[resteasy-dev] Question about how we do injections

[Ron Sigal]

I've been looking at an old issue, RESTEASY-1709 "Same JAX-RS Provider 
instance injected across applications", which I thought I had solved by 
injecting a javassist created proxy, but the reporter couldn't get it to 
work so it's been sitting for almost a year.

Anyway, I've been trying to port the old code to master, and I see that 
injection has changed to do a lot of stuff with CompletableFutures. In 
particular, a series of injections into, say, a resource, becomes a 
composition of CompletionStages, each one doing a single injection. I'm 
trying to understand why.

One reason I can see is that, at least in the case of an asynchronous 
invocation, you want to do as little as possible before returning a 
CompletableFuture. That would provide better responsiveness. But I have 
two questions:

   1. Is constructing a CompletableFuture that much faster than just 
doing the injection?

   2. I don't how much space a CompletableFuture takes, but we've turned 
a simple loop into a collection of CompletableFutures, which would seem 
to occupy more space. Isn't that counterproductive in terms of our 
general mandate to create a smaller footprint for container applications?

I'm not saying that the new code is wrong. I'm just saying that I don't 
understand why it's right.

Any thoughts?

-- 
My company's smarter than your company (unless you work for Red Hat)