[FFL-1720] Evaluation Logging: Storage & Network Infrastructure by typotter · Pull Request #3146 · DataDog/dd-sdk-android

typotter · 2026-01-22T08:49:01Z

🥞 Evaluation Logging Stacked Pull Requests 🥞

🔲 Integration & Configuration (PR #3147)
👉 Storage & Network Infrastructure (this PR)
☑️ Aggregation Engine & Test Utilities (PR #3145)
☑️FlagEvaluation Schema (PR #3166)
☑️ Event Schema & Data Models (PR #3144)
☑️ Evaluations Subfeature (PR #3159)
⎿ feature/flags-evaluations-logging (feature branch)

Datadog Internal
🎟️ Ticket: FFL-1720 - Implement Evaluation Logging for Android SDK

What does this PR do?

Implements the infrastructure for persisting evaluation events to disk and uploading them to Datadog's intake endpoint. Connects the aggregation engine (PR #3145) to the SDK Core's storage and network layer.

Motivation

We need to implement Evaluation Logging to provide comprehensive visibility into all feature flag evaluations, including defaults, errors, and successful matches. This goes beyond exposure logging by capturing aggregated metrics about evaluation frequency, error rates, and runtime default usage across all flags.

Additional Notes

Review checklist (to be filled by reviewers)

Feature or bugfix MUST have appropriate tests (unit, integration, e2e)
Make sure you discussed the feature or bugfix with the maintaining team in an Issue
Make sure each commit and the PR mention the Issue number (cf the CONTRIBUTING doc)

typotter · 2026-01-22T09:27:32Z

Warning

This pull request is not mergeable via GitHub because a downstack PR is open. Once all requirements are satisfied, merge this PR as a stack on Graphite.
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[FFL-1720] Evaluation Logging: Integration #3147
[FFL-1720] Evaluation Logging: Storage & Network Infrastructure #3146 👈 (View in Graphite)
[FFL-1720] Evaluation Logging: Aggregation Engine & Test Utilities #3145
[FFL-1720] Evaluation Logging: Event Schema & Data Models #3144
feature/flags-evaluations-logging

This stack of pull requests is managed by Graphite. Learn more about stacking.

...id-flags/src/main/kotlin/com/datadog/android/flags/internal/net/EvaluationsRequestFactory.kt

codecov-commenter · 2026-01-28T07:55:00Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 70.92%. Comparing base (66b62f4) to head (3a685c2).

Additional details and impacted files

@@                  Coverage Diff                   @@
##           graphite-base/3146    #3146      +/-   ##
======================================================
- Coverage               70.98%   70.92%   -0.06%     
======================================================
  Files                     905      906       +1     
  Lines                   33319    33353      +34     
  Branches                 5619     5623       +4     
======================================================
+ Hits                    23650    23654       +4     
- Misses                   8097     8127      +30     
  Partials                 1572     1572

Files with missing lines	Coverage Δ
...id/flags/internal/net/EvaluationsRequestFactory.kt	`100.00% <100.00%> (+25.00%)`	⬆️
...gs/internal/storage/EvaluationEventRecordWriter.kt	`100.00% <100.00%> (ø)`

... and 36 files with indirect coverage changes

🚀 New features to boost your workflow:

❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

0xnm · 2026-02-03T21:50:01Z

...lags/src/test/kotlin/com/datadog/android/flags/internal/net/EvaluationsRequestFactoryTest.kt

+    }
+
+    @Test
+    fun `M preserve batch data order W create() { multiple batch events }`(


does it actually matter? should we preserve the order?

0xnm · 2026-02-03T21:50:58Z

...gs/src/main/kotlin/com/datadog/android/flags/internal/storage/EvaluationEventRecordWriter.kt

+ * to the EVP intake endpoint by the SDK Core's upload mechanism.
+ */
+internal class EvaluationEventRecordWriter(private val sdkCore: FeatureSdkCore) : EvaluationEventWriter {
+    override fun writeAll(events: List<FlagEvaluation>) {


nit: maybe can be just write

0xnm · 2026-02-03T21:53:08Z

...rc/test/kotlin/com/datadog/android/flags/internal/storage/EvaluationEventRecordWriterTest.kt

+    fun `M use write context W writeAll() { events provided }`(
+        @Forgery event: FlagEvaluation
+    ) {
+        // Given
+        whenever(mockSdkCore.getFeature(Feature.FLAGS_EVALUATIONS_FEATURE_NAME)).thenReturn(mockFeature)
+        whenever(mockFeature.withWriteContext(any(), any()))
+            .thenAnswer { invocation ->
+                val callback = invocation.getArgument<(DatadogContext, EventWriteScope) -> Unit>(1)
+                val mockContext = mock<DatadogContext>()
+                callback.invoke(mockContext) { writerScope ->
+                    writerScope.invoke(mockEventBatchWriter)
+                }
+            }
+
+        // When
+        testedWriter.writeAll(listOf(event))
+
+        // Then - should use withWriteContext
+        verify(mockFeature).withWriteContext(any(), any())
+    }


I'm not sure this test makes sense, we already assert that events are written in the tests above

0xnm · 2026-02-03T21:54:47Z

...rc/test/kotlin/com/datadog/android/flags/internal/storage/EvaluationEventRecordWriterTest.kt

+    }
+
+    @Test
+    fun `M serialize events correctly W writeAll() { events with all fields }`() {


I would suggest to start creating tests in the reliability/single-fit for that kind, it is a better place to verify E2E functionality.

