SQLite database is busy -- warning or error?

[bjornfor]

Describe the bug
In Nix 2.3 you might see a warning: SQLite database '/nix/var/nix/db/db.sqlite' is busy when the database is busy. But in Nix >=2.8 (and possibly earlier?) you get a more confusing message:

warning: error: SQLite database '/nix/var/nix/db/db.sqlite' is busy

I've been asked about this more than once at $dayjob: "Is this message a warning or an error?". I'm pretty sure it's just a warning, and if that's correct, we should probably remove the error: part from that message.

Steps To Reproduce

1. Run many build actions at once.
2. See warning. (Or error :-) )

Expected behavior

I expect messages to be either warning or error, not both.

[fxcl]

warning: ignoring untrusted substituter 'https://mirrors.tuna.tsinghua.edu.cn/nix-channels/store'
warning: ignoring untrusted substituter 'https://mirrors.tuna.tsinghua.edu.cn/nix-channels/store'
error (ignored): error: SQLite database '/Users/kelvin/.cache/nix/eval-cache-v2/7942c12f17b7d7df4f7337c8024bd0045b3dfafd7e1afe035da25545ecb3c6ee.sqlite' is busy

[pmiddend]

I have to agree. Currently, for me, it's:

error (ignored): error: SQLite database '/home/gitlab-runner/.cache/nix/eval-cache-v4/7890a1703b64585540ff4a0e1dd18e705c16565d1f2cadfe3d98a9760d807b77.sqlite' is busy

Which, again, duplicates "error", and "(ignored)" doesn't really help in my opinion.

[bjornfor]

Related: #7998

[Ericson2314]

The specific rendering issue would be fixed by #7865

[9999years]

IMO this shouldn't be a warning or an error, but a (verbose) notice: waiting for lock on build cache.

[roberth]

The frequency of this message has been greatly reduced since

• Fix unnecessary reporting of SQLite busy errors #8199

However, the message prefix issue has not been solved. It seems that the error: part comes from e.what() call in

nix/src/libstore/sqlite.cc

Line 248 in de3df30

.msg = hintfmt(e.what())

We have more instances where we're logging an e.what() that may be subject to this issue. We could either provide an extra method that prints the message without prefix, or we could mutate it to a warning so that it can log itself correctly.