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fix(dot/peerset): fix sending on closed channel race condition when dropping peer #2573

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Merged
timwu20 merged 5 commits into from
Jun 10, 2022
Merged

fix(dot/peerset): fix sending on closed channel race condition when dropping peer #2573

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26b1dce
set channel to nil on close, check for nil chan
timwu20 May 31, 2022
14dc1e5
refactor parallel goroutines to single goroutine
timwu20 Jun 1, 2022
dd87ef1
cr feedback
timwu20 Jun 8, 2022
2fb93ba
bump to 45m
timwu20 Jun 10, 2022
6c62a28
bump up integration to 45m
timwu20 Jun 10, 2022
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11 changes: 7 additions & 4 deletions dot/peerset/peerset.go
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Original file line number Diff line number Diff line change
Expand Up @@ -690,10 +690,12 @@ func (ps *PeerSet) disconnect(setIdx int, reason DropReason, peers ...peer.ID) e
return fmt.Errorf("cannot disconnect: %w", err)
}

ps.resultMsgCh <- Message{
Status: Drop,
setID: uint64(setIdx),
PeerID: pid,
if ps.resultMsgCh != nil {
ps.resultMsgCh <- Message{
Status: Drop,
setID: uint64(setIdx),
PeerID: pid,
}

@qdm12 qdm12 May 31, 2022

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Shouldn't the producer close the channel? So somewhere here 🤔

@timwu20 timwu20 Jun 1, 2022

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I think there are problems with the arch of peerset.Handler that we should address at some point.

  • Right now this channel is returned by Handler.Messages(), but it's not a true pipeline. If handler.Messages() was called again and was consumed, then messages would be split among all readers.
  • IMO the producer is peerset.Peerset so the producer is actually closing the channel. Just on another goroutine.

}

// TODO: figure out the condition of connection refuse.
Expand Down Expand Up @@ -765,6 +767,7 @@ func (ps *PeerSet) periodicallyAllocateSlots(ctx context.Context) {
defer func() {
ticker.Stop()
close(ps.resultMsgCh)
ps.resultMsgCh = nil
}()

for {
Expand Down