C#•2y ago

Mutex? ASP Core - Only Allowing a Method to Be Run One at a Time

I have a scenario where I want all requests to an endpoint to have the ability to only be run one at a time. This method is asynchronous.

The situation: When a client of ours logs into their dashboard, it shows a "marketing tips" blog section which pulls blog articles from a 3rd party. However, I don't need every request to hit the 3rd party list API for those articles - every client will see the same article.

I want the HTTP request to list and cache those articles to only ever be running one at a time. In essence

If blogs need to be fetched from third party, do not let other processes run this request
Else, let processes run this request as often as they want (it will get the blogs from a local cache in this case)

Will a Mutex work for this case?

nox7OP•4/24/24, 2:16 PM

This is an example of what I am thinking to do for a service method, but am not sure if this is a proper Mutex implementation - because of the asynchronous access to Redis

public async Task GetBlogArticles()
{
    var redis = RedisProvider.GetConnectionNotNull();
    var redisDb = redis.GetDatabase();

    string cacheKey = "client:dashboard:blog-articles";
    var cachedBlogsRedisValue = await redisDb.StringGetAsync(cacheKey);
    if (!cachedBlogsRedisValue.HasValue)
    {
        // Needs to be cached, lock mutex and fetch from API
        FootbridgeBlogFetchMutex.WaitOne();
    }
    else
    {
        // No mutex lock needed, continue
    }
}

public async Task GetBlogArticles()
{
    var redis = RedisProvider.GetConnectionNotNull();
    var redisDb = redis.GetDatabase();

    string cacheKey = "client:dashboard:blog-articles";
    var cachedBlogsRedisValue = await redisDb.StringGetAsync(cacheKey);
    if (!cachedBlogsRedisValue.HasValue)
    {
        // Needs to be cached, lock mutex and fetch from API
        FootbridgeBlogFetchMutex.WaitOne();
    }
    else
    {
        // No mutex lock needed, continue
    }
}

Though, now I am starting to think to just store a Task object as a static method of the service class object and have any future calls await that task if it exists...

public async Task GetBlogArticles() { var redis = RedisProvider.GetConnectionNotNull(); var redisDb = redis.GetDatabase(); string cacheKey = "client:dashboard:blog-articles"; var cachedBlogsRedisValue = await redisDb.StringGetAsync(cacheKey); if (!cachedBlogsRedisValue.HasValue) { // Needs to be cached, lock mutex and fetch from API FootbridgeBlogFetchMutex.WaitOne(); } else { // No mutex lock needed, continue } }

Mutex? ASP Core - Only Allowing a Method to Be Run One at a Time

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