cmd/faucet: fix websocket race regression after switching to gorilla #22136
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holiman
reviewed
Jan 7, 2021
| timeouts map[string]time.Time // History of users and their funding timeouts | ||
| reqs []*request // Currently pending funding requests | ||
| update chan struct{} // Channel to signal request updates | ||
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| lock sync.RWMutex // Lock protecting the faucet's internals | ||
| } | ||
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| // wsConn wraps a websocket connection with a write mutex as the underlying | ||
| // websocket library does not synchronize access to the stream. | ||
| type wsConn struct { |
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We have a similar construct here: https://github.com/ethereum/go-ethereum/blob/master/ethstats/ethstats.go#L100 -- used for ethstats reporting. Would it make sense to use the same?
The other one as a separate lock for reading -- isnt' that needed in this case?
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Not sure it's worth it.
- The duplicated code is a couple lines
- Exposing it in ethstats seems wrong, we'd need to move it into some common package,
- Ethstats wraps the write directly, but we need setdeadline too wrapped together, so we'd need lower level access.
- We only read in a dedicated goroutine here, so no need for read locking (though I think it's the same in ethstats).
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About a year ago we switched over the websocket library in the faucet from Go's implementation to the Gorilla library. Unfortunately the former was thread safe whilst the latter was not, and we didn't update the faucet code to add mutexes. This was undetected for quite a long time since our faucet auto-restarts, so an occasional crash was just silently ignored.
Fixes