/// <summary>
/// Checks if the host is a valid candidate for the purpose of obtaining a connection.
/// This method obtains the <see cref="HostDistance"/> from the load balancing policy.
/// </summary>
/// <param name="host">Host to check.</param>
/// <param name="validHost">Output parameter that will contain the <see cref="ValidHost"/> instance.</param>
/// <returns><code>true</code> if the host is valid and <code>false</code> if not valid
/// (see documentation of <see cref="ValidHost.New"/>)</returns>
private bool TryValidateHost(Host host, out ValidHost validHost)
{
var distance = _session.InternalCluster.RetrieveAndSetDistance(host);
validHost = ValidHost.New(host, distance);
return(validHost != null);
}
/// <summary>
/// Attempts to obtain a connection to the provided <paramref name="validHost"/> and send the request with it.
/// If no connection could be obtained for the provided host, then attempts to obtain a connection
/// for the next host, following the query plan.
/// </summary>
/// <param name="validHost">First host to which the method tries to obtain a connection.</param>
/// <returns></returns>
private async Task SendToNextHostAsync(ValidHost validHost)
{
try
{
IConnection connection = null;
while (connection == null)
{
connection = await _parent.GetConnectionToValidHostAsync(validHost, _triedHosts).ConfigureAwait(false);
if (connection == null)
{
validHost = _parent.GetNextValidHost(_triedHosts);
}
}
_connection = connection;
_host = validHost.Host;
Send(_request, HandleResponse);
}
catch (Exception ex)
{
_host = validHost.Host;
HandleResponse(ex, null);
}
}
/// <summary>
/// Checks if the host is a valid candidate for the purpose of obtaining a connection.
/// This method obtains the <see cref="HostDistance"/> from the load balancing policy.
/// </summary>
/// <param name="host">Host to check.</param>
/// <param name="validHost">Output parameter that will contain the <see cref="ValidHost"/> instance.</param>
/// <returns><code>true</code> if the host is valid and <code>false</code> if not valid
/// (see documentation of <see cref="ValidHost.New"/>)</returns>
private bool TryValidateHost(Host host, out ValidHost validHost)
{
var distance = Cluster.RetrieveDistance(host, RequestOptions.LoadBalancingPolicy);
validHost = ValidHost.New(host, distance);
return(validHost != null);
}
/// <inheritdoc />
public Task <IConnection> GetConnectionToValidHostAsync(ValidHost validHost, IDictionary <IPEndPoint, Exception> triedHosts)
{
return(RequestHandler.GetConnectionFromHostAsync(validHost.Host, validHost.Distance, _session, triedHosts));
}
