private async Task PrepareOnTheRestOfTheNodes(PrepareRequest request, IInternalSession session)
{
Host host;
HostDistance distance;
var lbp = session.Cluster.Configuration.Policies.LoadBalancingPolicy;
var tasks = new List <Task>();
var triedHosts = new Dictionary <IPEndPoint, Exception>();
while ((host = GetNextHost(lbp, out distance)) != null)
{
var connection = await RequestHandler
.GetConnectionFromHostAsync(host, distance, session, triedHosts).ConfigureAwait(false);
if (connection == null)
{
continue;
}
// For each valid connection, send a the request in parallel
tasks.Add(connection.Send(request));
}
try
{
await Task.WhenAll(tasks).ConfigureAwait(false);
}
catch
{
// Don't consider individual failures
}
}
/// <summary>
/// Executes the prepare request on the first host selected by the load balancing policy.
/// When <see cref="QueryOptions.IsPrepareOnAllHosts"/> is enabled, it prepares on the rest of the hosts in
/// parallel.
/// </summary>
internal static async Task <PreparedStatement> Prepare(IInternalSession session, Serializer serializer,
PrepareRequest request)
{
var cluster = session.InternalCluster;
var lbp = cluster.Configuration.Policies.LoadBalancingPolicy;
var handler = new PrepareHandler(serializer, lbp.NewQueryPlan(session.Keyspace, null).GetEnumerator());
var ps = await handler.Prepare(request, session, null).ConfigureAwait(false);
var psAdded = cluster.PreparedQueries.GetOrAdd(ps.Id, ps);
if (ps != psAdded)
{
Logger.Warning("Re-preparing already prepared query is generally an anti-pattern and will likely " +
"affect performance. Consider preparing the statement only once. Query='{0}'", ps.Cql);
ps = psAdded;
}
var prepareOnAllHosts = cluster.Configuration.QueryOptions.IsPrepareOnAllHosts();
if (!prepareOnAllHosts)
{
return(ps);
}
await handler.PrepareOnTheRestOfTheNodes(request, session).ConfigureAwait(false);
return(ps);
}
private async Task <PreparedStatement> GetPreparedStatement(
Response response, PrepareRequest request, string keyspace, ICluster cluster)
{
if (response == null)
{
throw new DriverInternalError("Response can not be null");
}
var resultResponse = response as ResultResponse;
if (resultResponse == null)
{
throw new DriverInternalError("Excepted ResultResponse, obtained " + response.GetType().FullName);
}
var output = resultResponse.Output;
if (!(output is OutputPrepared))
{
throw new DriverInternalError("Expected prepared response, obtained " + output.GetType().FullName);
}
var prepared = (OutputPrepared)output;
var ps = new PreparedStatement(prepared.Metadata, prepared.QueryId, prepared.ResultMetadataId,
request.Query, keyspace, _serializer)
{
IncomingPayload = resultResponse.CustomPayload
};
await FillRoutingInfo(ps, cluster).ConfigureAwait(false);
return(ps);
}
private async Task <PreparedStatement> Prepare(PrepareRequest request, IInternalSession session,
Dictionary <IPEndPoint, Exception> triedHosts)
{
if (triedHosts == null)
{
triedHosts = new Dictionary <IPEndPoint, Exception>();
}
// It may throw a NoHostAvailableException which we should yield to the caller
var connection = await GetNextConnection(session, triedHosts)
.ConfigureAwait(false);
Response response;
try
{
response = await connection.Send(request).ConfigureAwait(false);
}
catch (Exception ex) when(CanBeRetried(ex))
{
triedHosts[connection.Address] = ex;
return(await Prepare(request, session, triedHosts).ConfigureAwait(false));
}
return(await GetPreparedStatement(response, request, connection.Keyspace, session.Cluster)
.ConfigureAwait(false));
}
internal static async Task PrepareAllQueries(Host host, ICollection <PreparedStatement> preparedQueries,
IEnumerable <IInternalSession> sessions)
{
if (preparedQueries.Count == 0)
{
return;
}
// Get the first connection for that host, in any of the existings connection pool
var connection = sessions.SelectMany(s => s.GetExistingPool(host.Address)?.ConnectionsSnapshot)
.FirstOrDefault();
if (connection == null)
{
Logger.Info($"Could not re-prepare queries on {host.Address} as there wasn't an open connection to" +
" the node");
return;
}
Logger.Info($"Re-preparing {preparedQueries.Count} queries on {host.Address}");
var tasks = new List <Task>(preparedQueries.Count);
using (var semaphore = new SemaphoreSlim(64, 64))
{
foreach (var query in preparedQueries.Select(ps => ps.Cql))
{
var request = new PrepareRequest(query);
await semaphore.WaitAsync().ConfigureAwait(false);
async Task SendSingle()
{
try
{
await connection.Send(request).ConfigureAwait(false);
}
finally
{
// ReSharper disable once AccessToDisposedClosure
// There is no risk of being disposed as the list of tasks is awaited upon below
semaphore.Release();
}
}
tasks.Add(Task.Run(SendSingle));
}
try
{
await Task.WhenAll(tasks).ConfigureAwait(false);
}
catch (Exception ex)
{
Logger.Error($"There was an error when re-preparing queries on {host.Address}", ex);
}
}
}
public async Task <PreparedStatement> Prepare(
PrepareRequest request, IInternalSession session, IEnumerator <Host> queryPlan)
{
var prepareResult = await SendRequestToOneNode(session, queryPlan, request).ConfigureAwait(false);
if (session.Cluster.Configuration.QueryOptions.IsPrepareOnAllHosts())
{
