Just visual clean-up, making logging statements look uniform. There's no reason to use `tracing::debug` instead of `debug`. If we ever need to migrate our logging lib in the future it would make things easier too.
Co-Authored-By: dapplion <35266934+dapplion@users.noreply.github.com>
Co-Authored-By: Jimmy Chen <jchen.tc@gmail.com>
Co-Authored-By: Michael Sproul <michaelsproul@users.noreply.github.com>
Which issue # does this PR address?
#8586
Please list or describe the changes introduced by this PR.
Remove `service_name` from `TaskExecutor`
Co-Authored-By: Abhivansh <31abhivanshj@gmail.com>
Which issue # does this PR address?
None
The `visualize_batch_state` functions uses the following loop `for mut batch_index in 0..BATCH_BUFFER_SIZE`, making it from `0` to `BATCH_BUFFER_SIZE - 1` (behind the scenes).
Hence we would never hit the following condition:
```rust
if batch_index != BATCH_BUFFER_SIZE {
visualization_string.push(',');
}
```
Replacing `!=` with `<` & `BATCH_BUFFER_SIZE -1` allows for the following change:
`[A,B,C,D,E,]` to become: `[A,B,C,D,E]`
Co-Authored-By: Antoine James <antoine@ethereum.org>
There are certain crates which we re-export within `types` which creates a fragmented DevEx, where there are various ways to import the same crates.
```rust
// consensus/types/src/lib.rs
pub use bls::{
AggregatePublicKey, AggregateSignature, Error as BlsError, Keypair, PUBLIC_KEY_BYTES_LEN,
PublicKey, PublicKeyBytes, SIGNATURE_BYTES_LEN, SecretKey, Signature, SignatureBytes,
get_withdrawal_credentials,
};
pub use context_deserialize::{ContextDeserialize, context_deserialize};
pub use fixed_bytes::FixedBytesExtended;
pub use milhouse::{self, List, Vector};
pub use ssz_types::{BitList, BitVector, FixedVector, VariableList, typenum, typenum::Unsigned};
pub use superstruct::superstruct;
```
This PR removes these re-exports and makes it explicit that these types are imported from a non-`consensus/types` crate.
Co-Authored-By: Mac L <mjladson@pm.me>
Organize and categorize `consensus/types` into modules based on their relation to key consensus structures/concepts.
This is a precursor to a sensible public interface.
While this refactor is very opinionated, I am open to suggestions on module names, or type groupings if my current ones are inappropriate.
Co-Authored-By: Mac L <mjladson@pm.me>
We want to not require checkpoint sync starts to include the required custody data columns, and instead fetch them from p2p.
Closes https://github.com/sigp/lighthouse/issues/6837
The checkpoint sync slot can:
1. Be the first slot in the epoch, such that the epoch of the block == the start checkpoint epoch
2. Be in an epoch prior to the start checkpoint epoch
In both cases backfill sync already fetches that epoch worth of blocks with current code. This PR modifies the backfill import filter function to allow to re-importing the oldest block slot in the DB.
I feel this solution is sufficient unless I'm missing something. ~~I have not tested this yet!~~ Michael has tested this and it works.
Co-Authored-By: dapplion <35266934+dapplion@users.noreply.github.com>
Co-Authored-By: Michael Sproul <michael@sigmaprime.io>
N/A
The difference is computed by taking the difference of expected with received. We were doing the inverse.
Thanks to Yassine for finding the issue.
Co-Authored-By: Pawan Dhananjay <pawandhananjay@gmail.com>
Take 2 of #8390.
Fixes the race condition properly instead of propagating the error. I think this is a better alternative, and doesn't seem to look that bad.
* Lift node id loading or generation from `NetworkService ` startup to the `ClientBuilder`, so that it can be used to compute custody columns for the beacon chain without waiting for Network bootstrap.
I've considered and implemented a few alternatives:
1. passing `node_id` to beacon chain builder and compute columns when creating `CustodyContext`. This approach isn't good for separation of concerns and isn't great for testability
2. passing `ordered_custody_groups` to beacon chain. `CustodyContext` only uses this to compute ordered custody columns, so we might as well lift this logic out, so we don't have to do error handling in `CustodyContext` construction. Less tests to update;.
