## Issue Addressed
NA
## Proposed Changes
Whilst investigating #2372, I [learned](https://github.com/sigp/lighthouse/issues/2372#issuecomment-851725049) that the error message returned from some failed Eth1 requests are always `NotReachable`. This makes debugging quite painful.
This PR adds more detail to these errors. For example:
- Bad infura key: `ERRO Failed to update eth1 cache error: Failed to update Eth1 service: "All fallback errored: https://mainnet.infura.io/ => EndpointError(RequestFailed(\"Response HTTP status was not 200 OK: 401 Unauthorized.\"))", retry_millis: 60000, service: eth1_rpc`
- Unreachable server: `ERRO Failed to update eth1 cache error: Failed to update Eth1 service: "All fallback errored: http://127.0.0.1:8545/ => EndpointError(RequestFailed(\"Request failed: reqwest::Error { kind: Request, url: Url { scheme: \\\"http\\\", cannot_be_a_base: false, username: \\\"\\\", password: None, host: Some(Ipv4(127.0.0.1)), port: Some(8545), path: \\\"/\\\", query: None, fragment: None }, source: hyper::Error(Connect, ConnectError(\\\"tcp connect error\\\", Os { code: 111, kind: ConnectionRefused, message: \\\"Connection refused\\\" })) }\"))", retry_millis: 60000, service: eth1_rpc`
- Bad server: `ERRO Failed to update eth1 cache error: Failed to update Eth1 service: "All fallback errored: http://127.0.0.1:8545/ => EndpointError(RequestFailed(\"Response HTTP status was not 200 OK: 501 Not Implemented.\"))", retry_millis: 60000, service: eth1_rpc`
## Additional Info
NA
## Issue Addressed
NA
## Primary Change
When investigating memory usage, I noticed that retrieving a block from an early slot (e.g., slot 900) would cause a sharp increase in the memory footprint (from 400mb to 800mb+) which seemed to be ever-lasting.
After some investigation, I found that the reverse iteration from the head back to that slot was the likely culprit. To counter this, I've switched the `BeaconChain::block_root_at_slot` to use the forwards iterator, instead of the reverse one.
I also noticed that the networking stack is using `BeaconChain::root_at_slot` to check if a peer is relevant (`check_peer_relevance`). Perhaps the steep, seemingly-random-but-consistent increases in memory usage are caused by the use of this function.
Using the forwards iterator with the HTTP API alleviated the sharp increases in memory usage. It also made the response much faster (before it felt like to took 1-2s, now it feels instant).
## Additional Changes
In the process I also noticed that we have two functions for getting block roots:
- `BeaconChain::block_root_at_slot`: returns `None` for a skip slot.
- `BeaconChain::root_at_slot`: returns the previous root for a skip slot.
I unified these two functions into `block_root_at_slot` and added the `WhenSlotSkipped` enum. Now, the caller must be explicit about the skip-slot behaviour when requesting a root.
Additionally, I replaced `vec![]` with `Vec::with_capacity` in `store::chunked_vector::range_query`. I stumbled across this whilst debugging and made this modification to see what effect it would have (not much). It seems like a decent change to keep around, but I'm not concerned either way.
Also, `BeaconChain::get_ancestor_block_root` is unused, so I got rid of it 🗑️.
## Additional Info
I haven't also done the same for state roots here. Whilst it's possible and a good idea, it's more work since the fwds iterators are presently block-roots-specific.
Whilst there's a few places a reverse iteration of state roots could be triggered (e.g., attestation production, HTTP API), they're no where near as common as the `check_peer_relevance` call. As such, I think we should get this PR merged first, then come back for the state root iters. I made an issue here https://github.com/sigp/lighthouse/issues/2377.
## Issue Addressed
#2325
## Proposed Changes
This pull request changes the behavior of the Peer Manager by including a minimum outbound-only peers requirement. The peer manager will continue querying for peers if this outbound-only target number hasn't been met. Additionally, when peers are being removed, an outbound-only peer will not be disconnected if doing so brings us below the minimum.
