From f7bbbdd6e3e0ae44b03f15351a88407034e70126 Mon Sep 17 00:00:00 2001
From: "Y.Matsuda" <44557218+ymtdzzz@users.noreply.github.com>
Date: Sun, 24 Jul 2022 04:08:20 +0900
Subject: [PATCH] Add `SpanExporter::ForceFlush` and default implementation
 (#845)

---
 opentelemetry-sdk/src/export/trace/mod.rs | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)

diff --git a/opentelemetry-sdk/src/export/trace/mod.rs b/opentelemetry-sdk/src/export/trace/mod.rs
index 25c09c32d7..272da1231d 100644
--- a/opentelemetry-sdk/src/export/trace/mod.rs
+++ b/opentelemetry-sdk/src/export/trace/mod.rs
@@ -45,6 +45,25 @@ pub trait SpanExporter: Send + Debug {
     /// can decide if they want to make the shutdown timeout
     /// configurable.
     fn shutdown(&mut self) {}
+
+    /// 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
+    /// as soon as possible, preferably before returning from this method.
+    ///
+    /// This function SHOULD provide a way to let the caller know
+    /// whether it succeeded, failed or timed out.
+    ///
+    /// This function SHOULD only be called in cases where it is absolutely necessary,
+    /// such as when using some FaaS providers that may suspend the process after
+    /// an invocation, but before the exporter exports the completed spans.
+    ///
+    /// This function SHOULD complete or abort within some timeout. This function can be
+    /// implemented as a blocking API or an asynchronous API which notifies the caller via
+    /// a callback or an event. OpenTelemetry client authors can decide if they want to
+    /// make the flush timeout configurable.
+    fn force_flush(&mut self) -> BoxFuture<'static, ExportResult> {
+        Box::pin(async { Ok(()) })
+    }
 }
 
 /// `SpanData` contains all the information collected by a `Span` and can be used