Log support in Rust code

[touilleMan]

Log support requirement

• We also want to have the logs enable during the rust tests Oxidation log in tests #4219

• Sentry support (see Add Sentry support #6458)
  If we use the tracing crate, we could use sentry-tracing.
  If we directly plug to python, python will handle sending the log to sentry.

• Python integration (see Log support: Rust-Python integration #6459)

  We want python & rust to share the same logging system.
  So it's either python -> rust or rust -> python (-> = that use the logging system of)

  Some interesting links:

  • https://github.com/PyO3/pyo3/blob/main/guide/src/ecosystem/logging.md
  • https://github.com/danielschemmel/tracing-for-pyo3-logging
  • https://docs.rs/pyo3-log/0.8.1/pyo3_log/
  • Python to Rust logging implementation PyO3/pyo3#1208

If we want to use both tracing crate and log crate, we could use tracing-log (included by default in tracing-subscriber)

Converting print into log entry

• Replace eprintln in core_fs::ManifestStorage::close_connection to log::warn
• Replace println in texts_fixtures::testbed::ensure_testbed_server_is_started to log::info
• Add log::info at the end of local_db::BackgroundSqliteExecutor::serve
• Replace eprintln in local_db::SqliteExecutor::exec to log::warn
• Replace eprintln in local_db::LocalDatabase::exec_job to log::warn

[touilleMan]

Regarding pyo3-log, deadlock might occurs when a log is done while the GIL is already held

This is not as bad as it seems given it only occurs when the log is done from a spawned thread while the initial thread holding the GIL waits on it.
In our bindings we should never need to do that (given we send the work in the tokio thread pool before doing any work).

Another solution to avoid this is to dedicate a background thread to the log (the log functions would then only push a message for this thread, which would itself do the GIL lock). The additional benefit of this approach is it avoids GIL congestion (and hence performance drop) in the Rust threads.

[mmmarcos]

What remained to be done was extracted into specific issues:

• Add Sentry support #6458
• Log support: Rust-Python integration #6459