feat(node/service): Introduce backpressure in DA watcher channels

[clabby]

Overview

Introduces backpressure within the DA watcher channels. This change ensures that if the consumers of the DA watcher events (L1 {head/finalized} updates, unsafe block signer updates) do not process their events in a timely manner, the DA watcher doesn't endlessly fill up the channel queue, and yields until the other actors can process its pending updates.

progress on #1993

[Copilot]

Pull Request Overview

This PR introduces backpressure within DA watcher channels by replacing unbounded mpsc channels with bounded ones and updating send operations to use asynchronous awaits.

• Changed channel types from unbounded to bounded (with a capacity of 16 or specified value) across multiple services and actors.
• Updated send-calls to use await to properly support backpressure in event propagation.
• Applied consistent mpsc type usage within validator, standard node service, and various actors (network, L1 watcher, engine, and derivation).

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
crates/node/service/src/service/validator.rs	Replaced unbounded channels with bounded channels to enforce backpressure; updated function signature accordingly.
crates/node/service/src/service/standard/node.rs	Updated channel types to use bounded channels for improved flow control.
crates/node/service/src/actors/network.rs	Modified channel types for consistent bounded behavior in network actor.
crates/node/service/src/actors/l1_watcher_rpc.rs	Updated channel send calls to use await, aligning with bounded channel behavior.
crates/node/service/src/actors/engine/finalizer.rs	Changed channel type for finalized block updates from unbounded to bounded.
crates/node/service/src/actors/engine/actor.rs	Updated channel types to support backpressure within engine actor events.
crates/node/service/src/actors/derivation.rs	Modified channel types in derivation logic to use bounded channels.

Comments suppressed due to low confidence (1)

crates/node/service/src/actors/l1_watcher_rpc.rs:186

• [nitpick] Ensure that awaiting on bounded channel sends does not introduce unintended bottlenecks if consumers are slow; consider reviewing consumer performance during peak activity.

self.head_sender.send(head_block_info).await?;

[Copilot]

[nitpick] Consider if the fixed channel capacity of 16 is adequate under peak load; making this capacity configurable might help improve resilience in variable workload conditions.

Suggested change

	let (new_head_tx, new_head_rx) = mpsc::channel(16);
	let (new_finalized_tx, new_finalized_rx) = mpsc::channel(16);
	let (new_head_tx, new_head_rx) = mpsc::channel(config.channel_capacity);
	let (new_finalized_tx, new_finalized_rx) = mpsc::channel(config.channel_capacity);

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 83.1%. Comparing base (3bf631f) to head (9ae9ef6).
Report is 3 commits behind head on main.

✅ All tests successful. No failed tests found.

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