Is it recommended for ASP.NET Web API actions to always include a CancellationToken?
Note: This is basically a question from Stack Overflow that was closed for a very long period of time and I fear it might get closed again as primarily opinion based.
I am wondering if my ASP.NET Core 3.1+ Web API should support cancellation for all its methods or only for those which are particularly long. Example:
[Route("api/[controller]")]
public class FooController : ControllerBase
{
private readonly AppDbContext _dbContext;
public FooController()
{
}
[HttpGet("{id}")]
public async Task<ActionResult<FooModel>> GetAsync(int id, CancellationToken ct = default)
{
// some await to async operation here
}
}
An obvious benefit is that all actions are cancellable, but this requires passing the token everywhere (not sure, but some tools such as R# might automatically detect when this is forgotten and suggest/apply automatically to add the token).
I am more interested in the performance aspect of this (e.g. does it make sense for calls that are known to be short?).
1 answer
A cancellation token doesn't inherently do anything. It's up to the code which does the work to call ThrowIfCancellationRequested. If the token isn't passed on and isn't explicitly checked then there's no point passing it in.
If the real question is whether to call ThrowIfCancellationRequested in a trivial method: if it's truly trivial then don't.
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