## Issue Addressed
Closes#800Closes#1713
## Proposed Changes
Implement the temporary state storage algorithm described in #800. Specifically:
* Add `DBColumn::BeaconStateTemporary`, for storing 0-length temporary marker values.
* Store intermediate states immediately as they are created, marked temporary. Delete the temporary flag if the block is processed successfully.
* Add a garbage collection process to delete leftover temporary states on start-up.
* Bump the database schema version to 2 so that a DB with temporary states can't accidentally be used with older versions of the software. The auto-migration is a no-op, but puts in place some infra that we can use for future migrations (e.g. #1784)
## Additional Info
There are two known race conditions, one potentially causing permanent faults (hopefully rare), and the other insignificant.
### Race 1: Permanent state marked temporary
EDIT: this has been fixed by the addition of a lock around the relevant critical section
There are 2 threads that are trying to store 2 different blocks that share some intermediate states (e.g. they both skip some slots from the current head). Consider this sequence of events:
1. Thread 1 checks if state `s` already exists, and seeing that it doesn't, prepares an atomic commit of `(s, s_temporary_flag)`.
2. Thread 2 does the same, but also gets as far as committing the state txn, finishing the processing of its block, and _deleting_ the temporary flag.
3. Thread 1 is (finally) scheduled again, and marks `s` as temporary with its transaction.
4.
a) The process is killed, or thread 1's block fails verification and the temp flag is not deleted. This is a permanent failure! Any attempt to load state `s` will fail... hope it isn't on the main chain! Alternatively (4b) happens...
b) Thread 1 finishes, and re-deletes the temporary flag. In this case the failure is transient, state `s` will disappear temporarily, but will come back once thread 1 finishes running.
I _hope_ that steps 1-3 only happen very rarely, and 4a even more rarely. It's hard to know
This once again begs the question of why we're using LevelDB (#483), when it clearly doesn't care about atomicity! A ham-fisted fix would be to wrap the hot and cold DBs in locks, which would bring us closer to how other DBs handle read-write transactions. E.g. [LMDB only allows one R/W transaction at a time](https://docs.rs/lmdb/0.8.0/lmdb/struct.Environment.html#method.begin_rw_txn).
### Race 2: Temporary state returned from `get_state`
I don't think this race really matters, but in `load_hot_state`, if another thread stores a state between when we call `load_state_temporary_flag` and when we call `load_hot_state_summary`, then we could end up returning that state even though it's only a temporary state. I can't think of any case where this would be relevant, and I suspect if it did come up, it would be safe/recoverable (having data is safer than _not_ having data).
This could be fixed by using a LevelDB read snapshot, but that would require substantial changes to how we read all our values, so I don't think it's worth it right now.
## Issue Addressed
Closes#1557
## Proposed Changes
Modify the pruning algorithm so that it mutates the head-tracker _before_ committing the database transaction to disk, and _only if_ all the heads to be removed are still present in the head-tracker (i.e. no concurrent mutations).
In the process of writing and testing this I also had to make a few other changes:
* Use internal mutability for all `BeaconChainHarness` functions (namely the RNG and the graffiti), in order to enable parallel calls (see testing section below).
* Disable logging in harness tests unless the `test_logger` feature is turned on
And chose to make some clean-ups:
* Delete the `NullMigrator`
* Remove type-based configuration for the migrator in favour of runtime config (simpler, less duplicated code)
* Use the non-blocking migrator unless the blocking migrator is required. In the store tests we need the blocking migrator because some tests make asserts about the state of the DB after the migration has run.
* Rename `validators_keypairs` -> `validator_keypairs` in the `BeaconChainHarness`
## Testing
To confirm that the fix worked, I wrote a test using [Hiatus](https://crates.io/crates/hiatus), which can be found here:
https://github.com/michaelsproul/lighthouse/tree/hiatus-issue-1557
That test can't be merged because it inserts random breakpoints everywhere, but if you check out that branch you can run the test with:
```
$ cd beacon_node/beacon_chain
$ cargo test --release --test parallel_tests --features test_logger
```
It should pass, and the log output should show:
```
WARN Pruning deferred because of a concurrent mutation, message: this is expected only very rarely!
```
## Additional Info
This is a backwards-compatible change with no impact on consensus.
## Issue Addressed
Closes#673
## Proposed Changes
Store a schema version in the database so that future releases can check they're running against a compatible database version. This would also enable automatic migration on breaking database changes, but that's left as future work.
The database config is also stored in the database so that the `slots_per_restore_point` value can be checked for consistency, which closes#673
The PR:
* Adds the ability to generate a crucial test scenario that isn't possible with `BeaconChainHarness` (i.e. two blocks occupying the same slot; previously forks necessitated skipping slots):
* New testing API: Instead of repeatedly calling add_block(), you generate a sorted `Vec<Slot>` and leave it up to the framework to generate blocks at those slots.
