/// <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.
var throttlingMode = (ThrottlingMode)(reasonCode & 3);
var condition = new ThrottlingCondition {
ThrottlingMode = throttlingMode
};
// Shift 8 bits to truncate throttling mode.
var groupCode = reasonCode >> 8;
// Determine throttling type for all well-known resources that may be subject to throttling
// conditions.
condition._throttledResources.Add(Tuple.Create(
ThrottledResourceType.PhysicalDatabaseSpace,
(ThrottlingType)(groupCode & 3)));
condition._throttledResources.Add(Tuple.Create(
ThrottledResourceType.PhysicalLogSpace,
(ThrottlingType)((groupCode = groupCode >> 2) & 3)));
condition._throttledResources.Add(Tuple.Create(
ThrottledResourceType.LogWriteIoDelay,
(ThrottlingType)((groupCode = groupCode >> 2) & 3)));
condition._throttledResources.Add(Tuple.Create(
ThrottledResourceType.DataReadIoDelay,
(ThrottlingType)((groupCode = groupCode >> 2) & 3)));
condition._throttledResources.Add(Tuple.Create(
ThrottledResourceType.Cpu,
(ThrottlingType)((groupCode = groupCode >> 2) & 3)));
condition._throttledResources.Add(Tuple.Create(
ThrottledResourceType.DatabaseSize,
(ThrottlingType)((groupCode = groupCode >> 2) & 3)));
condition._throttledResources.Add(Tuple.Create(
ThrottledResourceType.Internal,
(ThrottlingType)((groupCode = groupCode >> 2) & 3)));
condition._throttledResources.Add(Tuple.Create(
ThrottledResourceType.WorkerThreads,
(ThrottlingType)((groupCode = groupCode >> 2) & 3)));
condition._throttledResources.Add(Tuple.Create(
ThrottledResourceType.Internal,
(ThrottlingType)((groupCode >> 2) & 3)));
return(condition);
}
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)
{
if (ex != null)
{
SqlException sqlException;
if ((sqlException = ex as SqlException) != null)
{
// Enumerate through all errors found in the exception.
foreach (SqlError err in sqlException.Errors)
{
switch (err.Number)
{
case ThrottlingCondition.ThrottlingErrorNumber:
// SQL Error Code: 40501
// The service is currently busy. Retry the request after 10 seconds. Code:
// (reason code to be decoded). 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);
case 40197:
// SQL Error Code: 40197
// The service has encountered an error processing your request. Please try
// again.
case 10053:
// 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 10054:
// 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 10060:
// 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 40613:
// 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 40143:
// SQL Error Code: 40143
// The service has encountered an error processing your request. Please try
// again.
case 233:
// 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 64:
// 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 (int)ProcessNetLibErrorCode.EncryptionNotSupported:
// DBNETLIB Error Code: 20
// The instance of SQL Server you attempted to connect to does not support
// encryption.
return(true);
}
}
}
else if (ex is TimeoutException)
{
return(true);
}
else
{
EntityException entityException;
if ((entityException = ex as EntityException) != null)
{
return(this.IsTransient(entityException.InnerException));
}
}
}
return(false);
}