## Additional Info
Unit test for heartbeat function tests that disconnection behavior is correct. Continual querying for peers if outbound-only hasn't been met is not directly tested, but indirectly through unit testing of the helper function that counts the number of outbound-only peers.
EDIT: Am concerned about the behavior of ```update_peer_scores```. If we have connected to a peer with a score below the disconnection threshold (-20), then its connection status will remain connected, while its score state will change to disconnected.
```rust
let previous_state = info.score_state();
// Update scores
info.score_update();
Self::handle_score_transitions(
previous_state,
peer_id,
info,
&mut to_ban_peers,
&mut to_unban_peers,
&mut self.events,
&self.log,
);
```
```previous_state``` will be set to Disconnected, and then because ```handle_score_transitions``` only changes connection status for a peer if the state changed, the peer remains connected. Then in the heartbeat code, because we only disconnect healthy peers if we have too many peers, these peers don't get disconnected. I'm not sure realistically how often this scenario would occur, but it might be better to adjust the logic to account for scenarios where the score state implies a connection status different from the current connection status.
Co-authored-by: Kevin Lu <kevlu93@gmail.com>
## Issue Addressed
#2282
## Proposed Changes
Reduce the outbound requests made to eth1 endpoints by caching the results from `eth_chainId` and `net_version`.
Further reduce the overall request count by increasing `auto_update_interval_millis` from `7_000` (7 seconds) to `60_000` (1 minute).
This will result in a reduction from ~2000 requests per hour to 360 requests per hour (during normal operation). A reduction of 82%.
## Additional Info
If an endpoint fails, its state is dropped from the cache and the `eth_chainId` and `net_version` calls will be made for that endpoint again during the regular update cycle (once per minute) until it is back online.
Co-authored-by: Paul Hauner <paul@paulhauner.com>
The ordering of adding new peers to the peerdb and deciding when to dial them was not considered in a previous update.
This adds the condition that if a peer is not in the peer-db then it is an acceptable peer to dial.
This makes #2374 obsolete.
## Issue Addressed
NA
## Proposed Changes
Modify the configuration of [GNU malloc](https://www.gnu.org/software/libc/manual/html_node/The-GNU-Allocator.html) to reduce memory footprint.
- Set `M_ARENA_MAX` to 4.
- This reduces memory fragmentation at the cost of contention between threads.
- Set `M_MMAP_THRESHOLD` to 2mb
- This means that any allocation >= 2mb is allocated via an anonymous mmap, instead of on the heap/arena. This reduces memory fragmentation since we don't need to keep growing the heap to find big contiguous slabs of free memory.
- ~~Run `malloc_trim` every 60 seconds.~~
- ~~This shaves unused memory from the top of the heap, preventing the heap from constantly growing.~~
- Removed, see: https://github.com/sigp/lighthouse/pull/2299#issuecomment-825322646
*Note: this only provides memory savings on the Linux (glibc) platform.*
## Additional Info
I'm going to close#2288 in favor of this for the following reasons:
- I've managed to get the memory footprint *smaller* here than with jemalloc.
- This PR seems to be less of a dramatic change than bringing in the jemalloc dep.
- The changes in this PR are strictly runtime changes, so we can create CLI flags which disable them completely. Since this change is wide-reaching and complex, it's nice to have an easy "escape hatch" if there are undesired consequences.
## TODO
- [x] Allow configuration via CLI flags
- [x] Test on Mac
- [x] Test on RasPi.
- [x] Determine if GNU malloc is present?
- I'm not quite sure how to detect for glibc.. This issue suggests we can't really: https://github.com/rust-lang/rust/issues/33244
- [x] Make a clear argument regarding the affect of this on CPU utilization.
- [x] Test with higher `M_ARENA_MAX` values.
