bschofield edited a comment on pull request #663:
URL: https://github.com/apache/pulsar-client-go/pull/663#issuecomment-963945418
@BewareMyPower:
> However, for the code here, how could you ensure that when `changeState`
is called, the lock has already been acquired in `waitUntilReady`?
That's the point of using the lock: It doesn't matter whether
`changeState()` is called first, or `waitUntilReady()` is called first. Using
the lock prevents the race condition that can occur in the gap between the test
in `for c.getState() != connectionReady` and the call to `c.cond.Wait()`
occurring.
If `changeState` gets called before `waitUntilReady`, then the broadcast
happens first and all is well.
if `waitUntilReady` gets called before `changeState`, then `waitUntilReady`
will block on the `cond.Wait()`, whilst still holding the lock. However,
`cond.Wait()` call has a clever internal release of the lock which I think
should still allow the `changeState` to happen:
```go
func (c *Cond) Wait() {
c.checker.check()
t := runtime_notifyListAdd(&c.notify)
c.L.Unlock()
runtime_notifyListWait(&c.notify, t)
c.L.Lock()
}
```
(note that the `c.L` here is what we are calling `c.cond.L`).
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