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Beefy on-demand justifications as a custom RequestResponse protocol #12124
Beefy on-demand justifications as a custom RequestResponse protocol #12124
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…ustom-sync-protocol
…ustom-sync-protocol
Fix corner case where voter gets a single burst of finality notifications just when it starts. The notification stream was consumed by "wait_for_pallet" logic, then main loop would subscribe to finality notifications, but by that time some notifications might've been lost. Fix this by subscribing the main loop to notifications before waiting for pallet to become available. Share the same stream with the main loop so that notifications for blocks before pallet available are ignored, while _all_ notifications after pallet available are processed. Add regression test for this. Signed-off-by: acatangiu <adrian@parity.io>
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Left some minor comments but looks good!
client/beefy/src/communication/request_response/incoming_requests_handler.rs
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client/beefy/src/communication/request_response/outgoing_requests_engine.rs
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Thanks for the review! I've addressed all comments 👍
client/beefy/src/communication/request_response/incoming_requests_handler.rs
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pub async fn next(&mut self) -> Option<BeefyVersionedFinalityProof<B>> { | ||
let (peer, block, resp) = match &mut self.state { | ||
State::Idle(pending) => { | ||
let _ = pending.next().await; |
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A noobs async question: does this rely on next()
being polled in a select!
loop with other futures, otherwise we'll get stuck here forever?
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This whole function is async
(as seen in pub async fn
signature). This means it cannot be (directly) called from a normal sync context - the compiler will complain (this is because async
functions actually translates to sync functions returning impl Future
- a pretty good article on this here).
.await
does indeed mean "wait here until this is ready", but it can only be called inside an async
function, meaning "wait here" is not "block here", but rather "do something else until this is ready, then come back here".
The way this happens under the hood is by turning this whole function into a state machine where each await
is a transition from one state to another - a pretty good explanation here.
So to answer your question, no, this function does not rely on it being called in a select!
loop, the only requirements on it are the ones enforced by the compiler: the function needs to be called from either another async
context/fn or must be directly called by an "asynchronous runtime".
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@acatangiu thanks a lot for the detailed explanation!
bot merge |
Error: Statuses failed for b904741 |
…ustom-sync-protocol
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Waiting for commit status. |
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I know that I'm very late to the party. I still left some comments on stuff that could be improved. Sorry!
client/beefy/src/communication/request_response/outgoing_requests_engine.rs
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Better late than never 😛 thanks for the improvement ideas! Opened #12414 for them. |
* master: (42 commits) Adapt `pallet-contracts` to WeightV2 (#12421) Improved election pallet testing (#12327) Bump prost to 0.11+ (#12419) Use saturating add for alliance::disband witness data (#12418) [Fix] Rename VoterBagsList -> VoterList to match pdot (#12416) client/beefy: small code improvements (#12414) BEEFY: Simplify hashing for pallet-beefy-mmr (#12393) Add @koute to `docs/CODEOWNERS` and update stale paths (#12408) docs/CODEOWNERS: add @acatangiu as MMR owner (#12406) Remove unnecessary Clone trait bounds on CountedStorageMap (#12402) Fix `Weight::is_zero` (#12396) Beefy on-demand justifications as a custom RequestResponse protocol (#12124) Remove contracts RPCs (#12358) pallet-mmr: generate historical proofs (#12324) unsafe_pruning flag removed (#12385) Carry over where clauses defined in Config to Call and Hook (#12388) Properly set the max proof size weight on defaults and tests (#12383) BEEFY: impl TypeInfo for SignedCommitment (#12382) bounding staking: `BoundedElectionProvider` trait (#12362) New Pallet: Root offences (#11943) ...
…aritytech#12124) * client/beefy: create communication module and move gossip there * client/beefy: move beefy_protocol_name module to communication * client/beefy: move notification module under communication * client/beefy: add incoming request_response protocol handler * client/beefy: keep track of connected peers and their progress * client/beefy: add logic for generating Justif requests * client/beefy: cancel outdated on-demand justification requests * try Andre's suggestion for JustificationEngine * justif engine add justifs validation * client/beefy: impl OnDemandJustificationsEngine async next() * move beefy proto name test * client/beefy: initialize OnDemandJustificationsEngine * client/tests: allow for custom req-resp protocols * client/beefy: on-demand-justif: implement simple peer selection strategy * client/beefy: fix voter initialization Fix corner case where voter gets a single burst of finality notifications just when it starts. The notification stream was consumed by "wait_for_pallet" logic, then main loop would subscribe to finality notifications, but by that time some notifications might've been lost. Fix this by subscribing the main loop to notifications before waiting for pallet to become available. Share the same stream with the main loop so that notifications for blocks before pallet available are ignored, while _all_ notifications after pallet available are processed. Add regression test for this. Signed-off-by: acatangiu <adrian@parity.io> * client/beefy: make sure justif requests are always out for mandatory blocks * client/beefy: add test for on-demand justifications sync * client/beefy: tweak main loop event processing order * client/beefy: run on-demand-justif-handler under same async task as voter * client/beefy: add test for known-peers * client/beefy: reorg request-response module * client/beefy: add issue references for future work todos * client/beefy: consolidate on-demand-justifications engine state machine Signed-off-by: acatangiu <adrian@parity.io> * client/beefy: fix for polkadot companion * client/beefy: implement review suggestions * cargo fmt and clippy * fix merge damage * fix rust-doc * fix merge damage * fix merge damage * client/beefy: add test for justif proto name Signed-off-by: acatangiu <adrian@parity.io>
Description
Run a dedicated BEEFY justifications sync protocol as a libp2p
RequestResponse
protocol - where node can request BEEFY justifications for certain blocks from connected peers, and also answer any requests it gets.PR defines BEEFY own
RequestResponse
sub-protocol and adds support for:BeefyJustifsRequestHandler
inincoming_requests_handler.rs
OnDemandJustificationsEngine
inoutgoing_requests_engine.rs
BeefyJustifsRequestHandler
Run as independent async task, accepts incoming
request
s, decodes and validates request for BEEFY justification for blockb
.It then uses client backend to retrieve justification if available, encode and provide it as custom protocol
response
.OnDemandJustificationsEngine
Simple async state machine that be either:
b
" - self driving future that sequentially sends requests to all relevant peers until one provides valid justification or no more peers available. relevant peers are those seen (through gossip) voting for block numbers >=b
, meaning they should have justification forb
.main worker/voter
OnDemandJustificationsEngine
for every mandatory block it's currently working/voting/blocked on.OnDemandJustificationsEngine
inner future in its main loop.Tests
Added integration test that verifies all components and full workflow:
Fixes
Fixes #12093 (more details there).
polkadot companion: paritytech/polkadot#6035