在我的應用程序中，我使用的是Enterprise Library Topaz（瞬態故障處理應用程序塊）。我試圖實現SqlConnection.OpenWithRetryAsync。但它不工作。我的意思是，當我放置斷點時，它只會第一次觸及並引發異常。這裏是我已經試過這麼快，以異步方式打開連接時重試策略不起作用？
public static Task OpenWithRetryAsync(this SqlConnection connection, RetryPolicy retryPolicy)
{
return retryPolicy.ExecuteAsync(() =>
{
return connection.OpenAsync();
});
}
只要深入到源，發現我得到一個SQL錯誤，它不是瞬態的。我的錯誤代碼是10065和錯誤是，
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 socket operation was attempted to an unreachable host.)
當我跑了，
public static Task OpenWithRetryAsync(this SqlConnection connection, RetryPolicy retryPolicy)
{
return retryPolicy.ExecuteAsync(async() =>
{
try
{
await connection.OpenAsync();
}
catch(SqlException ex)
{
throw CreateSqlException(10060);// got it form http://blog.gauffin.org/2014/08/how-to-create-a-sqlexception/
}
});
}
然後我重試政策工作就像一個魅力。
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)
{
// 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;
case 0:
if ((err.Class == 20 || err.Class == 11) && err.State == 0 && err.Server != null && ex.InnerException == null)
{
if (string.Equals(err.Message, Resources.SQL_SevereError, StringComparison.CurrentCultureIgnoreCase))
{
return true;
}
}
return false;
// SQL Error Code: 4060
// Cannot open database "%.*ls" requested by the login. The login failed.
case 4060 :
// SQL Error Code: 10928
// Resource ID: %d. The %s limit for the database is %d and has been reached.
case 10928:
// SQL Error Code: 10929
// Resource ID: %d. The %s minimum guarantee is %d, maximum limit is %d and the current usage for the database is %d.
// However, the server is currently too busy to support requests greater than %d for this database.
case 10929:
// 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: 40197
// The service has encountered an error processing your request. Please try again.
case 40197:
// SQL Error Code: 40540
// The service has encountered an error processing your request. Please try again.
case 40540:
// 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
{
EntityException entityException;
if ((entityException = ex as EntityException) != null)
{
return this.IsTransient(entityException.InnerException);
}
}
}
return false;
}
的ADO.NET SqlConnection類帶有一個OpenWithRetry方法
例如：
connection.OpenWithRetry(retryPolicy);
看一看這個網站，我發現，當我看着它變得非常有用已實施重試策略