feat(outbox): introduce the outbox state component

[victor-dumitrescu]

Closes RV-868.

What

This MR introduces a new PVM state component for the outbox.

Why

We need to support the outbox functionality for the RISC-V PVM. The state of the outbox needs to be captured in state commitments.

How

The outbox is initially implemented as a fixed-size array of levels, each of which are in turn a fixed-size array of messages. Once dynamically sized arrays become available, the outbox will switch to use these instead.

The outbox is configured with a size, which is the number of levels for which it can store messages. This is so that a smaller outbox can be used for testing. The maximum number of messages per level and the maximum size of a message are outbox constants and not configurable by the PVM.

The outbox implements all the traits required to be added as a component of the PVM state. The initial interface for writing and reading messages is defined, but the functionality is not yet implemented.

Manually Testing

make all

Regressions

Altering the PVM state structure results in changes to regressions.

Tasks for the Author

• Link all Linear issues related to this MR using magic words (e.g. part of, relates to, closes).
• Eliminate dead code and other spurious artefacts introduced in your changes.
• Document new public functions, methods and types.
• Make sure the documentation for updated functions, methods, and types is correct.
• Add tests for bugs that have been fixed.
• Explain changes to regression test captures when applicable.
• Write commit messages in agreement with our guidelines.
• Self-review your changes to ensure they are high-quality.
• Complete all of the above before assigning this MR to reviewers.

[codecov]

Codecov Report

❌ Patch coverage is 89.25620% with 13 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.49%. Comparing base (40f2494) to head (81ffeab).
⚠️ Report is 5 commits behind head on main.

Files with missing lines	Patch %	Lines
src/riscv/lib/src/pvm/outbox.rs	90.38%	0 Missing and 10 partials ⚠️
src/riscv/lib/src/pvm/common.rs	66.66%	0 Missing and 3 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #746      +/-   ##
==========================================
- Coverage   89.49%   89.49%   -0.01%     
==========================================
  Files         109      110       +1     
  Lines       20769    20888     +119     
  Branches    20769    20888     +119     
==========================================
+ Hits        18587    18693     +106     
  Misses       1803     1803              
- Partials      379      392      +13     

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[github-actions]

Benchmark results for revision 8059e5e:

Metric	Duration	TPS
Mean	1.478874464s	27.048
Worst	1.488650175s	26.870
Best	1.471970777s	27.174
Standard Deviation	±4.787855ms	±0.088

Full results

Run	Transfers	Duration	TPS
1	40	1.486116363s	26.916
2	40	1.479587466s	27.035
3	40	1.483494242s	26.963
4	40	1.482509146s	26.981
5	40	1.480002724s	27.027
6	40	1.482904176s	26.974
7	40	1.488650175s	26.870
8	40	1.482562085s	26.980
9	40	1.472306583s	27.168
10	40	1.476716478s	27.087
11	40	1.472833712s	27.159
12	40	1.477164834s	27.079
13	40	1.483178049s	26.969
14	40	1.480717428s	27.014
15	40	1.478352459s	27.057
16	40	1.473345501s	27.149
17	40	1.476203001s	27.097
18	40	1.476689143s	27.088
19	40	1.47218494s	27.170
20	40	1.471970777s	27.174

Compare the results above with those for the default branch.

[vapourismo]

Benchmark results for revision 923758d:

Metric Duration TPS
Mean 1.544861953s 25.893
Worst 1.557480239s 25.683
Best 1.532724079s 26.097
Standard Deviation ±6.920934ms ±0.116
Full results
Run Transfers Duration TPS
1 40 1.553918762s 25.741
2 40 1.542646705s 25.929
3 40 1.552139902s 25.771
4 40 1.537382024s 26.018
5 40 1.550761497s 25.794
6 40 1.543773288s 25.911
7 40 1.55007051s 25.805
8 40 1.53566341s 26.047
9 40 1.537054505s 26.024
10 40 1.551582606s 25.780
11 40 1.536111997s 26.040
12 40 1.557480239s 25.683
13 40 1.55126305s 25.785
14 40 1.544787858s 25.894
15 40 1.539875554s 25.976
16 40 1.546785598s 25.860
17 40 1.544595499s 25.897
18 40 1.549552508s 25.814
19 40 1.532724079s 26.097
20 40 1.539069471s 25.990
Compare the results above with those for the default branch.

Please investigate this performance regression.

[victor-dumitrescu]

Please investigate this performance regression.

While this result shows a regression, comparing the current results with the current main doesn't seem to show it.

I couldn't reproduce locally (M1 MBP). I tried having the outbox as the second field of Pvm, keeping the decreasing ordering by size, but I also could not see an effect.