refactor: read state barrier

[bsbds]

Fix 1 and 2 in #497

Please briefly answer these questions:

• what problem are you trying to solve? (or if there's no problem, what's the motivation for this change?)

• what changes does this pull request make?

• are there any non-obvious implications of these changes? (does it break compatibility with previous versions, etc)

[codecov]

Codecov Report

Attention: 20 lines in your changes are missing coverage. Please review.

Comparison is base (974c3a9) 54.18% compared to head (ccbe667) 54.24%.

Additional details and impacted files

@@            Coverage Diff             @@
##           master     #503      +/-   ##
==========================================
+ Coverage   54.18%   54.24%   +0.06%     
==========================================
  Files         101      101              
  Lines       18239    18271      +32     
  Branches    18239    18271      +32     
==========================================
+ Hits         9883     9912      +29     
- Misses       7767     7770       +3     
  Partials      589      589              

Files	Coverage Δ
...urp/src/server/cmd_worker/conflict_checked_mpmc.rs	84.49% <100.00%> (ø)
curp/src/server/curp_node.rs	30.02% <0.00%> (ø)
xline/src/server/barriers.rs	92.85% <97.22%> (+15.68%)	⬆️
curp/src/server/raw_curp/mod.rs	66.51% <0.00%> (-0.73%)	⬇️

... and 2 files with indirect coverage changes

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[iGxnon]

A bit vec queue might be sufficient to solve this gracefully.

Based on your description, I found that the Tracker in #450 may be able to meet this requirement. It has a higher memory compression ratio and better complexity than a binary heap.

[bsbds]

A bit vec queue might be sufficient to solve this gracefully.

Based on your description, I found that the [Tracker](https://github.com//pull/450/files#diff-d16e0732694070d1f04f3160ccafa6b615b4cfd085837a472c1d3e13fe4ceb34) in #450 may be able to meet this requirement. It has a higher memory compression ratio and better complexity than a binary heap.

Yeah I can rebase this on #450

[bsbds]

After refactoring this PR is no longer needed