## Issue Addressed
NA
## Proposed Changes
Myself and others (#3678) have observed that when running with lots of validators (e.g., 1000s) the cardinality is too much for Prometheus. I've seen Prometheus instances just grind to a halt when we turn the validator monitor on for our testnet validators (we have 10,000s of Goerli validators). Additionally, the debug log volume can get very high with one log per validator, per attestation.
To address this, the `bn --validator-monitor-individual-tracking-threshold <INTEGER>` flag has been added to *disable* per-validator (i.e., non-aggregated) metrics/logging once the validator monitor exceeds the threshold of validators. The default value is `64`, which is a finger-to-the-wind value. I don't actually know the value at which Prometheus starts to become overwhelmed, but I've seen it work with ~64 validators and I've seen it *not* work with 1000s of validators. A default of `64` seems like it will result in a breaking change to users who are running millions of dollars worth of validators whilst resulting in a no-op for low-validator-count users. I'm open to changing this number, though.
Additionally, this PR starts collecting aggregated Prometheus metrics (e.g., total count of head hits across all validators), so that high-validator-count validators still have some interesting metrics. We already had logging for aggregated values, so nothing has been added there.
I've opted to make this a breaking change since it can be rather damaging to your Prometheus instance to accidentally enable the validator monitor with large numbers of validators. I've crashed a Prometheus instance myself and had a report from another user who's done the same thing.
## Additional Info
NA
## Breaking Changes Note
A new label has been added to the validator monitor Prometheus metrics: `total`. This label tracks the aggregated metrics of all validators in the validator monitor (as opposed to each validator being tracking individually using its pubkey as the label).
Additionally, a new flag has been added to the Beacon Node: `--validator-monitor-individual-tracking-threshold`. The default value is `64`, which means that when the validator monitor is tracking more than 64 validators then it will stop tracking per-validator metrics and only track the `all_validators` metric. It will also stop logging per-validator logs and only emit aggregated logs (the exception being that exit and slashing logs are always emitted).
These changes were introduced in #3728 to address issues with untenable Prometheus cardinality and log volume when using the validator monitor with high validator counts (e.g., 1000s of validators). Users with less than 65 validators will see no change in behavior (apart from the added `all_validators` metric). Users with more than 65 validators who wish to maintain the previous behavior can set something like `--validator-monitor-individual-tracking-threshold 999999`.
## Issue Addressed
Recent discussions with other client devs about optimistic sync have revealed a conceptual issue with the optimisation implemented in #3738. In designing that feature I failed to consider that the execution node checks the `blockHash` of the execution payload before responding with `SYNCING`, and that omitting this check entirely results in a degradation of the full node's validation. A node omitting the `blockHash` checks could be tricked by a supermajority of validators into following an invalid chain, something which is ordinarily impossible.
## Proposed Changes
I've added verification of the `payload.block_hash` in Lighthouse. In case of failure we log a warning and fall back to verifying the payload with the execution client.
I've used our existing dependency on `ethers_core` for RLP support, and a new dependency on Parity's `triehash` crate for the Merkle patricia trie. Although the `triehash` crate is currently unmaintained it seems like our best option at the moment (it is also used by Reth, and requires vastly less boilerplate than Parity's generic `trie-root` library).
Block hash verification is pretty quick, about 500us per block on my machine (mainnet).
The optimistic finalized sync feature can be disabled using `--disable-optimistic-finalized-sync` which forces full verification with the EL.
## Additional Info
This PR also introduces a new dependency on our [`metastruct`](https://github.com/sigp/metastruct) library, which was perfectly suited to the RLP serialization method. There will likely be changes as `metastruct` grows, but I think this is a good way to start dogfooding it.
I took inspiration from some Parity and Reth code while writing this, and have preserved the relevant license headers on the files containing code that was copied and modified.
I've needed to do this work in order to do some episub testing.
This version of libp2p has not yet been released, so this is left as a draft for when we wish to update.
Co-authored-by: Diva M <divma@protonmail.com>
Our custom RPC implementation is lagging from the libp2p v50 version.
We are going to need to change a bunch of function names and would be nice to have consistent ordering of function names inside the handlers.
This is a precursor to the libp2p upgrade to minimize merge conflicts in function ordering.
The notion of "phases" doesn't exist anymore in the Ethereum roadmap. Also fix dead link to roadmap.
