Implementing Double Delete Caching with C#

Question

Problem BackGround

I've read YungPeng's article (A Very Insightful Article) about Consistency between Redis Cache and SQL Database, and the double delete method looks simple enough, so I was considering to move it to our code(C#).

Specifically, I wanted to implement the mutable operation in double delete which can be summarized as follows according to YungPeng:

Delete the entry in Redis;

Create, update or delete the data to MySQL;

Sleep for a while (say 500ms);

Delete the entry in Redis again.

Questions

However, I have two questions about this:

Waiting for the process to sleep 500ms, delete Redis then return to the caller (Step 3,4) seems very slow. Would it be reasonable to queue the task (that sleeps and clears Redis) first then return to caller without waiting for the task to complete?
If my suggestion in question 1 is reasonable, how would I do it in C#? Would the following code be acceptable?

public async Task WriteOperation()
{
  await ClearRedis();
  await WriteDB();
  Task.Run( () => { // Sleep 0.5 seconds then clear Redis } ); // Notice how I didn't await this
  return;
}

Is it really ok to never await the Task? Will it ever be excuted? Would that Task finish roughly around 0.5 seconds?

Thanks in advance!

I just completed a rewrite of a task scheduler answer that might be interesting for you. stackoverflow.com/a/63550072/14072498 — Roar S.
– Roar S., Commented Aug 24, 2020 at 8:13

Roar S. · Accepted Answer · 2020-08-21 10:52:04Z

1

You can do something like this:

public async Task ClearRedisWithDelay()
{
    await Task.Delay(500);
    await ClearRedis();
}

and call

ClearRedisWithDelay

without await.

There are a few downsides with this approach: https://stackoverflow.com/a/54485904/14072498

Your own suggestion from your comment

 Task.Run(async () => { await Task.Delay(500); await ClearRedis(); })

will do the job in a new thread which should be acceptable.

The only guarantee regarding time, is a delay of min. 500 ms before calling ClearRedis.

edited Aug 21, 2020 at 10:52

answered Aug 21, 2020 at 9:43

Roar S.

11.5k1 gold badge21 silver badges55 bronze badges

Sign up to request clarification or add additional context in comments.

3 Comments

blueishpoop Over a year ago

Right, something more like Task.Run(async () => { await Task.Delay(500); await ClearRedis(); }) ? Because I don't want to await this Task to slowdown my code.

Roar S. Over a year ago

That should work, you don't actually need to await ClearRedis(), Resharper gives a warning when skipping await in my code though, so keep it. Doesn't matter, your are in a new thread.

Roar S. Over a year ago

Updated my answer with an alternative to Task.Run

Collectives™ on Stack Overflow

Implementing Double Delete Caching with C#

Problem BackGround

Questions

1 Answer 1

3 Comments

Your Answer

Linked

Hot Network Questions

Collectives™ on Stack Overflow

Problem BackGround

Questions

1 Answer 1

3 Comments

Your Answer

Sign up or log in

Post as a guest

Linked

Related