* Jumping backwards to an earlier epoch is a hard error, so that tests necessarily generate blocks in a epoch-by-epoch manner.
* Configures the test logger so that output is printed on the console in case a test fails. The logger also plays well with `--nocapture`, contrary to the existing testing framework
* Rewrites existing fork pruning tests to use the new API
* Adds a tests that triggers finalization at a non epoch boundary slot
* Renamed `BeaconChainYoke` to `BeaconChainTestingRig` because the former has been too confusing
* Fixed multiple tests (e.g. `block_production_different_shuffling_long`, `delete_blocks_and_states`, `shuffling_compatible_simple_fork`) that relied on a weird (and accidental) feature of the old `BeaconChainHarness` that attestations aren't produced for epochs earlier than the current one, thus masking potential bugs in test cases.
Co-authored-by: Michael Sproul <michael@sigmaprime.io>
## Issue Addressed
Closes#1488
## Proposed Changes
* Prevent the pruning algorithm from over-eagerly deleting states at skipped slots when they are shared with the canonical chain.
* Add `debug` logging to the pruning algorithm so we have so better chance of debugging future issues from logs.
* Modify the handling of the "finalized state" in the beacon chain, so that it's always the state at the first slot of the finalized epoch (previously it was the state at the finalized block). This gives database pruning a clearer and cleaner view of things, and will marginally impact the pruning of the op pool, observed proposers, etc (in ways that are safe as far as I can tell).
* Remove duplicated `RevertedFinalizedEpoch` check from `after_finalization`
* Delete useless and unused `max_finality_distance`
* Add tests that exercise pruning with shared states at skip slots
* Delete unnecessary `block_strategy` argument from `add_blocks` and friends in the test harness (will likely conflict with #1380 slightly, sorry @adaszko -- but we can fix that)
* Bonus: add a `BeaconChain::with_head` method. I didn't end up needing it, but it turned out quite nice, so I figured we could keep it?
## Additional Info
Any users who have experienced pruning errors on Medalla will need to resync after upgrading to a release including this change. This should end unbounded `chain_db` growth! 🎉
## Issue Addressed
NA
## Proposed Changes
- Adds a new function to allow getting a state with a bad state root history for attestation verification. This reduces unnecessary tree hashing during attestation processing, which accounted for 23% of memory allocations (by bytes) in a recent `heaptrack` observation.
- Don't clone caches on intermediate epoch-boundary states during block processing.
- Reject blocks that are known to fork choice earlier during gossip processing, instead of waiting until after state has been loaded (this only happens in edge-case).
- Avoid multiple re-allocations by creating a "forced" exact size iterator.
## Additional Info
NA
* Layer do_atomically() abstractions properly
* Reduce allocs and DRY get_key_for_col()
* Parameterize HotColdDB with hot and cold item stores
* -impl Store for MemoryStore
* Replace Store uses with HotColdDB
* Ditch Store trait
* cargo fmt
* Style fix
* Readd missing dep that broke the build
* Remove redundant method
* Pull out a method out of a struct
* More precise db access abstractions
* Move fake trait method out of it
* cargo fmt
* Fix compilation error after refactoring
* Move another fake method out the Store trait
* Get rid of superfluous method
* Fix refactoring bug
* Rename: SimpleStoreItem -> StoreItem
* Get rid of the confusing DiskStore type alias
* Get rid of SimpleDiskStore type alias
* Correction: A method took both self and a ref to Self
* Improve error handling in block iteration
* Introduce atomic DB operations
* Fix race condition
An invariant was violated: For every block hash in head_tracker, that
block is accessible from the store.
* Address compiler warning
* Prune abandoned fork choice forks
* New approach to pruning
* Wrap some block hashes in a newtype pattern
For increased type safety.
* Add Graphviz chain dump emitter for debugging
* Fix broken test case
* Make prunes_abandoned_forks use real DiskStore
* Mark finalized blocks in the GraphViz output
* Refine debug stringification of Slot and Epoch
Before this commit: print!("{:?}", Slot(123)) == "Slot(\n123\n)".
After this commit: print!("{:?", Slot(123)) == "Slot(123)".
* Simplify build_block()
* Rewrite test case using more composable test primitives
* Working rewritten test case
* Tighten fork prunning test checks
* Add another pruning test case
* Bugfix: Finalized blocks weren't always properly detected
* Pruning: Add pruning_does_not_touch_blocks_prior_to_finalization test case
* Tighten pruning tests: check if heads are tracked properly
* Add a failing test case for a buggy scenario
* Change name of function to a more accurate one
* Fix failing test case
* Test case: Were skipped slots' states pruned?
