CODEWITHSUNDEEP
asp.netsql-serveriisentity-framework-6database-concurrency
Lionet Chen
Lionet Chen

Reputation: 842

Concurrency control when read/write SQLServer with EF6 from IIS web request

I am writing a ASP.NET ApiController that is hosted on IIS. In an action I need to invoke a Web Service named A provided by a company named Tencent. The service requires that I use a key to authenticate. The key is generate by calling another web interface, named B from Tencent and key is valid for 3 hours. Service B has a limitation on calls per day. Therefore I can't call B whenever I want to use A. I can only call B once and store the key in the database for future use.

That means every time I want to use Service A, I need to check the validation of key from database, and if it's expired, call B and get a new one.

Now, when I need to renew my key by calling B, what if before a new key is returned, the ApiController action is called again? The new request would also find that the key in database is stale, then goes on calling B again, invalidating A's newly gained key, causing A to fetch key again, endless loop.

My questions is, how do you get rid of this kind of worry? How do I start? From SQL or IIS or ASP.NET?

I am reading/writing database with EF6 and using ASP.NET MVC 5.

Thanks for your help!

-- Complement -- I was advised to use lock keyword. However I want to have a peace of mind knowing that lock will safe guard the database read/write piece across all IIS requests. So is there any article about how IIS handles multiple requests to the same ASP.NET module and concurrency control on that?

Upvotes: 2

Views: 164

Answers (1)

Stig
Stig

Reputation: 1299

Use a lock around the code in question. The lock keyword ensures that one thread does not enter a critical section of code while another thread is in the critical section. If another thread tries to enter a locked code, it will wait, block, until the object is released.

See https://msdn.microsoft.com/en-us/library/c5kehkcz.aspx

If it’s in a clustered environment they you will also need to create a transaction at the database level, which will check the last updated/expiry before performing an update.

Upvotes: 1

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