Refactor scope registry #41825
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Refactor scope registry #41825
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We're spending time validating symbol parameters of the ScopeRegistry. It's an internal class, and we can stop validating symbols by converting to methods (you'll automatically get an error if you try to call a method that doesn't exist). Second, since we only have 3 things to keep track of, rather than keep those things in a hash, just break it out in to 3 instance variables. (This is absolutely not a memory bottleneck, but technically this patch will save some memory as the 3 ivars will be embedded in the object rather than require a full st_table for the original wrapper hash)
I noticed in profiles of simple queries (like `Post.where(id: 1).first`)
we're spending lots of time looking up the current thread. I couldn't
find any way to speed this up in Ruby, so I thought maybe we could call
`Thread.current` fewer times per query.
This patch should eliminate 4 calls to `Thread.current` per query.
For this benchmark:
```ruby
StackProf.run(mode: :wall, out: 'out.dump') do
8000.times { Post.where(id: id).first }
end
```
`Thread.current` goes from 7% to 4.7% of time:
```
==================================
Mode: wall(1000)
Samples: 1633 (0.00% miss rate)
GC: 51 (3.12%)
==================================
TOTAL (pct) SAMPLES (pct) FRAME
140 (8.6%) 140 (8.6%) String#sub!
114 (7.0%) 114 (7.0%) Thread.current
```
```
==================================
Mode: wall(1000)
Samples: 1719 (0.00% miss rate)
GC: 51 (2.97%)
==================================
TOTAL (pct) SAMPLES (pct) FRAME
134 (7.8%) 134 (7.8%) String#sub!
99 (5.8%) 99 (5.8%) Module#===
81 (4.7%) 81 (4.7%) Thread.current
```
This isn't huge, but I think we need to find more sources of
Thread.current. It's surprising to me that we spend so much time
looking up the current thread when doing a query that is so "easy"
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I'm trying to reduce the number of calls to
Thread.currentas it seems we call this a lot even for simple queries.