Co-authored-by: Michael Sproul <micsproul@gmail.com>
## Issue Addressed
While testing withdrawals with @ethDreamer we noticed lighthouse is sending empty batches when an error occurs. As LH peer receiving this, we would consider this a low tolerance action because the peer is claiming the batch is right and is empty.
## Proposed Changes
If any kind of error occurs, send a error response instead
## Additional Info
Right now we don't handle such thing as a partial batch with an error. If an error is received, the whole batch is discarded. Because of this it makes little sense to send partial batches that end with an error, so it's better to do the proposed solution instead of sending empty batches.
## Proposed Changes
Update the Gnosis chain bootnodes. The current list of Gnosis bootnodes were abandoned at some point before the Gnosis merge and are now failing to bootstrap peers. There's a workaround list of bootnodes here: https://docs.gnosischain.com/updates/20221208-temporary-bootnodes
The list from this PR represents the long-term bootnodes run by the Gnosis team. We will also try to set up SigP bootnodes for Gnosis chain at some point.
## Proposed Changes
With proposer boosting implemented (#2822) we have an opportunity to re-org out late blocks.
This PR adds three flags to the BN to control this behaviour:
* `--disable-proposer-reorgs`: turn aggressive re-orging off (it's on by default).
* `--proposer-reorg-threshold N`: attempt to orphan blocks with less than N% of the committee vote. If this parameter isn't set then N defaults to 20% when the feature is enabled.
* `--proposer-reorg-epochs-since-finalization N`: only attempt to re-org late blocks when the number of epochs since finalization is less than or equal to N. The default is 2 epochs, meaning re-orgs will only be attempted when the chain is finalizing optimally.
For safety Lighthouse will only attempt a re-org under very specific conditions:
1. The block being proposed is 1 slot after the canonical head, and the canonical head is 1 slot after its parent. i.e. at slot `n + 1` rather than building on the block from slot `n` we build on the block from slot `n - 1`.
2. The current canonical head received less than N% of the committee vote. N should be set depending on the proposer boost fraction itself, the fraction of the network that is believed to be applying it, and the size of the largest entity that could be hoarding votes.
3. The current canonical head arrived after the attestation deadline from our perspective. This condition was only added to support suppression of forkchoiceUpdated messages, but makes intuitive sense.
4. The block is being proposed in the first 2 seconds of the slot. This gives it time to propagate and receive the proposer boost.
## Additional Info
For the initial idea and background, see: https://github.com/ethereum/consensus-specs/pull/2353#issuecomment-950238004
There is also a specification for this feature here: https://github.com/ethereum/consensus-specs/pull/3034
Co-authored-by: Michael Sproul <micsproul@gmail.com>
Co-authored-by: pawan <pawandhananjay@gmail.com>
## Issue Addressed
NA
## Proposed Changes
This is a *potentially* contentious change, but I find it annoying that the validator monitor logs `WARN` and `ERRO` for imperfect attestations. Perfect attestation performance is unachievable (don't believe those photo-shopped beauty magazines!) since missed and poorly-packed blocks by other validators will reduce your performance.
When the validator monitor is on with 10s or more validators, I find the logs are washed out with ERROs that are not worth investigating. I suspect that users who really want to know if validators are missing attestations can do so by matching the content of the log, rather than the log level.
I'm open to feedback about this, especially from anyone who is relying on the current log levels.
## Additional Info
NA
## Breaking Changes Notes
The validator monitor will no longer emit `WARN` and `ERRO` logs for sub-optimal attestation performance. The logs will now be emitted at `INFO` level. This change was introduced to avoid cluttering the `WARN` and `ERRO` logs with alerts that are frequently triggered by the actions of other network participants (e.g., a missed block) and require no action from the user.
## Issue Addressed
Implementing the light_client_gossip topics but I'm not there yet.
Which issue # does this PR address?
Partially #3651
## Proposed Changes
Add light client gossip topics.
Please list or describe the changes introduced by this PR.
I'm going to Implement light_client_finality_update and light_client_optimistic_update gossip topics. Currently I've attempted the former and I'm seeking feedback.
## Additional Info
I've only implemented the light_client_finality_update topic because I wanted to make sure I was on the correct path. Also checking that the gossiped LightClientFinalityUpdate is the same as the locally constructed one is not implemented because caching the updates will make this much easier. Could someone give me some feedback on this please?
Please provide any additional information. For example, future considerations
or information useful for reviewers.
