Thread safety in OptionsManager

[fedotovalex]

In the current implementation of OptionsManager, if I do something like this:

public void ConfigureServices(IServiceCollection services)
{
    services.Configure<MyOptions>(options => {
          // some code, maybe not trivial
    });
}

and then later, from multiple threads:

var options = services.GetRequiredService<IOptions<MyOptions>>().Value;

the configuration action may be invoked more than once, which is not intuitively expected.

If this is the desired behavior, it needs to be documented very clearly. Personally, I would prefer the options manager to deal with concurrency issues and guarantee that the configuration action is only invoked once.

[herecydev]

Isn't it dangerous to assume any default lifetime? I certainly wouldn't expect that the framework to bind singleton for you. Though wouldn't this sort out your issue.

[HaoK]

By default AddOptions adds OptionsManager as a singleton, so it's only done once in the normal case.

[divega]

@HaoK I believe @fedotovalex is referring to the case of two threads (e.g. two concurrent requests) invoking .Value concurrently on the same singleton. I just checked and we don't have any code dealing with concurrency? Didn't we have it?

[HaoK]

ec13249