Add 'bugsnag.sampling.p' attribute

Author: imjoehaines

packages/core/lib/attributes.ts

@@ -60,9 +60,12 @@ export function attributeToJson (key: string, attribute: SpanAttribute): JsonAtt
       if (Number.isNaN(attribute) || !Number.isFinite(attribute)) {
         return undefined
       }
-      if (Number.isInteger(attribute)) {
+
+      // 'bugsnag.sampling.p' must always be sent as a doubleValue
+      if (key !== 'bugsnag.sampling.p' && Number.isInteger(attribute)) {
         return { key, value: { intValue: `${attribute}` } }
       }
+
       return { key, value: { doubleValue: attribute } }
     case 'boolean':
       return { key, value: { boolValue: attribute } }

packages/core/lib/span.ts

@@ -94,6 +94,10 @@ export class SpanInternal implements SpanContext {
 
   end (endTime: number, samplingProbability: SpanProbability): SpanEnded {
     this.endTime = endTime
+    let _samplingProbability = samplingProbability
+
+    this.attributes.set('bugsnag.sampling.p', _samplingProbability.raw)
+
     return {
       id: this.id,
       name: this.name,
@@ -104,7 +108,13 @@ export class SpanInternal implements SpanContext {
       events: this.events,
       samplingRate: this.samplingRate,
       endTime,
-      samplingProbability,
+      get samplingProbability (): SpanProbability {
+        return _samplingProbability
+      },
+      set samplingProbability (samplingProbability: SpanProbability) {
+        _samplingProbability = samplingProbability
+        this.attributes.set('bugsnag.sampling.p', _samplingProbability.raw)
+      },
       parentSpanId: this.parentSpanId
     }
   }

packages/core/tests/span-factory.test.ts

@@ -139,6 +139,7 @@ describe('SpanFactory', () => {
         expect(jestLogger.warn).not.toHaveBeenCalled()
       })
     })
+
     describe('isFirstClass', () => {
       it('omits first class span attribute by default', () => {
         const clock = new IncrementingClock('1970-01-01T00:00:00.000Z')

packages/core/tests/span.test.ts

@@ -1,4 +1,3 @@
-
 import { DefaultSpanContextStorage, Kind } from '@bugsnag/core-performance'
 import {
   ControllableBackgroundingListener,
@@ -7,14 +6,18 @@ import {
   IncrementingIdGenerator,
   StableIdGenerator,
   VALID_API_KEY,
+  createSamplingProbability,
   createTestClient,
   spanAttributesSource
 } from '@bugsnag/js-performance-test-utilities'
 import {
   InMemoryPersistence,
+  SpanAttributes,
   SpanFactory,
+  SpanInternal,
   spanToJson,
   spanContextEquals,
+  type SpanAttribute,
   type SpanEnded
 } from '../lib'
 import Sampler from '../lib/sampler'
@@ -103,6 +106,39 @@ describe('SpanInternal', () => {
       }))
     })
   })
+
+  describe('bugsnag.sampling.p', () => {
+    it.each([0.25, 0.5, 0.1, 1, 0, 0.4, 0.3])('is set to the correct value on "end"', (probability) => {
+      const span = new SpanInternal(
+        'span id',
+        'trace id',
+        'name',
+        1234,
+        new SpanAttributes(new Map<string, SpanAttribute>())
+      )
+
+      const endedSpan = span.end(5678, createSamplingProbability(probability))
+
+      // @ts-expect-error 'attributes' is private but very awkward to test otherwise
+      expect(endedSpan.attributes.attributes.get('bugsnag.sampling.p')).toBe(probability)
+    })
+
+    it.each([0.25, 0.5, 0.1, 1, 0, 0.4, 0.3])('is updated when samplingProbability is changed', (probability) => {
+      const span = new SpanInternal(
+        'span id',
+        'trace id',
+        'name',
+        1234,
+        new SpanAttributes(new Map<string, SpanAttribute>())
+      )
+
+      const endedSpan = span.end(5678, createSamplingProbability(probability))
+      endedSpan.samplingProbability = createSamplingProbability(probability + 0.1)
+
+      // @ts-expect-error 'attributes' is private but very awkward to test otherwise
+      expect(endedSpan.attributes.attributes.get('bugsnag.sampling.p')).toBe(probability + 0.1)
+    })
+  })
 })
 
 describe('Span', () => {
@@ -415,7 +451,12 @@ describe('Span', () => {
 
       await jest.runOnlyPendingTimersAsync()
 
-      expect(delivery.requests).toHaveLength(1)
+      expect(delivery).toHaveSentSpan(expect.objectContaining({
+        name: 'test span',
+        attributes: expect.arrayContaining([
+          { key: 'bugsnag.sampling.p', value: { doubleValue: 1 } }
+        ])
+      }))
     })
 
     it('will always be discarded when probability is 0', async () => {
@@ -491,15 +532,21 @@ describe('Span', () => {
       await jest.runOnlyPendingTimersAsync()
 
       expect(delivery).toHaveSentSpan(expect.objectContaining({
-        name: 'span 1'
+        name: 'span 1',
+        attributes: expect.arrayContaining([
+          { key: 'bugsnag.sampling.p', value: { doubleValue: 0.14 } }
+        ])
       }))
 
       expect(delivery).not.toHaveSentSpan(expect.objectContaining({
         name: 'span 2'
       }))
 
       expect(delivery).toHaveSentSpan(expect.objectContaining({
-        name: 'span 3'
+        name: 'span 3',
+        attributes: expect.arrayContaining([
+          { key: 'bugsnag.sampling.p', value: { doubleValue: 0.14 } }
+        ])
       }))
     })