Fix max packet sizes
Fix max_payload_size function
Add merge block test
Fix max size calculation; fix up test
Clear comments
Add a payload_size_function
Use safe arith for payload calculation
Return an error if block too big in block production
Separate test to check if block is over limit
## Issue Addressed
Mitigates #1096
## Proposed Changes
Add a flag to the beacon node called `--disable-lock-timeouts` which allows opting out of lock timeouts.
The lock timeouts serve a dual purpose:
1. They prevent any single operation from hogging the lock for too long. When a timeout occurs it logs a nasty error which indicates that there's suboptimal lock use occurring, which we can then act on.
2. They allow deadlock detection. We're fairly sure there are no deadlocks left in Lighthouse anymore but the timeout locks offer a safeguard against that.
However, timeouts on locks are not without downsides:
They allow for the possibility of livelock, particularly on slower hardware. If lock timeouts keep failing spuriously the node can be prevented from making any progress, even if it would be able to make progress slowly without the timeout. One particularly concerning scenario which could occur would be if a DoS attack succeeded in slowing block signature verification times across the network, and all Lighthouse nodes got livelocked because they timed out repeatedly. This could also occur on just a subset of nodes (e.g. dual core VPSs or Raspberri Pis).
By making the behaviour runtime configurable this PR allows us to choose the behaviour we want depending on circumstance. I suspect that long term we could make the timeout-free approach the default (#2381 moves in this direction) and just enable the timeouts on our testnet nodes for debugging purposes. This PR conservatively leaves the default as-is so we can gain some more experience before switching the default.
## Issue Addressed
Closes#1891Closes#1784
## Proposed Changes
Implement checkpoint sync for Lighthouse, enabling it to start from a weak subjectivity checkpoint.
## Additional Info
- [x] Return unavailable status for out-of-range blocks requested by peers (#2561)
- [x] Implement sync daemon for fetching historical blocks (#2561)
- [x] Verify chain hashes (either in `historical_blocks.rs` or the calling module)
- [x] Consistency check for initial block + state
- [x] Fetch the initial state and block from a beacon node HTTP endpoint
- [x] Don't crash fetching beacon states by slot from the API
- [x] Background service for state reconstruction, triggered by CLI flag or API call.
Considered out of scope for this PR:
- Drop the requirement to provide the `--checkpoint-block` (this would require some pretty heavy refactoring of block verification)
Co-authored-by: Diva M <divma@protonmail.com>
## 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
Solution 2 proposed here: https://github.com/sigp/lighthouse/issues/1435#issuecomment-692317639
## Proposed Changes
- Adds an optional `--wss-checkpoint` flag that takes a string `root:epoch`
- Verify that the given checkpoint exists in the chain, or that the the chain syncs through this checkpoint. If not, shutdown and prompt the user to purge state before restarting.
## Additional Info
Co-authored-by: Paul Hauner <paul@paulhauner.com>
## Issue Addressed
NA
## Proposed Changes
Sets the default max skips to 700 so that it can cover the 693 slot skip from `80894 - 80201`.
## Additional Info
NA
## Proposed Changes
To mitigate the impact of minority forks on RAM and disk usage, this change rejects blocks whose parent lies more than 320 slots (10 epochs, ~1 hour) in the past. The behaviour is configurable via `lighthouse bn --max-skip-slots N`, and can be turned off entirely using `--max-skip-slots none`.
Co-authored-by: Paul Hauner <paul@paulhauner.com>
