fix(NODE-7859): reschedule RTT measurements after a failed ping - #5057
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RTTPinger only armed its next timer on the success path, so the first interruption of the dedicated RTT connection stopped it permanently. Neither the connect() nor the command() rejection handler scheduled a retry, leaving latestRtt frozen at its last good value and feeding a stale RTT into server selection indefinitely. The SDAM spec's RttMonitor pseudocode places the heartbeatFrequencyMS wait outside the error handler, so a failed ping continues the loop. Extract scheduleNextMeasurement() and call it from both rejection handlers, guarded so a closed pinger does not re-arm. latestRtt is deliberately left untouched on failure: "If a hello or legacy hello call fails, the RTT is not updated", and the pseudocode's error branch explicitly does not reset the average. Reported in HELP-100351.
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RTTPinger only sets the next timer on the success, so any interruption of the RTT connection stopped it permanently. Neither the connect() nor the command() rejection handler scheduled a retry, leaving latestRtt frozen at its last good value and feeding a stale RTT into server selection indefinitely.
The SDAM spec's RttMonitor pseudocode places the heartbeatFrequencyMS wait outside the error handler, so a failed ping continues the loop. Extract scheduleNextMeasurement() and call it from both rejection handlers, guarded so a closed pinger does not re-arm.
latestRtt is deliberately left untouched on failure: "If a hello or legacy hello call fails, the RTT is not updated", and the pseudocode's error branch explicitly does not reset the average.
Reported in HELP-100351.
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What is the motivation for this change?
For bug fixes
Current (incorrect) behavior:
Expected behavior:
How to reproduce:
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npm run check:lint)type(NODE-xxxx)[!]: descriptionfeat(NODE-1234)!: rewriting everything in coffeescript