- [x] Test with longer trim intervals
- [x] Add some stats about memory savings
- [x] Remove `malloc_trim` calls & code
## Issue Addressed
Windows incompatibility.
## Proposed Changes
On windows, lighthouse needs to default to STDIN as tty doesn't exist. Also Windows uses ACLs for file permissions. So to mirror chmod 600, we will remove every entry in a file's ACL and add only a single SID that is an alias for the file owner.
Beyond that, there were several changes made to different unit tests because windows has slightly different error messages as well as frustrating nuances around killing a process :/
## Additional Info
Tested on my Windows VM and it appears to work, also compiled & tested on Linux with these changes. Permissions look correct on both platforms now. Just waiting for my validator to activate on Prater so I can test running full validator client on windows.
Co-authored-by: ethDreamer <37123614+ethDreamer@users.noreply.github.com>
Co-authored-by: Michael Sproul <micsproul@gmail.com>
## Issue Addressed
The latest version of Rust has new clippy rules & the codebase isn't up to date with them.
## Proposed Changes
Small formatting changes that clippy tells me are functionally equivalent
## Issue Addressed
N/A
## Proposed Changes
Add unit tests for the various CLI flags associated with the beacon node and validator client. These changes require the addition of two new flags: `dump-config` and `immediate-shutdown`.
## Additional Info
Both `dump-config` and `immediate-shutdown` are marked as hidden since they should only be used in testing and other advanced use cases.
**Note:** This requires changing `main.rs` so that the flags can adjust the program behavior as necessary.
Co-authored-by: Paul Hauner <paul@paulhauner.com>
## Issue Addressed
#2276
## Proposed Changes
Add the `SensitiveUrl` struct which wraps `Url` and implements custom `Display` and `Debug` traits to redact user secrets from being logged in eth1 endpoints, beacon node endpoints and metrics.
## Additional Info
This also includes a small rewrite of the eth1 crate to make requests using `Url` instead of `&str`.
Some error messages have also been changed to remove `Url` data.
## Issue Addressed
#2107
## Proposed Change
The peer manager will mark peers as disconnected in the discv5 DHT when they disconnect or dial fails
## Additional Info
Rationale for this particular change is explained in my comment on #2107
## Issue Addressed
Resolves#2186
## Proposed Changes
404 for any block-related information on a slot that was skipped or orphaned
Affected endpoints:
- `/eth/v1/beacon/blocks/{block_id}`
- `/eth/v1/beacon/blocks/{block_id}/root`
- `/eth/v1/beacon/blocks/{block_id}/attestations`
- `/eth/v1/beacon/headers/{block_id}`
## Additional Info
Co-authored-by: realbigsean <seananderson33@gmail.com>
## Issue Addressed
NA
## Proposed Changes
Bump versions.
## Additional Info
This is a minor release (not patch) due to the very slight change introduced by #2291.
## Proposed Changes
Use two instances of max cover when packing attestations into blocks: one for the previous epoch, and one for the current epoch. This reduces the amount of computation done by roughly half due to the `O(n^2)` running time of max cover (`2 * (n/2)^2 = n^2/2`). This should help alleviate some load on block proposal, particularly on Prater.
## Issue Addressed
NA
## Proposed Changes
- Adds a specific log and metric for when a block is enshrined as head with a delay that will caused bad attestations
- We *technically* already expose this information, but it's a little tricky to determine during debugging. This makes it nice and explicit.
- Fixes a minor reporting bug with the validator monitor where it was expecting agg. attestations too early (at half-slot rather than two-thirds-slot).
## Additional Info
NA
## Issue Addressed
NA
## Proposed Changes
- Ensure that the [target consistency check](b356f52c5c) is always performed on aggregates.
- Add a regression test.
## Additional Info
NA
This is a small PR that cleans up compiler warnings.
The most controversial change is removing the `data_dir` field from the `BeaconChainBuilder`.
