Skip to content

README.md

Latest commit

 

History

History
23 lines (17 loc) · 1.94 KB

README.md

File metadata and controls

23 lines (17 loc) · 1.94 KB

TideTracker Project

Technical Implementation: Threading and Synchronization

Why Threads are Used

This project uses the threading module to manage the transition between Access Point (AP) mode and Station (client) mode during WiFi configuration.

WiFi management is a blocking and destructive process. When a user submits new credentials via the web UI:

  1. Asynchronous Response: The HTTP server must send a "TESTING" response to the browser immediately so the user sees a confirmation.
  2. Avoiding Connection Cutoff: If this were done synchronously, the server would call stop_hotspot() before sending the response, instantly killing the connection and leaving the user with a browser network error.
  3. Background Processing: By spawning a background thread, the server can respond to the user first, then proceed to tear down the hotspot and test the new credentials.

The NM_LOCK (Thread Safety)

Because the HTTP server remains active (listening for status polls from the browser) while the background thread interacts with the WiFi hardware, there is a risk of deadlocks or race conditions within the NetworkManager DBus interface.

The NM_LOCK in netman.py ensures that only one thread can communicate with NetworkManager at a time. This synchronizes:

  • Background tests: Connecting, deactivating, and falling back.
  • UI Status updates: Periodic scanning and connection status checks.

Persistent Fallback and Resilience

To ensure the device remains accessible even after failed configuration attempts:

  • Auto-Capture: On startup, the script attempts to capture and save the current working WiFi connection as a persistent fallback point in tidetracker_persistent_data.json.
  • Automatic Reversion: If a new connection attempt fails (due to incorrect credentials or lack of internet), the background thread automatically attempts to restore the previous working connection before deciding to relaunch the hotspot.