await _reprepareHandler.ReprepareOnAllNodesWithExistingConnections(session, request, prepareResult).ConfigureAwait(false);
}
return(prepareResult.PreparedStatement);
}
/// <inheritdoc />
public async Task ReprepareOnAllNodesWithExistingConnections(
IInternalSession session, PrepareRequest request, PrepareResult prepareResult)
{
var pools = session.GetPools();
var hosts = session.InternalCluster.AllHosts();
var poolsByHosts = pools.Join(
hosts, po => po.Key,
h => h.Address,
(pair, host) => new { host, pair.Value }).ToDictionary(k => k.host, k => k.Value);
if (poolsByHosts.Count == 0)
{
PrepareHandler.Logger.Warning("Could not prepare query on all hosts because there are no connection pools.");
return;
}
using (var semaphore = new SemaphoreSlim(64, 64))
{
var tasks = new List <Task>(poolsByHosts.Count);
foreach (var poolKvp in poolsByHosts)
{
if (poolKvp.Key.Address.Equals(prepareResult.HostAddress))
{
continue;
}
if (prepareResult.TriedHosts.ContainsKey(poolKvp.Key.Address))
{
PrepareHandler.Logger.Warning(
$"An error occured while attempting to prepare query on {{0}}:{Environment.NewLine}{{1}}",
poolKvp.Key.Address,
prepareResult.TriedHosts[poolKvp.Key.Address]);
continue;
}
await semaphore.WaitAsync().ConfigureAwait(false);
tasks.Add(ReprepareOnSingleNodeAsync(poolKvp, prepareResult.PreparedStatement, request, semaphore, false));
}
await Task.WhenAll(tasks).ConfigureAwait(false);
}
}
/// <summary>
/// Sends a prepare request before retrying the statement
/// </summary>
private void PrepareAndRetry(PreparedQueryNotFoundException ex, Host host)
{
BoundStatement boundStatement = null;
if (_parent.Statement is BoundStatement statement1)
{
boundStatement = statement1;
}
else if (_parent.Statement is BatchStatement batch)
{
bool SearchBoundStatement(Statement s) =>
s is BoundStatement statement && statement.PreparedStatement.Id.SequenceEqual(ex.UnknownId);
boundStatement = (BoundStatement)batch.Queries.FirstOrDefault(SearchBoundStatement);
}
if (boundStatement == null)
{
throw new DriverInternalError("Expected Bound or batch statement");
}
var preparedKeyspace = boundStatement.PreparedStatement.Keyspace;
var request = new PrepareRequest(_parent.Serializer, boundStatement.PreparedStatement.Cql, preparedKeyspace, null);
if (!_parent.Serializer.ProtocolVersion.SupportsKeyspaceInRequest() &&
preparedKeyspace != null && _session.Keyspace != preparedKeyspace)
{
Logger.Warning(string.Format("The statement was prepared using another keyspace, changing the keyspace temporarily to" +
" {0} and back to {1}. Use keyspace and table identifiers in your queries and avoid switching keyspaces.",
preparedKeyspace, _session.Keyspace));
_connection
.SetKeyspace(preparedKeyspace)
.ContinueSync(_ =>
{
Send(request, host, NewReprepareResponseHandler(ex));
return(true);
});
return;
}
Send(request, host, NewReprepareResponseHandler(ex));
}
/// <summary>
/// Sends a prepare request before retrying the statement
/// </summary>
private void PrepareAndRetry(byte[] id)
{
Logger.Info(String.Format("Query {0} is not prepared on {1}, preparing before retrying executing.", BitConverter.ToString(id), _connection.Address));
BoundStatement boundStatement = null;
if (_parent.Statement is BoundStatement)
{
boundStatement = (BoundStatement)_parent.Statement;
}
else if (_parent.Statement is BatchStatement)
{
var batch = (BatchStatement)_parent.Statement;
bool SearchBoundStatement(Statement s) =>
s is BoundStatement && ((BoundStatement)s).PreparedStatement.Id.SequenceEqual(id);
boundStatement = (BoundStatement)batch.Queries.FirstOrDefault(SearchBoundStatement);
}
if (boundStatement == null)
{
throw new DriverInternalError("Expected Bound or batch statement");
}
var request = new PrepareRequest(boundStatement.PreparedStatement.Cql);
if (boundStatement.PreparedStatement.Keyspace != null && _session.Keyspace != boundStatement.PreparedStatement.Keyspace)
{
Logger.Warning(String.Format("The statement was prepared using another keyspace, changing the keyspace temporarily to" +
" {0} and back to {1}. Use keyspace and table identifiers in your queries and avoid switching keyspaces.",
boundStatement.PreparedStatement.Keyspace, _session.Keyspace));
_connection
.SetKeyspace(boundStatement.PreparedStatement.Keyspace)
.ContinueSync(_ =>
{
Send(request, ReprepareResponseHandler);
return(true);
});
return;
}
Send(request, ReprepareResponseHandler);
}
private async Task <PrepareResult> SendRequestToOneNode(IInternalSession session, IEnumerator <Host> queryPlan, PrepareRequest request)
{
var triedHosts = new Dictionary <IPEndPoint, Exception>();
while (true)
{
// It may throw a NoHostAvailableException which we should yield to the caller
var hostConnectionTuple = await GetNextConnection(session, queryPlan, triedHosts).ConfigureAwait(false);
var connection = hostConnectionTuple.Item2;
var host = hostConnectionTuple.Item1;
try
{
var result = await connection.Send(request).ConfigureAwait(false);
return(new PrepareResult
{
PreparedStatement = await GetPreparedStatement(result, request, request.Keyspace ?? connection.Keyspace, session.Cluster).ConfigureAwait(false),
TriedHosts = triedHosts,
HostAddress = host.Address
});
}
catch (Exception ex) when(PrepareHandler.CanBeRetried(ex))
{
triedHosts[host.Address] = ex;
}
}
}