It was removed because it was never read.
Co-authored-by: Paul Hauner <paul@paulhauner.com>
Co-authored-by: Herman Junge <hermanjunge@protonmail.com>
Co-authored-by: Michael Sproul <michael@sigmaprime.io>
## Issue Addressed
Which issue # does this PR address?
## Proposed Changes
Avoids cloning the `BeaconState` each time Prometheus scrapes our metrics (generally every 5s 😱).
I think the original motivation behind this was *"don't hold the lock on the head whilst we do computation on it"*, however I think is flawed since our computation here is so small that it'll be quicker than the clone.
The primary motivation here is to maintain a small memory footprint by holding less in memory (i.e., the cloned `BeaconState`) and to avoid the fragmentation-creep that occurs when cloning the big contiguous slabs of memory in the `BeaconState`.
I also collapsed the active/slashed/withdrawn counters into a single loop to increase efficiency.
## Additional Info
NA
## Issue Addressed
Resolves#2094
## Proposed Changes
Fixes scripts for creating local testnets. Adds an option in `lighthouse boot_node` to run with a previously generated enr.
## Issue Addressed
NA
## Proposed Changes
I noticed the following error on one of our nodes:
```
Mar 18 00:03:35 ip-xxxx lighthouse-bn[333503]: Mar 18 00:03:35.103 ERRO Unable to validate aggregate error: ObservedAttestersError(EpochTooLow { epoch: Epoch(23961), lowest_permissible_epoch: Epoch(23962) }), peer_id: 16Uiu2HAm5GL5KzPLhvfg9MBBFSpBqTVGRFSiTg285oezzWcZzwEv
```
The slot during this log was 766,815 (the last slot of the epoch). I believe this is due to an off-by-one error in `observed_attesters` where we were failing to provide enough capacity to store observations from the previous, current and next epochs. See code comments for further reasoning.
Here's a link to the spec: https://github.com/ethereum/eth2.0-specs/blob/v1.0.1/specs/phase0/p2p-interface.md#beacon_aggregate_and_proof
## Additional Info
NA
## Issue Addressed
Closes#2274
## Proposed Changes
* Modify the `YamlConfig` to collect unknown fields into an `extra_fields` map, instead of failing hard.
* Log a debug message if there are extra fields returned to the VC from one of its BNs.
This restores Lighthouse's compatibility with Teku beacon nodes (and therefore Infura)
## Issue Addressed
Closes#2052
## Proposed Changes
- Refactor the attester/proposer duties endpoints in the BN
- Performance improvements
- Fixes some potential inconsistencies with the dependent root fields.
- Removes `http_api::beacon_proposer_cache` and just uses the one on the `BeaconChain` instead.
- Move the code for the proposer/attester duties endpoints into separate files, for readability.
- Refactor the `DutiesService` in the VC
- Required to reduce the delay on broadcasting new blocks.
- Gets rid of the `ValidatorDuty` shim struct that came about when we adopted the standard API.
- Separate block/attestation duty tasks so that they don't block each other when one is slow.
- In the VC, use `PublicKeyBytes` to represent validators instead of `PublicKey`. `PublicKey` is a legit crypto object whilst `PublicKeyBytes` is just a byte-array, it's much faster to clone/hash `PublicKeyBytes` and this change has had a significant impact on runtimes.
- Unfortunately this has created lots of dust changes.
- In the BN, store `PublicKeyBytes` in the `beacon_proposer_cache` and allow access to them. The HTTP API always sends `PublicKeyBytes` over the wire and the conversion from `PublicKey` -> `PublickeyBytes` is non-trivial, especially when queries have 100s/1000s of validators (like Pyrmont).
- Add the `state_processing::state_advance` mod which dedups a lot of the "apply `n` skip slots to the state" code.
- This also fixes a bug with some functions which were failing to include a state root as per [this comment](072695284f/consensus/state_processing/src/state_advance.rs (L69-L74)). I couldn't find any instance of this bug that resulted in anything more severe than keying a shuffling cache by the wrong block root.