Co-Authored-By: Jimmy Chen <jchen.tc@gmail.com>
FIx flaky tests that depends on timing. Previously the test processes all 128 columns and expect reconstruction to happen after all columns are processed. There is a race here, and reconstruction could be triggered before all columns are processed.
I've updated the tests to process 64 columns, just enough for reconstruction and wait for 50ms for reconstruction to be triggered.
This PR requires the change made in https://github.com/sigp/lighthouse/pull/8194 for the test to pass consistently (blob count set to 1 for all blocks instead of random blob count between 0..max)
Co-Authored-By: Jimmy Chen <jchen.tc@gmail.com>
Co-Authored-By: Jimmy Chen <jimmy@sigmaprime.io>
### Downgrade a non error to `Debug`
I noticed this error on one of our hoodi nodes:
```
Nov 04 05:13:38.892 ERROR Error during data column reconstruction block_root: 0x4271b9efae7deccec3989bd2418e998b83ce8144210c2b17200abb62b7951190, error: DuplicateFullyImported(0x4271b9efae7deccec3989bd2418e998b83ce8144210c2b17200abb62b7951190)
```
This shouldn't be logged as an error and it's due to a normal race condition, and it doesn't impact the node negatively.
### Remove spammy logs
This logs is filling up the log files quite quickly and it is also something we'd expect during normal operation - getting columns via EL before gossip. We haven't found this debug log to be useful, so I propose we remove it to avoid spamming debug logs.
```
Received already available column sidecar. Ignoring the column sidecar
```
In the process of removing this, I noticed we aren't propagating the validation result, which I think we should so I've added this. The impact should be quite minimal - the message will stay in the gossip memcache for a bit longer but should be evicted in the next heartbeat.
Co-Authored-By: Jimmy Chen <jchen.tc@gmail.com>
`beacon-chain-tests` is now regularly taking 1h+ on CI since Fulu fork was added.
This PR attemtpts to reduce the test time by bringing down the number of blobs generated in tests - instead of generating 0..max_blobs, the generator now generates 0..1 blobs by default, and this can be modified by setting `harness.execution_block_generator.set_min_blob_count(n)`.
Note: The blobs are pre-generated and doesn't require too much CPU to generate however processing a larger number of them on the beacon chain does take a lot of time.
This PR also include a few other small improvements
- Our slowest test (`chain_segment_varying_chunk_size`) runs 3x faster in Fulu just by reusing chain segments
- Avoid re-running fork specific tests on all forks
- Fix a bunch of tests that depends on the harness's existing random blob generation, which is fragile
beacon chain test time on test machine is **~2x** faster:
### `unstable`
```
Summary [ 751.586s] 291 tests run: 291 passed (13 slow), 0 skipped
```
### this branch
```
Summary [ 373.792s] 291 tests run: 291 passed (2 slow), 0 skipped
```
The next set of tests to optimise is the ones that use [`get_chain_segment`](77a9af96de/beacon_node/beacon_chain/tests/block_verification.rs (L45)), as it by default build 320 blocks with supernode - an easy optimisation would be to build these blocks with cgc = 8 for tests that only require fullnodes.
Co-Authored-By: Jimmy Chen <jchen.tc@gmail.com>
Co-Authored-By: Jimmy Chen <jimmy@sigmaprime.io>
Custody backfill sync has a bug when we request columns from more than one peer per batch. The fix here ensures we wait for all requests to be completed before performing verification and importing the responses.
I've also added an endpoint `lighthouse/custody/backfill` that resets a nodes earliest available data column to the current epoch so that custody backfill can be triggered. This endpoint is needed to rescue any nodes that may have missing columns due to the custody backfill sync bug without requiring a full re-sync.
Co-Authored-By: Eitan Seri- Levi <eserilev@gmail.com>
Co-Authored-By: Eitan Seri-Levi <eserilev@ucsc.edu>
Co-Authored-By: Jimmy Chen <jchen.tc@gmail.com>
Co-Authored-By: Michael Sproul <michaelsproul@users.noreply.github.com>
During custody backfill sync there could be an edge case where we update CGC at the same time where we are importing a batch of columns which may cause us to incorrectly overwrite values when calling `backfill_validator_custody_requirements`. To prevent this race condition, the expected cgc is now passed into this function and is used to check if the expected cgc == the current validator cgc. If the values arent equal, this probably indicates that a very recent CGC occurred so we do not prune/update values in the `epoch_validator_custody_requirements` map.
