test(csharp): add E2E tests for TelemetryClient standalone (Phase 7 E2E GATE) #175

jadewang-db · 2026-01-22T18:42:23Z

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stack/wi-3.1-feature-flag-cache [Files changed]
- stack/wi-3.4-databricks-telemetry-exporter [Files changed]
  - stack/wi-3.5-metrics-aggregator [Files changed]
    - stack/wi-3.5-circuit-breaker-manager [Files changed]
      - stack/e2e-feature-flag-cache-tests [Files changed]
        
        stack/databricks-activity-listener [Files changed]
        
        stack/circuit-breaker-telemetry-exporter [Files changed]
        
        stack/telemetry-client-manager-wi-3.2 [Files changed]
        
        stack/telemetry-client-wi-5.5 [Files changed]
        
        stack/telemetry-client-manager-e2e-wi-7 [Files changed]
        stack/telemetry-client-e2e-tests-wi-7-standalone [Files changed]
        stack/wi-6.1-databricks-connection-telemetry-integration [Files changed]
        stack/wi-6.2-telemetry-tags-driver-activities [Files changed]
        stack/wi-9-full-integration-e2e-tests [Files changed]

Implements per-host feature flag caching with reference counting to avoid repeated API calls and rate limiting. Key features: - FeatureFlagContext: Holds cached telemetry enabled state, last fetched timestamp, reference count, and configurable cache duration (default 15 min) - FeatureFlagCache: Singleton managing per-host contexts with thread-safe ConcurrentDictionary storage API: - GetInstance(): Returns the singleton instance - GetOrCreateContext(host): Creates/returns context and increments RefCount - ReleaseContext(host): Decrements RefCount, removes context when zero - IsTelemetryEnabledAsync(): Returns cached value if valid, otherwise fetches Thread safety ensured via ConcurrentDictionary and Interlocked operations. Includes 46 comprehensive unit tests covering all exit criteria. Co-Authored-By: Claude <noreply@anthropic.com>

…(WI-3.1) Refactored FeatureFlagCache based on updated design doc requirements: - Moved from Telemetry namespace to root namespace (AdbcDrivers.Databricks) to make it a generic, reusable component - Added HTTP API integration to fetch flags from /api/2.0/connector-service/feature-flags/OSS_JDBC/{version} - Implemented background refresh scheduler with server-provided TTL - Added FeatureFlagsResponse model for API response parsing - Updated FeatureFlagContext interface: - GetFlagValue(string) - get individual flag value - GetAllFlags() - get all cached flags as dictionary - IsFeatureEnabled(string) - check if flag is "true" - Shutdown() - stop background refresh scheduler - IDisposable for proper cleanup - Updated FeatureFlagCache.GetOrCreateContext() to accept HttpClient and driver version parameters - Updated all unit tests for new interface Co-Authored-By: Claude <noreply@anthropic.com>

…I-3.1) Integrated feature flag cache into the connection lifecycle: - Fetch feature flags from server during connection initialization - Merge flags into Properties dictionary with proper priority: User Properties > Feature Flags > Driver Defaults - Track host for proper context cleanup on Dispose - Release feature flag context when connection is disposed - All feature flag operations are fail-safe (errors logged, not thrown) The feature flag endpoint used is: GET /api/2.0/connector-service/feature-flags/OSS_JDBC/{driver_version} Co-Authored-By: Claude <noreply@anthropic.com>

…-3.1) - Add EnsureSuccessStatusCode pattern for HTTP response handling - Extract common HTTP fetch code into single FetchFeatureFlags method - Make feature flag endpoint configurable via optional parameter - Replace Debug.WriteLine with Activity trace pattern - Add E2E tests for FeatureFlagCache using real Databricks instance Co-Authored-By: Claude (databricks-claude-opus-4-5) <noreply@anthropic.com>

…WI-3.1) - Move MergePropertiesWithFeatureFlags, TryGetHost, CreateFeatureFlagHttpClient, and MergeProperties helper methods from DatabricksConnection to FeatureFlagCache - Replace Debug.WriteLine with ActivitySource tracing for structured events - DatabricksConnection now delegates to FeatureFlagCache.GetInstance().MergePropertiesWithFeatureFlags() Co-Authored-By: Claude (databricks-claude-opus-4-5) <noreply@anthropic.com>

…ructor (WI-3.1) Replace hardcoded "1.0.0" with ApacheUtility.GetAssemblyVersion() to use the actual driver version in the test constructor. Co-Authored-By: Claude (databricks-claude-opus-4-5) <noreply@anthropic.com>