0xnm · 2026-02-03T21:55:10Z

...rc/test/kotlin/com/datadog/android/flags/internal/storage/EvaluationEventRecordWriterTest.kt

+    }
+
+    @Test
+    fun `M write event with UTF-8 encoding W writeAll() { event provided }`(


same for this test

0xnm · 2026-02-03T22:02:28Z

...gs/src/main/kotlin/com/datadog/android/flags/internal/storage/EvaluationEventRecordWriter.kt

+internal class EvaluationEventRecordWriter(private val sdkCore: FeatureSdkCore) : EvaluationEventWriter {
+    override fun writeAll(events: List<FlagEvaluation>) {
+        if (events.isEmpty()) return
+


one more thing: it is better to wrap a code block below synchronized(this) to avoid race condition when the same batch is accessed

typotter force-pushed the typo/FFL-1720-pr3-storage-network branch from fa56eda to a83f2d5 Compare January 22, 2026 09:27

typotter force-pushed the typo/FFL-1720-pr2-aggregation branch from e1704c3 to 95f4c0a Compare January 22, 2026 09:27

This was referenced Jan 22, 2026

[FFL-1720] Evaluation Logging: Event Schema & Data Models #3144

Merged

[FFL-1720] Evaluation Logging: Aggregation Engine & Test Utilities #3145

Open

typotter mentioned this pull request Jan 22, 2026

[FFL-1720] Evaluation Logging: Integration #3147

Open

3 tasks

typotter force-pushed the typo/FFL-1720-pr2-aggregation branch from 95f4c0a to a0e7df9 Compare January 22, 2026 16:29

typotter force-pushed the typo/FFL-1720-pr3-storage-network branch 2 times, most recently from 7ceef6b to 7c8d6b7 Compare January 22, 2026 21:27

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dd-oleksii reviewed Jan 23, 2026

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sameerank reviewed Jan 26, 2026

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sameerank mentioned this pull request Jan 26, 2026

FFL-1721 Emit flagevaluation EVP Track DataDog/dd-sdk-ios#2646

Open

5 tasks

typotter mentioned this pull request Jan 27, 2026

[Flags] Evaluations subfeature #3159

Merged

3 tasks

typotter force-pushed the typo/FFL-1720-pr2-aggregation branch 2 times, most recently from 968dc68 to 80c8de7 Compare January 28, 2026 06:55

typotter force-pushed the typo/FFL-1720-pr3-storage-network branch from 7c8d6b7 to a195a29 Compare January 28, 2026 06:56

typotter force-pushed the typo/FFL-1720-pr2-aggregation branch from 2eb16ca to 0cfb30a Compare January 28, 2026 07:27

typotter force-pushed the typo/FFL-1720-pr3-storage-network branch from a195a29 to 4f4c253 Compare January 28, 2026 07:35

typotter force-pushed the typo/FFL-1720-pr2-aggregation branch from 0cfb30a to 141cded Compare January 28, 2026 07:50

typotter requested review from dd-oleksii and sameerank January 28, 2026 07:51

typotter force-pushed the typo/FFL-1720-pr2-aggregation branch from 141cded to 4bfc37e Compare January 28, 2026 16:33

typotter force-pushed the typo/FFL-1720-pr3-storage-network branch from 4f4c253 to df51ceb Compare January 28, 2026 16:35

typotter force-pushed the typo/FFL-1720-pr2-aggregation branch from 4bfc37e to 550f9f0 Compare January 28, 2026 17:05

typotter force-pushed the typo/FFL-1720-pr3-storage-network branch from 3618528 to cce61c1 Compare January 28, 2026 23:04

typotter marked this pull request as ready for review January 29, 2026 05:56

typotter requested a review from a team as a code owner January 29, 2026 05:56

typotter mentioned this pull request Jan 30, 2026

[Flags] FlagEvaluation schema #3166

Merged

3 tasks

typotter force-pushed the typo/FFL-1720-pr2-aggregation branch from 4b1cbc1 to 7e2293e Compare January 30, 2026 17:36

typotter force-pushed the typo/FFL-1720-pr3-storage-network branch from 8813c89 to 56da165 Compare January 30, 2026 20:54

typotter force-pushed the typo/FFL-1720-pr2-aggregation branch from 512a272 to e0d2ae7 Compare February 2, 2026 04:47

typotter force-pushed the typo/FFL-1720-pr3-storage-network branch from 56da165 to 5ba6fec Compare February 2, 2026 04:47

typotter requested a review from 0xnm February 2, 2026 05:00

typotter force-pushed the typo/FFL-1720-pr3-storage-network branch 3 times, most recently from e84dada to fb01eef Compare February 2, 2026 06:20

dd-oleksii approved these changes Feb 2, 2026

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typotter changed the base branch from typo/FFL-1720-pr2-aggregation to graphite-base/3146 February 2, 2026 18:39

typotter added 14 commits February 2, 2026 11:45

storage writer and network request factory

db50e7f

tests

c644f0d

write All

70d0be1

lint

718b08a

safe listof call

17d0475

update tests

5f60edb

lint and api

11db057

improve tests

99da5be

stack artifact

727f037

drop writeone

f6e69ad

drop superfluous synchronized

e55b8ea

Update network and storage to use FlagEvaluation

7d2af2e

use updated schema

0bee77e

merge artifacts

3a685c2

typotter force-pushed the graphite-base/3146 branch from eb19187 to 66b62f4 Compare February 2, 2026 18:47

typotter force-pushed the typo/FFL-1720-pr3-storage-network branch from fb01eef to 3a685c2 Compare February 2, 2026 18:47

0xnm approved these changes Feb 3, 2026

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0xnm reviewed Feb 3, 2026

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[FFL-1720] Evaluation Logging: Storage & Network Infrastructure#3146

[FFL-1720] Evaluation Logging: Storage & Network Infrastructure#3146
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🥞 Evaluation Logging Stacked Pull Requests 🥞

What does this PR do?

Motivation

Additional Notes

Review checklist (to be filled by reviewers)

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