Co-Authored-By: Eitan Seri-Levi <eserilev@ucsc.edu>
https://github.com/sigp/lighthouse/issues/8012
Replace all instances of `VariableList::from` and `FixedVector::from` to their `try_from` variants.
While I tried to use proper error handling in most cases, there were certain situations where adding an `expect` for situations where `try_from` can trivially never fail avoided adding a lot of extra complexity.
Co-Authored-By: Mac L <mjladson@pm.me>
Co-Authored-By: Michael Sproul <michaelsproul@users.noreply.github.com>
Co-Authored-By: Michael Sproul <michael@sigmaprime.io>
Testing non-finality checkpoint synced these logs showed up in my INFO grep and were noisy. INFO should only include the notifier and exceptional events. I don't see why the user would care about this info.
Downgrade to debug
Co-Authored-By: dapplion <35266934+dapplion@users.noreply.github.com>
#7756 introduces a logging issue, where the relevant log:
da5b231720/beacon_node/network/src/network_beacon_processor/rpc_methods.rs (L380-L385)
obtains the `block_root` from `slots_by_block_root.keys()`. If the `block_root` is empty (block not found in the data availability checker), then the log will not show any block root:
`DEBUG BlobsByRoot outgoing response processed peer_id: 16Uiu2HAmCBxs1ZFfsbAfhSA98rUUL8Q1egLPb6WpGdKZxX6HqQYX, block_root: [], returned: 4`
This PR revises to return the `block_root` in the request as a vector of block root
Co-Authored-By: Tan Chee Keong <tanck@sigmaprime.io>
Testing non finalized checkpoint sync noticed this log that dumps blob data in Debug format to the logs.
Log only block root and commitment of each blob
Co-Authored-By: dapplion <35266934+dapplion@users.noreply.github.com>
Addresses #8218
A simplified version of #8241 for the initial release.
I've tried to minimise the logic change in this PR, although introducing the `NodeCustodyType` enum still result in quite a bit a of diff, but the actual logic change in `CustodyContext` is quite small.
The main changes are in the `CustdoyContext` struct
* ~~combining `validator_custody_count` and `current_is_supernode` fields into a single `custody_group_count_at_head` field. We persist the cgc of the initial cli values into the `custody_group_count_at_head` field and only allow for increase (same behaviour as before).~~
* I noticed the above approach caused a backward compatibility issue, I've [made a fix](15569bc085) and changed the approach slightly (which was actually what I had originally in mind):
* when initialising, only override the `validator_custody_count` value if either flag `--supernode` or `--semi-supernode` is used; otherwise leave it as the existing default `0`. Most other logic remains unchanged.
All existing validator custody unit tests are still all passing, and I've added additional tests to cover semi-supernode, and restoring `CustodyContext` from disk.
Note: I've added a `WARN` if the user attempts to switch to a `--semi-supernode` or `--supernode` - this currently has no effect, but once @eserilev column backfill is merged, we should be able to support this quite easily.
Things to test
- [x] cgc in metadata / enr
- [x] cgc in metrics
- [x] subscribed subnets
- [x] getBlobs endpoint
Co-Authored-By: Jimmy Chen <jchen.tc@gmail.com>
#7603
#### Custody backfill sync service
Similar in many ways to the current backfill service. There may be ways to unify the two services. The difficulty there is that the current backfill service tightly couples blocks and their associated blobs/data columns. Any attempts to unify the two services should be left to a separate PR in my opinion.
#### `SyncNeworkContext`
`SyncNetworkContext` manages custody sync data columns by range requests separetly from other sync RPC requests. I think this is a nice separation considering that custody backfill is its own service.
#### Data column import logic
The import logic verifies KZG committments and that the data columns block root matches the block root in the nodes store before importing columns
#### New channel to send messages to `SyncManager`
Now external services can communicate with the `SyncManager`. In this PR this channel is used to trigger a custody sync. Alternatively we may be able to use the existing `mpsc` channel that the `SyncNetworkContext` uses to communicate with the `SyncManager`. I will spend some time reviewing this.
