precomputed client #236
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precomputed client #236
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Add EppoPrecomputedClient for precomputed flag assignments computed server-side at the edge endpoint. Key features: - Subject-specific initialization (client bound to user at init time) - HTTP POST to edge endpoint: https://fs-edge-assignment.eppo.cloud/assignments - Obfuscation support with MD5 hashing and Base64 decoding - All assignment methods: string, boolean, integer, numeric, JSON, bandit - Offline mode with initialConfiguration for sync without network - Polling support for configuration updates - Assignment logging with deduplication via IAssignmentCache - Graceful mode for error handling New files: - DTOs: PrecomputedFlag, PrecomputedBandit, PrecomputedConfigurationResponse, BanditResult - Utilities: ObfuscationUtils (MD5 hashing) - Storage: PrecomputedCacheFile, PrecomputedConfigurationStore - Client: EppoPrecomputedClient with Builder pattern - Exception: MissingSubjectKeyException - Tests: Unit and instrumented tests
Add a new activity to the example app demonstrating the EppoPrecomputedClient. The new tab allows users to: - Initialize the precomputed client with a subject ID - Test different flag types (string, boolean, integer, numeric) - View assignment logs in real-time Files changed: - PrecomputedActivity.java: New activity for precomputed client demo - activity_precomputed.xml: Layout for the precomputed activity - MainActivity.java: Add button to launch precomputed activity - activity_main.xml: Add precomputed button to main layout - AndroidManifest.xml: Register PrecomputedActivity - strings.xml: Add new string resources
Use MD5 hash of subject key instead of safeCacheKey() to ensure consistent length and avoid StringIndexOutOfBoundsException when subject key is shorter than 8 characters.
- Add dynamic subject attributes table to PrecomputedActivity - Users can add/remove key-value pairs for subject attributes - Numeric values are automatically detected and typed correctly - Add HTTP request/response logging to EppoPrecomputedClient - Log request URL, payload, and detailed error messages
Both keys and values in bandit actionNumericAttributes and actionCategoricalAttributes are Base64 encoded in the server response.
- Update Makefile to fetch precomputed-v1.json test data - Add tests for all assignment types using sdk-test-data fixtures - Add bandit action tests - Tests validate string, boolean, integer, numeric, and JSON flags
Keep sdk-test-data tests for canonical evaluation behavior. Keep mock data tests only for SDK behavior: cache, lifecycle, validation, logging.
The extraLogging and metaData parameters were swapped, causing getMetaData() to return the wrong map and failing the test.
- Rename MainActivity to HomeActivity - Rename SecondActivity to StandardClientActivity - Add action bar back button to StandardClientActivity and PrecomputedActivity - Set parent activity for proper up navigation
…ctivity - Replace single Initialize button with "From Server" and "From Disk" buttons - From Server: fetches configuration from edge endpoint - From Disk: uses offline mode with cached configuration only - Update status messages to indicate initialization source
- Disable Get Assignment button until client is initialized - Update Clear Cache to also delete precomputed cache files - Show count of deleted precomputed caches in toast message
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Pull request overview
This PR introduces a new EppoPrecomputedClient that solves Android ANR (Application Not Responding) issues during initialization for deployments with many flags and complex targeting rules. Instead of evaluating flags client-side, all assignments are computed server-side and delivered as a batch, providing instant O(1) lookups with zero evaluation time.
Changes:
- Implemented
EppoPrecomputedClientwith builder pattern matching existingEppoClientAPI style, supporting all flag types and bandit actions - Added supporting infrastructure including
PrecomputedConfigurationStorefor in-memory/disk caching,ObfuscationUtilsfor MD5 hashing, and related DTOs - Enhanced example app with new
PrecomputedActivitydemonstrating the precomputed client functionality
Reviewed changes
Copilot reviewed 20 out of 20 changed files in this pull request and generated 1 comment.
Show a summary per file
| File | Description |
|---|---|
example/src/main/res/values/strings.xml |
Added string resource for launching precomputed client |
example/src/main/res/layout/activity_precomputed.xml |
New layout for precomputed client demo with subject attributes, flag type selection, and assignment logging |
example/src/main/res/layout/activity_home.xml |
Added button to launch precomputed activity |
example/src/main/java/cloud/eppo/androidexample/StandardClientActivity.java |
Renamed from SecondActivity and added back navigation support |
example/src/main/java/cloud/eppo/androidexample/PrecomputedActivity.java |
New activity demonstrating precomputed client with server/disk initialization options |
example/src/main/java/cloud/eppo/androidexample/HomeActivity.java |
Renamed from MainActivity, added precomputed activity launcher and cache clearing for precomputed clients |
example/src/main/AndroidManifest.xml |
Updated activity names and added parent activity declarations for back navigation |
eppo/src/test/java/cloud/eppo/android/PrecomputedConfigurationResponseTest.java |
Unit tests for precomputed configuration response deserialization |
eppo/src/test/java/cloud/eppo/android/ObfuscationUtilsTest.java |
Unit tests for MD5 hashing utility |
eppo/src/main/java/cloud/eppo/android/util/ObfuscationUtils.java |
Utility class for MD5 hashing used in flag key obfuscation |
eppo/src/main/java/cloud/eppo/android/exceptions/MissingSubjectKeyException.java |
New exception for missing subject key validation |
eppo/src/main/java/cloud/eppo/android/dto/PrecomputedFlag.java |
DTO for precomputed flag assignments with Base64-encoded fields |
eppo/src/main/java/cloud/eppo/android/dto/PrecomputedConfigurationResponse.java |
Wire protocol response from precomputed edge endpoint |
eppo/src/main/java/cloud/eppo/android/dto/PrecomputedBandit.java |
DTO for precomputed bandit assignments |
eppo/src/main/java/cloud/eppo/android/dto/BanditResult.java |
Return type for bandit action assignments |
eppo/src/main/java/cloud/eppo/android/PrecomputedConfigurationStore.java |
Configuration storage with disk caching |
eppo/src/main/java/cloud/eppo/android/PrecomputedCacheFile.java |
Disk cache file management for precomputed configuration |
eppo/src/main/java/cloud/eppo/android/EppoPrecomputedClient.java |
Main precomputed client implementation with assignment methods, logging, and polling |
eppo/src/androidTest/java/cloud/eppo/android/EppoPrecomputedClientTest.java |
Integration tests for precomputed client using test data |
Makefile |
Updated test data copying to include precomputed configuration files |
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| * Example activity demonstrating the EppoPrecomputedClient. The precomputed client computes all |
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Corrected spelling of 'recieve' to 'receive' in class documentation.
Suggested change
| * Example activity demonstrating the EppoPrecomputedClient. The precomputed client computes all | |
| * Example activity demonstrating the EppoPrecomputedClient. The precomputed client receives all |
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Eppo Internal:
🎟️ Fixes issue
📜 Design Doc: link if applicable
Motivation and Context
When using the standard client with very large flag deployments (many flags with complex targeting rules), the client-side evaluation during initialization can exceed Android's 5-second ANR (Application Not Responding) threshold. This creates a poor user experience with unresponsive apps on startup.
The Precomputed API solves this by:
Description
Core SDK Changes
New EppoPrecomputedClient - A new client optimized for precomputed assignments:
Supporting Classes:
How has this been documented?
Example App Improvements
How has this been tested?