feat: prefill RPC caches for new validated tipsets

[hanabi1224]

Summary of changes

Changes introduced in this pull request:

Reference issue to close (if applicable)

Closes

Other information and links

Change checklist

• I have performed a self-review of my own code,
• I have made corresponding changes to the documentation. All new code adheres to the team's documentation standards,
• I have added tests that prove my fix is effective or that my feature works (if possible),
• I have made sure the CHANGELOG is up-to-date. All user-facing changes should be reflected in this document.

Outside contributions

• I have read and agree to the CONTRIBUTING document.
• I have read and agree to the AI Policy document. I understand that failure to comply with the guidelines will lead to rejection of the pull request.

Summary by CodeRabbit

• New Features

  • Added a validated-tipset subscription so external consumers can receive validated tipset notifications.

• Performance

  • Proactive RPC cache warming when new validated tipsets arrive to reduce latency during sync.
  • RPC block conversion now uses shared state access for more efficient processing.

• Bug Fixes

  • Broadcasts only emit for tipsets accepted into the heaviest state; lagged events are skipped with warnings.

• Refactor

  • Simplified block/state handling to streamline RPC flows.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: f57411cc-97a4-437f-a8fc-d41dc1e937f6

📥 Commits

Reviewing files that changed from the base of the PR and between 1fad063 and 8b14ea1.

📒 Files selected for processing (1)

• src/daemon/mod.rs

🚧 Files skipped from review as they are similar to previous changes (1)

• src/daemon/mod.rs

---

Walkthrough

Adds a validated-tipset broadcast channel in the sync state machine, refactors ETH block conversion to accept &StateManager, and starts a daemon subscriber that warms RPC caches by converting validated tipsets into ETH blocks when RPC is enabled.

Changes

Validated Tipset Broadcast and RPC Cache Warming

Layer / File(s)	Summary
Validated Tipset Broadcast Infrastructure src/chain_sync/chain_follower.rs	ChainFollower::subscribe_validated_tipset() returns a broadcast::Receiver<TipsetKey>; SyncStateMachine adds validated_tipset_broadcast_tx (capacity 1024); validated-tipset acceptance now uses try_mark_tipset_as_validated(...) -> bool; update() broadcasts only on success and when subscribers exist; test updated to call the new API.
Block::from_filecoin_tipset Refactoring src/rpc/methods/eth.rs, src/rpc/methods/chain.rs	Block::from_filecoin_tipset signature changed to accept &StateManager instead of Ctx; internal calls updated to use state_manager for executed tipsets and chain config; RPC handlers (eth_getBlockByHash, eth_getBlockByNumber, new_heads) pass &ctx.state_manager.
RPC Cache Warming Loop src/daemon/mod.rs	start_chain_follower_service optionally spawns a background subscriber when config.client.enable_rpc is true; the loop subscribes to validated-tipset broadcasts and warms RPC caches by loading tipsets and invoking Block::from_filecoin_tipset (both TxInfo::Full and TxInfo::Hash) for each delivered tipset while the node is not synced; lagged events are skipped and subscription closure exits the loop.

Estimated code review effort

🎯 4 (Complex) | ⏱️ ~45 minutes

Possibly related PRs

• ChainSafe/forest#6759: Adds subscriber checks before publishing head-change broadcast events, similar conditional broadcast gating used here.
• ChainSafe/forest#6402: Prior changes to the tipset-to-ETH-block conversion pipeline and related RPC call sites.

Suggested reviewers

• LesnyRumcajs
• akaladarshi

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 73.33% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately describes the main change: adding RPC cache prefilling functionality for validated tipsets.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch hm/prefill-rpc-cache

✨ Simplify code

• Create PR with simplified code
• Commit simplified code in branch hm/prefill-rpc-cache

---

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[coderabbitai]

Actionable comments posted: 2

Caution

Some comments are outside the diff and can’t be posted inline due to platform limitations.

⚠️ Outside diff range comments (1)

src/chain_sync/chain_follower.rs (1)

631-637: ⚠️ Potential issue | 🔴 Critical | ⚡ Quick win

Use broadcast::channel instead of Sender::new for Tokio broadcast initialization.

Line 636 uses tokio::sync::broadcast::Sender::new(1024), which is not part of Tokio 1.x's public API. The correct approach is tokio::sync::broadcast::channel(capacity), which returns a tuple of (Sender, Receiver).