Co-authored-by: GeemoCandama <104614073+GeemoCandama@users.noreply.github.com>
## Issue Addressed
NA
## Proposed Changes
In #3725 I introduced a `CRIT` log for unrevealed payloads, against @michaelsproul's [advice](https://github.com/sigp/lighthouse/pull/3725#discussion_r1034142113). After being woken up in the middle of the night by a block that was not revealed to the BN but *was* revealed to the network, I have capitulated. This PR implements @michaelsproul's suggestion and reduces the severity to `ERRO`.
Additionally, I have dropped a `CRIT` to an `ERRO` for when a block is published late. The block in question was indeed published late on the network, however now that we have builders that can slow down block production I don't think the error is "actionable" enough to warrant a `CRIT` for the user.
## Additional Info
NA
## Issue Addressed
#3766
## Proposed Changes
Adds an endpoint to get the graffiti that will be used for the next block proposal for each validator.
## Usage
```bash
curl -H "Authorization: Bearer api-token" http://localhost:9095/lighthouse/ui/graffiti | jq
```
```json
{
"data": {
"0x81283b7a20e1ca460ebd9bbd77005d557370cabb1f9a44f530c4c4c66230f675f8df8b4c2818851aa7d77a80ca5a4a5e": "mr f was here",
"0xa3a32b0f8b4ddb83f1a0a853d81dd725dfe577d4f4c3db8ece52ce2b026eca84815c1a7e8e92a4de3d755733bf7e4a9b": "mr v was here",
"0x872c61b4a7f8510ec809e5b023f5fdda2105d024c470ddbbeca4bc74e8280af0d178d749853e8f6a841083ac1b4db98f": null
}
}
```
## Additional Info
This will only return graffiti that the validator client knows about.
That is from these 3 sources:
1. Graffiti File
2. validator_definitions.yml
3. The `--graffiti` flag on the VC
If the graffiti is set on the BN, it will not be returned. This may warrant an additional endpoint on the BN side which can be used in the event the endpoint returns `null`.
## Proposed Changes
Adds docs for the following endpoints:
- `/lighthouse/analysis/attestation_performance`
- `/lighthouse/analysis/block_packing_efficiency`
## Issue Addressed
#3724
## Proposed Changes
Exposes certain `validator_monitor` as an endpoint on the HTTP API. Will only return metrics for validators which are actively being monitored.
### Usage
```bash
curl -X GET "http://localhost:5052/lighthouse/ui/validator_metrics" -H "accept: application/json" | jq
```
```json
{
"data": {
"validators": {
"12345": {
"attestation_hits": 10,
"attestation_misses": 0,
"attestation_hit_percentage": 100,
"attestation_head_hits": 10,
"attestation_head_misses": 0,
"attestation_head_hit_percentage": 100,
"attestation_target_hits": 5,
"attestation_target_misses": 5,
"attestation_target_hit_percentage": 50
}
}
}
}
```
## Additional Info
Based on #3756 which should be merged first.
## Proposed Changes
Now that the Gnosis merge is scheduled, all users should have upgraded beyond Lighthouse v3.0.0. Accordingly we can delete schema migrations for versions prior to v3.0.0.
## Additional Info
I also deleted the state cache stuff I added in #3714 as it turned out to be useless for the light client proofs due to the one-slot offset.
## Issue Addressed
#3724
## Proposed Changes
Adds an endpoint to quickly count the number of occurances of each status in the validator set.
## Usage
```bash
curl -X GET "http://localhost:5052/lighthouse/ui/validator_count" -H "accept: application/json" | jq
```
```json
{
"data": {
"active_ongoing":479508,
"active_exiting":0,
"active_slashed":0,
"pending_initialized":28,
"pending_queued":0,
"withdrawal_possible":933,
"withdrawal_done":0,
"exited_unslashed":0,
"exited_slashed":3
}
}
```
## Issue Addressed
Closes https://github.com/sigp/lighthouse/issues/2327
## Proposed Changes
This is an extension of some ideas I implemented while working on `tree-states`:
- Cache the indexed attestations from blocks in the `ConsensusContext`. Previously we were re-computing them 3-4 times over.
- Clean up `import_block` by splitting each part into `import_block_XXX`.
- Move some stuff off hot paths, specifically:
- Relocate non-essential tasks that were running between receiving the payload verification status and priming the early attester cache. These tasks are moved after the cache priming:
- Attestation observation
- Validator monitor updates
- Slasher updates
- Updating the shuffling cache
- Fork choice attestation observation now happens at the end of block verification in parallel with payload verification (this seems to save 5-10ms).
