Method setupServerPool

nats.go:1990–2038

Create the server pool using the options given. We will place a Url option first, followed by any Server Options. We will randomize the server pool unless the NoRandomize flag is set.

()

// Server Options. We will randomize the server pool unless
// the NoRandomize flag is set.
func (nc *Conn) setupServerPool() error {
	nc.srvPool = make([]*Server, 0, srvPoolSize)
	nc.urls = make(map[string]struct{}, srvPoolSize)

	// Create srv objects from each url string in nc.Opts.Servers
	// and add them to the pool.
	for _, urlString := range nc.Opts.Servers {
		if err := nc.addURLToPool(urlString, false, false); err != nil {
			return err
		}
	}

	// Randomize if allowed to
	if !nc.Opts.NoRandomize {
		nc.shufflePool(0)
	}

	// Normally, if this one is set, Options.Servers should not be,
	// but we always allowed that, so continue to do so.
	if nc.Opts.Url != _EMPTY_ {
		// Add to the end of the array
		if err := nc.addURLToPool(nc.Opts.Url, false, false); err != nil {
			return err
		}
		// Then swap it with first to guarantee that Options.Url is tried first.
		last := len(nc.srvPool) - 1
		if last > 0 {
			nc.srvPool[0], nc.srvPool[last] = nc.srvPool[last], nc.srvPool[0]
		}
	} else if len(nc.srvPool) <= 0 {
		// Place default URL if pool is empty.
		if err := nc.addURLToPool(DefaultURL, false, false); err != nil {
			return err
		}
	}

	// Check for Scheme hint to move to TLS mode.
	for _, srv := range nc.srvPool {
		if srv.URL.Scheme == tlsScheme || srv.URL.Scheme == wsSchemeTLS {
			// FIXME(dlc), this is for all in the pool, should be case by case.
			nc.Opts.Secure = true
			if nc.Opts.TLSConfig == nil {
				nc.Opts.TLSConfig = &tls.Config{MinVersion: tls.VersionTLS12}
			}
		}
	}

	return nc.pickServer()
}

// Helper function to return scheme
func (nc *Conn) connScheme() string {