Implement inbound RPC.partial dispatch (step 3)#463
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Captures the MVP scope, jvm-libp2p/client responsibility boundary, client-facing API, routing semantics, per-group lifecycle and DoS caps, and the implementation plan for the gossipsub partial-messages extension. Lands ahead of implementation so sub-issues of libp2p#435 can reference a stable design anchor.
Step 1 of the partial-messages extension: plumb SubOpts.requestsPartial / SubOpts.supportsSendingPartial through subscribe announcements in both directions, and track the per-peer-per-topic receive state. - AbstractRouter parses the flags with the spec-mandated coercion (supportsSendingPartial := requestsPartial || supportsSendingPartial) and zeroes them on subscribe=false. - New enqueueSubscribe hook unifies outbound subscribe enqueueing so GossipRouter can attach per-topic flags in a single override. - GossipRouter exposes setTopicPartialFlags(topic, ...) to configure flags advertised for a locally-subscribed topic, and stores inbound flags in a new PartialSubscriptionState (plain HashMap on the pubsub event loop). State is cleaned on peer disconnect, topic unsubscribe, and per-peer unsubscribe. - Outbound unsubscribe MUST NOT carry partial flags; enforced at the SubscriptionPart wire-build site. No routing behaviour changes yet. See docs/partial-messages.md §4.5, §5, §6.1 for context.
…t addSubscription overload
- `PartialSubscriptionWireTest`: route reads of `partialSubscriptionState`
through `submitOnEventThread { ... }.join()`. The state container is
not thread-safe; direct access from the JUnit thread races the event
loop and can surface as `ConcurrentModificationException` or stale
reads. Two helpers (`peerFlagsOnEventLoop`, `snapshotPartialStateOnEventLoop`)
establish the happens-before barrier.
- `RpcPartsQueue`: remove the 2-arg `addSubscription(topic, status)`
default overload. The remaining 4-arg abstract method is the single
source of truth; `addSubscribe` / `addUnsubscribe` remain the
convenience entry points.
- `PartialSubFlags.coerce(requestsPartial, supportsSendingPartial)`: single source of truth for the spec coercion rule `supportsSendingPartial := requestsPartial || supportsSendingPartial`. Used from `GossipRouter.setTopicPartialFlags` for the outbound side. AbstractRouter keeps the inline expression for the receive side to avoid a reverse layering dependency (pubsub -> gossip); a comment notes the rule is applied on both sides. - `PartialSubscriptionState.setPeerFlags`: document that passing `PartialSubFlags.NONE` (or any equivalent all-false flags) is treated as a removal. Makes the set-sometimes-deletes invariant explicit for readers. - `AbstractRouter.handleMessageSubscriptions`: add Kdoc now that the method is `protected open`. Documents the "call super" contract for overrides (GossipRouter relies on this to keep peersTopics and partialSubscriptionState in sync) and the flag-normalisation precondition.
…ure/partial-messages-support
Introduces the public partial-messages API surface and the internal state management layer required before any routing logic lands: Public API (io.libp2p.pubsub.gossip.partialmessages): - PartialMessagesHandler<PeerState> — onIncomingRpc + onEmitGossip; PartialMessagesPeerFeedback passed per-call (resolves open question from design doc §9) - PublishAction<PeerState> / PublishActionsFn<PeerState> - PartialMessagesPeerFeedback interface + FeedbackKind enum Internal state management: - GroupId — content-equality ByteArray wrapper for use as map key - GroupState<PeerState> — per-(topic,groupId) container with mutable TTL and app-opaque peerStates - PartialGroupStateStore<PeerState> — TTL countdown, GC on ttl≤0 or empty peerStates, DoS caps (255/topic, 8/topic/peer, matching go-libp2p defaults), onPeerDisconnected, onTopicUnsubscribed - PartialMessagesAdapter (internal interface) / PartialMessagesAdapterImpl<PeerState> — erases PeerState at the GossipRouter boundary via a single @Suppress("UNCHECKED_CAST") in the builder Wiring: - GossipRouterBuilder: partialMessagesHandler field; build-time error if PARTIAL_MESSAGES extension enabled without a handler - GossipRouter: internal var partialMessages: PartialMessagesAdapter? No routing changes in this step.
Replaces the stub in GossipRouter.processPartialMessageExtension with the full flow: drop RPCs missing topicID or groupID, then delegate to PartialMessagesAdapterImpl which gets-or-creates the GroupState (with DoS cap enforcement) and calls handler.onIncomingRpc with the live peerStates map.
This was referenced Apr 27, 2026
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Summary
GossipRouter.processPartialMessageExtensionwith the full inbound dispatch flowonIncomingRpctoPartialMessagesAdapter/PartialMessagesAdapterImpl: validates groupID, gets-or-createsGroupState(with DoS cap enforcement viaPartialGroupStateStore), and callshandler.onIncomingRpcwith the livepeerStatesmaptopicID/groupIDbefore touching the state storePart of #435. Follows step 2 (
6adf574).What's in scope
Step 3 from
docs/partial-messages.md:Test plan
PartialMessagesAdapterImplTest— unit tests: correct dispatch, empty peerStates on first call, same peerStates object reused for same group, optional field forwarding, per-topic and per-peer DoS cap enforcement, independent groups per topicPartialMessagesInboundRpcTest— integration tests through GossipRouter: missing/empty topicID dropped, missing/empty groupID dropped, no-prior-handshake guard, extension-disabled guard, multi-group dispatch./gradlew :libp2p:testpasses in full