Repository navigation
[Mocha] Fix Postgres outbox dropping fault replies to a caller's reply queue - #10529
Merged
Merged
Conversation
github-actions
Bot
added
📚 documentation
Contributor
Patch coverage78.7% of changed lines covered (48/61)
Uncovered changed lines (JSON){
"sha": "0a79a89123d8fbcd25788e6f8a139e816492d17c",
"files": [
{ "path": "src/Mocha/src/Mocha.EntityFrameworkCore.Postgres/Scheduling/ScheduledMessageDispatcher.cs", "ranges": [[156, 156], [158, 158], [174, 176], [240, 242]] },
{ "path": "src/Mocha/src/Mocha.EntityFrameworkCore.Postgres/Outbox/OutboxProcessor.cs", "ranges": [[168, 168], [170, 170], [239, 241]] }
]
}Project coverage: 58.6% (315584/538115 lines) |
tobias-tengler
changed the title
tobias-tengler
marked this pull request as ready for review
October 12, 2026 14:36
Contributor
There was a problem hiding this comment.
🟢 Approval recommended
The fix is focused and integration-tested, with only a minor naming issue remaining.
1 open finding
What changed in this PR
Fixes Postgres outbox delivery of fault replies targeting caller-owned reply queues.
Changes:
- Routes replies and faults through reply dispatch endpoints.
- Adds targeted Postgres outbox integration coverage.
- Improves dropped-message diagnostics and scheduling documentation.
| File | Description |
|---|---|
website/content/docs/mocha/scheduling.md |
Documents dropped-message causes. |
PostgresOutboxFaultReplyTests.cs |
Tests fault reply delivery. |
Helpers/MessagingTestHost.cs |
Adds test host lifecycle support. |
HeaderMessageKindExtensions.cs |
Detects replies and faults. |
InMemoryScheduledMessageWorker.cs |
Routes faults through reply dispatch. |
ScheduledMessageDispatcher.cs |
Improves routing and diagnostics. |
OutboxProcessor.cs |
Fixes persisted fault reply routing. |
🧠 Review effort: Balanced
💡 Add a code-review agent skill or configure MCP servers for context-aware, tailored reviews. Learn more in the docs.
PascalSenn
reviewed
Oct 12, 2026
A fault reply to a caller whose reply queue is not a configured dispatch endpoint is dropped by the Postgres outbox processor and the scheduled message dispatcher. The tests reproduce the drop and pin the log messages that name the cause.
The outbox processor and the scheduled message dispatcher only routed MessageKind.Reply through the transport's reply dispatch endpoint. A MessageKind.Fault reply took the generic dispatch lookup, which cannot resolve a caller's reply queue, and was deleted with a "Could not deserialize message body" log. Faults now take the reply dispatch endpoint like replies, and the three drop causes are logged separately.
The tests started the runtime by hand and waited a fixed delay before disposing the provider. MessagingTestHost starts the registered hosted services in order and stops them in reverse, so the workers are stopped before the provider is disposed. The scheduler test moves into its own file on the same helper.
A reply or fault never reaches the scheduled message dispatcher through the bus, since only publish, send and request set a scheduled time. The test had to forge a scheduler row to reach that branch. The dispatcher keeps routing faults like replies so it mirrors the outbox processor.
The Postgres outbox processor and scheduled message dispatcher deleted a row when they could not deserialize its envelope, resolve its message type or resolve its destination. During a rolling deployment an old instance could delete a message written by a newer instance that only the newer instance understands. Both processors now leave such a row in place with its incremented attempt count, so the existing backoff retries it and another instance can send it. The skip is logged as a warning. Once the row reaches the attempt limit it is no longer selected and an exhausted entry is logged at critical level. The outbox lock query returns the attempt count for that, and its limit is a named constant. Also renames the reply check in the in-memory scheduled worker to say that it covers faults as well.
tobias-tengler
force-pushed
the
tte/mocha-outbox-fault-reply
branch
from
October 13, 2026 07:09
20301d9 to
ff0da33
Compare
PascalSenn
approved these changes
Oct 13, 2026
This was referenced Oct 25, 2026
Merged
This was referenced Oct 27, 2026
This file contains hidden or bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment
Add this suggestion to a batch that can be applied as a single commit.This suggestion is invalid because no changes were made to the code.Suggestions cannot be applied while the pull request is closed.Suggestions cannot be applied while viewing a subset of changes.Only one suggestion per line can be applied in a batch.Add this suggestion to a batch that can be applied as a single commit.Applying suggestions on deleted lines is not supported.You must change the existing code in this line in order to create a valid suggestion.Outdated suggestions cannot be applied.This suggestion has been applied or marked resolved.Suggestions cannot be applied from pending reviews.Suggestions cannot be applied on multi-line comments.Suggestions cannot be applied while the pull request is queued to merge.Suggestion cannot be applied right now. Please check back later.
When a request handler fails, Mocha answers the caller with a
NotAcknowledgedEventof kindMessageKind.Fault. With the Postgres outbox, the outbox processor only routedMessageKind.Replythrough the transport's reply dispatch endpoint. A fault took the generic dispatch lookup instead, which cannot resolve a caller's reply queue, so the processor deleted the row and logged "Could not deserialize message body". The caller never received the fault and ran into its own timeout.This PR routes faults through the reply dispatch endpoint like replies, in the outbox processor as well as the Postgres and in-memory scheduled message dispatchers, which share the same lookup. The processors now log the three drop causes separately: an unreadable envelope, an unknown message type and an unresolvable destination. An integration test reproduces the drop with a reply address outside the host's topology and verifies the caller receives the fault.