[0xaboomar]

This PR introduces the following major refactors:

• Create and configure a shared http.Client with connection pooling to be reused across the application.
• Encapsulate GTFS-RT data into a thread-safe RealtimeStore struct.
• Ensure realtime data is fetched once per server and passed to all dependent functions (e.g., telemetry, invalid vehicles, out-of-bounds tracking).
• Remove redundant GTFS-RT API calls and centralize fetch-and-parse logic in FetchAndStoreGTFSRTFeed.

To Do:

• The Go SDK provides its own HTTP client for GetAgenciesWithCoverage; explore whether it can be configured to reuse connections via a shared http.Transport or injected client.

[coveralls]

coverage: 49.204% (-5.0%) from 54.223%
when pulling 89289fd on Abo-Omar-74:refactor/reuse-http-client-realtime-store
into fb33cf1 on OneBusAway:main.

[Copilot]

Pull Request Overview

This PR implements connection pooling and realtime data sharing to eliminate redundant GTFS-RT API calls. The refactor centralizes GTFS-RT data fetching and enables multiple functions to reuse the same parsed data.

• Creates a shared HTTP client with connection pooling for improved performance across all API calls
• Introduces thread-safe RealtimeStore to share parsed GTFS-RT data between functions
• Refactors metrics collection to fetch GTFS-RT data once and pass it to dependent functions

Reviewed Changes

Copilot reviewed 19 out of 20 changed files in this pull request and generated 14 comments.

Show a summary per file

File	Description
internal/utils/helpers.go	Adds GTFS-RT data hashing utility for test validation
internal/utils/customTime.go	Adds custom time type with YYYYMMDD JSON marshaling
internal/utils/cache.go	Adds generic file I/O functions for map serialization
internal/gtfs/realtime_store.go	Creates thread-safe store for sharing GTFS-RT data
internal/gtfs/gtfs_bundles.go	Refactors GTFS-RT fetching to store data and extract service date logic
internal/metrics/gtfs-realtime-bindings.go	Updates functions to use shared realtime store and vehicle tracking
internal/app/client.go	Implements pooled HTTP client with optimized connection settings
internal/app/app.go	Adds new dependencies to application structure
cmd/watchdog/main.go	Integrates new components and context-based lifecycle management

Comments suppressed due to low confidence (1)

internal/utils/customTime.go:8

• The constant name YYYYMMDD should follow Go naming conventions and be either exported (capitalized) or unexported (lowercase). Since it's used only within this package, consider renaming it to 'yyyymmdd' or if it needs to be exported, add a comment explaining its purpose.

const YYYYMMDD = "20060102"

[aaronbrethorst]

@Abo-Omar-74 Be sure to run go fmt ./...!

[0xaboomar]

I have applied Copilot's suggestions

[0xaboomar]

Follow Up

Add internal performance metrics

The changes introduce internal latency instrumentation for outgoing HTTP requests to external APIs and improve visibility into memory usage. These metrics enhance observability without adding significant system load.

Tracking external API Response Times

• Added latencyTrackingRoundTripper to wrap the HTTP transport and measure request duration.
• Introduced http_outgoing_request_duration_seconds Prometheus histogram, labeled by URL, method, and status code.
• Integrated the instrumented transport into the pooled HTTP client used across the app.

Memory Usage Tracking

Memory usage is tracked via Prometheus's default /metrics handler, utilizing Go’s built-in metrics, which update as the application runs, eliminating the need for a custom polling goroutine.

[aaronbrethorst]

nice work 👍