Add config options to coarsely disable log/tracing without initialization.

Signed-off-by: Jason Volk <jason@zemos.net>

src/core/config/mod.rs

@@ -912,6 +912,26 @@ pub struct Config {
 	#[serde(default)]
 	pub log_to_stderr: bool,
 
+	/// Setting to false disables the logging/tracing system at a lower level.
+	/// In contrast to configuring an empty `log` string where the system is
+	/// still operating but muted, when this option is false the system was not
+	/// initialized and is not operating. Changing this option has no effect
+	/// after startup. This option is intended for developers and expert use
+	/// only: configuring an empty log string is preferred over using this.
+	///
+	/// default: true
+	#[serde(default = "true_fn")]
+	pub log_enable: bool,
+
+	/// Setting to false disables the logging/tracing system at a lower level
+	/// similar to `log_enable`. In this case the system is configured normally,
+	/// but not registered as the global handler in the final steps. This option
+	/// is for developers and expert use only.
+	///
+	/// default: true
+	#[serde(default = "true_fn")]
+	pub log_global_default: bool,
+
 	/// OpenID token expiration/TTL in seconds.
 	///
 	/// These are the OpenID tokens that are primarily used for Matrix account

src/core/log/mod.rs

@@ -8,23 +8,31 @@ pub mod fmt_span;
 mod reload;
 mod suppress;
 
-pub use capture::Capture;
-pub use console::{ConsoleFormat, ConsoleWriter, is_systemd_mode};
-pub use reload::{LogLevelReloadHandles, ReloadHandle};
-pub use suppress::Suppress;
-pub use tracing::Level;
+use std::sync::Arc;
+
+pub use tracing::{Level, subscriber::Subscriber};
 pub use tracing_core::{Event, Metadata};
 pub use tracing_subscriber::EnvFilter;
 
+pub use self::{
+	capture::Capture,
+	console::{ConsoleFormat, ConsoleWriter, is_systemd_mode},
+	reload::{LogLevelReloadHandles, ReloadHandle},
+	suppress::Suppress,
+};
+
 /// Logging subsystem. This is a singleton member of super::Server which holds
 /// all logging and tracing related state rather than shoving it all in
 /// super::Server directly.
-pub struct Log {
+pub struct Logging {
+	/// Subscriber assigned to globals and defaults; may also be NoSubscriber.
+	pub subscriber: Arc<dyn Subscriber + Send + Sync>,
+
 	/// General log level reload handles.
 	pub reload: LogLevelReloadHandles,
 
 	/// Tracing capture state for ephemeral/oneshot uses.
-	pub capture: std::sync::Arc<capture::State>,
+	pub capture: Arc<capture::State>,
 }
 
 // Wraps for logging macros. Use these macros rather than extern tracing:: or

src/core/server.rs

@@ -9,7 +9,7 @@ use std::{
 use ruma::OwnedServerName;
 use tokio::{runtime, sync::broadcast};
 
-use crate::{Err, Result, config, config::Config, log::Log, metrics::Metrics};
+use crate::{Err, Result, config, config::Config, log::Logging, metrics::Metrics};
 
 /// Server runtime state; public portion
 pub struct Server {
@@ -41,7 +41,7 @@ pub struct Server {
 	pub signal: broadcast::Sender<&'static str>,
 
 	/// Logging subsystem state
-	pub log: Log,
+	pub log: Logging,
 
 	/// Metrics subsystem state
 	pub metrics: Metrics,
@@ -49,7 +49,7 @@ pub struct Server {
 
 impl Server {
 	#[must_use]
-	pub fn new(config: Config, runtime: Option<runtime::Handle>, log: Log) -> Self {
+	pub fn new(config: Config, runtime: Option<runtime::Handle>, log: Logging) -> Self {
 		Self {
 			name: config.server_name.clone(),
 			config: config::Manager::new(config),