chore: modify LogExporter and SpanExporter interfaces to support returning failure

Address review comments

Author: scottgerring

opentelemetry-otlp/CHANGELOG.md

@@ -1,9 +1,9 @@
 # Changelog
 
 ## vNext
-
 - Bump msrv to 1.75.0.
-
+- `OtlpHttpClient.shutdown` `TonicLogsClient.shutdown`, and `TonicTracesClient.shutdown` now explicitly return a result. The
+    semantics of the method have not changed, but you will have a new lint encouraging you to consume these results.
 
 ## 0.27.0
 

opentelemetry-otlp/src/exporter/http/logs.rs

@@ -49,8 +49,9 @@ impl LogExporter for OtlpHttpClient {
         Ok(())
     }
 
-    fn shutdown(&mut self) {
-        let _ = self.client.lock().map(|mut c| c.take());
+    fn shutdown(&mut self) -> LogResult<()> {
+        let _ = self.client.lock()?.take();
+        Ok(())
     }
 
     fn set_resource(&mut self, resource: &opentelemetry_sdk::Resource) {

opentelemetry-otlp/src/exporter/http/trace.rs

@@ -2,7 +2,7 @@ use std::sync::Arc;
 
 use futures_core::future::BoxFuture;
 use http::{header::CONTENT_TYPE, Method};
-use opentelemetry::{otel_debug, trace::TraceError};
+use opentelemetry::trace::{TraceError, TraceResult};
 use opentelemetry_sdk::export::trace::{ExportResult, SpanData, SpanExporter};
 
 use super::OtlpHttpClient;
@@ -64,8 +64,9 @@ impl SpanExporter for OtlpHttpClient {
         })
     }
 
-    fn shutdown(&mut self) {
-        let _ = self.client.lock().map(|mut c| c.take());
+    fn shutdown(&mut self) -> TraceResult<()> {
+        let _ = self.client.lock()?.take();
+        Ok(())
     }
 
     fn set_resource(&mut self, resource: &opentelemetry_sdk::Resource) {

opentelemetry-otlp/src/exporter/tonic/logs.rs

@@ -89,8 +89,9 @@ impl LogExporter for TonicLogsClient {
         Ok(())
     }
 
-    fn shutdown(&mut self) {
+    fn shutdown(&mut self) -> LogResult<()> {
         let _ = self.inner.take();
+        Ok(())
     }
 
     fn set_resource(&mut self, resource: &opentelemetry_sdk::Resource) {

opentelemetry-otlp/src/exporter/tonic/trace.rs

@@ -92,8 +92,9 @@ impl SpanExporter for TonicTracesClient {
         })
     }
 
-    fn shutdown(&mut self) {
+    fn shutdown(&mut self) -> TraceResult<()> {
         let _ = self.inner.take();
+        Ok(())
     }
 
     fn set_resource(&mut self, resource: &opentelemetry_sdk::Resource) {

opentelemetry-sdk/CHANGELOG.md

@@ -2,6 +2,11 @@
 
 ## vNext
 
+- If you are an exporter author, the trait functions `LogExporter.shutdown` and `TraceExporter.shutdown` must now return a result. Note that implementing shutdown is optional as the trait provides a default implementation that returns Ok(()).
+
+- The trait functions `LogExporter.shutdown` and `TraceExporter.shutdown` now explicitly return a result. The
+  semantics of the method have not changed, but you will have a new lint encouraging you to consume these results.
+
 - *Breaking(Affects custom metric exporter authors only)* `start_time` and `time` is moved from DataPoints to aggregations (Sum, Gauge, Histogram, ExpoHistogram) see [#2377](https://github.com/open-telemetry/opentelemetry-rust/pull/2377) and [#2411](https://github.com/open-telemetry/opentelemetry-rust/pull/2411), to reduce memory.
 
 - *Breaking* `start_time` is no longer optional for `Sum` aggregation, see [#2367](https://github.com/open-telemetry/opentelemetry-rust/pull/2367), but is still optional for `Gauge` aggregation see [#2389](https://github.com/open-telemetry/opentelemetry-rust/pull/2389).
@@ -14,6 +19,7 @@
     [#2338](https://github.com/open-telemetry/opentelemetry-rust/pull/2338)
   - `ResourceDetector.detect()` no longer supports timeout option.
   - `opentelemetry::global::shutdown_tracer_provider()` Removed from the API, should now use `tracer_provider.shutdown()` see [#2369](https://github.com/open-telemetry/opentelemetry-rust/pull/2369) for a migration example. "Tracer provider" is cheaply cloneable, so users are encouraged to set a clone of it as the global (ex: `global::set_tracer_provider(provider.clone()))`, so that instrumentations and other components can obtain tracers from `global::tracer()`. The tracer_provider must be kept around to call shutdown on it at the end of application (ex: `tracer_provider.shutdown()`)
+
 - *Feature*: Add `ResourceBuilder` for an easy way to create new `Resource`s
 - *Breaking*: Remove `Resource::{new,empty,from_detectors,new_with_defaults,from_schema_url,merge,default}` from public api. To create Resources you should only use `Resource::builder()` or `Resource::builder_empty()`. See [#2322](https://github.com/open-telemetry/opentelemetry-rust/pull/2322) for a migration guide.
   Example Usage:
@@ -156,6 +162,7 @@ metadata, a feature introduced in version 0.1.40. [#2418](https://github.com/ope
     - Continue enabling one of the async runtime feature flags: `rt-tokio`,
       `rt-tokio-current-thread`, or `rt-async-std`.
 
