private async Task SyncConfig(CancellationToken cancellationToken)
{
var runningHosts = _balancer.GetConfig().ToDictionary(c => new Uri(c.HostUri), c => c);
var newConfig = _configOptions.CurrentValue;
var newHosts = newConfig.Hosts.ToDictionary(c => new Uri(c.HostUri), c => c);
// TODO optimize alive-ness request
// var consideredAlive = _sessionHandler.GetAliveHosts(DateTimeOffset.Now - TimeSpan.FromSeconds(30));
var hostsStatus = await CheckAliveStatus(from h in newConfig.Hosts select new Uri(h.HostUri));
Predicate <Uri> isAlive = uri =>
hostsStatus.TryGetValue(uri, out var x) && x &&
newHosts.TryGetValue(uri, out var config) && config.Limit > 0;
var toBeRemoved =
(from host in runningHosts.Keys
where !newHosts.ContainsKey(host) || !isAlive(host)
select host).ToArray();
var toBeStarted =
(from host in newHosts.Keys
where (!runningHosts.ContainsKey(host) || !areConfigsEqual(newHosts[host], runningHosts[host])) && isAlive(host)
select host).ToArray();
if (toBeRemoved.Any() || toBeStarted.Any())
{
_logger.LogInformation("Detected changes in configuration or availability of the hosts");
}
await Task.WhenAll(
from host in toBeRemoved
select _balancer.DeleteHost(host)
);
await Task.WhenAll(
from host in toBeStarted
select _balancer.AddHost(newHosts[host])
);
// TODO update status monitor queue
// if (hostsStatus.Any(status => status.Value == false))
// {
// var deadHosts = from h in newConfig.Hosts where !isAlive(h.HostUri) select h.HostUri;
// _logger.LogWarning("Hosts not available: {0}", string.Join(", ", deadHosts.ToArray()));
// }
}