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fix(aggregator): guard nil subscription in SubscribeToNewTasksV3 error goroutine #2294

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fix(aggregator): guard nil subscription in SubscribeToNewTasksV3 error goroutine #2294

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23 changes: 21 additions & 2 deletions core/chainio/avs_subscriber.go
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Original file line number Diff line number Diff line change
Expand Up @@ -120,22 +120,31 @@ func (s *AvsSubscriber) SubscribeToNewTasksV3(newTaskCreatedChan chan *servicema
s.logger.Info("Starting error handling goroutine")
var errMain, errFallback error
var auxSub, auxSubFallback event.Subscription

// Guard against nil subscriptions: if a subscription failed on startup,
// replace its Err() channel with a never-sending channel so the select
// below never blocks on a nil interface (which would panic).
subErrCh := nilSafeErrCh(sub)
subFallbackErrCh := nilSafeErrCh(subFallback)

for errMain == nil || errFallback == nil { //while one is active
select {
case err := <-sub.Err():
case err := <-subErrCh:
s.logger.Warn("Error in new task subscription of main connection", "err", err)

auxSub, errMain = SubscribeToNewTasksV3Retryable(&bind.WatchOpts{}, s.AvsContractBindings.ServiceManager, internalChannel, nil, retry.NetworkRetryParams())
if errMain == nil {
sub = auxSub // update the subscription only if it was successful
subErrCh = nilSafeErrCh(sub)
s.logger.Info("Resubscribed to fallback new task subscription")
}
case err := <-subFallback.Err():
case err := <-subFallbackErrCh:
s.logger.Warn("Error in new task subscription of fallback connection", "err", err)

auxSubFallback, errFallback = SubscribeToNewTasksV3Retryable(&bind.WatchOpts{}, s.AvsContractBindings.ServiceManagerFallback, internalChannel, nil, retry.NetworkRetryParams())
if errFallback == nil {
subFallback = auxSubFallback // update the subscription only if it was successful
subFallbackErrCh = nilSafeErrCh(subFallback)
s.logger.Info("Resubscribed to fallback new task subscription")
}
}
Expand Down Expand Up @@ -221,6 +230,16 @@ func (s *AvsSubscriber) getLatestNotRespondedTaskFromEthereumV3() (*servicemanag
return lastLog, nil
}

// nilSafeErrCh returns sub.Err() if sub is non-nil, otherwise a channel that
// never sends. This prevents a nil-interface method call panic in the
// error-handling goroutine when one of the two subscriptions failed on startup.
func nilSafeErrCh(sub event.Subscription) <-chan error {
if sub == nil {
return make(chan error) // never sends; effectively disables this case
}
return sub.Err()
}

func (s *AvsSubscriber) WaitForOneBlock(startBlock uint64) error {
currentBlock, err := s.BlockNumberRetryable(context.Background(), retry.NetworkRetryParams())
if err != nil {
Expand Down