我本人和同事都承担了查找Azure Table Storage连接重试逻辑的任务。经过一番搜索,我发现了这个非常酷的企业库套件,其中包含Microsoft.Practices.TransientFaultHandling
命名空间。
在给出一些代码示例之后,我最终创建了一个Incremental
重试策略,并使用retryPolicy
的ExecuteAction
回调处理程序包装了我们的一个存储调用:
/// <inheritdoc />
public void SaveSetting(int userId, string bookId, string settingId, string itemId, JObject value)
{
// Define your retry strategy: retry 5 times, starting 1 second apart, adding 2 seconds to the interval each retry.
var retryStrategy = new Incremental(5, TimeSpan.FromSeconds(1), TimeSpan.FromSeconds(2));
var storageAccount = CloudStorageAccount.Parse(CloudConfigurationManager.GetSetting(StorageConnectionStringName));
try
{
retryPolicy.ExecuteAction(() =>
{
var tableClient = storageAccount.CreateCloudTableClient();
var table = tableClient.GetTableReference(SettingsTableName);
table.CreateIfNotExists();
var entity = new Models.Azure.Setting
{
PartitionKey = GetPartitionKey(userId, bookId),
RowKey = GetRowKey(settingId, itemId),
UserId = userId,
BookId = bookId.ToLowerInvariant(),
SettingId = settingId.ToLowerInvariant(),
ItemId = itemId.ToLowerInvariant(),
Value = value.ToString(Formatting.None)
};
table.Execute(TableOperation.InsertOrReplace(entity));
});
}
catch (StorageException exception)
{
ExceptionHelpers.CheckForPropertyValueTooLargeMessage(exception);
throw;
}
}
}
感觉很棒,我去看我的同事,他自鸣得意地说,我们可以做同样的事情而不必包含Enterprise Library,因为
CloudTableClient
对象已经具有重试策略的 setter 。他的代码最终看起来像:/// <inheritdoc />
public void SaveSetting(int userId, string bookId, string settingId, string itemId, JObject value)
{
var storageAccount = CloudStorageAccount.Parse(CloudConfigurationManager.GetSetting(StorageConnectionStringName));
var tableClient = storageAccount.CreateCloudTableClient();
// set retry for the connection
tableClient.RetryPolicy = new ExponentialRetry(TimeSpan.FromSeconds(2), 3);
var table = tableClient.GetTableReference(SettingsTableName);
table.CreateIfNotExists();
var entity = new Models.Azure.Setting
{
PartitionKey = GetPartitionKey(userId, bookId),
RowKey = GetRowKey(settingId, itemId),
UserId = userId,
BookId = bookId.ToLowerInvariant(),
SettingId = settingId.ToLowerInvariant(),
ItemId = itemId.ToLowerInvariant(),
Value = value.ToString(Formatting.None)
};
try
{
table.Execute(TableOperation.InsertOrReplace(entity));
}
catch (StorageException exception)
{
ExceptionHelpers.CheckForPropertyValueTooLargeMessage(exception);
throw;
}
}
我的问题:
除了它们的实现之外,这两种方法之间是否还有主要区别?他们俩似乎都实现了相同的目标,但是在某些情况下,最好使用一个而不是另一个吗?
最佳答案
从功能上讲,两者是相同的-如果出现暂时性错误,它们都会重试请求。但是几乎没有区别:
存储客户端库中的
var retryManager = EnterpriseLibraryContainer.Current.GetInstance<RetryManager>();
var retryPolicy = retryManager.GetRetryPolicy<StorageTransientErrorDetectionStrategy>(ConfigurationHelper.ReadFromServiceConfigFile(Constants.DefaultRetryStrategyForTableStorageOperationsKey));
retryPolicy.Retrying += (sender, args) =>
{
// Log details of the retry.
var message = string.Format(CultureInfo.InvariantCulture, TableOperationRetryTraceFormat, "TableStorageHelper::CreateTableIfNotExist", storageAccount.Credentials.AccountName,
tableName, args.CurrentRetryCount, args.Delay);
TraceHelper.TraceError(message, args.LastException);
};
try
{
var isTableCreated = retryPolicy.ExecuteAction(() =>
{
var table = storageAccount.CreateCloudTableClient().GetTableReference(tableName);
return table.CreateIfNotExists(requestOptions, operationContext);
});
return isTableCreated;
}
catch (Exception)
{
throw;
}
在上面的代码示例中,我可以拦截重试操作,并在需要的地方做一些事情。对于存储客户端库,这是不可能的。
综上所述,通常建议使用存储客户端库重试策略来重试存储操作,因为它是软件包不可或缺的一部分,因此将与库的最新更改保持同步。