- Payload verification now happens _before_ advancing the pre-state and writing it to disk! States were previously being written eagerly and adding ~20-30ms in front of verifying the execution payload. State catchup also sometimes takes ~500ms if we get a cache miss and need to rebuild the tree hash cache.
The remaining task that's taking substantial time (~20ms) is importing the block to fork choice. I _think_ this is because of pull-tips, and we should be able to optimise it out with a clever total active balance cache in the state (which would be computed in parallel with payload verification). I've decided to leave that for future work though. For now it can be observed via the new `beacon_block_processing_post_exec_pre_attestable_seconds` metric.
Co-authored-by: Michael Sproul <micsproul@gmail.com>
## Issue Addressed
our bootnodes as of now support only ipv4. this makes it so that they support ipv6
## Proposed Changes
- Adds code necessary to update the bootnodes to run on dual stack nodes and therefore contact and store ipv6 nodes.
- Adds some metrics about connectivity type of stored peers. It might have been nice to see some metrics over the sessions but that feels out of scope right now.
## Additional Info
- some code quality improvements sneaked in since the changes seemed small
- I think it depends on the OS, but enabling mapped addresses on an ipv6 node without dual stack support enabled could fail silently, making these nodes effectively ipv6 only. In the future I'll probably change this to use two sockets, which should fail loudly
## Issue Addressed
#3704
## Proposed Changes
Adds is_syncing_finalized: bool parameter for block verification functions. Sets the payload_verification_status to Optimistic if is_syncing_finalized is true. Uses SyncState in NetworkGlobals in BeaconProcessor to retrieve the syncing status.
## Additional Info
I could implement FinalizedSignatureVerifiedBlock if you think it would be nicer.
## Issue Addressed
NA
## Proposed Changes
This PR sets out to improve the logging/metrics experience when interacting with the builder. Namely, it:
- Adds/changes metrics (see "Metrics Changes" section).
- Adds new logs which show the duration of requests to the builder/local EL.
- Refactors existing logs for consistency and so that the `parent_hash` is include in all relevant logs (we can grep for this field when trying to trace the flow of block production).
Additionally, when I was implementing this PR I noticed that we skip some verification of the builder payload in the scenario where the builder return `Ok` but the local EL returns with `Err`. Namely, we were skipping the bid signature and other values like parent hash and prev randao. In this PR I've changed it so we *always* check these values and reject the bid if they're incorrect. With these changes, we'll sometimes choose to skip a proposal rather than propose something invalid -- that's the only side-effect to the changes that I can see.
## Metrics Changes
- Changed: `execution_layer_request_times`:
- `method = "get_blinded_payload_local"`: time taken to get a payload from a local EE.
- `method = "get_blinded_payload_builder"`: time taken to get a blinded payload from a builder.
- `method = "post_blinded_payload_builder"`: time taken to get a builder to reveal a payload they've previously supplied us.
- `execution_layer_get_payload_outcome`
- `outcome = "success"`: we successfully produced a payload from a builder or local EE.
- `outcome = "failure"`: we were unable to get a payload from a builder or local EE.
- New: `execution_layer_builder_reveal_payload_outcome`
- `outcome = "success"`: a builder revealed a payload from a signed, blinded block.
- `outcome = "failure"`: the builder did not reveal the payload.
- New: `execution_layer_get_payload_source`
- `type = "builder"`: we used a payload from a builder to produce a block.
- `type = "local"`: we used a payload from a local EE to produce a block.
- New: `execution_layer_get_payload_builder_rejections` has a `reason` field to describe why we rejected a payload from a builder.
- New: `execution_layer_payload_bids` tracks the bid (in gwei) from the builder or local EE (local EE not yet supported, waiting on EEs to expose the value). Can only record values that fit inside an i64 (roughly 9 million ETH).
## Additional Info
NA
## Issue Addressed
Related to #3672
## Proposed Changes
- Added a guide to run a node. Mainly, copy and paste from 'Merge Migration' and 'Checkpoint Sync'.
- Ranked it high in ToC:
- Introduction
- Installation
- Run a Node
- Become a Validator
...
- Hid 'Merge Migration' in ToC.
## Additional Info
- Should I add/rephrase/delete something?
- Now there is some redundancy:
- 'Run a node' and 'Checkpoint Sync' contain similar information.
- Same for 'Run a node' and 'Become a Validator'.
Co-authored-by: kevinbogner <114221396+kevinbogner@users.noreply.github.com>
Co-authored-by: Michael Sproul <micsproul@gmail.com>
## Issue Addressed
#3723
## Proposed Changes
Adds a new CLI flag `--gui` which enables all the various flags required for the gui to function properly.
