Add automatic reconnection with exponential backoff

[kixelated]

Summary

This PR adds automatic reconnection functionality to the MOQ native client, allowing it to maintain persistent connections with exponential backoff retry logic.

Key Changes

• New reconnect module: Implements Reconnect handle and Backoff configuration for managing automatic reconnection attempts

  • Backoff struct with configurable initial delay (default 1s), multiplier (default 2x), and maximum delay (default 30s)
  • Supports CLI arguments and environment variables for backoff configuration
  • Supports serialization/deserialization via serde

• Reconnect handle: Spawns a background tokio task that:

  • Attempts to connect to a given URL
  • Waits for the session to close
  • Automatically reconnects with exponential backoff on failure
  • Can be stopped by dropping the handle or calling close()

• Client integration:

  • Added backoff field to ClientConfig with CLI and serde support
  • Added backoff field to Client struct
  • New Client::reconnect() method to start the background reconnection loop
  • Backoff configuration is passed through from config to the reconnect task

Implementation Details

• The reconnect loop resets the backoff delay to initial value on successful connection
• Exponential backoff is capped at the configured maximum delay
• Uses tokio::task::AbortHandle for clean task cancellation
• Includes unit tests for backoff default values
• Comprehensive logging at info/warn levels for connection state changes

https://claude.ai/code/session_01BTTwQv5UW7yFAuYiKBPM8X

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ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 75220528-f0d0-49d3-8882-17797b1eafc7

📥 Commits

Reviewing files that changed from the base of the PR and between b57b9f8 and ea68a48.

📒 Files selected for processing (7)

• js/lite/src/connection/reload.ts
• rs/hang/examples/subscribe.rs
• rs/hang/examples/video.rs
• rs/moq-boy/src/main.rs
• rs/moq-cli/src/client.rs
• rs/moq-clock/src/main.rs
• rs/moq-native/src/reconnect.rs

Walkthrough

This change introduces configurable exponential-backoff reconnection functionality to the MOQ native client. A new reconnect module is created, exposing a Backoff struct that configures initial delay, multiplier, and maximum delay with CLI argument parsing and serde support. A Reconnect handle spawns a background task that attempts connections, logs status, and on failure sleeps using exponentially-backed-off delays before retrying. The Client stores a Backoff instance and exposes a reconnect() method that returns a Reconnect handle. The new module is re-exported through the library root.

🚥 Pre-merge checks | ✅ 3

✅ Passed checks (3 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'Add automatic reconnection with exponential backoff' directly and clearly describes the main feature being added to the codebase.
Description check	✅ Passed	The description is comprehensive and closely related to the changeset, providing clear context about the new reconnect module, Backoff configuration, Reconnect handle, and Client integration.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

_{✏️ Tip: You can configure your own custom pre-merge checks in the settings.}

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch claude/add-rust-reconnect-support-HSOCD

✨ Simplify code

• Create PR with simplified code
• Commit simplified code in branch claude/add-rust-reconnect-support-HSOCD

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🧹 Nitpick comments (1)

rs/moq-native/src/reconnect.rs (1)

70-83: Consider adding a delay or jitter after session close.

When a session closes (lines 74-75), reconnection happens immediately without any delay. If the server accepts connections but quickly terminates sessions (e.g., due to overload or misconfiguration), this could cause rapid reconnection attempts. Consider adding a small base delay or jitter after clean session closure.

♻️ Optional: Add minimal delay after session close

 				Ok(session) => {
 					tracing::info!(%url, "connected");
 					delay = backoff.initial;
 					let _ = session.closed().await;
 					tracing::warn!(%url, "session closed, reconnecting");
+					// Small delay before reconnecting to avoid hammering server
+					tokio::time::sleep(Duration::from_millis(100)).await;
 				}

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@rs/moq-native/src/reconnect.rs` around lines 70 - 83, The Ok branch for
client.connect handles clean session closure immediately restarting the loop
(involving session.closed()). After session.closed().await, introduce a short
sleep with jitter instead of immediate reconnect: compute a small base delay
(e.g., backoff.initial or a configured min_close_delay) add randomized jitter,
await tokio::time::sleep on that duration, and then reset delay =
backoff.initial as currently done; this change is localized to the Ok(session)
arm around session.closed() to prevent tight reconnect loops when the server is
closing sessions.

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In `@rs/moq-native/src/reconnect.rs`:
- Around line 70-83: The Ok branch for client.connect handles clean session
closure immediately restarting the loop (involving session.closed()). After
session.closed().await, introduce a short sleep with jitter instead of immediate
reconnect: compute a small base delay (e.g., backoff.initial or a configured
min_close_delay) add randomized jitter, await tokio::time::sleep on that
duration, and then reset delay = backoff.initial as currently done; this change
is localized to the Ok(session) arm around session.closed() to prevent tight
reconnect loops when the server is closing sessions.

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: b248db0b-bebc-4639-ab66-d49ac85d474f

📥 Commits

Reviewing files that changed from the base of the PR and between 55b28a5 and b57b9f8.

📒 Files selected for processing (3)

• rs/moq-native/src/client.rs
• rs/moq-native/src/lib.rs
• rs/moq-native/src/reconnect.rs