[litep2p](https://github.com/altonen/litep2p) is a libp2p-compatible P2P
networking library. It supports all of the features of `rust-libp2p`
that are currently being utilized by Polkadot SDK.
Compared to `rust-libp2p`, `litep2p` has a quite different architecture
which is why the new `litep2p` network backend is only able to use a
little of the existing code in `sc-network`. The design has been mainly
influenced by how we'd wish to structure our networking-related code in
Polkadot SDK: independent higher-levels protocols directly communicating
with the network over links that support bidirectional backpressure. A
good example would be `NotificationHandle`/`RequestResponseHandle`
abstractions which allow, e.g., `SyncingEngine` to directly communicate
with peers to announce/request blocks.
I've tried running `polkadot --network-backend litep2p` with a few
different peer configurations and there is a noticeable reduction in
networking CPU usage. For high load (`--out-peers 200`), networking CPU
usage goes down from ~110% to ~30% (80 pp) and for normal load
(`--out-peers 40`), the usage goes down from ~55% to ~18% (37 pp).
These should not be taken as final numbers because:
a) there are still some low-hanging optimization fruits, such as
enabling [receive window
auto-tuning](https://github.com/libp2p/rust-yamux/pull/176), integrating
`Peerset` more closely with `litep2p` or improving memory usage of the
WebSocket transport
b) fixing bugs/instabilities that incorrectly cause `litep2p` to do less
work will increase the networking CPU usage
c) verification in a more diverse set of tests/conditions is needed
Nevertheless, these numbers should give an early estimate for CPU usage
of the new networking backend.
This PR consists of three separate changes:
* introduce a generic `PeerId` (wrapper around `Multihash`) so that we
don't have use `NetworkService::PeerId` in every part of the code that
uses a `PeerId`
* introduce `NetworkBackend` trait, implement it for the libp2p network
stack and make Polkadot SDK generic over `NetworkBackend`
* implement `NetworkBackend` for litep2p
The new library should be considered experimental which is why
`rust-libp2p` will remain as the default option for the time being. This
PR currently depends on the master branch of `litep2p` but I'll cut a
new release for the library once all review comments have been
addresses.
---------
Signed-off-by: Alexandru Vasile <alexandru.vasile@parity.io>
Co-authored-by: Dmitry Markin <dmitry@markin.tech>
Co-authored-by: Alexandru Vasile <60601340+lexnv@users.noreply.github.com>
Co-authored-by: Alexandru Vasile <alexandru.vasile@parity.io>
**Update:** Pushed additional changes based on the review comments.
**This pull request fixes various spelling mistakes in this
repository.**
Most of the changes are contained in the first **3** commits:
- `Fix spelling mistakes in comments and docs`
- `Fix spelling mistakes in test names`
- `Fix spelling mistakes in error messages, panic messages, logs and
tracing`
Other source code spelling mistakes are separated into individual
commits for easier reviewing:
- `Fix the spelling of 'authority'`
- `Fix the spelling of 'REASONABLE_HEADERS_IN_JUSTIFICATION_ANCESTRY'`
- `Fix the spelling of 'prev_enqueud_messages'`
- `Fix the spelling of 'endpoint'`
- `Fix the spelling of 'children'`
- `Fix the spelling of 'PenpalSiblingSovereignAccount'`
- `Fix the spelling of 'PenpalSudoAccount'`
- `Fix the spelling of 'insufficient'`
- `Fix the spelling of 'PalletXcmExtrinsicsBenchmark'`
- `Fix the spelling of 'subtracted'`
- `Fix the spelling of 'CandidatePendingAvailability'`
- `Fix the spelling of 'exclusive'`
- `Fix the spelling of 'until'`
- `Fix the spelling of 'discriminator'`
- `Fix the spelling of 'nonexistent'`
- `Fix the spelling of 'subsystem'`
- `Fix the spelling of 'indices'`
- `Fix the spelling of 'committed'`
- `Fix the spelling of 'topology'`
- `Fix the spelling of 'response'`
- `Fix the spelling of 'beneficiary'`
- `Fix the spelling of 'formatted'`
- `Fix the spelling of 'UNKNOWN_PROOF_REQUEST'`
- `Fix the spelling of 'succeeded'`
- `Fix the spelling of 'reopened'`
- `Fix the spelling of 'proposer'`
- `Fix the spelling of 'InstantiationNonce'`
- `Fix the spelling of 'depositor'`
- `Fix the spelling of 'expiration'`
- `Fix the spelling of 'phantom'`
- `Fix the spelling of 'AggregatedKeyValue'`
- `Fix the spelling of 'randomness'`
- `Fix the spelling of 'defendant'`
- `Fix the spelling of 'AquaticMammal'`
- `Fix the spelling of 'transactions'`
- `Fix the spelling of 'PassingTracingSubscriber'`
- `Fix the spelling of 'TxSignaturePayload'`
- `Fix the spelling of 'versioning'`
- `Fix the spelling of 'descendant'`
- `Fix the spelling of 'overridden'`
- `Fix the spelling of 'network'`
Let me know if this structure is adequate.
