app: fetch only the requested indices from cache

[KaloyanTanev]

1. Fetch only the requested validator indices from cache
2. Make a request to the BN if some of the requested indices are missing
3. Store the newly fetched indices in the cache, amending the previous epoch

category: feature
ticket: #4009

[Copilot]

Pull request overview

Implements more granular duties caching so callers can request a subset of validator indices, reuse cached duties when available, and fall back to beacon-node fetches only for missing indices (per issue #4009) to reduce duplicate BN load.

Changes:

• Adds index-aware filtering for proposer/attester/sync duties cache reads and introduces “fetch missing indices” flow.
• Introduces new store-or-amend paths for duties caching (notably for sync duties).
• Updates duties cache test scaffolding for new request-shape expectations.

Reviewed changes

Copilot reviewed 2 out of 2 changed files in this pull request and generated 14 comments.

File	Description
app/eth2wrap/cache.go	Adds selective duty retrieval, missing-index fetch logic, and new store/amend behavior for duties caches.
app/eth2wrap/cache_test.go	Adjusts proposer duties mock generation used by duties cache tests.

Comments suppressed due to low confidence (2)

app/eth2wrap/cache.go:583

• Same issue as proposer: this function does not amend existing epoch entries, so partially missing attester duties can never be added to the cache under the new logic. This will cause repeated BN calls for the same missing indices and defeats the cache.

// storeOrAmendAttesterDuties stores attester duties in the cache for the given epoch if they don't exist and false if they already exists.
func (c *DutiesCache) storeOrAmendAttesterDuties(epoch eth2p0.Epoch, duties []eth2v1.AttesterDuty, metadata map[string]any) bool {
	c.attesterDuties.Lock()
	defer c.attesterDuties.Unlock()

	_, ok := c.attesterDuties.duties[epoch]
	if ok {
		return false
	}

app/eth2wrap/cache.go:567

• Despite the name/comment, this method does not “amend” existing duties: it returns false if the epoch is already present. With the new partial-fetch behavior, this means missing indices fetched from the BN will never be added to the cache, causing repeated BN requests for the same missing indices. Implement an amend/merge path (similar to storeOrAmendSyncDuties) and consider whether metadata should be merged/updated as well.

// storeOrAmendProposerDuties stores proposer duties in the cache for the given epoch if they don't exist and false if they already exists.
func (c *DutiesCache) storeOrAmendProposerDuties(epoch eth2p0.Epoch, duties []eth2v1.ProposerDuty, metadata map[string]any) bool {
	c.proposerDuties.Lock()
	defer c.proposerDuties.Unlock()

	_, ok := c.proposerDuties.duties[epoch]
	if ok {
		return false
	}

---

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[codecov]

Codecov Report

❌ Patch coverage is 18.23899% with 130 lines in your changes missing coverage. Please review.
✅ Project coverage is 56.42%. Comparing base (09d332b) to head (f9c5cc0).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
app/eth2wrap/cache.go	18.83%	124 Missing and 1 partial ⚠️
app/app.go	0.00%	4 Missing ⚠️
app/vmock.go	0.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4327      +/-   ##
==========================================
- Coverage   56.60%   56.42%   -0.19%     
==========================================
  Files         237      237              
  Lines       31555    31658     +103     
==========================================
  Hits        17862    17862              
- Misses      11403    11509     +106     
+ Partials     2290     2287       -3     

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 5 comments.

Comments suppressed due to low confidence (1)

app/eth2wrap/cache_test.go:283

• The cache now supports partial index requests and amending an epoch with newly fetched duties, but this test only covers the “all indices” path. Add coverage for: (1) requesting a subset that is fully served from cache without calling the BN, and (2) requesting a subset where some indices are missing, asserting the BN is called only for the missing indices and the cache is amended.

	// Create a cache.
	valCache := eth2wrap.NewDutiesCache(eth2Cl, slices.Collect(maps.Keys(valSet)))
	ctx := t.Context()

	// First call should populate the cache
	_, err = valCache.ProposerDutiesCache(ctx, 0, slices.Collect(maps.Keys(valSet)))
	require.NoError(t, err)
	require.True(t, proposerDutiesCalled)

	// Second call should use the cache
	proposerDutiesCalled = false
	_, err = valCache.ProposerDutiesCache(ctx, 0, slices.Collect(maps.Keys(valSet)))
	require.NoError(t, err)

---

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[Copilot]

Pull request overview

Copilot reviewed 4 out of 4 changed files in this pull request and generated 5 comments.

Comments suppressed due to low confidence (1)

app/eth2wrap/cache_test.go:283

• Test coverage: this test still only covers the full-index cache hit path. Since the cache now supports partial hits + fetching only missing indices and amending the cached epoch, add an assertion-driven case for that behavior (e.g., cache a subset first, then request a superset and verify only missing indices invoke ProposerDutiesFunc).

	// First call should populate the cache
	_, err = valCache.ProposerDutiesCache(ctx, 0, slices.Collect(maps.Keys(valSet)))
	require.NoError(t, err)
	require.True(t, proposerDutiesCalled)

	// Second call should use the cache
	proposerDutiesCalled = false
	_, err = valCache.ProposerDutiesCache(ctx, 0, slices.Collect(maps.Keys(valSet)))
	require.NoError(t, err)

---

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[sonarqubecloud]

Quality Gate passed

Issues
3 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarQube Cloud