/// <summary>
/// Determines the throttling conditions from the specified reason code.
/// </summary>
/// <param name="reasonCode">The reason code returned by SQL Azure which contains the throttling mode and the exceeded resource types.</param>
/// <returns>An instance of the object holding the decoded reason codes returned from SQL Azure when encountering throttling conditions.</returns>
public static ThrottlingCondition FromReasonCode(int reasonCode)
{
if (reasonCode > 0)
{
// Decode throttling mode from the last 2 bits.
ThrottlingMode throttlingMode = (ThrottlingMode)(reasonCode & 3);
var condition = new ThrottlingCondition()
{
ThrottlingMode = throttlingMode
};
// Shift 8 bits to truncate throttling mode.
int groupCode = reasonCode >> 8;
// Determine throttling type for all well-known resources that may be subject to throttling conditions.
condition.throttledResources.Add(Tuple.Create <ThrottledResourceType, ThrottlingType>(ThrottledResourceType.PhysicalDatabaseSpace, (ThrottlingType)(groupCode & 3)));
condition.throttledResources.Add(Tuple.Create <ThrottledResourceType, ThrottlingType>(ThrottledResourceType.PhysicalLogSpace, (ThrottlingType)((groupCode = groupCode >> 2) & 3)));
condition.throttledResources.Add(Tuple.Create <ThrottledResourceType, ThrottlingType>(ThrottledResourceType.LogWriteIODelay, (ThrottlingType)((groupCode = groupCode >> 2) & 3)));
condition.throttledResources.Add(Tuple.Create <ThrottledResourceType, ThrottlingType>(ThrottledResourceType.DataReadIODelay, (ThrottlingType)((groupCode = groupCode >> 2) & 3)));
condition.throttledResources.Add(Tuple.Create <ThrottledResourceType, ThrottlingType>(ThrottledResourceType.CPU, (ThrottlingType)((groupCode = groupCode >> 2) & 3)));
condition.throttledResources.Add(Tuple.Create <ThrottledResourceType, ThrottlingType>(ThrottledResourceType.DatabaseSize, (ThrottlingType)((groupCode = groupCode >> 2) & 3)));
condition.throttledResources.Add(Tuple.Create <ThrottledResourceType, ThrottlingType>(ThrottledResourceType.Internal, (ThrottlingType)((groupCode = groupCode >> 2) & 3)));
condition.throttledResources.Add(Tuple.Create <ThrottledResourceType, ThrottlingType>(ThrottledResourceType.WorkerThreads, (ThrottlingType)((groupCode = groupCode >> 2) & 3)));
condition.throttledResources.Add(Tuple.Create <ThrottledResourceType, ThrottlingType>(ThrottledResourceType.Internal, (ThrottlingType)((groupCode = groupCode >> 2) & 3)));
return(condition);
}
else
{
return(Unknown);
}
}
/// <summary>
/// Determines whether the specified exception represents a transient failure that can be compensated by a retry.
/// </summary>
/// <param name="ex">The exception object to be verified.</param>
/// <returns>True if the specified exception is considered as transient, otherwise false.</returns>
public bool IsTransient(Exception ex)
{
SqlException sqlException = null;
EntityException entityException = null;
if (ex != null)
{
if ((sqlException = ex as SqlException) != null)
{
// Enumerate through all errors found in the exception.
foreach (SqlError err in sqlException.Errors)
{
switch (err.Number)
{
// SQL Error Code: 40501
// The service is currently busy. Retry the request after 10 seconds. Code: (reason code to be decoded).
case ThrottlingCondition.ThrottlingErrorNumber:
// Decode the reason code from the error message to determine the grounds for throttling.
var condition = ThrottlingCondition.FromError(err);
// Attach the decoded values as additional attributes to the original SQL exception.
sqlException.Data[condition.ThrottlingMode.GetType().Name] = condition.ThrottlingMode.ToString();
sqlException.Data[condition.GetType().Name] = condition;
return(true);
// SQL Error Code: 40197
// The service has encountered an error processing your request. Please try again.
case 40197:
// SQL Error Code: 10053
// A transport-level error has occurred when receiving results from the server.
// An established connection was aborted by the software in your host machine.
case 10053:
// SQL Error Code: 10054
// A transport-level error has occurred when sending the request to the server.
// (provider: TCP Provider, error: 0 - An existing connection was forcibly closed by the remote host.)
case 10054:
// SQL Error Code: 10060
// A network-related or instance-specific error occurred while establishing a connection to SQL Server.
// The server was not found or was not accessible. Verify that the instance name is correct and that SQL Server
// is configured to allow remote connections. (provider: TCP Provider, error: 0 - A connection attempt failed
// because the connected party did not properly respond after a period of time, or established connection failed
// because connected host has failed to respond.)"}
case 10060:
// SQL Error Code: 40613
// Database XXXX on server YYYY is not currently available. Please retry the connection later. If the problem persists, contact customer
// support, and provide them the session tracing ID of ZZZZZ.
case 40613:
// SQL Error Code: 40143
// The service has encountered an error processing your request. Please try again.
case 40143:
// SQL Error Code: 233
// The client was unable to establish a connection because of an error during connection initialization process before login.
// Possible causes include the following: the client tried to connect to an unsupported version of SQL Server; the server was too busy
// to accept new connections; or there was a resource limitation (insufficient memory or maximum allowed connections) on the server.
// (provider: TCP Provider, error: 0 - An existing connection was forcibly closed by the remote host.)
case 233:
// SQL Error Code: 64
// A connection was successfully established with the server, but then an error occurred during the login process.
// (provider: TCP Provider, error: 0 - The specified network name is no longer available.)
case 64:
// DBNETLIB Error Code: 20
// The instance of SQL Server you attempted to connect to does not support encryption.
case (int)ProcessNetLibErrorCode.EncryptionNotSupported:
return(true);
}
}
}
else if (ex is TimeoutException)
{
return(true);
}
else if ((entityException = ex as EntityException) != null)
{
return(IsTransient(entityException.InnerException));
}
}
return(false);
}