Previously, it was only possible to retry the same request on a
different protocol name that had the exact same binary payloads.
Introduce a way of trying a different request on a different protocol if
the first one fails with Unsupported protocol.
This helps with adding new req-response versions in polkadot while
preserving compatibility with unupgraded nodes.
The way req-response protocols were bumped previously was that they were
bundled with some other notifications protocol upgrade, like for async
backing (but that is more complicated, especially if the feature does
not require any changes to a notifications protocol). Will be needed for
implementing https://github.com/polkadot-fellows/RFCs/pull/47
TODO:
- [x] add tests
- [x] add guidance docs in polkadot about req-response protocol
versioning
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 <>
Alin Dima