Import raft

[cole-miller]

Still WIP but this is already enough to get the dqlite tests passing (on my machine, both with bundled raft and external raft). Major points:

• the new source structure is: raft sources under src/raft; the public includes raft.h, raft/uv.h, and raft/fixture.h concatenated into src/raft.h
• raft_uv is build unconditionally, as is raft_fixture
• libraft is not built separately, it all goes into libdqlite.a
• imported files are from latest raft master, 070b1b124d9c1f96553fef1c1356cde0c2e81ccf
• configure.ac and Makefile.am should be updated, we inherit some stuff from the raft versions of these files

Still todo:

• get the tests to pass on GHA
• update the downstream workflow and Jepsen
• fix RAFT_API and visibility of raft stuff generally
• import raft tests and get them passing
• normalize style (e.g. spaces vs. tabs) across the codebase
• test with bundled raft in CI
• update dqlite.pc.in
• can we avoid building raft_fixture unless necessary?
• other things that I'm forgetting

[codecov]

Codecov Report

Attention: 1195 lines in your changes are missing coverage. Please review.

Comparison is base (85615e4) 61.30% compared to head (f99d254) 81.17%.
Report is 7 commits behind head on master.

Files	Patch %	Lines
src/raft/uv_fs.c	57.65%	140 Missing and 73 partials ⚠️
src/raft/replication.c	75.86%	123 Missing and 80 partials ⚠️
src/raft/uv_append.c	85.02%	34 Missing and 34 partials ⚠️
src/raft/client.c	71.98%	41 Missing and 24 partials ⚠️
src/raft/uv.c	84.63%	33 Missing and 32 partials ⚠️
src/raft/fixture.c	94.38%	28 Missing and 26 partials ⚠️
src/raft/compress.c	68.30%	33 Missing and 12 partials ⚠️
src/raft/uv_prepare.c	75.79%	29 Missing and 9 partials ⚠️
src/raft/recv_install_snapshot.c	31.37%	23 Missing and 12 partials ⚠️
src/raft/start.c	67.00%	13 Missing and 20 partials ⚠️
... and 28 more

Additional details and impacted files

@@             Coverage Diff             @@
##           master     #568       +/-   ##
===========================================
+ Coverage   61.30%   81.17%   +19.87%     
===========================================
  Files          34      187      +153     
  Lines        6836    26683    +19847     
  Branches     2031     4865     +2834     
===========================================
+ Hits         4191    21661    +17470     
- Misses       1349     3478     +2129     
- Partials     1296     1544      +248     

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[cole-miller]

I've got the clang-tidy check mostly working for patches. For some reason the identifier case check doesn't work for type names (https://discourse.llvm.org/t/clang-tidying-c-code-structcase-not-working/76863), but otherwise it seems to run as expected.

[cole-miller]

I have been unable to reproduce that test failure locally and it doesn't seem to be recurring in CI after a few re-runs. I propose we merge this, see if it comes back, and fix the test in a follow-up if it turns flaky again.

[freeekanayaka]

Hey @cole-miller now that this PR is merged, any plan to cut a new dqlite release soon? So distributions can start update their packages to the new layout. Thanks.