* Style fix: Simplify dereferencing
* Tighten pruning tests: check if abandoned states are deleted
* Towards atomicity of db ops
* Correct typo
* Prune also skipped slots' states
* New logic for handling skipped states
* Make skipped slots test pass
* Post conflict resolution fixes
* Formatting fixes
* Tests passing
* Block hashes in Graphviz node labels
* Removed unused changes
* Fix bug with states having < SlotsPerHistoricalRoot roots
* Consolidate State/BlockRootsIterator for pruning
* Address review feedback
* Fix a bug in pruning tests
* Detach prune_abandoned_forks() from its object
* Move migrate.rs from store to beacon_chain
* Move forks pruning onto a background thread
* Bugfix: Heads weren't pruned when prune set contained only the head
* Rename: freeze_to_state() -> process_finalization()
* Eliminate redundant function parameter
Co-authored-by: Michael Sproul <michael@sigmaprime.io>
* Start updating types
* WIP
* Signature hacking
* Existing EF tests passing with fake_crypto
* Updates
* Delete outdated API spec
* The refactor continues
* It compiles
* WIP test fixes
* All release tests passing bar genesis state parsing
* Update and test YamlConfig
* Update to spec v0.10 compatible BLS
* Updates to BLS EF tests
* Add EF test for AggregateVerify
And delete unused hash2curve tests for uncompressed points
* Update EF tests to v0.10.1
* Use optional block root correctly in block proc
* Use genesis fork in deposit domain. All tests pass
* Cargo fmt
* Fast aggregate verify test
* Update REST API docs
* Cargo fmt
* Fix unused import
* Bump spec tags to v0.10.1
* Add `seconds_per_eth1_block` to chainspec
* Update to timestamp based eth1 voting scheme
* Return None from `get_votes_to_consider` if block cache is empty
* Handle overflows in `is_candidate_block`
* Revert to failing tests
* Fix eth1 data sets test
* Choose default vote according to spec
* Fix collect_valid_votes tests
* Fix `get_votes_to_consider` to choose all eligible blocks
* Uncomment winning_vote tests
* Add comments; remove unused code
* Reduce seconds_per_eth1_block for simulation
* Addressed review comments
* Add test for default vote case
* Fix logs
* Remove unused functions
* Meter default eth1 votes
* Fix comments
* Address review comments; remove unused dependency
* Disable/delete two outdated tests
* Bump eth1 default vote warn to error
* Delete outdated eth1 test
Co-authored-by: Pawan Dhananjay <pawandhananjay@gmail.com>
* Add LRU caches to store
* Improvements to LRU caches
* Take state by value in `Store::put_state`
* Store blocks by value, configurable cache sizes
* Use a StateBatch to efficiently store skip states
* Fix store tests
* Add CloneConfig test, remove unused metrics
* Use Mutexes instead of RwLocks for LRU caches
* Sparse hot DB and block root tree
* Fix store_tests
* Ensure loads of hot states on boundaries are fast
* Milder error for unaligned finalized blocks
* Draft of checkpoint freezer DB
* Fix bugs
* Adjust root iterators for checkpoint database
* Fix freezer state lookups with no slot hint
* Fix split comment
* Use "restore point" to refer to frozen states
* Resolve some FIXMEs
* Configurable slots per restore point
* Document new freezer DB functions
* Fix up StoreConfig
* Fix new test for merge
* Document SPRP default CLI flag, clarify tests
* Implement freezer database for state vectors
* Improve BeaconState safe accessors
And fix a bug in the compact committees accessor.
* Banish dodgy type bounds back to gRPC
* Clean up
* Switch to exclusive end points in chunked vec
* Cleaning up and start of tests
* Randao fix, more tests
* Fix unsightly hack
* Resolve test FIXMEs
* Config file support
* More clean-ups, migrator beginnings
* Finish migrator, integrate into BeaconChain
* Fixups
* Fix store tests
* Fix BeaconChain tests
* Fix LMD GHOST tests
* Address review comments, delete 'static bounds
* Cargo format
* Address review comments
* Fix LMD ghost tests
* Update to spec v0.9.0
* Update to v0.9.1
* Bump spec tags for v0.9.1
* Formatting, fix CI failures
* Resolve accidental KeyPair merge conflict
* Document new BeaconState functions
* Fix incorrect cache drops in `advance_caches`
* Update fork choice for v0.9.1
* Clean up some FIXMEs
* Fix a few docs/logs
* Update for new builder paradigm, spec changes
* Freezer DB integration into BeaconNode
* Cleaning up
* This works, clean it up
* Cleanups
* Fix and improve store tests
* Refine store test
* Delete unused beacon_chain_builder.rs
* Fix CLI
* Store state at split slot in hot database
* Make fork choice lookup fast again
* Store freezer DB split slot in the database
* Handle potential div by 0 in chunked_vector
* Exclude committee caches from freezer DB
* Remove FIXME about long-running test