…-3.1) - Add proxy support using HiveServer2ProxyConfigurator - Handle protocol prefix in host (e.g., "https://myhost.databricks.com") - Add configurable timeout via FeatureFlagTimeoutSeconds parameter - Use consistent User-Agent format: DatabricksJDBCDriverOSS/{version} (ADBC) - Rename variables to localProperties/remoteProperties for clarity - Remove IsFeatureEnabled method from FeatureFlagContext - Use EnsureSuccessOrThrow extension method for HTTP error handling - Enhance E2E tests to verify flags fetched and cache cleanup Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Add support for OAuth client_credentials (M2M) authentication in addition to token-based (PAT) auth for feature flag API calls. This ensures feature flags work with all supported authentication methods. - Add AuthHelper class with shared token extraction methods - Update FeatureFlagCache to use AuthHelper.GetAccessToken - Update HttpHandlerFactory to use AuthHelper.GetTokenFromProperties Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Move the test factory method from production to test code: - Make FeatureFlagContext constructor internal instead of private - Make Ttl setter internal to allow tests to configure TTL - Remove CreateForTesting from FeatureFlagContext.cs - Add CreateTestContext helper method in FeatureFlagCacheTests.cs This addresses the PR review feedback that test-only code should not be in production source files. Co-Authored-By: Claude Opus 4.5 <noreply@anthropic.com>

Implement the HTTP exporter that sends telemetry events to Databricks service. Key features: - ITelemetryExporter interface with ExportAsync method - Creates TelemetryRequest wrapper with uploadTime and protoLogs - Uses /telemetry-ext for authenticated requests - Uses /telemetry-unauth for unauthenticated requests - Implements retry logic for transient failures - Uses ExceptionClassifier for terminal vs retryable errors - Never throws exceptions (all swallowed and logged at TRACE level) - Cancellation is propagated (not swallowed) Files added: - src/Telemetry/ITelemetryExporter.cs - src/Telemetry/DatabricksTelemetryExporter.cs - test/Unit/Telemetry/DatabricksTelemetryExporterTests.cs Co-Authored-By: Claude <noreply@anthropic.com>

Implement MetricsAggregator that aggregates Activity data by statement_id and handles exception buffering with terminal vs retryable classification. Key features: - ProcessActivity extracts tags and aggregates by statement_id using ConcurrentDictionary<string, StatementTelemetryContext> - CompleteStatement emits aggregated TelemetryEvent - RecordException flushes terminal exceptions immediately - RecordException buffers retryable exceptions until CompleteStatement - FlushAsync exports when batch size or time interval reached - Uses TelemetryTagRegistry to filter tags - Creates TelemetryFrontendLog wrapper with workspace_id - All exceptions swallowed and logged at TRACE level Implementation details: - Connection events emit immediately (no aggregation needed) - Statement events aggregate until CompleteStatement is called - Timer-based periodic flush using System.Threading.Timer - Thread-safe aggregation using ConcurrentDictionary - Nested StatementTelemetryContext holds aggregated metrics and buffered exceptions per statement Test coverage: - 29 unit tests covering all exit criteria - Tests for exception handling, tag filtering, frontend log wrapping - End-to-end statement lifecycle tests Co-Authored-By: Claude <noreply@anthropic.com>

Implement CircuitBreakerManager as a singleton that manages circuit breakers per host. Each host gets its own circuit breaker instance for isolation, preventing one failing endpoint from affecting others. Key features: - Singleton pattern with GetInstance() method - Per-host circuit breaker isolation using ConcurrentDictionary - Thread-safe concurrent access - Case-insensitive host matching - Support for both default and custom configurations This follows the JDBC driver pattern in CircuitBreakerManager.java. Co-Authored-By: Claude <noreply@anthropic.com>

Add comprehensive E2E tests for feature flag fetching from real Databricks endpoints and validate caching and reference counting behavior: - FeatureFlagCache_FetchFromRealEndpoint_ReturnsBoolean: Tests real endpoint - FeatureFlagCache_CachesValue_DoesNotRefetchWithinTTL: Validates caching - FeatureFlagCache_InvalidHost_ReturnsDefaultFalse: Tests error handling - FeatureFlagCache_RefCountingWorks_CleanupAfterRelease: Tests ref counting Additional tests cover: - Cache expiry and refetch behavior - Null/empty host handling - Unknown host behavior - Multiple hosts with independent ref counts - Concurrent reference counting thread safety - False value caching - Cancellation propagation Co-Authored-By: Claude <noreply@anthropic.com>

