fix: bound queued incoming QoS 0 publishes - #96
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hugues bouvier (huguesBouvier) wants to merge 1 commit into
Closed
fix: bound queued incoming QoS 0 publishes#96hugues bouvier (huguesBouvier) wants to merge 1 commit into
hugues bouvier (huguesBouvier) wants to merge 1 commit into
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Cap queued QoS 0 publishes with permits while leaving QoS 1 and 2 under MQTT protocol flow control. Excess QoS 0 messages are dropped without blocking connection progress. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
Author
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Vendored SDK mirror is open at Azure/iot-operations-sdks#1437. This source PR is fully green; the mirror PR local Rust checks pass, while its secret-dependent integration jobs require a maintainer-owned branch because it originates from a fork. |
Collaborator
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As discussed offline, we can take this on the vendored version for now, and spend some time considering how to best fix this for the full version here. |
Collaborator
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Moved to track in #105 |
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Summary
Context
The incoming application-message channel is unbounded. QoS 1/2 traffic is constrained by MQTT Receive Maximum and packet identifiers, but QoS 0 has no protocol-level flow control. If an application stops draining
Receiver, QoS 0 publishes can accumulate until the process runs out of memory.This was observed while investigating Azure-NBC PR 16518887. The permit is carried with each queued QoS 0 publish and released when the receiver drains or drops it, preserving message order without blocking socket progress.
Validation
make checkmake test