/// <summary>
/// Create an exponential backoff retry policy given a detection strategy.
/// </summary>
/// <param name="strategy"></param>
/// <returns></returns>
private static RetryPolicy Exponential(ITransientErrorDetectionStrategy strategy, int retryCount)
{
if (retryCount == 0)
return RetryPolicy.NoRetry;
if (retryCount == 1)
{
var retryPolicy = new RetryPolicy(strategy, 1);
retryPolicy.RetryStrategy.FastFirstRetry = true;
return retryPolicy;
}
var minBackoff = TimeSpan.FromSeconds(1);
var maxBackoff = TimeSpan.FromSeconds(10);
var deltaBackoff = TimeSpan.FromSeconds(5);
// if retryCount is equal to Int16.MaxValue (32767)
// then increase the backoff intervals.
if (retryCount == Int16.MaxValue)
{
minBackoff = TimeSpan.FromSeconds(1);
maxBackoff = TimeSpan.FromSeconds(300);
deltaBackoff = TimeSpan.FromSeconds(10);
}
// 30 60 120 240
var exponentialBackoff = new ExponentialBackoff(retryCount, minBackoff, maxBackoff, deltaBackoff);
return new RetryPolicy(strategy, exponentialBackoff);
}
private static RetryPolicy Exponential(ITransientErrorDetectionStrategy strategy)
{
var retryCount = 3;
var minBackoff = TimeSpan.FromSeconds(1);
var maxBackoff = TimeSpan.FromSeconds(10);
var deltaBackoff = TimeSpan.FromSeconds(5);
var exponentialBackoff = new ExponentialBackoff(retryCount, minBackoff, maxBackoff, deltaBackoff);
return new RetryPolicy(strategy, exponentialBackoff);
}
private void InitializeBackoffStrategy()
{
// Create Backoff Strategy
_backoffStrategy = new ExponentialBackoff(
"exponentialBackoffStrategy",
Convert.ToInt32(ConfigurationManager.AppSettings["TransientFaultHandlingRetryCount"].Trim()),
TimeSpan.FromSeconds(Convert.ToInt32(ConfigurationManager.AppSettings["TransientFaultHandlingMinBackoffDelaySeconds"].Trim())),
TimeSpan.FromSeconds(Convert.ToInt32(ConfigurationManager.AppSettings["TransientFaultHandlingMaxBackoffDelaySeconds"].Trim())),
TimeSpan.FromSeconds(Convert.ToInt32(ConfigurationManager.AppSettings["TransientFaultHandlingDeltaBackoffSeconds"].Trim())));
// Set default retry manager
RetryManager.SetDefault(new RetryManager(new List<RetryStrategy> { _backoffStrategy }, "exponentialBackoffStrategy"));
}
private static RetryPolicy Exponential(ITransientErrorDetectionStrategy stgy,
int retryCount,
double maxBackoffDelayInSeconds,
double delta)
{
var maxBackoff = TimeSpan.FromSeconds(maxBackoffDelayInSeconds);
var deltaBackoff = TimeSpan.FromSeconds(delta);
var minBackoff = TimeSpan.FromSeconds(0);
var exponentialBackoff = new ExponentialBackoff(retryCount,
minBackoff,
maxBackoff,
deltaBackoff);
return new RetryPolicy(stgy, exponentialBackoff);
}
/// <summary>
/// Initialize the Sql Azure settings and connections
/// </summary>
public void InitializeSqlAzure()
{
this.SqlConnectionString = ConfigurationManager.AppSettings["SqlAzureConnectionString"];
if(String.IsNullOrWhiteSpace(this.SqlConnectionString))
{
throw new ArgumentException("A required AppSetting cannot be null or empty", "SqlAzureConnectionString");
}
this.SqlTableName = ConfigurationManager.AppSettings["SqlAzureTableName"];
if (String.IsNullOrWhiteSpace(this.SqlTableName))
{
throw new ArgumentException("A required AppSetting cannot be null or empty", "SqlAzureTableName");
}
var columns = ConfigurationManager.AppSettings["SqlAzureTableColumns"];
if (String.IsNullOrWhiteSpace(columns))
{
throw new ArgumentException("A required AppSetting cannot be null or empty", "SqlAzureTableColumns");
}
this.SqlTableColumns = columns.Split(new char[] { ',', ';' }, StringSplitOptions.RemoveEmptyEntries).Select(c => c.Trim()).ToList();
//Reference: https://msdn.microsoft.com/en-us/library/azure/dn864744.aspx
//1. Define an Exponential Backoff retry strategy for Azure SQL Database throttling (ExponentialBackoff Class). An exponential back-off strategy will gracefully back off the load on the service.
int retryCount = 4;
int minBackoffDelayMilliseconds = 2000;
int maxBackoffDelayMilliseconds = 8000;
int deltaBackoffMilliseconds = 2000;
ExponentialBackoff exponentialBackoffStrategy =
new ExponentialBackoff("exponentialBackoffStrategy",
retryCount,
TimeSpan.FromMilliseconds(minBackoffDelayMilliseconds),
TimeSpan.FromMilliseconds(maxBackoffDelayMilliseconds),
TimeSpan.FromMilliseconds(deltaBackoffMilliseconds));
//2. Set a default strategy to Exponential Backoff.
RetryManager manager = new RetryManager(
new List<RetryStrategy>
{
exponentialBackoffStrategy
},
"exponentialBackoffStrategy");
//3. Set a default Retry Manager. A RetryManager provides retry functionality, or if you are using declarative configuration, you can invoke the RetryPolicyFactory.CreateDefault
RetryManager.SetDefault(manager);
//4. Define a default SQL Connection retry policy and SQL Command retry policy. A policy provides a retry mechanism for unreliable actions and transient conditions.
ConnectionRetryPolicy = manager.GetDefaultSqlConnectionRetryPolicy();
CommandRetryPolicy = manager.GetDefaultSqlCommandRetryPolicy();
//5. Create a function that will retry the connection using a ReliableSqlConnection.
InitializeSqlAzureConnection();
}
private static RetryPolicy Exponential(
ITransientErrorDetectionStrategy strategy,
int retryCount = 3,
double maxBackoffDelayInSeconds = 1024,
double delta = 2)
{
var exponentialBackoff = new ExponentialBackoff(retryCount,
TimeSpan.FromSeconds(0),
TimeSpan.FromSeconds(maxBackoffDelayInSeconds),
TimeSpan.FromSeconds(delta));
return new RetryPolicy(strategy,
exponentialBackoff);
}
