private bool ReadNotifyMessages(SqlConnection connection)
{
var identifiers = new EventMessageIdentifiers();
var eventFilter = GetEventFilter();
if (eventFilter == null)
{
GetMessageIdentifiers(connection, identifiers);
}
else
{
GetMessageIdentifiers(connection, identifiers, eventFilter);
}
// Unlike reading entire messages this method always reads all the identifiers, so we don't
// need to wait until the next read to tell the client that all messages have been read.
if (identifiers.Count > 0)
{
HandleEventMessages(identifiers);
_raiseExistingRead = true;
}
if (_raiseExistingRead)
{
_raiseExistingRead = false;
OnExistingMessagesRead(System.EventArgs.Empty);
}
return(false);
}
private void GetMessageIdentifiers(SqlConnection connection, EventMessageIdentifiers identifiers, Filter eventFilter)
{
using (var command = new SqlCommand(Sql.GetMessageIdentifierRangeFilter, connection))
{
command.CommandType = CommandType.StoredProcedure;
// The stored procedure takes a time (in ticks) as parameter instead of message ID, because
// messages in the database are not necessarily ordered by ID.
command.Parameters.Add("@fromTime", SqlDbType.BigInt).Value = _lastReadMessageTime;
command.Parameters.Add("@eventFilter", SqlDbType.VarChar).Value = SqlUtil.RegexToSqlLike(eventFilter.Pattern.Value);
using (SqlDataReader reader = command.ExecuteReader())
{
while (reader.Read())
{
_lastReadMessageTime = reader.GetInt64(1);
int id = reader.GetInt32(0);
EventMessageIdentifier identifier = new SqlEventMessageIdentifier(id, _lastReadMessageTime);
identifiers.Add(identifier);
}
}
}
}
protected void HandleEventMessages(EventMessageIdentifiers identifiers)
{
_messageNotifyHandler.HandleEventMessages(identifiers);
}
