attestation validation when attestation is incoming but make it
more strict when adding to block
* share attestation validation logic between attestation pool and state
transition
* remove a bunch of redundant logging
* fix potential underflow in attestation delay checking
* fix committee used for attestation shard selection when attesting
* fix attestation data construction
* working justification, 1 node, 64 validators
* closer to tn1 params: 256 validators
* more debugging output; switch to minimum test case
* working justification and finalization in local network simulation
* fix currently incorrect state transition/attestation test assumption
* rename get_genesis_beacon_state(...) to initialize_beacon_state_from_eth1(...); remove unused vestiges get_temporary_block_header(...) and get_empty_block(...); partly align initialize_beacon_state_from_eth1(...) with 0.8.0 version; implement CompactCommittee object type; update process_final_updates(...) to 0.8.0
* mark get_shard_delta(...) as 0.8.0
* mark get_total_active_balance(...) and epoch transition helper functions as 0.8.0
* move FORK_CHOICE_BALANCE_INCREMENT, not in spec anymore, to sole user in fork_choice
* replace BeaconState.finalized_{epoch,root} with BeaconState.finalized_checkpoint; rename get_delayed_activation_exit_epoch(...) to compute_activation_exit_epoch(...) and mark as 0.8.0; update get_churn_limit(...)/get_validator_churn_limit(...) to 0.8.0; update process_registry_updates(...) to 0.8.0
* update process_crosslinks(...) to 0.8.0; mark compute_start_slot_of_epoch(...) and get_committee_count(...) as 0.8.0
* mark Fork, is_slashable_validator(...), and get_beacon_proposer_index(...) as 0.8.0
* rename LATEST_SLASHED_EXIT_LENGTH to EPOCHS_PER_SLASHINGS_VECTOR; update process_slashings(...) to 0.8.0; remove pointless type conversion warning in get_previous_epoch(...)
* convert remaining references to finalized_epoch to finalized_checkpoint.epoch
* update slash_validator(...) to 0.8.0; mark inital value, Gwei, and time constants as 0.8.0; mark hash(...) and processBlockHeader(...) as 0.8.0
* rename WHISTLEBLOWING_REWARD_QUOTIENT to WHISTLEBLOWER_REWARD_QUOTIENT; rename LATEST_ACTIVE_INDEX_ROOTS_LENGTH to EPOCHS_PER_HISTORICAL_VECTOR (randao will also get merged into this); remove get_active_index_root(...); mark time parameter, signature domain types, and max operations per block constants as 0.8.0; update rewards and penalties constants to 0.8.0
* update is_valid_indexed_attestation(...) to 0.8.0; mark process_slot(...) as 0.8.0
* replace BeaconState.{current,previous}_justified_{epoch,root} with BeaconState.{current,previous}_justified_checkpoint