**Note:** The usage of the words `Merkle`, `Merkelize`, `Merklization`,
`Merkelization`, `Merkleization`, is somewhat inconsistent but I left it
as it is.
~~**Note:** In some places the term `Receival` is used to refer to
message reception, IMO `Reception` is the correct word here, but I left
it as it is.~~
~~**Note:** In some places the term `Overlayed` is used instead of the
more acceptable version `Overlaid` but I also left it as it is.~~
~~**Note:** In some places the term `Applyable` is used instead of the
correct version `Applicable` but I also left it as it is.~~
**Note:** Some usage of British vs American english e.g. `judgement` vs
`judgment`, `initialise` vs `initialize`, `optimise` vs `optimize` etc.
are both present in different places, but I suppose that's
understandable given the number of contributors.
~~**Note:** There is a spelling mistake in `.github/CODEOWNERS` but it
triggers errors in CI when I make changes to it, so I left it as it
is.~~
Adds availability-write regression tests.
The results for the `availability-distribution` subsystem are volatile,
so I had to reduce the precision of the test.
### What's been done
- `subsystem-bench` has been split into two parts: a cli benchmark
runner and a library.
- The cli runner is quite simple. It just allows us to run `.yaml` based
test sequences. Now it should only be used to run benchmarks during
development.
- The library is used in the cli runner and in regression tests. Some
code is changed to make the library independent of the runner.
- Added first regression tests for availability read and write that
replicate existing test sequences.
### How we run regression tests
- Regression tests are simply rust integration tests without the
harnesses.
- They should only be compiled under the `subsystem-benchmarks` feature
to prevent them from running with other tests.
- This doesn't work when running tests with `nextest` in CI, so
additional filters have been added to the `nextest` runs.
- Each benchmark run takes a different time in the beginning, so we
"warm up" the tests until their CPU usage differs by only 1%.
- After the warm-up, we run the benchmarks a few more times and compare
the average with the exception using a precision.
### What is still wrong?
- I haven't managed to set up approval voting tests. The spread of their
results is too large and can't be narrowed down in a reasonable amount
of time in the warm-up phase.
- The tests start an unconfigurable prometheus endpoint inside, which
causes errors because they use the same 9999 port. I disable it with a
flag, but I think it's better to extract the endpoint launching outside
the test, as we already do with `valgrind` and `pyroscope`. But we still
use `prometheus` inside the tests.
### Future work
* https://github.com/paritytech/polkadot-sdk/issues/3528
* https://github.com/paritytech/polkadot-sdk/issues/3529
* https://github.com/paritytech/polkadot-sdk/issues/3530
* https://github.com/paritytech/polkadot-sdk/issues/3531
---------
Co-authored-by: Alexander Samusev <41779041+alvicsam@users.noreply.github.com>
Aaro Altonen