Add DatabricksActivityListener that listens to 'Databricks.Adbc.Driver' ActivitySource, extracts metrics from activities, and delegates to MetricsAggregator. This implements Phase 5 of the telemetry design. Key features: - ShouldListenTo returns true for 'Databricks.Adbc.Driver' source - Sample callback respects feature flag (AllDataAndRecorded when enabled, None when disabled) - ActivityStopped callback delegates to MetricsAggregator.ProcessActivity - All callbacks wrapped in try-catch with TRACE logging - StopAsync flushes pending metrics via MetricsAggregator.FlushAsync - Supports dynamic feature flag checking via optional Func<bool> Co-Authored-By: Claude <noreply@anthropic.com>

Implement wrapper exporter that protects inner telemetry exporter with circuit breaker pattern. Key features: - Wraps ITelemetryExporter with circuit breaker protection - Uses CircuitBreakerManager.GetCircuitBreaker(host) for per-host isolation - Exports events when circuit is closed - Drops events silently when circuit is open (logged at DEBUG level) - Circuit breaker tracks failures BEFORE exceptions are swallowed This follows the design in Section 3.3 of the telemetry design document. Co-Authored-By: Claude <noreply@anthropic.com>

Implement per-host telemetry client management with reference counting to prevent rate limiting from concurrent connections. - ITelemetryClient: Interface for telemetry clients with ExportAsync and CloseAsync methods - TelemetryClientHolder: Holds client and reference count with atomic operations using Interlocked - TelemetryClientManager: Singleton factory managing one client per host using ConcurrentDictionary for thread-safety - TelemetryClientAdapter: Adapter bridging ITelemetryExporter to ITelemetryClient interface Key features: - GetInstance() returns singleton - GetOrCreateClient() creates/returns client and increments RefCount - ReleaseClientAsync() decrements RefCount, closes client when zero - Same host returns same client instance (case-insensitive) - Thread-safe with ConcurrentDictionary and atomic ref counting - All exceptions swallowed per telemetry design requirement Co-Authored-By: Claude <noreply@anthropic.com>

Implement TelemetryClient that coordinates listener, aggregator, and exporter. Manages background flush task and graceful shutdown. Changes: - Add TelemetryClient.cs implementing ITelemetryClient interface - Constructor initializes full telemetry pipeline: DatabricksTelemetryExporter → CircuitBreakerTelemetryExporter → MetricsAggregator → DatabricksActivityListener - ExportAsync delegates to the circuit breaker protected exporter - CloseAsync implements graceful shutdown per design doc Section 9.3: - Cancels background flush task - Stops listener (which flushes pending metrics) - Waits for background task with 5s timeout - Disposes all resources - All exceptions swallowed and logged at TRACE level - Background flush task periodically exports pending metrics - Update TelemetryClientManager.CreateClient() to use TelemetryClient - Add comprehensive unit tests (21 tests) covering: - Constructor initialization - Export delegation - Close with flush and cancellation - Exception swallowing during close - Background flush behavior - Thread safety Test file: csharp/test/Unit/Telemetry/TelemetryClientTests.cs Co-Authored-By: Claude <noreply@anthropic.com>

…ATE) Add end-to-end tests for TelemetryClientManager per-host client management: - TelemetryClientManager_SameHost_ReturnsSameClient: Validates same host returns same client - TelemetryClientManager_DifferentHosts_ReturnsDifferentClients: Validates different hosts get different clients - TelemetryClientManager_ConcurrentAccess_ThreadSafe: Validates thread-safety under concurrent access - TelemetryClientManager_LastRelease_ClosesClient: Validates reference counting and cleanup Additional tests for comprehensive coverage: - Case-insensitive host comparison - Mixed hosts handling - Concurrent release behavior - Concurrent get and release operations - Concurrent access to multiple hosts - Unknown host release handling - Exception swallowing during close Co-Authored-By: Claude <noreply@anthropic.com>

…2E GATE) Add comprehensive E2E tests for TelemetryClient in isolation against real Databricks endpoint. Tests validate: - Single event export to real endpoint - Batch event export to real endpoint - Authenticated endpoint usage (/telemetry-ext) - Circuit breaker opens after consecutive failures (default threshold 5) - Circuit breaker recovers after timeout period (half-open -> closed) - Graceful close flushes all pending events - Idempotent close behavior - Export after close doesn't throw The tests use mock exporters for circuit breaker behavior testing since the DatabricksTelemetryExporter swallows exceptions internally. This allows the CircuitBreakerTelemetryExporter wrapper to properly track failures. Co-Authored-By: Claude <noreply@anthropic.com>

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Jade Wang and others added 9 commits February 3, 2026 18:10

Address comments and refactoring

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test(csharp): add E2E tests for TelemetryClient standalone (Phase 7 E2E GATE) #175

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jadewang-db commented Jan 22, 2026 •

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