Use Timer object to improve timekeeping code

[DomGarguilo]

#4364 added the NanoTime util. This PR uses that in a few places that seem helpful.

[keith-turner]

still looking at this

[ctubbsii]

I think everything here is technically correct.

However, I think the purpose of this class is to try to be more expressive, to be able to interact with time durations in a more natural high level way, rather than deal with the arithmetic and comparisons at a low level. I don't think the subtract and compareTo methods are helping at all, and might even make things worse because (at least for me) compareTo can be pretty opaque and I have to remind myself about how the operands relate to the sign.

A higher level utility method, like hasElapased(Duration) can be done more efficiently, so fewer Duration objects are needed to be constructed, and can make things much more readable. A reset() method could also be added to make it easy to reuse the timer.

Also, we don't need both OpTimer and NanoTime, and NanoTime could be renamed.

[DomGarguilo]

I think everything here is technically correct.

However, I think the purpose of this class is to try to be more expressive, to be able to interact with time durations in a more natural high level way, rather than deal with the arithmetic and comparisons at a low level. I don't think the subtract and compareTo methods are helping at all, and might even make things worse because (at least for me) compareTo can be pretty opaque and I have to remind myself about how the operands relate to the sign.

A higher level utility method, like hasElapased(Duration) can be done more efficiently, so fewer Duration objects are needed to be constructed, and can make things much more readable. A reset() method could also be added to make it easy to reuse the timer.

Also, we don't need both OpTimer and NanoTime, and NanoTime could be renamed.

Converted this PR to draft for now. I think these suggestions are good and I can open up a new PR to incorporate them at somepoint.

[DomGarguilo]

This PR has been updated to use the new Timer object.

[DomGarguilo]

There was a bug in my new converted logic in DistributedReadWriteLock.tryLock() that was causing a test failure. The check in an if statement just needed to be inverted and now everything seems to be working well.

This should be ready to merge after it gets reviewed.

[ctubbsii]

There is a class called RunnableStartedAt that I think the code that uses it could also benefit from being rewritten using a Timer. RunnableStartedAt uses millis and is basically used to store start times for later timer comparisons, but it would probably be better if these just stored a started Timer instead, and I think that class could be deleted.

[ctubbsii]

Do you know if there's a possibility of using reset for this, instead of replacing the timer? It seems odd to replace the timer.

[DomGarguilo]

Timer lastMemoryCheckTime is initialized as null and then the code checks if its null in places to see if the check has happened yet. We could probably achieve the same with one Timer and a boolean flag that indicates if the check has happened yet but this seemed like this best way to do things from what I can tell.