/// <summary>
/// Initializes a new instance of the <see cref="CqlConnection" /> class.
/// </summary>
/// <param name="config"> The config. </param>
public CqlConnection(ClusterConfig config)
{
//add the config to the list, or get an existing instance with the same parameters
ClusterConfig c = Configs.GetOrAdd(config.ToString(), config);
//get the cluster based on the instance
Cluster cluster = Clusters.GetOrAdd(c, conf => new Cluster(conf));
//set the connection provider to the found cluster
_cluster = cluster;
}
/// <summary>
/// Initializes a new instance of the <see cref="CqlConnection" /> class.
/// </summary>
/// <param name="connectionString"> The connection string. </param>
public CqlConnection(string connectionString)
{
//get the cluster config, or add one if none exists
ClusterConfig config = Configs.GetOrAdd(connectionString, connString =>
{
//create new config
var cc = new ClusterConfig(connString);
//get if a similar already exists, or add it otherwise
return(Configs.GetOrAdd(cc.ToString(), cc));
});
//fetch the cluster, or create one
Cluster cluster = Clusters.GetOrAdd(config, conf => new Cluster(conf));
//set the connection provider to the cluster
_cluster = cluster;
}
/// <summary>
/// Opens the cluster for queries. Contains actual implementation and will be called only once per cluster
/// </summary>
/// <returns></returns>
/// <exception cref="CqlException">Cannot construct ring from provided seeds!</exception>
private async Task OpenAsyncInternal(Logger logger)
{
logger.LogInfo("Opening Cluster with parameters: {0}", _config.ToString());
//try to connect to the seeds in turn
foreach (IPAddress seedAddress in _config.NodeAddresses)
{
try
{
var seed = new Node(seedAddress, this);
_nodes = await DiscoverNodesAsync(seed, logger).ConfigureAwait(false);
}
catch (Exception ex)
{
//seed not reachable, try next
logger.LogWarning("Could not discover nodes via seed {0}: {1}", seedAddress, ex);
}
}
if (_nodes == null)
{
var ex = new CqlException("Cannot construct ring from provided seeds!");
logger.LogCritical("Unable to setup Cluster based on given configuration: {0}", ex);
throw ex;
}
logger.LogInfo("Nodes detected: " + string.Join(", ", _nodes.Select(n => n.Address)));
//setup cluster connection strategy
switch (_config.ConnectionStrategy)
{
case ConnectionStrategy.Balanced:
_connectionSelector = new BalancedConnectionStrategy(_nodes, _config);
break;
case ConnectionStrategy.Random:
_connectionSelector = new RandomConnectionStrategy(_nodes, _config);
break;
case ConnectionStrategy.Exclusive:
_connectionSelector = new ExclusiveConnectionStrategy(_nodes, _config);
break;
case ConnectionStrategy.PartitionAware:
_connectionSelector = new PartitionAwareConnectionStrategy(_nodes, _config);
if (_config.DiscoveryScope != DiscoveryScope.Cluster || _config.DiscoveryScope != DiscoveryScope.DataCenter)
{
logger.LogWarning("PartitionAware connection strategy performs best if DiscoveryScope is set to cluster or datacenter");
}
break;
}
//setup throttle
int concurrent = _config.MaxConcurrentQueries <= 0
? _nodes.Count * _config.MaxConnectionsPerNode * 256
: _config.MaxConcurrentQueries;
logger.LogInfo("Cluster is configured to allow {0} parallel queries", concurrent);
_throttle = new SemaphoreSlim(concurrent, concurrent);
//setup prepared query cache
_prepareResultCache = new ConcurrentDictionary <string, ConcurrentDictionary <IPAddress, ResultFrame> >();
//setup maintenance connection
SetupMaintenanceConnection(logger);
}
