Set up configurable FFI/Rust driver logging

[flyingsilverfin]

Usage and product changes

Rather than having Python/Java/other wrappers invoke logging initialization explicitly, we now just do it on open of the Rust driver automatically.

This should fix warnings in Python:

Failed to initialize logging: attempted to set a logger after the logging system was already initialized

We also remove uses of the log create in the //c layer, and use tracing instead.

We can now configure logging in the Rust-driver component with the following variables: TYPEDB_DRIVER_LOG=info|debug|warn|trace or using the usual RUST_LOG variable. By default, ffi-based drivers calling init_logging will use INFO logging.

Rust applications should continue set up their own logging subscriber, as usual.

Implementation

Remove C-layer static logging initialization, and rely on just the Rust driver's once lock that is execute on driver open.

[dmitrii-ubskii]

This can be made simpler.

Suggested change

	let clib_level = if let Ok(typedb_driver_clib_log) = std::env::var("TYPEDB_DRIVER_CLIB_LOG") {
	typedb_driver_clib_log
	} else {
	"info".to_owned()
	};
	// Try to get log level from TYPEDB_DRIVER_LOG first
	let env_filter = if let Ok(typedb_log_level) = std::env::var("TYPEDB_DRIVER_LOG") {
	EnvFilter::new(&format!("typedb_driver={},typedb_driver_clib={}", typedb_log_level, clib_level))
	} else if let Ok(rust_log) = std::env::var("RUST_LOG") {
	// If RUST_LOG is set, use it but scope it to typedb_driver only
	EnvFilter::new(&format!("typedb_driver={},typedb_driver_clib={}", rust_log, clib_level))
	} else {
	EnvFilter::new(&format!("typedb_driver=info,typedb_driver_clib={}", clib_level))
	};
	let clib_level = std::env::var("TYPEDB_DRIVER_CLIB_LOG").unwrap_or_else(|_| "info".to_owned());
	let typedb_log_level = std::env::var("TYPEDB_DRIVER_LOG")
	.or_else(|_| std::env::var("RUST_LOG"))
	.unwrap_or_else(|_| "info".to_owned());
	let env_filter = EnvFilter::new(&format!("typedb_driver={},typedb_driver_clib={}", typedb_log_level, clib_level));

[dmitrii-ubskii]

What happens if RUST_LOG is set to e.g. tonic=trace?

[dmitrii-ubskii]

I think we should look for TYPEDB_DRIVER_CLIB_LOG_LEVEL and TYPEDB_DRIVER_LOG_LEVEL. We can then use RUST_LOG to initialize the EnvFilter and add the two log levels (if set) as directives. If nothing is set, then we can fall back to info on both our libs.

This way, RUST_LOG=tonic=info,typedb_driver=error will work as expected and will not get overridden to typedb_driver=info by us unnecessarily.

[dmitrii-ubskii]

Why registry and not Subscriber::buiilder?