From 4a2b4dbd49301e8ee80598317980c825dc5c0d56 Mon Sep 17 00:00:00 2001
From: kwasniew <kwasniewski.mateusz@gmail.com>
Date: Mon, 22 Sep 2025 11:16:57 +0200
Subject: [PATCH] feat: infinity representation serializable

---
 .../metrics/impact/batch-histogram.test.ts    | 33 ++++++++++++++++---
 .../metrics/impact/batch-histogram.ts         | 16 +++++----
 2 files changed, 37 insertions(+), 12 deletions(-)

diff --git a/src/lib/features/metrics/impact/batch-histogram.test.ts b/src/lib/features/metrics/impact/batch-histogram.test.ts
index 38a3f20e78..6e7e0e7019 100644
--- a/src/lib/features/metrics/impact/batch-histogram.test.ts
+++ b/src/lib/features/metrics/impact/batch-histogram.test.ts
@@ -26,7 +26,7 @@ describe('BatchHistogram', () => {
                     { le: 1, count: 7 },
                     { le: 2.5, count: 9 },
                     { le: 5, count: 10 },
-                    { le: Number.POSITIVE_INFINITY, count: 10 },
+                    { le: '+Inf', count: 10 },
                 ],
             },
         );
@@ -71,7 +71,7 @@ describe('BatchHistogram', () => {
                     { le: 1, count: 4 },
                     { le: 2.5, count: 5 },
                     { le: 5, count: 5 },
-                    { le: Number.POSITIVE_INFINITY, count: 5 },
+                    { le: '+Inf', count: 5 },
                 ],
             },
         );
@@ -87,7 +87,7 @@ describe('BatchHistogram', () => {
                     { le: 1, count: 2 },
                     { le: 2.5, count: 3 },
                     { le: 5, count: 3 },
-                    { le: Number.POSITIVE_INFINITY, count: 3 },
+                    { le: '+Inf', count: 3 },
                 ],
             },
         );
@@ -125,7 +125,7 @@ describe('BatchHistogram', () => {
                 sum: 1.5,
                 buckets: [
                     { le: 1, count: 2 },
-                    { le: Number.POSITIVE_INFINITY, count: 3 },
+                    { le: '+Inf', count: 3 },
                 ],
             },
         );
@@ -137,7 +137,7 @@ describe('BatchHistogram', () => {
                 sum: 3.0,
                 buckets: [
                     { le: 1, count: 1 },
-                    { le: Number.POSITIVE_INFINITY, count: 2 },
+                    { le: '+Inf', count: 2 },
                 ],
             },
         );
@@ -170,4 +170,27 @@ describe('BatchHistogram', () => {
             /test_histogram_count{app="my_app",service="web"} 2/,
         );
     });
+
+    test('should handle "+Inf" string from SDK serialization', async () => {
+        histogram.recordBatch(
+            { client: 'sdk' },
+            {
+                count: 5,
+                sum: 12.3,
+                buckets: [
+                    { le: 1, count: 3 },
+                    { le: '+Inf', count: 5 }, // String instead of Infinity
+                ],
+            },
+        );
+
+        const metrics = await registry.metrics();
+
+        expect(metrics).toMatch(/test_histogram_bucket{client="sdk",le="1"} 3/);
+        expect(metrics).toMatch(
+            /test_histogram_bucket{client="sdk",le="\+Inf"} 5/,
+        );
+        expect(metrics).toMatch(/test_histogram_sum{client="sdk"} 12\.3/);
+        expect(metrics).toMatch(/test_histogram_count{client="sdk"} 5/);
+    });
 });
diff --git a/src/lib/features/metrics/impact/batch-histogram.ts b/src/lib/features/metrics/impact/batch-histogram.ts
index ec9ed4a446..4b604c294b 100644
--- a/src/lib/features/metrics/impact/batch-histogram.ts
+++ b/src/lib/features/metrics/impact/batch-histogram.ts
@@ -1,7 +1,7 @@
 import type { Registry } from 'prom-client';
 
 interface BucketData {
-    le: number;
+    le: number | '+Inf';
     count: number;
 }
 
@@ -22,7 +22,7 @@ export class BatchHistogram {
         {
             count: number;
             sum: number;
-            buckets: Map<number, number>;
+            buckets: Map<number | '+Inf', number>;
         }
     > = new Map();
 
@@ -86,15 +86,17 @@ export class BatchHistogram {
 
             for (const [le, cumulativeCount] of Array.from(
                 data.buckets.entries(),
-            ).sort((a, b) => a[0] - b[0])) {
+            ).sort((a, b) => {
+                // Sort buckets: numbers first (ascending), then '+Inf' last
+                if (a[0] === '+Inf') return 1;
+                if (b[0] === '+Inf') return -1;
+                return (a[0] as number) - (b[0] as number);
+            })) {
                 values.push({
                     value: cumulativeCount,
                     labels: {
                         ...labels,
-                        le:
-                            le === Number.POSITIVE_INFINITY
-                                ? '+Inf'
-                                : le.toString(),
+                        le: le.toString(),
                     },
                     metricName: `${this.name}_bucket`,
                 });