Add force_flush to LogExporter

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

@@ -143,6 +143,14 @@ pub trait LogExporter: Send + Sync + Debug {
         // By default, all logs are enabled
         true
     }
+
+    ///
+    /// This method SHOULD block the current thread until all pending log records are exported.
+    /// If the export was not successful, an error is returned.
+    ///
+    fn force_flush(&mut self) -> ExportResult {
+        Ok(())
+    }
     /// Set the resource for the exporter.
     fn set_resource(&mut self, _resource: &Resource) {}
 }

opentelemetry-sdk/src/logs/log_processor.rs

@@ -174,7 +174,11 @@
     }
 
     fn force_flush(&self) -> LogResult<()> {
-        Ok(())
+        if let Ok(mut exporter) = self.exporter.lock() {
+            exporter.force_flush()
+        } else {
+            Err(LogError::MutexPoisoned("SimpleLogProcessor".into()))
+        }
     }
 
     fn shutdown(&self) -> LogResult<()> {
@@ -1063,6 +1067,20 @@
         let _ = provider.shutdown();
     }
 
+    #[tokio::test(flavor = "multi_thread")]
+    async fn test_batch_forceflush() {
+        let exporter = InMemoryLogExporterBuilder::default().build();
+
+        let processor = BatchLogProcessor::new(exporter.clone(), BatchConfig::default());
+
+        let mut record = LogRecord::default();
+        let instrumentation = InstrumentationScope::default();
+
+        processor.emit(&mut record, &instrumentation);
+        processor.force_flush().unwrap();
+        assert_eq!(1, exporter.get_emitted_logs().unwrap().len());
+    }
+
     #[tokio::test(flavor = "multi_thread")]
     async fn test_batch_shutdown() {
         // assert we will receive an error