- Swap the VC block service to use `mpsc` from `tokio` instead of `futures`. This is consistent with the rest of the code base.
~~This PR *reduces* the size of the codebase 🎉~~ It *used* to reduce the size of the code base before I added more comments.
## Observations on Prymont
- Proposer duties times down from peaks of 450ms to consistent <1ms.
- Current epoch attester duties times down from >1s peaks to a consistent 20-30ms.
- Block production down from +600ms to 100-200ms.
## Additional Info
- ~~Blocked on #2241~~
- ~~Blocked on #2234~~
## TODO
- [x] ~~Refactor this into some smaller PRs?~~ Leaving this as-is for now.
- [x] Address `per_slot_processing` roots.
- [x] Investigate slow next epoch times. Not getting added to cache on block processing?
- [x] Consider [this](072695284f/beacon_node/store/src/hot_cold_store.rs (L811-L812)) in the scenario of replacing the state roots
Co-authored-by: pawan <pawandhananjay@gmail.com>
Co-authored-by: Michael Sproul <michael@sigmaprime.io>
## Proposed Changes
While investigating an incorrect head + target vote for the epoch boundary block 708544, I noticed that the state advance failed to prime the proposer cache, as per these logs:
```
Mar 09 21:42:47.448 DEBG Subscribing to subnet target_slot: 708544, subnet: Y, service: attestation_service
Mar 09 21:49:08.063 DEBG Advanced head state one slot current_slot: 708543, state_slot: 708544, head_root: 0xaf5e69de09f384ee3b4fb501458b7000c53bb6758a48817894ec3d2b030e3e6f, service: state_advance
Mar 09 21:49:08.063 DEBG Completed state advance initial_slot: 708543, advanced_slot: 708544, head_root: 0xaf5e69de09f384ee3b4fb501458b7000c53bb6758a48817894ec3d2b030e3e6f, service: state_advance
Mar 09 21:49:14.787 DEBG Proposer shuffling cache miss block_slot: 708544, block_root: 0x9b14bf68667ab1d9c35e6fd2c95ff5d609aa9e8cf08e0071988ae4aa00b9f9fe, parent_slot: 708543, parent_root: 0xaf5e69de09f384ee3b4fb501458b7000c53bb6758a48817894ec3d2b030e3e6f, service: beacon
Mar 09 21:49:14.800 DEBG Successfully processed gossip block root: 0x9b14bf68667ab1d9c35e6fd2c95ff5d609aa9e8cf08e0071988ae4aa00b9f9fe, slot: 708544, graffiti: , service: beacon
Mar 09 21:49:14.800 INFO New block received hash: 0x9b14…f9fe, slot: 708544
Mar 09 21:49:14.984 DEBG Head beacon block slot: 708544, root: 0x9b14…f9fe, finalized_epoch: 22140, finalized_root: 0x28ec…29a7, justified_epoch: 22141, justified_root: 0x59db…e451, service: beacon
Mar 09 21:49:15.055 INFO Unaggregated attestation validator: XXXXX, src: api, slot: 708544, epoch: 22142, delay_ms: 53, index: Y, head: 0xaf5e69de09f384ee3b4fb501458b7000c53bb6758a48817894ec3d2b030e3e6f, service: val_mon
Mar 09 21:49:17.001 DEBG Slot timer sync_state: Synced, current_slot: 708544, head_slot: 708544, head_block: 0x9b14…f9fe, finalized_epoch: 22140, finalized_root: 0x28ec…29a7, peers: 55, service: slot_notifier
```
The reason for this is that the condition was backwards, so that whole block of code was unreachable.