Proposed fix

 impl SyncStateMachine {
pub fn new(
cs: ChainStore,
bad_block_cache: Option<BadBlockCache>,
stateless_mode: bool,
) -> Self {
+ let (validated_tipset_broadcast_tx, _) = tokio::sync::broadcast::channel(1024);
Self {
cs,
bad_block_cache,
tipsets: HashMap::default(),
stateless_mode,
- validated_tipset_broadcast_tx: tokio::sync::broadcast::Sender::new(1024),+ validated_tipset_broadcast_tx,
}
}

🤖 Prompt for AI Agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.
In `@src/chain_sync/chain_follower.rs` around lines 631 - 637, The initialization
uses tokio::sync::broadcast::Sender::new which doesn't exist in Tokio 1.x;
replace it by calling tokio::sync::broadcast::channel(capacity) and assign the
returned Sender to validated_tipset_broadcast_tx (e.g., let
(validated_tipset_broadcast_tx, _rx) = tokio::sync::broadcast::channel(1024)
before constructing Self), keeping the symbol validated_tipset_broadcast_tx as
the Sender used in the struct and ensuring any needed Receiver is retained or
discarded appropriately.

🤖 Prompt for all review comments with AI agents

Verify each finding against current code. Fix only still-valid issues, skip the
rest with a brief reason, keep changes minimal, and validate.
Inline comments:
In `@src/daemon/mod.rs`:
- Around line 350-383: The loop prefetches tipsets and calls
crate::rpc::eth::Block::from_filecoin_tipset even when RPC is disabled; guard
this work with the RPC flag by checking enable_rpc (or the equivalent config
passed in) before entering the spawn or before handling Ok(tsk) so that when
enable_rpc is false you skip loading from validated_tipset_rx and the
Block::from_filecoin_tipset calls. Locate the validated_tipset_rx handling in
the service spawn and short-circuit using the enable_rpc boolean (or avoid
spawning the inner tokio::spawn that uses state_manager.chain_index() and
Block::from_filecoin_tipset) to prevent unnecessary CPU/IO when RPC is disabled.
- Around line 360-375: The spawned task currently uses the `?` operator on
`state_manager.chain_index().load_required_tipset(&tsk)?`, which will silently
propagate errors; change this to explicitly handle the Result: call
`state_manager.chain_index().load_required_tipset(&tsk)`, match on Err/Ok, and
on Err log a warning (including `tsk` and the error) and return early from the
task (e.g., via `return`/`anyhow::Ok(())`) so the subsequent
`Block::from_filecoin_tipset` calls only run when the tipset loaded
successfully; reference `state_manager.chain_index().load_required_tipset(&tsk)`
and the cache warmup loop invoking
`crate::rpc::eth::Block::from_filecoin_tipset`.
---
Outside diff comments:
In `@src/chain_sync/chain_follower.rs`:
- Around line 631-637: The initialization uses
tokio::sync::broadcast::Sender::new which doesn't exist in Tokio 1.x; replace it
by calling tokio::sync::broadcast::channel(capacity) and assign the returned
Sender to validated_tipset_broadcast_tx (e.g., let
(validated_tipset_broadcast_tx, _rx) = tokio::sync::broadcast::channel(1024)
before constructing Self), keeping the symbol validated_tipset_broadcast_tx as
the Sender used in the struct and ensuring any needed Receiver is retained or
discarded appropriately.

🪄 Autofix (Beta)

Fix all unresolved CodeRabbit comments on this PR:

• Push a commit to this branch (recommended)
• Create a new PR with the fixes

---

ℹ️ Review info

⚙️ Run configuration

Configuration used: Repository UI

Review profile: CHILL

Plan: Pro

Run ID: a8bf0584-72dc-4011-844e-4225fbdc22ff

📥 Commits

Reviewing files that changed from the base of the PR and between 08b2a2b and 1f0a3f3.

📒 Files selected for processing (4)

• src/chain_sync/chain_follower.rs
• src/daemon/mod.rs
• src/rpc/methods/chain.rs
• src/rpc/methods/eth.rs

[codecov]

Codecov Report

❌ Patch coverage is 15.15152% with 56 lines in your changes missing coverage. Please review.
✅ Project coverage is 64.32%. Comparing base (862316d) to head (8b14ea1).
✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/daemon/mod.rs	0.00%	35 Missing ⚠️
src/chain_sync/chain_follower.rs	20.00%	16 Missing ⚠️
src/rpc/methods/eth.rs	60.00%	1 Missing and 3 partials ⚠️
src/rpc/methods/chain.rs	0.00%	1 Missing ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
src/rpc/methods/chain.rs	55.65% <0.00%> (ø)
src/rpc/methods/eth.rs	65.68% <60.00%> (ø)
src/chain_sync/chain_follower.rs	36.26% <20.00%> (-0.53%)	⬇️
src/daemon/mod.rs	27.04% <0.00%> (-1.51%)	⬇️

... and 5 files with indirect coverage changes

---

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[LesnyRumcajs]

no green checkmark, no review