Linq-to-Sql 读取-测试-写入作为一项操作
我有 Tasks 表：Id (PK)、TaskName、Status
状态为以下之一：已排队、忙碌、完成。
我想使用多个线程来处理任务，为此我需要能够在一个操作中完成：
var task = db.Tasks.FirstOrDefault(t=>t.Status == (byte) TaskStatus.Queued);
task.Status = (byte) TaskStatus.Busy;
db.SubmitChanges();
显然，如果操作不是原子的，我可能会遇到并发问题。使用 Linq-to-Sql 执行上述操作的预期方法是什么（如果存在）？
我知道我可以用 1) storproc 或 2) db.ExecuteCommand("...") 或 3) 处理冲突 with try/catch - 但我想确定没有更好的方法。
我知道这是一个非常基本的问题，但我无法找到明确的答案。
I have Tasks table: Id (PK), TaskName, Status
Status is one of: Queued, Busy, Complete.
I want to use multiple threads to process the tasks, and for that I need to be able to do in one operation:
var task = db.Tasks.FirstOrDefault(t=>t.Status == (byte) TaskStatus.Queued);
task.Status = (byte) TaskStatus.Busy;
db.SubmitChanges();
Obviously if operation is not atomic I can get concurrency issues. What is (if one exists) an intended way to do the above using Linq-to-Sql?
I know I can do that with 1) storproc or 2) db.ExecuteCommand("...") or 3) handle the conflict with try/catch - but I want to be sure there is no a better way.
I know it is a very basic question, but I wasn't able to find a definite answer to this.
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如果您想确保这在数据库中以原子方式发生（无论哪个线程或应用程序调用它），您可能应该在存储过程中执行此操作并在适当的级别锁定。存储过程应该检索并更新记录，然后释放并返回它（确认！我不是指 TSQL
return语句，但你知道我的意思是select它，我信任！）因此，L2S 只需调用存储过程并返回一个要处理的任务，该任务已设置为“Busy”。 L2S 既不知道（也不关心）锁定什么/如何锁定 - 因此不会使问题复杂化并带来更多死锁的机会。
If you are wanting to be sure that this is happening atomically in the database (regardless of what thread or application is calling it), you probably should do it in a sproc and lock at an appropriate level there. The sproc should retrieve and update the record, then release and return it (Ack! I don't mean the TSQL
returnstatement, but you know I meanselectit, I trust!)So L2S just calls the sproc and gets back a task to work on, already set as
Busy. L2S neither knows (nor cares) what/how things were locked - and therefore can not complicate matters and introduce more chances for deadlocks.