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op-node: Use resubscriber context when watching head #8128

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ajsutton wants to merge 1 commit into from
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op-node: Use resubscriber context when watching head #8128

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5 changes: 4 additions & 1 deletion op-node/node/node.go
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Original file line number Diff line number Diff line change
Expand Up @@ -171,10 +171,13 @@ func (n *OpNode) initL1(ctx context.Context, cfg *Config) error {

// Keep subscribed to the L1 heads, which keeps the L1 maintainer pointing to the best headers to sync
n.l1HeadsSub = event.ResubscribeErr(time.Second*10, func(ctx context.Context, err error) (event.Subscription, error) {
if errors.Is(err, context.Canceled) {
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@Inphi Inphi Nov 10, 2023

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an issue could occur during network reconnects. Not totally sure, but iirc the context will end up being canceled. So the op-node will fail to receive head changes in that event.
Worth confirming this won't occur locally or by adding a test.

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@ajsutton ajsutton Nov 10, 2023

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You appear to be right. What's the point of passing in a context that can't actually be used??? If you don't ignore Canceled errors then it winds up in an infinite loop because Unsubscribe cancels the context which prevents new resubscribe attempts from succeeding and then calls this method again in an infinite loop.

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@Inphi Inphi Nov 14, 2023

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Late response. But the passed in context lets users to prevent a resubscribe based the parent context, like during shutdown. Problem here is both the shutdown signal and other sources of cancelations are observed the same way. eth.WatchHeadChanges already check for both cases. So once we have the deadlock fixes in it should resolve itself.

return nil, err
}
if err != nil {
n.log.Warn("resubscribing after failed L1 subscription", "err", err)
}
return eth.WatchHeadChanges(n.resourcesCtx, n.l1Source, n.OnNewL1Head)
return eth.WatchHeadChanges(ctx, n.l1Source, n.OnNewL1Head)
})
go func() {
err, ok := <-n.l1HeadsSub.Err()
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