[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>
This commit introduces a new concept called `NotificationService` which
allows Polkadot protocols to communicate with the underlying
notification protocol implementation directly, without routing events
through `NetworkWorker`. This implies that each protocol has its own
service which it uses to communicate with remote peers and that each
`NotificationService` is unique with respect to the underlying
notification protocol, meaning `NotificationService` for the transaction
protocol can only be used to send and receive transaction-related
notifications.
The `NotificationService` concept introduces two additional benefits:
* allow protocols to start using custom handshakes
* allow protocols to accept/reject inbound peers
Previously the validation of inbound connections was solely the
responsibility of `ProtocolController`. This caused issues with light
peers and `SyncingEngine` as `ProtocolController` would accept more
peers than `SyncingEngine` could accept which caused peers to have
differing views of their own states. `SyncingEngine` would reject excess
peers but these rejections were not properly communicated to those peers
causing them to assume that they were accepted.
With `NotificationService`, the local handshake is not sent to remote
peer if peer is rejected which allows it to detect that it was rejected.
This commit also deprecates the use of `NetworkEventStream` for all
notification-related events and going forward only DHT events are
provided through `NetworkEventStream`. If protocols wish to follow each
other's events, they must introduce additional abtractions, as is done
for GRANDPA and transactions protocols by following the syncing protocol
through `SyncEventStream`.
Fixes https://github.com/paritytech/polkadot-sdk/issues/512
Fixes https://github.com/paritytech/polkadot-sdk/issues/514
Fixes https://github.com/paritytech/polkadot-sdk/issues/515
Fixes https://github.com/paritytech/polkadot-sdk/issues/554
Fixes https://github.com/paritytech/polkadot-sdk/issues/556
---
These changes are transferred from
https://github.com/paritytech/substrate/pull/14197 but there are no
functional changes compared to that PR
---------
Co-authored-by: Dmitry Markin <dmitry@markin.tech>
Co-authored-by: Alexandru Vasile <60601340+lexnv@users.noreply.github.com>
Submit the outstanding PRs from the old repos(these were already
reviewed and approved before the repo rorg, but not yet submitted):
Main PR: https://github.com/paritytech/substrate/pull/14014
Companion PRs: https://github.com/paritytech/polkadot/pull/7134,
https://github.com/paritytech/cumulus/pull/2489
The changes in the PR:
1. ChainSync currently calls into the block request handler directly.
Instead, move the block request handler behind a trait. This allows new
protocols to be plugged into ChainSync.
2. BuildNetworkParams is changed so that custom relay protocol
implementations can be (optionally) passed in during network creation
time. If custom protocol is not specified, it defaults to the existing
block handler
3. BlockServer and BlockDownloader traits are introduced for the
protocol implementation. The existing block handler has been changed to
implement these traits
4. Other changes:
[X] Make TxHash serializable. This is needed for exchanging the
serialized hash in the relay protocol messages
[X] Clean up types no longer used(OpaqueBlockRequest,
OpaqueBlockResponse)
---------
Co-authored-by: Dmitry Markin <dmitry@markin.tech>
Co-authored-by: command-bot <>
* Prepare `sc-network` for `ProtocolController`/`NotificationService`
The upcoming notification protocol refactoring requires that protocols
are able to communicate with `sc-network` over unique and direct links.
This means that `sc-network` side of the link has to be created before
`sc-network` is initialized and that it is allowed to consume the object
as the receiver half of the link may not implement `Clone`.
Remove request-response and notification protocols from `NetworkConfiguration`
and create a new object that contains the configurations of these protocols
and which is consumable by `sc-network`. This is needed needed because, e.g.,
the receiver half of `NotificationService` is not clonable so `sc-network`
must consume it when it's initializing the protocols in `Notifications`.
Similar principe applies to `PeerStore`/`ProtocolController`: as per current
design, protocols are created before the network so `Protocol` cannot be
the one creating the `PeerStore` object. `FullNetworkConfiguration` will be
used to store the objects that `sc-network` will use to communicate with
protocols and it will also allow protocols to allocate handles so they
can directly communicate with `sc-network`.
* Fixes
* Update client/service/src/builder.rs
Co-authored-by: Dmitry Markin <dmitry@markin.tech>
* Updates
* Doc updates + cargo-fmt
---------
Co-authored-by: Dmitry Markin <dmitry@markin.tech>
* Attempt to relieve pressure on `mpsc_network_worker`
`SyncingEngine` interacting with `NetworkWorker` can put a lot of strain
on the channel if the number of inbound connections is high. This is
because `SyncingEngine` is notified of each inbound substream which it
then can either accept or reject and this causes a lot of message
exchange on the already busy channel.
Use a direct channel pair between `Protocol` and `SyncingEngine`
to exchange notification events. It is a temporary change to alleviate
the problems caused by syncing being an independent protocol and the
fix will be removed once `NotificationService` is implemented.
* Apply review comments
* fixes
* trigger ci
* Fix tests
Verify that both peers have a connection now that the validation goes
through `SyncingEngine`. Depending on how the tasks are scheduled,
one of them might not have the peer registered in `SyncingEngine` at which
point the test won't make any progress because block announcement received
from an unknown peer is discarded.
Move polling of `ChainSync` at the end of the function so that if a block
announcement causes a block request to be sent, that can be sent in the
same call to `SyncingEngine::poll()`.
---------
Co-authored-by: parity-processbot <>
* Move service tests to `client/network/tests`
These tests depend on `sc-network` and `sc-network-sync` so they should
live outside the crate.
* Move some configs from `sc-network-common` to `sc-network`
* Move `NetworkService` traits to `sc-network`
* Move request-responses to `sc-network`
* Remove more stuff
* Remove rest of configs from `sc-network-common` to `sc-network`
* Remove more stuff
* Fix warnings
* Update client/network/src/request_responses.rs
Co-authored-by: Dmitry Markin <dmitry@markin.tech>
* Fix cargo doc
---------
Co-authored-by: Dmitry Markin <dmitry@markin.tech>
Aaro Altonen