net: change resolverConfig.dnsConfig to an atomic.Pointer

We were using a RWMutex RLock around a single memory load,
which is not a good use of a RWMutex--it introduces extra work
for the RLock but contention around a single memory load is unlikely.
And, the tryUpdate method was not acquiring the mutex anyhow.

The new atomic.Pointer type is type-safe and easy to use correctly
for a simple use-case like this.

Change-Id: Ib3859c03414c44d2e897f6d15c92c8e4b5c81a11
Reviewed-on: https://go-review.googlesource.com/c/go/+/451416
TryBot-Result: Gopher Robot <gobot@golang.org>
Reviewed-by: Damien Neil <dneil@google.com>
Auto-Submit: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@golang.org>
Reviewed-by: Ian Lance Taylor <iant@google.com>
Run-TryBot: Ian Lance Taylor <iant@google.com>

0 files changed, 0 insertions, 0 deletions