Looking at the attestations for the block included in the block after, we can see that lots of validators missed it. Some of them may be Lighthouse v1.1.1-v1.2.0-rc.0, but it's probable that they would have missed even with the proposer cache primed, given how late the block 708544 arrived (the cache miss occurred 3.787s after the slot start): https://beaconcha.in/block/708545#attestations
This is a small PR which prevents unwanted bootnodes from being added to the DHT and being dialed when the `--disable-discovery` flag is set.
The main reason one would want to disable discovery is to connect to a fix set of peers. Currently, regardless of what the user does, Lighthouse will populate its DHT with previously known peers and also fill it with the spec's bootnodes. It will then dial the bootnodes that are capable of being dialed. This prevents testing with a fixed peer list.
This PR prevents these excess nodes from being added and dialed if the user has set `--disable-discovery`.
## Issue Addressed
NA
## Proposed Changes
- Use the pre-states from #2174 during block production.
- Running this on Pyrmont shows block production times dropping from ~550ms to ~150ms.
- Create `crit` and `warn` logs when a block is published to the API later than we expect.
- On mainnet we are issuing a warn if the block is published more than 1s later than the slot start and a crit for more than 3s.
- Rename some methods on the `SnapshotCache` for clarity.
- Add the ability to pass the state root to `BeaconChain::produce_block_on_state` to avoid computing a state root. This is a very common LH optimization.
- Add a metric that tracks how late we broadcast blocks received from the HTTP API. This is *technically* a duplicate of a `ValidatorMonitor` log, but I wanted to have it for the case where we aren't monitoring validators too.
## Issue Addressed
Closes#1787
## Proposed Changes
* Abstract the `ValidatorPubkeyCache` over a "backing" which is either a file (legacy), or the database.
* Implement a migration from schema v2 to schema v3, whereby the contents of the cache file are copied to the DB, and then the file is deleted. The next release to include this change must be a minor version bump, and we will need to warn users of the inability to downgrade (this is our first DB schema change since mainnet genesis).
* Move the schema migration code from the `store` crate into the `beacon_chain` crate so that it can access the datadir and the `ValidatorPubkeyCache`, etc. It gets injected back into the `store` via a closure (similar to what we do in fork choice).
## Issue Addressed
NA
## Problem this PR addresses
There's an issue where Lighthouse is banning a lot of peers due to the following sequence of events:
1. Gossip block 0xabc arrives ~200ms early
- It is propagated across the network, with respect to [`MAXIMUM_GOSSIP_CLOCK_DISPARITY`](https://github.com/ethereum/eth2.0-specs/blob/v1.0.0/specs/phase0/p2p-interface.md#why-is-there-maximum_gossip_clock_disparity-when-validating-slot-ranges-of-messages-in-gossip-subnets).
- However, it is not imported to our database since the block is early.
2. Attestations for 0xabc arrive, but the block was not imported.
- The peer that sent the attestation is down-voted.
- Each unknown-block attestation causes a score loss of 1, the peer is banned at -100.
- When the peer is on an attestation subnet there can be hundreds of attestations, so the peer is banned quickly (before the missed block can be obtained via rpc).
## Potential solutions
I can think of three solutions to this:
1. Wait for attestation-queuing (#635) to arrive and solve this.
- Easy
- Not immediate fix.
- Whilst this would work, I don't think it's a perfect solution for this particular issue, rather (3) is better.
1. Allow importing blocks with a tolerance of `MAXIMUM_GOSSIP_CLOCK_DISPARITY`.
- Easy
- ~~I have implemented this, for now.~~
1. If a block is verified for gossip propagation (i.e., signature verified) and it's within `MAXIMUM_GOSSIP_CLOCK_DISPARITY`, then queue it to be processed at the start of the appropriate slot.
- More difficult
- Feels like the best solution, I will try to implement this.
**This PR takes approach (3).**
## Changes included
- Implement the `block_delay_queue`, based upon a [`DelayQueue`](https://docs.rs/tokio-util/0.6.3/tokio_util/time/delay_queue/struct.DelayQueue.html) which can store blocks until it's time to import them.
