fix: Fix stack-overflow inducing infinite feedback loop when calling tracing::event! after SdkLoggerProvider::shutdown

Author: lucamuscat

opentelemetry-appender-tracing/tests/test_no_stack_overflow_after_shutdown.rs

@@ -0,0 +1,20 @@
+use opentelemetry_appender_tracing::layer;
+use opentelemetry_sdk::logs::SdkLoggerProvider;
+use tracing::info;
+use tracing_subscriber::{layer::SubscriberExt, util::SubscriberInitExt};
+
+#[test]
+fn test_no_stack_overflow_when_event_is_emitted_after_shutdown() {
+    let exporter = opentelemetry_stdout::LogExporter::default();
+    let provider: SdkLoggerProvider = SdkLoggerProvider::builder()
+        .with_batch_exporter(exporter)
+        .build();
+
+    let otel_layer = layer::OpenTelemetryTracingBridge::new(&provider);
+
+    tracing_subscriber::registry().with(otel_layer).init();
+
+    provider.shutdown().unwrap();
+
+    info!("Don't crash")
+}

opentelemetry-sdk/src/logs/logger.rs

@@ -33,7 +33,7 @@ impl opentelemetry::logs::Logger for SdkLogger {
 
     /// Emit a `LogRecord`.
     fn emit(&self, mut record: Self::LogRecord) {
-        if Context::is_current_telemetry_suppressed() {
+        if Context::is_current_telemetry_suppressed() || self.provider.is_shutdown() {
             return;
         }
         let provider = &self.provider;

opentelemetry-sdk/src/logs/logger_provider.rs

@@ -129,6 +129,10 @@ impl SdkLoggerProvider {
     pub fn shutdown(&self) -> OTelSdkResult {
         self.shutdown_with_timeout(Duration::from_secs(5))
     }
+
+    pub(crate) fn is_shutdown(&self) -> bool {
+        self.inner.is_shutdown.load(Ordering::SeqCst)
+    }
 }
 
 #[derive(Debug)]