Currently enables the `--http` and `--validator-monitor-auto` flags.
## Issue Addressed
#3732
## Proposed Changes
Add a CLI flag to allow users to opt out of the restrictive permissions of the log files.
## Additional Info
This is not recommended for most users. The log files can contain sensitive information such as validator indices, public keys and API tokens (see #2438). However some users using a multi-user setup may find this helpful if they understand the risks involved.
## Issue Addressed
Partially addresses #3651
## Proposed Changes
Adds server-side support for light_client_bootstrap_v1 topic
## Additional Info
This PR, creates each time a bootstrap without using cache, I do not know how necessary a cache is in this case as this topic is not supposed to be called frequently and IMHO we can just prevent abuse by using the limiter, but let me know what you think or if there is any caveat to this, or if it is necessary only for the sake of good practice.
Co-authored-by: Pawan Dhananjay <pawandhananjay@gmail.com>
## Issue Addressed
NA
## Proposed Changes
- Bump versions
- Pin the `nethermind` version since our method of getting the latest tags on `master` is giving us an old version (`1.14.1`).
- Increase timeout for execution engine startup.
## Additional Info
- [x] ~Awaiting further testing~
## Issue Addressed
Partially addresses #3707
## Proposed Changes
Drop `ERRO` log to `WARN` until we identify the exact conditions that lead to this case.
Add a message which hopefully reassures users who only see this log once 😅
Add the block hash to the error message in case it will prove useful in debugging the root cause.
## Issue Addressed
<!--Which issue # does this PR address?-->
Removed some unnecessary `mut`. 🙂
<!--
## Proposed Changes
Please list or describe the changes introduced by this PR.
-->
<!--
## Additional Info
Please provide any additional information. For example, future considerations
or information useful for reviewers.
-->
## Proposed Changes
With a few different changes to the gossip topics in flight (light clients, Capella, 4844, etc) I think this simplification makes sense. I noticed it while plumbing through a new Capella topic.
## Issue Addressed
Closes#3709
## Proposed Changes
Add the job `compile-with-beta-compiler` to `test-suite`. This job has the following steps:
1. Use `actions/checkout@v3`. (Needed to run make in a later step.)
2. Install the dependencies listed in [build from source guide](https://lighthouse-book.sigmaprime.io/installation-source.html).
3. Change the compiler to the current beta version with `rustup override`.
4. Run `make`.
This PR adds some health endpoints for the beacon node and the validator client.
Specifically it adds the endpoint:
`/lighthouse/ui/health`
These are not entirely stable yet. But provide a base for modification for our UI.
These also may have issues with various platforms and may need modification.
## Issue Addressed
Closes https://github.com/sigp/lighthouse/issues/3656
## Proposed Changes
* Replace `set-output` by `$GITHUB_OUTPUT` usage
* Avoid rate-limits when installing `protoc` by making authenticated requests (continuation of https://github.com/sigp/lighthouse/pull/3621)
* Upgrade all Ubuntu 18.04 usage to 22.04 (18.04 is end of life)
* Upgrade macOS-latest to explicit macOS-12 to silence warning
* Use `actions/checkout@v3` and `actions/cache@v3` to avoid deprecated NodeJS v12
## Additional Info
Can't silence the NodeJS warnings entirely due to https://github.com/sigp/lighthouse/issues/3705. Can fix that in future.
## Issue Addressed
Closes#3612
## Proposed Changes
- Iterates through BNs until it finds a non-optimistic head.
A slight change in error behavior:
- Previously: `spawn_contribution_tasks` did not return an error for a non-optimistic block head. It returned `Ok(())` logged a warning.
- Now: `spawn_contribution_tasks` returns an error if it cannot find a non-optimistic block head. The caller of `spawn_contribution_tasks` then logs the error as a critical error.
Co-authored-by: Michael Sproul <micsproul@gmail.com>
## Issue Addressed
Part of https://github.com/sigp/lighthouse/issues/3651.
## Proposed Changes
Add a flag for enabling the light client server, which should be checked before gossip/RPC traffic is processed (e.g. https://github.com/sigp/lighthouse/pull/3693, https://github.com/sigp/lighthouse/pull/3711). The flag is available at runtime from `beacon_chain.config.enable_light_client_server`.