- Add a new `DelayedImportBlock` variant to the `beacon_processor::WorkEvent` enum to handle this new event.
- In the `BeaconProcessor`, refactor a `tokio::select!` to a struct with an explicit `Stream` implementation. I experienced some issues with `tokio::select!` in the block delay queue and I also found it hard to debug. I think this explicit implementation is nicer and functionally equivalent (apart from the fact that `tokio::select!` randomly chooses futures to poll, whereas now we're deterministic).
- Add a testing framework to the `beacon_processor` module that tests this new block delay logic. I also tested a handful of other operations in the beacon processor (attns, slashings, exits) since it was super easy to copy-pasta the code from the `http_api` tester.
- To implement these tests I added the concept of an optional `work_journal_tx` to the `BeaconProcessor` which will spit out a log of events. I used this in the tests to ensure that things were happening as I expect.
- The tests are a little racey, but it's hard to avoid that when testing timing-based code. If we see CI failures I can revise. I haven't observed *any* failures due to races on my machine or on CI yet.
- To assist with testing I allowed for directly setting the time on the `ManualSlotClock`.
- I gave the `beacon_processor::Worker` a `Toolbox` for two reasons; (a) it avoids changing tons of function sigs when you want to pass a new object to the worker and (b) it seemed cute.
## Issue Addressed
- Resolves#2215
## Proposed Changes
Addresses a potential loop when the majority of peers indicate that we are contactable via an IPv6 address.
See https://github.com/sigp/discv5/pull/62 for further rationale.
## Additional Info
The alternative to this PR is to use `--disable-enr-auto-update` and then manually supply an `--enr-address` and `--enr-upd-port`. However, that requires the user to know their IP addresses in order for discovery to work properly. This might not be practical/achievable for some users, hence this hotfix.
The current implementation assumes the range offset of slots downloaded on a batch to equal zero. This conflicts with the condition to consider this chain as sync. For finalized sync, it results in one extra batch being downloaded which can't be processed.
CC @wemeetagain
## Issue Addressed
NA
## Proposed Changes
Add an optimization to perform `per_slot_processing` from the *leading-edge* of block processing to the *trailing-edge*. Ultimately, this allows us to import the block at slot `n` faster because we used the tail-end of slot `n - 1` to perform `per_slot_processing`.
Additionally, add a "block proposer cache" which allows us to cache the block proposer for some epoch. Since we're now doing trailing-edge `per_slot_processing`, we can prime this cache with the values for the next epoch before those blocks arrive (assuming those blocks don't have some weird forking).
There were several ancillary changes required to achieve this:
- Remove the `state_root` field of `BeaconSnapshot`, since there's no need to know it on a `pre_state` and in all other cases we can just read it from `block.state_root()`.
- This caused some "dust" changes of `snapshot.beacon_state_root` to `snapshot.beacon_state_root()`, where the `BeaconSnapshot::beacon_state_root()` func just reads the state root from the block.
- Rename `types::ShuffingId` to `AttestationShufflingId`. I originally did this because I added a `ProposerShufflingId` struct which turned out to be not so useful. I thought this new name was more descriptive so I kept it.
- Address https://github.com/ethereum/eth2.0-specs/pull/2196
- Add a debug log when we get a block with an unknown parent. There was previously no logging around this case.
- Add a function to `BeaconState` to compute all proposers for an epoch without re-computing the active indices for each slot.
## Additional Info
- ~~Blocked on #2173~~
- ~~Blocked on #2179~~ That PR was wrapped into this PR.
- There's potentially some places where we could avoid computing the proposer indices in `per_block_processing` but I haven't done this here. These would be an optimization beyond the issue at hand (improving block propagation times) and I think this PR is already doing enough. We can come back for that later.
## TODO
- [x] Tidy, improve comments.
- [x] ~~Try avoid computing proposer index in `per_block_processing`?~~
