Network Failure & Drop Simulation

Stress-testing download resumability, retry state machines, and graceful failure handling under severe network loss.

Table of Contents

1. The Hostile Reality of Player Networks
2. Step 1: Crafting the “Subway Tunnel” Fault Profile
3. Step 2: Running the Rehearsal
   1. What You Should Observe in the Client Binary:
4. Step 3: Capturing Evidence with a Repro-Pack

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The Hostile Reality of Player Networks

In development environments with high-speed fiber internet, Addressables downloads almost never fail. In the real world, your players download updates:

• On crowded cellular towers with 800 ms latency spikes.
• On subway trains passing through tunnels with total socket resets.
• Behind restrictive hotel or airport captive portals that intercept HTTP streams.

This workflow explains how to use PatchProof’s Fault Profiles to harden your game’s networking code.

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Step 1: Crafting the “Subway Tunnel” Fault Profile

1. Open Tools > PatchProof > Origin & Fault Profiles.
2. Click “New Fault Profile” and name it SubwayTunnel_Drop.
3. Configure Rule 1 (Socket Reset):
   • Fault Type: ConnectionDrop
   • URL Pattern: .*_assets_.*\.bundle (Targets primary gameplay bundles).
   • Trigger Byte Offset: 262144 (Drops the connection after exactly 256 KB transferred).
4. Configure Rule 2 (High Latency Retry):
   • Fault Type: LatencyDelay
   • URL Pattern: .*
   • Delay Milliseconds: 1500 (Forces all subsequent requests to wait 1.5 seconds).
5. Click “Save Fault Profile”.

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Step 2: Running the Rehearsal

1. Open Tools > PatchProof > Rehearsal Room.
2. Set your candidate update pairing.
3. In the Active Fault Profile dropdown, select SubwayTunnel_Drop.
4. Click “Run Selected Scenario” (targeting the FreshCache_ConnectionDrop tile).

What You Should Observe in the Client Binary:

1. The client begins downloading the bundle.
2. The download progress bar reaches ~15% and stops.
3. The local origin closes the TCP socket.
4. Good Client Behavior:
   • The client catches the ConnectionError.
   • A non-blocking retry indicator appears: “Connection interrupted. Retrying in 3… 2… 1…”
   • The client initiates a new request with an HTTP Range: bytes=262144- header.
   • The download finishes, and the asset loads cleanly.
5. Bad Client Behavior (Bug Discovered!):
   • The game freezes completely on the main thread.
   • An unhandled NullReferenceException is logged.
   • The client crashes to desktop or enters an infinite reload loop.

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Step 3: Capturing Evidence with a Repro-Pack

If your game fails the test:

1. Immediately click “Export Repro-Pack” on the failed tile in the Rehearsal Room.
2. The exported archive contains the exact SubwayTunnel_Drop profile and the request trace showing the socket abort at byte 262,144.
3. Hand the package to your gameplay networking engineer to implement proper retry backoff logic.