Additionally, a new method `BeaconChain::with_mutable_state_for_block` is added which I envisage being used for computing light client updates. Unfortunately its performance will be quite poor on average because it will only run quickly with access to the tree hash cache. Each slot the tree hash cache is only available for a brief window of time between the head block being processed and the state advance at 9s in the slot. When the state advance happens the cache is moved and mutated to get ready for the next slot, which makes it no longer useful for merkle proofs related to the head block. Rather than spend more time trying to optimise this I think we should continue prototyping with this code, and I'll make sure `tree-states` is ready to ship before we enable the light client server in prod (cf. https://github.com/sigp/lighthouse/pull/3206).
## Additional Info
I also fixed a bug in the implementation of `BeaconState::compute_merkle_proof` whereby the tree hash cache was moved with `.take()` but never put back with `.restore()`.
## Issue Addressed
#3702
Which issue # does this PR address?
#3702
## Proposed Changes
Added checkpoint-sync-url-timeout flag to cli. Added timeout field to ClientGenesis::CheckpointSyncUrl to utilize timeout set
## Additional Info
Please provide any additional information. For example, future considerations
or information useful for reviewers.
Co-authored-by: GeemoCandama <104614073+GeemoCandama@users.noreply.github.com>
Co-authored-by: Michael Sproul <micsproul@gmail.com>
## Issue Addressed
Closes#3460
## Proposed Changes
`blocks` and `block_min_delay` are never updated in the epoch summary
Co-authored-by: Michael Sproul <micsproul@gmail.com>
## Issue Addressed
This PR addresses partially #3651
## Proposed Changes
This PR adds the following methods:
* a new method to trait `TreeHash`, `hash_tree_leaves` which returns all the Merkle leaves of the ssz object.
* a new method to `BeaconState`: `compute_merkle_proof` which generates a specific merkle proof for given depth and index by using the `hash_tree_leaves` as leaves function.
## Additional Info
Now here is some rationale on why I decided to go down this route: adding a new function to commonly used trait is a pain but was necessary to make sure we have all merkle leaves for every object, that is why I just added `hash_tree_leaves` in the trait and not `compute_merkle_proof` as well. although it would make sense it gives us code duplication/harder review time and we just need it from one specific object in one specific usecase so not worth the effort YET. In my humble opinion.
Co-authored-by: Michael Sproul <micsproul@gmail.com>
## Issue Addressed
Which issue # does this PR address?
## Proposed Changes
* Add v3.2 and v3.3 to database migrations table
* Remove docs on `--subscribe-all-subnets` and `--import-all-attestations` from redundancy docs
* Clarify that the merge has already occurred on the merge migration page
## Issue Addressed
NA
## Proposed Changes
Adds clarification to an error log when there is an error submitting a validator registration.
There seems to be a few cases where relays return errors during validator registration, including spurious timeouts and when a validator has been very recently activated/made pending.
Changing this log helps indicate that it's "just another registration error" rather than something more serious. I didn't drop this to a `WARN` since I still have hope we can eliminate these errors completely by chatting with relays and adjusting timeouts.
## Additional Info
NA
## Issue Addressed
New lints for rust 1.65
## Proposed Changes
Notable change is the identification or parameters that are only used in recursion
## Additional Info
na
## Summary
The deposit cache now has the ability to finalize deposits. This will cause it to drop unneeded deposit logs and hashes in the deposit Merkle tree that are no longer required to construct deposit proofs. The cache is finalized whenever the latest finalized checkpoint has a new `Eth1Data` with all deposits imported.
This has three benefits:
1. Improves the speed of constructing Merkle proofs for deposits as we can just replay deposits since the last finalized checkpoint instead of all historical deposits when re-constructing the Merkle tree.
2. Significantly faster weak subjectivity sync as the deposit cache can be transferred to the newly syncing node in compressed form. The Merkle tree that stores `N` finalized deposits requires a maximum of `log2(N)` hashes. The newly syncing node then only needs to download deposits since the last finalized checkpoint to have a full tree.
3. Future proofing in preparation for [EIP-4444](https://eips.ethereum.org/EIPS/eip-4444) as execution nodes will no longer be required to store logs permanently so we won't always have all historical logs available to us.
## More Details
Image to illustrate how the deposit contract merkle tree evolves and finalizes along with the resulting `DepositTreeSnapshot`
## Other Considerations
I've changed the structure of the `SszDepositCache` so once you load & save your database from this version of lighthouse, you will no longer be able to load it from older versions.
Co-authored-by: ethDreamer <37123614+ethDreamer@users.noreply.github.com>
