From 85c4a95c65c36b3cf60a8c9f0b68f489ce3ee3b5 Mon Sep 17 00:00:00 2001
From: Angelo Di Paolo <angelojdipaolo@icloud.com>
Date: Thu, 12 Dec 2024 09:20:21 -0800
Subject: [PATCH] Synchronize access race in HistogramMetric (#609)

---
 .../Metrics/HistogramMetricSdk.swift           | 14 +++++++++-----
 .../OpenTelemetrySdk/Metrics/MeterSdk.swift    | 18 +++++++++++-------
 2 files changed, 20 insertions(+), 12 deletions(-)

diff --git a/Sources/OpenTelemetrySdk/Metrics/HistogramMetricSdk.swift b/Sources/OpenTelemetrySdk/Metrics/HistogramMetricSdk.swift
index 795ec44e..76e8a0c6 100644
--- a/Sources/OpenTelemetrySdk/Metrics/HistogramMetricSdk.swift
+++ b/Sources/OpenTelemetrySdk/Metrics/HistogramMetricSdk.swift
@@ -10,6 +10,7 @@ internal class HistogramMetricSdk<T: SignedNumeric & Comparable>: HistogramMetri
     public private(set) var boundInstruments = [LabelSet: BoundHistogramMetricSdkBase<T>]()
     let metricName: String
     let explicitBoundaries: Array<T>?
+    let bindUnbindLock = Lock()
 
     init(name: String, explicitBoundaries: Array<T>? = nil) {
         metricName = name
@@ -17,12 +18,15 @@ internal class HistogramMetricSdk<T: SignedNumeric & Comparable>: HistogramMetri
     }
 
     func bind(labelset: LabelSet) -> BoundHistogramMetric<T> {
-        var boundInstrument = boundInstruments[labelset]
-        if boundInstrument == nil {
-            boundInstrument = createMetric()
-            boundInstruments[labelset] = boundInstrument!
+        bindUnbindLock.withLock {
+            var boundInstrument = boundInstruments[labelset]
+            if boundInstrument == nil {
+                boundInstrument = createMetric()
+                boundInstruments[labelset] = boundInstrument!
+            }
+            
+            return boundInstrument!
         }
-        return boundInstrument!
     }
 
     func bind(labels: [String: String]) -> BoundHistogramMetric<T> {
diff --git a/Sources/OpenTelemetrySdk/Metrics/MeterSdk.swift b/Sources/OpenTelemetrySdk/Metrics/MeterSdk.swift
index 2d2d92d7..e75a54c1 100644
--- a/Sources/OpenTelemetrySdk/Metrics/MeterSdk.swift
+++ b/Sources/OpenTelemetrySdk/Metrics/MeterSdk.swift
@@ -195,14 +195,18 @@ class MeterSdk: Meter {
                 let metricName = histogram.key
                 let measureInstrument = histogram.value
                 var metric = Metric(namespace: meterName, name: metricName, desc: meterName + metricName, type: AggregationType.doubleHistogram, resource: resource, instrumentationScopeInfo: instrumentationScopeInfo)
-                measureInstrument.boundInstruments.forEach { boundInstrument in
-                    let labelSet = boundInstrument.key
-                    let aggregator = boundInstrument.value.getAggregator()
-                    aggregator.checkpoint()
-                    var metricData = aggregator.toMetricData()
-                    metricData.labels = labelSet.labels
-                    metric.data.append(metricData)
+
+                measureInstrument.bindUnbindLock.withLock {
+                    measureInstrument.boundInstruments.forEach { boundInstrument in
+                        let labelSet = boundInstrument.key
+                        let aggregator = boundInstrument.value.getAggregator()
+                        aggregator.checkpoint()
+                        var metricData = aggregator.toMetricData()
+                        metricData.labels = labelSet.labels
+                        metric.data.append(metricData)
+                    }
                 }
+
                 metricProcessor.process(metric: metric)
             }