[FIXED] Missing connection status check causing unexpected delay during connection close

[kolomenkin]

It happens when connection close was started and it signaled conditional variable before waiting for the same variable was started in reconnect thread.

The code example to reproduce the problem:

int main()
{
  printf("Begin...\n");
  natsConnection * connection = nullptr;
  natsOptions * options = nullptr;
  constexpr auto onConnectHandler = [](natsConnection *, void *)
  {
  };

  natsOptions_Create(&options);
  natsOptions_SetRetryOnFailedConnect(options, true, onConnectHandler, nullptr);
  natsOptions_SetURL(options, "nats://localhost:54321");

  const auto ts1 = nats_Now();
  const natsStatus err = natsConnection_Connect(&connection, options);
  const auto ts2 = nats_Now();

  if (err == NATS_NOT_YET_CONNECTED || err == NATS_OK)
  {
    natsConnection_Close(connection);
  }
  const auto ts3 = nats_Now();

  printf("connection err code: %s\n", natsStatus_GetText(err));
  printf("Connect took: %lld ms\n", (ts2 - ts1));
  printf("Connection close took: %lld ms\n", (ts3 - ts2));
  return 0;
}

Program output:

Begin...
connection err code: Not Yet Connected
Connect took: 2017 ms
Connection close took: 2057 ms

Here we are connecting to a NATS server which is offline. NATS_NOT_YET_CONNECTED status is returned.
We have 2 seconds before next connection try.
I expect connection to close very fast.
But closing freezes for these 2 seconds.

[kozlovic]

LGTM. Thank you for the contribution. I will add a test after merging this.