+
 ## 0.27.1
 
 Released 2024-Nov-27

opentelemetry-sdk/src/export/logs/mod.rs

@@ -83,7 +83,10 @@ pub trait LogExporter: Send + Sync + Debug {
     ///
     async fn export(&self, batch: LogBatch<'_>) -> LogResult<()>;
     /// Shuts down the exporter.
-    fn shutdown(&mut self) {}
+    fn shutdown(&mut self) -> LogResult<()> {
+        Ok(())
+    }
+
     #[cfg(feature = "spec_unstable_logs_enabled")]
     /// Chek if logs are enabled.
     fn event_enabled(&self, _level: Severity, _target: &str, _name: &str) -> bool {

opentelemetry-sdk/src/export/trace.rs

@@ -7,8 +7,13 @@ use std::borrow::Cow;
 use std::fmt::Debug;
 use std::time::SystemTime;
 
-/// Describes the result of an export.
-pub type ExportResult = Result<(), TraceError>;
+/// Describes the results of other operations on the trace API.
+pub type TraceResult<T> = Result<T, TraceError>;
+
+/// Describes the results of an export
+/// Note: This is an alias we will remove in the future, favouring
+/// using TraceResult directly.
+pub type ExportResult = TraceResult<()>;
 
 /// `SpanExporter` defines the interface that protocol-specific exporters must
 /// implement so that they can be plugged into OpenTelemetry SDK and support
@@ -30,7 +35,7 @@ pub trait SpanExporter: Send + Sync + Debug {
     ///
     /// Any retry logic that is required by the exporter is the responsibility
     /// of the exporter.
-    fn export(&mut self, batch: Vec<SpanData>) -> BoxFuture<'static, ExportResult>;
+    fn export(&mut self, batch: Vec<SpanData>) -> BoxFuture<'static, TraceResult<()>>;
 
     /// Shuts down the exporter. Called when SDK is shut down. This is an
     /// opportunity for exporter to do any cleanup required.
@@ -43,7 +48,9 @@ pub trait SpanExporter: Send + Sync + Debug {
     /// flush the data and the destination is unavailable). SDK authors
     /// can decide if they want to make the shutdown timeout
     /// configurable.
-    fn shutdown(&mut self) {}
+    fn shutdown(&mut self) -> TraceResult<()> {
+        Ok(())
+    }
 
     /// This is a hint to ensure that the export of any Spans the exporter
     /// has received prior to the call to this function SHOULD be completed

opentelemetry-sdk/src/logs/log_processor.rs

@@ -144,7 +144,7 @@ impl<T: LogExporter> LogProcessor for SimpleLogProcessor<T> {
         self.is_shutdown
             .store(true, std::sync::atomic::Ordering::Relaxed);
         if let Ok(mut exporter) = self.exporter.lock() {
-            exporter.shutdown();
+            exporter.shutdown()?;
             Ok(())
         } else {
             Err(LogError::MutexPoisoned("SimpleLogProcessor".into()))
@@ -650,7 +650,13 @@ impl<R: RuntimeChannel> BatchLogProcessorWithAsyncRuntime<R> {
                         )
                         .await;
 
-                        exporter.shutdown();
+                        if let Err(e) = exporter.shutdown() {
+                            otel_warn!(
+                               name: "BatchLogProcessor.Shutdown.Failed",
+                               message = "failed shutting down exporter cleanly",
+                               error = format!("{:?}", e)
+                            );
+                        };
 
                         if let Err(send_error) = ch.send(result) {
                             otel_debug!(
@@ -934,8 +940,6 @@ mod tests {
             Ok(())
         }
 
-        fn shutdown(&mut self) {}
-
         fn set_resource(&mut self, resource: &Resource) {
             self.resource
                 .lock()

opentelemetry-sdk/src/testing/logs/in_memory_exporter.rs

@@ -195,10 +195,11 @@ impl LogExporter for InMemoryLogExporter {
         Ok(())
     }
 
-    fn shutdown(&mut self) {
+    fn shutdown(&mut self) -> LogResult<()> {
         if self.should_reset_on_shutdown {
             self.reset();
         }
+        Ok(())
     }
 
     fn set_resource(&mut self, resource: &Resource) {