From f6fb7a6d53146e8ac493747c4bc4c9a7f83c8968 Mon Sep 17 00:00:00 2001
From: Julian Tescher <jatescher@gmail.com>
Date: Thu, 9 Nov 2023 18:24:28 -0500
Subject: [PATCH] Fix metric export data for unused gauges (#1363)

---
 opentelemetry-sdk/CHANGELOG.md                       | 4 ++++
 opentelemetry-sdk/src/metrics/internal/last_value.rs | 6 +++++-
 2 files changed, 9 insertions(+), 1 deletion(-)

diff --git a/opentelemetry-sdk/CHANGELOG.md b/opentelemetry-sdk/CHANGELOG.md
index 2e3efa34e3..efdbe4a960 100644
--- a/opentelemetry-sdk/CHANGELOG.md
+++ b/opentelemetry-sdk/CHANGELOG.md
@@ -2,6 +2,10 @@
 
 ## vNext
 
+### Fixed
+
+- Fix metric export corruption if gauges have not received a last value. (#1363)
+
 ## v0.21.0
 
 ### Added
diff --git a/opentelemetry-sdk/src/metrics/internal/last_value.rs b/opentelemetry-sdk/src/metrics/internal/last_value.rs
index 28e9a0a107..57f35fc166 100644
--- a/opentelemetry-sdk/src/metrics/internal/last_value.rs
+++ b/opentelemetry-sdk/src/metrics/internal/last_value.rs
@@ -55,8 +55,12 @@ impl<T: Number<T>> LastValue<T> {
     pub(crate) fn compute_aggregation(&self, dest: &mut Vec<DataPoint<T>>) {
         let mut values = match self.values.lock() {
             Ok(guard) if !guard.is_empty() => guard,
-            _ => return,
+            _ => {
+                dest.clear(); // poisoned or no values recorded yet
+                return;
+            }
         };
+
         let n = values.len();
         if n > dest.capacity() {
             dest.reserve(n - dest.capacity());