bschofield commented on pull request #663:
URL: https://github.com/apache/pulsar-client-go/pull/663#issuecomment-963931326
Thanks for taking a look at this, @BewareMyPower and @cckellogg!
> So I think c.Lock() is the same as c.cond.L.Lock().
I'm pretty sure that's not the case. If we take a look at the definition of
the connection type:
```go
type connection struct {
sync.Mutex
cond *sync.Cond
[...]
```
...then we can see that `connection` struct is built out of a `sync.Mutex`
using struct composition. That means that calls to `c.Lock()` are calling the
`sync.Mutex` which is part of the `connection` struct itself.
If we next take a look at the definition of `sync.Cond` we see:
```go
type Cond struct {
noCopy noCopy
// L is held while observing or changing the condition
L Locker
[...]
```
(where `Locker` is go's interface type for a `sync.Mutex`). So these are two
separate locks: they are not the same.
Another way we can convince ourselves of this is by noting that it is
forbidden to copy a `sync.Mutex`, you have to take pointers to it. Since the
struct composition on `connection` does not use a pointer type, there would be
no way to alias the mutex inside `cond` to the mutex on `connection`. They must
be different things.
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