Stop response-handler errors from poisoning the nREPL response queue#3896
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Stop response-handler errors from poisoning the nREPL response queue#3896
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`nrepl-client-filter' decodes a batch of responses from the wire and walks them in a `while' loop, dispatching each in turn. A demoted- errors wrapper guarded the global `nrepl-response-handler-functions' hook but stopped there -- the per-request `nrepl--dispatch-response' call ran unprotected. If that call signaled (because of a buggy callback, or because no handler was registered for the response's id), the loop aborted and any later decoded responses sitting in the queue were dropped. Two changes: - Wrap `nrepl--dispatch-response' in `with-demoted-errors' too. Handler bugs are logged but no longer corrupt the response stream. - Soften `nrepl--dispatch-response''s no-callback case from `error' to `message'. The dispatcher cannot do anything actionable with an unknown id; logging is sufficient. Adds two specs in test/nrepl-client-tests.el covering the soft no-handler path and locking in the dispatcher's "errors propagate unless the filter wraps you" contract.
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Found during a wider audit of request handling.
nrepl-client-filterdecodes a batch of responses from the wire and walks them in awhileloop, dispatching each in turn. Awith-demoted-errorsguard wrapped the globalnrepl-response-handler-functionshook but stopped there -- the per-requestnrepl--dispatch-responsecall ran unprotected.If that call signaled (because a callback threw, or because no handler was registered for the response's id), the
while (queue-head response-q)loop aborted and any later decoded responses sitting in the queue were dropped on the floor. The next response stream might keep working, but anything already decoded was lost.This PR makes two changes:
nrepl--dispatch-responseinwith-demoted-errorstoo. Handler bugs become log entries, not stream corruption.nrepl--dispatch-response's no-callback case fromerrortomessage. The dispatcher cannot do anything actionable with an unknown id; logging is sufficient and avoids forcing the filter to demote.Two new specs in
test/nrepl-client-tests.elcover the soft no-handler path and lock in the dispatcher's contract (errors propagate unless the filter wraps you).