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clean() rebuilt pending from outgoing_pub/outgoing_rel and reset collision_ping_count, but never took self.collision. When the session is lost across a reconnect (clean_session = true, or session_present = false dropping pending), the colliding pkid is never re-acked, so the stashed publish is silently lost and the request branch stays disabled: the client loops CollisionTimeout -> reconnect -> clean() forever, sending nothing but pings and CONNECTs. Push the stashed publish into pending during clean() (v4 and v5); its outgoing_pub slot is free after the sweep and it already carries a pkid. Adds regression tests for both protocol versions. Fixes bytebeamio#1056 Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
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Fixes #1056.
Problem
MqttState::clean()rebuildspendingfromoutgoing_pub/outgoing_reland resetscollision_ping_count, but never takesself.collision. When the session is lost across a reconnect (clean_session = true, orsession_present = falsedroppingpending), the colliding pkid is never re-acked, so:!collisiongate ineventloop.rs), so the client loopsCollisionTimeout→ reconnect →clean()forever, sending nothing but pings and CONNECTs.Full analysis in #1056.
Fix
Push the stashed publish into
pendingduringclean()— itsoutgoing_pubslot is free after the sweep and it already carries a pkid, so it rides the normal retransmission path. Applied to both v4 and v5 state, with a regression test each (clean_recovers_collision_stashed_publish).On a resumed session the old self-heal path (
check_collisionon the ack of the colliding pkid) still works; this change only matters when that ack can never arrive.Tests:
cargo test -p rumqttc --lib --no-default-features— 75 passed.🤖 Generated with Claude Code