Co-Authored-By: Eitan Seri-Levi <eserilev@ucsc.edu>
Co-Authored-By: Eitan Seri- Levi <eserilev@gmail.com>
Co-Authored-By: dapplion <35266934+dapplion@users.noreply.github.com>
N/A
1. In the batch retry logic, we were failing to set the batch state to `AwaitingDownload` before attempting a retry. This PR sets it to `AwaitingDownload` before the retry and sets it back to `Downloading` if the retry suceeded in sending out a request
2. Remove all peer scoring logic from retrying and rely on just de priorotizing the failed peer. I finally concede the point to @dapplion 😄
3. Changes `block_components_by_range_request` to accept `block_peers` and `column_peers`. This is to ensure that we use the full synced peerset for requesting columns in order to avoid splitting the column peers among multiple head chains. During forward sync, we want the block peers to be the peers from the syncing chain and column peers to be all synced peers from the peerdb.
Also, fixes a typo and calls `attempt_send_awaiting_download_batches` from more places
Co-Authored-By: Pawan Dhananjay <pawandhananjay@gmail.com>
@michaelsproul noticed this warning on a devnet-3 node
```
Oct 01 16:37:29.896 WARN Error when importing rpc custody columns error: ParentUnknown { parent_root: 0xe4cc85a2137b76eb083d7076255094a90f10caaec0afc8fd36807db742f6ff13 }, block_hash: 0x43ce63b2344990f5f4d8911b8f14e3d3b6b006edc35bbc833360e667df0edef7
```
We're also seeing similar `WARN` logs for blobs on our live nodes.
It's normal to get parent unknown in lookups and it's handled here
a134d43446/beacon_node/network/src/sync/block_lookups/mod.rs (L611-L619)
These shouldn't be a `WARN`, and we also log the same error in block lookups at `DEBUG` level here:
a134d43446/beacon_node/network/src/sync/block_lookups/mod.rs (L643-L648)
So i've removed these extra WARN logs.
I've also lower the level of an `ERROR` log when unable to serve data column root requests - it's unexpected, but is unlikely to impact the nodes performance, so I think we can downgrade this.
Co-Authored-By: Jimmy Chen <jchen.tc@gmail.com>
- PR https://github.com/sigp/lighthouse/pull/8045 introduced a regression of how lookup sync interacts with the da_checker.
Now in unstable block import from the HTTP API also insert the block in the da_checker while the block is being execution verified. If lookup sync finds the block in the da_checker in `NotValidated` state it expects a `GossipBlockProcessResult` message sometime later. That message is only sent after block import in gossip.
I confirmed in our node's logs for 4/4 cases of stuck lookups are caused by this sequence of events:
- Receive block through API, insert into da_checker in fn process_block in put_pre_execution_block
- Create lookup and leave in AwaitingDownload(block in processing cache) state
- Block from HTTP API finishes importing
- Lookup is left stuck
Closes https://github.com/sigp/lighthouse/issues/8104
- https://github.com/sigp/lighthouse/pull/8110 was my initial solution attempt but we can't send the `GossipBlockProcessResult` event from the `http_api` crate without adding new channels, which seems messy.
For a given node it's rare that a lookup is created at the same time that a block is being published. This PR solves https://github.com/sigp/lighthouse/issues/8104 by allowing lookup sync to import the block twice in that case.
Co-Authored-By: dapplion <35266934+dapplion@users.noreply.github.com>
#8105 (to be confirmed)
I noticed a large number of failed discovery requests after deploying latest `unstable` to some of our testnet and mainnet nodes. This is because of a recent PeerDAS change to attempt to maintain sufficient peers across data column subnets - this shouldn't be enabled on network without peerdas scheduled, otherwise it will keep retrying discovery on these subnets and never succeed.
Also removed some unused files.
Co-Authored-By: Jimmy Chen <jchen.tc@gmail.com>
Co-Authored-By: Jimmy Chen <jimmy@sigmaprime.io>
This PR consolidates the `reqresp_pre_import_cache` into the `data_availability_checker` for the following reasons:
- the `reqresp_pre_import_cache` suffers from the same TOCTOU bug we had with `data_availability_checker` earlier, and leads to unbounded memory leak, which we have observed over the last 6 months on some nodes.
- the `reqresp_pre_import_cache` is no longer necessary, because we now hold blocks in the `data_availability_checker` for longer since (#7961), and recent blocks can be served from the DA checker.
This PR also maintains the following functionalities
- Serving pre-executed blocks over RPC, and they're now served from the `data_availability_checker` instead.
