Add execute metrics

[t-nelson]

Problem

Execution is occasionally slow but cause is not captured in current metrics

Summary of Changes

Add more timings

Republish of #22043, since I apparently broke Github over there

[codecov]

Codecov Report

Merging #22296 (d7c54f6) into master (d922065) will increase coverage by 0.0%.
The diff coverage is 88.7%.

@@           Coverage Diff            @@
##           master   #22296    +/-   ##
========================================
  Coverage    81.0%    81.0%            
========================================
  Files         551      551            
  Lines      149617   149775   +158     
========================================
+ Hits       121301   121454   +153     
- Misses      28316    28321     +5     

[Lichtso]

Two things:

• Have you run and measured these against MB? Because some of the metrics might measure so little that the measurement itself is more expensive.
• There is a lot of b = b.saturating_add(a); which is not only hard to read but also error prone as it can lead to copy pasta like d = b.saturating_add(a);. A small wrapper function or macro like saturating_add_inplace(&mut b, a); would be better I think.

[t-nelson]

Two things:

* Have you run and measured these against MB? Because some of the metrics might measure so little that the measurement itself is more expensive.

You're right! I noticed some things were being measured that were unlikely to be expensive during a rebase. I'll re-evaluate the inherited commits

* There is a lot of `b = b.saturating_add(a);` which is not only hard to read but also error prone as it can lead to copy pasta like `d = b.saturating_add(a);`. A small wrapper function or macro like `saturating_add_inplace(&mut b, a);` would be better I think.

Will add. Jack wants it too, which is consensus enough for me 🙂