我正在构建一个 T4 模板,以帮助人们以一致且简单的方式构建 Azure 队列。我希望使其自我记录,并有一定的一致性。
首先,我将队列名称放在文件顶部,队列名称必须为小写,因此我添加了 ToLower()。
公共构造函数使用内置的 StorageClient API 访问连接字符串。我已经看到许多不同的方法,希望得到几乎适用于所有情况的解决方案。(有想法吗?请分享)
我不喜欢不必要的 HTTP 请求来检查队列是否已创建,因此我将其设置为 static bool。我没有实现 Lock(monitorObject),因为我认为这是不需要的。
与大多数 MSDN 文档使用字符串并使用逗号进行解析不同,我在将对象传递到队列时对其进行序列化。
为进一步优化,我使用JSON 序列化器扩展方法以充分利用 8k 的限制。不确定编码是否会进一步优化此过程
添加重试逻辑以处理队列出现的某些情况(请参见 HTML 链接)
Q:DataContext 是否是此类的适当名称?
Q:按我所做的方式命名队列操作名称是否是不良实践?
您认为我应该进行哪些其他更改?
public class AgentQueueDataContext
{
// Queue names must always be in lowercase
// Is named like a const, but isn't one because .ToLower won't compile...
static string AGENT_QUEUE_ACTION_NAME = "AgentQueueActions".ToLower();
static bool QueuesWereCreated { get; set; }
DataModel.SecretDataSource secDataSource = null;
CloudStorageAccount cloudStorageAccount = null;
CloudQueueClient cloudQueueClient = null;
CloudQueue queueAgentQueueActions = null;
static AgentQueueDataContext()
{
QueuesWereCreated = false;
}
public AgentQueueDataContext() : this(false)
{
}
public AgentQueueDataContext(bool CreateQueues)
{
// This pattern of setting up queues is from:
// ttp://convective.wordpress.com/2009/11/15/queues-azure-storage-client-v1-0/
//
this.cloudStorageAccount = CloudStorageAccount.FromConfigurationSetting("DataConnectionString");
this.cloudQueueClient = cloudStorageAccount.CreateCloudQueueClient();
this.secDataSource = new DataModel.SecretDataSource();
queueAgentQueueActions = cloudQueueClient.GetQueueReference(AGENT_QUEUE_ACTION_NAME);
if (QueuesWereCreated == false || CreateQueues)
{
queueAgentQueueActions.CreateIfNotExist();
QueuesWereCreated = true;
}
}
// This is the method that will be spawned using ThreadStart
public void CheckQueue()
{
while (true)
{
try
{
CloudQueueMessage msg = queueAgentQueueActions.GetMessage();
bool DoRetryDelayLogic = false;
if (msg != null)
{
// Deserialize using JSON (allows more data to be stored)
AgentQueueEntry actionableMessage = msg.AsString.FromJSONString<AgentQueueEntry>();
switch (actionableMessage.ActionType)
{
case AgentQueueActionEnum.EnrollNew:
{
// Add to
break;
}
case AgentQueueActionEnum.LinkToSite:
{
// Link within Agent itself
// Link within Site
break;
}
case AgentQueueActionEnum.DisableKey:
{
// Disable key in site
// Disable key in AgentTable (update modification time)
break;
}
default:
{
break;
}
}
//
// Only delete the message if the requested agent has been missing for
// at least 10 minutes
//
if (DoRetryDelayLogic)
{
if (msg.InsertionTime != null)
if (msg.InsertionTime < DateTime.UtcNow + new TimeSpan(0, 10, 10))
continue;
// ToDo: Log error: AgentID xxx has not been found in table for xxx minutes.
// It is likely the result of a the registratoin host crashing.
// Data is still consistent. Deleting queued message.
}
//
// If execution made it to this point, then we are either fully processed, or
// there is sufficent reason to discard the message.
//
try
{
queueAgentQueueActions.DeleteMessage(msg);
}
catch (StorageClientException ex)
{
// As of July 2010, this is the best way to detect this class of exception
// Description: ttp://blog.smarx.com/posts/deleting-windows-azure-queue-messages-handling-exceptions
if (ex.ExtendedErrorInformation.ErrorCode == "MessageNotFound")
{
// pop receipt must be invalid
// ignore or log (so we can tune the visibility timeout)
}
else
{
// not the error we were expecting
throw;
}
}
}
else
{
// allow control to fall to the bottom, where the sleep timer is...
}
}
catch (Exception e)
{
// Justification: Thread must not fail.
//Todo: Log this exception
// allow control to fall to the bottom, where the sleep timer is...
// Rationale: not doing so may cause queue thrashing on a specific corrupt entry
}
// todo: Thread.Sleep() is bad
// Replace with something better...
Thread.Sleep(9000);
}