- Using the cache for de-duplicating lookup requests.
Co-Authored-By: Jimmy Chen <jchen.tc@gmail.com>
Co-Authored-By: Jimmy Chen <jimmy@sigmaprime.io>
Part of #7866
- Continuation of #7921
In the above PR, we enabled rayon for batch KZG verification in chain segment processing. However, using the global rayon thread pool for backfill is likely to create resource contention with higher-priority beacon processor work.
This PR introduces a dedicated low-priority rayon thread pool `LOW_PRIORITY_RAYON_POOL` and uses it for processing backfill chain segments.
This prevents backfill KZG verification from using the global rayon thread pool and competing with high-priority beacon processor tasks for CPU resources.
However, this PR by itself doesn't prevent CPU oversubscription because other tasks could still fill up the global rayon thread pool, and having an extra thread pool could make things worse. To address this we need the beacon
processor to coordinate total CPU allocation across all tasks, which is covered in:
- #7789
Co-Authored-By: Jimmy Chen <jchen.tc@gmail.com>
Co-Authored-By: Eitan Seri- Levi <eserilev@gmail.com>
Co-Authored-By: Eitan Seri-Levi <eserilev@ucsc.edu>
Lookup sync has a cache of block roots "failed_chains". If a peer triggers a lookup for a block or descendant of a root in failed_chains the lookup is dropped and the peer penalized. However blocks are inserted into failed_chains for a single reason:
- If a chain is longer than 32 blocks the lookup is dropped to prevent OOM risks. However the peer is not at fault, since discovering an unknown chain longer than 32 blocks is not malicious. We just drop the lookup to sync the blocks from range forward sync.
This discrepancy is probably an oversight when changing old code. Before we used to add blocks that failed too many times to process to that cache. However, we don't do that anymore. Adding a block that fails too many times to process is an optimization to save resources in rare cases where peers keep sending us invalid blocks. In case that happens, today we keep trying to process the block, downscoring the peers and eventually disconnecting them. _IF_ we found that optimization to be necessary we should merge this PR (_Stricter match of BlockError in lookup sync_) first. IMO we are fine without the failed_chains cache and the ignored_chains cache will be obsolete with [tree sync](https://github.com/sigp/lighthouse/issues/7678) as the OOM risk of long lookup chains does not exist anymore.
Closes https://github.com/sigp/lighthouse/issues/7577
Rename `failed_chains` for `ignored_chains` and don't penalize peers that trigger lookups for those blocks
Co-Authored-By: dapplion <35266934+dapplion@users.noreply.github.com>
#7697
If we're three seconds into the current slot just trigger reconstruction. I don't know what the correct reconstruction deadline number is, but it should probably be at least half a second before the attestation deadline
Co-Authored-By: Eitan Seri- Levi <eserilev@gmail.com>
Co-Authored-By: Eitan Seri-Levi <eserilev@ucsc.edu>
I was looking into some long `PendingComponents` span and noticed the block event wasn't added to the span, so it wasn't possible to see when the block was added from the trace view, this PR fixes this.
<img width="637" height="430" alt="image" src="https://github.com/user-attachments/assets/65040b1c-11e7-43ac-951b-bdfb34b665fb" />
Additionally I've noticed a lot of noises and confusion in sync logs due to the initial`peer_id` being included as part of the syncing chain span, causing all logs under the span to have that `peer_id`, which may not be accurate for some sync logs, I've removed `peer_id` from the `SyncingChain` span, and also cleaned up a bunch of spans to use `%` (display) for slots and epochs to make logs easier to read.
Co-Authored-By: Jimmy Chen <jchen.tc@gmail.com>
Fixes the issue described in #7980 where Lighthouse repeatedly sends `DataColumnsByRoot` requests to the same peers that return empty responses, causing sync to get stuck.
The root cause was we don't count empty responses as failures, leading to excessive retries to unresponsive peers.
- Track per peer attempts to limit retry attempts per peer (`MAX_CUSTODY_PEER_ATTEMPTS = 3`)
- Replaced random peer selection with hashing within each lookup to prevent splitting lookup into too many small requests and improve request batching efficiency.
