feat(csharp): implement CircuitBreakerTelemetryExporter (WI-3.3) by jadewang-db · Pull Request #171 · adbc-drivers/databricks

jadewang-db · 2026-01-22T18:42:19Z

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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]

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>

Update all CircuitBreaker tests to use the new constructor that takes a CircuitBreakerConfig object instead of individual parameters. Changes: - Add helper methods CreateDefaultConfig() and CreateConfig() for cleaner test setup - Replace `new CircuitBreaker()` with `new CircuitBreaker(CreateDefaultConfig())` - Replace `new CircuitBreaker(failureThreshold: N)` with `new CircuitBreaker(CreateConfig(failureThreshold: N))` - Replace `new CircuitBreaker(failureThreshold: N, timeout: T)` with `new CircuitBreaker(CreateConfig(failureThreshold: N, timeout: T))` - Add new tests for constructor with null config and config storage 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>

Rewrite E2E tests for FeatureFlagCache to use the actual production API: - Use MergePropertiesWithFeatureFlagsAsync() instead of non-existent IsTelemetryEnabledAsync() - Use HasContext(), TryGetContext(), RemoveContext(), Clear() for cache management testing - Remove tests for non-existent reference counting (RefCount property) - Remove tests for non-existent TelemetryEnabled, LastFetched, IsExpired - Fix namespace import from Telemetry to correct namespace - Add tests for TryGetHost protocol stripping and Uri extraction The previous tests were testing an API that didn't exist and would not compile. 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>

jadewang-db had a problem deploying to azure-prod January 22, 2026 18:42 — with GitHub Actions Error

jadewang-db force-pushed the stack/circuit-breaker-telemetry-exporter branch from 74ce91f to 91db593 Compare January 22, 2026 22:24

jadewang-db had a problem deploying to azure-prod January 22, 2026 22:24 — with GitHub Actions Error

jadewang-db force-pushed the stack/circuit-breaker-telemetry-exporter branch from 91db593 to 4473de5 Compare January 23, 2026 21:14

jadewang-db had a problem deploying to azure-prod January 23, 2026 21:15 — with GitHub Actions Error

jadewang-db force-pushed the stack/circuit-breaker-telemetry-exporter branch from 4473de5 to 0a01595 Compare January 23, 2026 21:43

jadewang-db had a problem deploying to azure-prod January 23, 2026 21:44 — with GitHub Actions Error

jadewang-db force-pushed the stack/circuit-breaker-telemetry-exporter branch from 0a01595 to 3e416c9 Compare January 26, 2026 22:43

jadewang-db had a problem deploying to azure-prod January 26, 2026 22:43 — with GitHub Actions Error

jadewang-db force-pushed the stack/circuit-breaker-telemetry-exporter branch from 3e416c9 to b5801d2 Compare January 26, 2026 23:01

jadewang-db had a problem deploying to azure-prod January 26, 2026 23:01 — with GitHub Actions Error

jadewang-db had a problem deploying to azure-prod February 3, 2026 18:24 — with GitHub Actions Error

jadewang-db force-pushed the stack/circuit-breaker-telemetry-exporter branch from b5f3cd9 to 9b5e88c Compare February 3, 2026 18:32

jadewang-db had a problem deploying to azure-prod February 3, 2026 18:32 — with GitHub Actions Error

jadewang-db force-pushed the stack/circuit-breaker-telemetry-exporter branch from 9b5e88c to e886588 Compare February 10, 2026 01:30

jadewang-db had a problem deploying to azure-prod February 10, 2026 01:30 — with GitHub Actions Error

jadewang-db force-pushed the stack/circuit-breaker-telemetry-exporter branch from e886588 to 383d3ef Compare February 10, 2026 18:35

jadewang-db had a problem deploying to azure-prod February 10, 2026 18:35 — with GitHub Actions Error

jadewang-db force-pushed the stack/circuit-breaker-telemetry-exporter branch from 383d3ef to 1b1acfe Compare February 11, 2026 04:41

jadewang-db had a problem deploying to azure-prod February 11, 2026 04:41 — with GitHub Actions Error

jadewang-db force-pushed the stack/circuit-breaker-telemetry-exporter branch from 1b1acfe to 6b6bbad Compare February 17, 2026 23:08

jadewang-db had a problem deploying to azure-prod February 17, 2026 23:08 — with GitHub Actions Error

Jade Wang and others added 4 commits February 26, 2026 18:39

address comments

e76e259

Fix flaky test

a325755

change to use the new proto model

cded7cd

jadewang-db force-pushed the stack/circuit-breaker-telemetry-exporter branch from 6b6bbad to 09c48b4 Compare February 26, 2026 18:54

jadewang-db had a problem deploying to azure-prod February 26, 2026 18:54 — with GitHub Actions Error

Jade Wang and others added 8 commits February 27, 2026 22:47

metric aggregator change after proto

2bf4693

address initial comments

bde22f7

jadewang-db force-pushed the stack/circuit-breaker-telemetry-exporter branch from 09c48b4 to 2c0a48c Compare February 27, 2026 22:47

jadewang-db requested a deployment to azure-prod February 27, 2026 22:47 — with GitHub Actions Waiting

jadewang-db closed this Mar 4, 2026

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feat(csharp): implement CircuitBreakerTelemetryExporter (WI-3.3)#171

feat(csharp): implement CircuitBreakerTelemetryExporter (WI-3.3)#171
jadewang-db wants to merge 12 commits intomainfrom
stack/circuit-breaker-telemetry-exporter

jadewang-db commented Jan 22, 2026 •

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jadewang-db commented Jan 22, 2026 •

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