Question

我尝试使用Microsoft.WindowsAzure.StorageClient.RetryPolicy;无需连接到Azure服务

var _retry = RetryPolicyFactory.GetRetryPolicy<StorageTransientErrorDetectionStrategy>("Incremental Retry Strategy");
  var result = _retry.ExecuteAction(()=> InnerRequest(data));

问题是 - InnerRequest方法应该做什么让RetryPolicy开始工作？它应该抛出某种指定的异常吗？

Answer 1

Microsoft.Practices.EnterpriseLibrary.WindowsAzure.TransientFaultHandling 程序集中提供的错误检测策略（如代码段中的 StorageTransientErrorDetectionStrategy ）会自动检测到瞬态错误，并且这将触发重试政策。

实际上，这取决于您在 Microsoft.Practices.TransientFaultHandling.Core 程序集中可以找到的内容。 Azure特定程序集中的每个错误检测策略都实现以下接口：

/// <summary>
/// Defines an interface which must be implemented by custom components responsible for detecting specific transient conditions.
/// </summary>
public interface ITransientErrorDetectionStrategy
{
    /// <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>
    bool IsTransient(Exception ex);
}

以下是您使用的 StorageTransientErrorDetectionStrategy 的示例：

WebException webException = ex as WebException;
if (webException != null && (webException.Status == WebExceptionStatus.ProtocolError || webException.Status == WebExceptionStatus.ConnectionClosed))
{
    return true;
}
DataServiceRequestException dataServiceException = ex as DataServiceRequestException;
if (dataServiceException != null && StorageTransientErrorDetectionStrategy.IsErrorStringMatch(StorageTransientErrorDetectionStrategy.GetErrorCode(dataServiceException), new string[]
{
    "InternalError", 
    "ServerBusy", 
    "OperationTimedOut", 
    "TableServerOutOfMemory"
}))
{
    return true;
}
StorageServerException serverException = ex as StorageServerException;
if (serverException != null)
{
    if (StorageTransientErrorDetectionStrategy.IsErrorCodeMatch(serverException, new StorageErrorCode[]
    {
        1, 
        2
    }))
    {
        return true;
    }
    if (StorageTransientErrorDetectionStrategy.IsErrorStringMatch(serverException, new string[]
    {
        "InternalError", 
        "ServerBusy", 
        "OperationTimedOut"
    }))
    {
        return true;
    }
}
StorageClientException storageException = ex as StorageClientException;
return (storageException != null && StorageTransientErrorDetectionStrategy.IsErrorStringMatch(storageException, new string[]
{
    "InternalError", 
    "ServerBusy", 
    "TableServerOutOfMemory"
})) || ex is TimeoutException;

P＆amp; P RetryPolicy，什么是瞬态异常

1 个答案: