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Stop logging a fault for valid PTO cases #62

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Merged
ekinnear merged 1 commit into from
Jul 31, 2026
Merged

Stop logging a fault for valid PTO cases #62

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15 changes: 14 additions & 1 deletion Sources/SwiftNetwork/QUIC/Recovery.swift
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Original file line number Diff line number Diff line change
Expand Up @@ -1125,11 +1125,13 @@ struct Recovery: ~Copyable, PrefixedLoggable, NonCopyableTimerUser {
let peerCompletedValidation = peerCompletedValidation(connection: connection)
var shouldClearTimer = false
var discardInitialRecoveryState = false
var hadAckElicitingInFlight = false
applyToAllInnerStatesMutable { innerState, packetNumberSpace in
let ackElicitingPacketsInFlight = innerState.ackElicitingPacketsInFlight
if ackElicitingPacketsInFlight == 0 {
return
}
hadAckElicitingInFlight = true
connection.log.datapath(
"PTO \(path.recoveryState.PTOCount) (\(packetNumberSpace)) fired on path \(path.identifier) with \(ackElicitingPacketsInFlight) ack-eliciting packets in flight"
)
Expand Down Expand Up @@ -1190,7 +1192,18 @@ struct Recovery: ~Copyable, PrefixedLoggable, NonCopyableTimerUser {
if !sentPTO {
connection.log.datapath("Sending a PING as PTO")
if peerCompletedValidation {
connection.log.fault("PTO fired after validation")
if hadAckElicitingInFlight {

@agnosticdev agnosticdev Jul 31, 2026

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cc @rnro who had a PR in this neck of the woods.

// A PTO fired with ack-eliciting packets still in flight, but the probe could
// not be sent because the retransmit was flow-controlled or otherwise
// unavailable. Under heavy loss this is a legitimate loss-recovery outcome
// rather than an anomaly, so log it at error level instead of faulting. The
// timer is still cleared below so the PTO does not immediately re-arm and spin.
connection.log.error("PTO fired after validation but could not send probe, likely flow-controlled")
} else {
// A PTO fired after validation with nothing ack-eliciting in flight. The PTO
// timer should not have been armed in that state, so log a fault.
connection.log.fault("PTO fired after validation")
}
shouldClearTimer = true
} else {
// Anti deadlock PING frame (i.e PADDED PING). The PING will be padded when we send an initial packet.
Expand Down
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