GTFS RT Trip Updates provider > keep feed in memory

[mmathieum]

Fix #108

[mmathieum]

/gemini review

[gemini-code-assist]

Code Review

This pull request refactors GTFS Realtime utility functions by simplifying logic, adjusting return types, and removing unused parameters in sorting methods. It also introduces a file-backed memory cache for trip updates in the GTFSRealTimeTripUpdatesProvider. Feedback highlights that the static cache implementation may cause data collisions in multi-agency environments, lacks thread safety and proper memory visibility in its lazy initialization, and performs redundant disk I/O during the data loading process.

[Copilot]

Pull request overview

This PR addresses #108 by reducing repeated disk reads for GTFS Realtime Trip Updates, keeping the parsed TripUpdate list in memory and refreshing it when new data is downloaded.

Changes:

• Add lazy-loaded, in-memory caching for GTFS RT Trip Updates parsed from gtfs_rt_trip_update.pb.
• Update Trip Updates fetching flow to reset/reload the in-memory cache when new data is downloaded.
• Remove unused “nowMs” parameters from GTFS RT sorting helpers and update call sites (TripUpdates + VehiclePositions).

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
src/main/java/org/mtransit/android/commons/provider/vehiclelocations/GTFSRealTimeVehiclePositionsProvider.kt	Updates vehicle sorting call to match new helper signature.
src/main/java/org/mtransit/android/commons/provider/status/GTFSRealTimeTripUpdatesProvider.kt	Implements in-memory TripUpdate caching and refresh logic during network load.
src/main/java/org/mtransit/android/commons/provider/gtfs/GtfsRealtimeExt.kt	Refactors helpers (expression bodies, explicit return types) and removes unused parameters from sort functions.

[gemini-code-assist]

Code Review

This pull request refactors GTFS Realtime extension methods by removing unused parameters and standardizing return types, while also introducing an in-memory cache for trip updates in GTFSRealTimeTripUpdatesProvider to reduce file I/O. Feedback suggests marking the cache backing field as @volatile to ensure thread safety in the double-checked locking implementation and recommends using a keyed map instead of a single field to prevent data corruption when multiple providers are active.

[mmathieum]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces memory caching for GTFS Real-Time trip updates to reduce disk I/O and improves memory management by implementing onLowMemory and onTrimMemory hooks. It also includes several refactors to extension functions, such as removing unused parameters and standardizing return types. Feedback focuses on a potential bug where the singleton cache could incorrectly share data between different transit agencies and suggests a more thread-safe approach for updating the cache during data retrieval.

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 2 comments.

[mmathieum]

/gemini review

[gemini-code-assist]

Code Review

This pull request introduces an in-memory cache for GTFS Real-Time trip updates and implements memory management via onLowMemory and onTrimMemory to clear the cache under pressure. It also refactors several extension functions to remove unused parameters and improve code structure. Feedback identifies a significant risk of data corruption if multiple providers are used, as the cache and file names are currently shared across all instances. Furthermore, performing disk I/O within synchronized blocks could potentially block the UI thread during memory trim operations, leading to responsiveness issues.

[mmathieum]

/gemini review

[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 3 comments.

[gemini-code-assist]

Code Review

This pull request implements memory management for GTFS Real-Time trip updates by introducing a memory cache that is cleared during low-memory or memory-trim events. The GTFSRealTimeTripUpdatesProvider is refactored to use a lazy-loading property for these updates, and GtfsRealtimeExt.kt is cleaned up by removing unused parameters and adjusting return types. I have no feedback to provide.