- Added `single_block_lookup` root span to track all lookups created and added more debug logs:
<img width="1264" height="501" alt="image" src="https://github.com/user-attachments/assets/983629ba-b6d0-41cf-8e93-88a5b96c2f31" />
Co-Authored-By: Jimmy Chen <jchen.tc@gmail.com>
Co-Authored-By: Jimmy Chen <jimmy@sigmaprime.io>
N/A
Extracts (3) from https://github.com/sigp/lighthouse/pull/7946.
Prior to peerdas, a batch should never have been in `AwaitingDownload` state because we immediataly try to move from `AwaitingDownload` to `Downloading` state by sending batches. This was always possible as long as we had peers in the `SyncingChain` in the pre-peerdas world.
However, this is no longer the case as a batch can be stuck waiting in `AwaitingDownload` state if we have no peers to request the columns from. This PR makes `AwaitingDownload` to be an allowable in between state. If a batch is found to be in this state, then we attempt to send the batch instead of erroring like before.
Note to reviewer: We need to make sure that this doesn't lead to a bunch of batches stuck in `AwaitingDownload` state if the chain can be progressed.
Backfill already retries all batches in AwaitingDownload state so we just need to make `AwaitingDownload` a valid state during processing and validation.
This PR explicitly adds the same logic for forward sync to download batches stuck in `AwaitingDownload`.
Apart from that, we also force download of the `processing_target` when sync stops progressing. This is required in cases where `self.batches` has > `BATCH_BUFFER_SIZE` batches that are waiting to get processed but the `processing_batch` has repeatedly failed at download/processing stage. This leads to sync getting stuck and never recovering.
Closes:
- #7865
- #7855
Changes extracted from earlier PR #7876
This PR fixes two main things with a few other improvements mentioned below:
- Prevent Lighthouse from repeatedly sending `DataColumnByRoot` requests to an unsynced peer, causing lookup sync to get stuck
- Allows Lighthouse to send discovery requests if there isn't enough **synced** peers in the required sampling subnets - this fixes the stuck sync scenario where there isn't enough usable peers in sampling subnet but no discovery is attempted.
- Make peer discovery queries if custody subnet peer count drops below the minimum threshold
- Update peer pruning logic to prioritise uniform distribution across all data column subnets and avoid pruning sampling peers if the count is below the target threshold (2)
- Check sync status when making discovery requests, to make sure we don't ignore requests if there isn't enough synced peers in the required sampling subnets
- Optimise some of the `PeerDB` functions checking custody peers
- Only send lookup requests to peers that are synced or advanced
Addresses #7866.
Use Rayon to speed up batch KZG verification during range / backfill sync.
While I was analysing the traces, I also discovered a bug that resulted in only the first 128 columns in a chain segment batch being verified. This PR fixes it, so we might actually observe slower range sync due to more cells being KZG verified.
I've also updated the handling of batch KZG failure to only find the first invalid KZG column when verification fails as this gets very expensive during range/backfill sync.
N/A
Currently, backfill is allowed to create upto 20 pending batches which is unnecessarily high imo. Forward sync also allows a max of 5 batches to be buffered at a time. This PR reduces the batch size to match with forward sync.
Having high number of batches is a little annoying with peerdas because we try to create and send 20 requests (even though we are processing them in a rate limited manner). Requests with peerdas is a lot more heavy as we distribute requests across multiple peers leading to lot of requests that may keep getting retried. This could take resources away from processing at head.
This method is a footgun because it truncates the list. It is the source of a recent bug:
- https://github.com/sigp/lighthouse/pull/7927
- Delete uses of `RuntimeVariableList::from_vec` and replace them with `::new` which does validation and can fail.
- Propagate errors where possible, unwrap in tests and use `expect` for obviously-safe uses (in `chain_spec.rs`).
N/A
In https://github.com/sigp/lighthouse/pull/7897 , we seem to have modified data columns by range to return all the columns we have for the requested epoch disregarding what columns the peer requested.
When gossip data column processing completes and results in a block import, sync is currently not notified of the successful import. This is inconsistent with how blob processing and block processing both notify sync.
This fix ensures lookup sync receives block import notifications when blocks become available through gossip data column.
Adds the required boilerplate code for the Gloas (Glamsterdam) hard fork. This allows PRs testing Gloas-candidate features to test fork transition.
This also includes de-duplication of post-Bellatrix readiness notifiers from #6797 (credit to @dapplion)
