0.1.0-0-pre.4

crates/common/game-logging-lib/src/runtime.rs

@@ -0,0 +1,31 @@
+// file: crates/common/game-logging-lib/src/runtime.rs
+// version: 1
+
+/// Error returned when the process-global tracing subscriber is already configured.
+#[derive(Clone, Copy, Debug, Eq, PartialEq)]
+pub struct LoggingInitError;
+
+impl std::fmt::Display for LoggingInitError {
+    fn fmt(&self, formatter: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        return formatter.write_str("the process-global tracing subscriber is already configured");
+    }
+}
+
+impl std::error::Error for LoggingInitError {}
+
+/// Guard keeping the non-blocking tracing writer alive for the application lifetime.
+pub struct LoggingWorkerGuard {
+    _worker_guard: tracing_appender::non_blocking::WorkerGuard,
+}
+
+/// Initializes a process-global non-blocking tracing subscriber writing formatted events to standard error.
+///
+/// The returned guard must remain alive for as long as events may still be emitted.
+pub fn init_console_tracing() -> std::result::Result<LoggingWorkerGuard, LoggingInitError> {
+    let (writer, worker_guard) = tracing_appender::non_blocking(std::io::stderr());
+    let subscriber = tracing_subscriber::fmt().with_target(true).with_writer(writer).finish();
+    if tracing::subscriber::set_global_default(subscriber).is_err() {
+        return std::result::Result::Err(LoggingInitError);
+    }
+    return std::result::Result::Ok(LoggingWorkerGuard { _worker_guard: worker_guard });
+}