perf: use singleflight for more db queries to better handle many similar parallel requests

[maxmanuylov]

So far many similar parallel requests lead to a lot of DB calls fetching the same tuples and competing for DB pool.

This PR uses singleflight for such requests as well to improve the performance.

Summary by CodeRabbit

• New Features

  • Improved response handling for repeated data lookups, especially when multiple identical requests arrive at the same time.

• Bug Fixes

  • Reduced duplicate work for common read operations, which can improve performance and consistency under load.
  • Kept results isolated between different tenants, filters, and pagination requests.
  • Ensured query results can be reused safely without affecting other requests.

[github-actions]

All contributors have signed the CLA ✍️ ✅
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[coderabbitai]

📝 Walkthrough

Walkthrough

DataReader in the singleflight proxy is extended with separate singleflight groups for QueryRelationships, QuerySingleAttribute, and QueryAttributes, adding key-builder and iterator-drain helpers. HeadSnapshot now uses a renamed field. Test mocks and suites are expanded to cover the new deduplication behavior.

Changes

Singleflight-backed query deduplication

Layer / File(s)	Summary
DataReader struct and singleflight-wrapped query methods internal/storage/proxies/singleflight/data_reader.go	Adds headSnapshotGroup, queryRelationshipsGroup, querySingleAttrGroup, and queryAttributesGroup fields; converts QueryRelationships, QuerySingleAttribute, and QueryAttributes to build dedup keys, execute via singleflight, drain iterators into slices, and return new iterators; HeadSnapshot uses the renamed headSnapshotGroup; adds fmt/strings imports and internal key-builder/drain helpers.
Mock DataReader query implementations and counters internal/storage/proxies/singleflight/data_reader_test.go	MockDataReader gains per-method counter maps and a mutex, new QueryRelationships/QuerySingleAttribute/QueryAttributes implementations with call counting, a shared getCallCount helper, and ErrorMockDataReader returns errors for the new query methods; adds anypb import.
Test suite updates for query dedup coverage internal/storage/proxies/singleflight/data_reader_test.go	Removes old delegation-only tests, updates HeadSnapshot assertions to use GetCallCount, and adds tests for concurrent dedup, tenant/filter isolation, sequential non-dedup, error propagation, empty results, and iterator independence for the new query methods.

Estimated code review effort: 3 (Moderate) | ~25 minutes

Possibly related PRs

• Permify/permify#2649: Expands the same data_reader_test.go Singleflight test coverage, including ErrorMockDataReader error propagation and call-count assertions for DataReader methods.

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 44.44% 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 clearly summarizes the main change: expanding singleflight deduplication for parallel database queries.
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.

✨ Finishing Touches

🧪 Generate unit tests (beta)

• Create PR with unit tests

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[maxmanuylov]

I have read the CLA Document and I hereby sign the CLA

[coderabbitai]

Actionable comments posted: 2

🤖 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 `@internal/storage/proxies/singleflight/data_reader_test.go`:
- Around line 385-390: The test goroutine in data_reader_test.go is calling
Ginkgo assertions inside go func() without recovery, which can make failures
escape the spec. Add defer GinkgoRecover() at the start of each goroutine that
uses Expect, including the QueryRelationships helper in the singleflight data
reader tests, so assertion failures are handled by Ginkgo instead of crashing or
flaking the suite.

In `@internal/storage/proxies/singleflight/data_reader.go`:
- Around line 33-43: Clone the materialized protobuf results before returning
from the singleflight paths in data_reader.go: the tuples returned by the
QueryRelationships flow and the attribute objects returned by
QuerySingleAttribute and QueryAttributes should be deep-copied after
draining/materializing and before constructing the final iterator or response.
Use the existing helpers around queryRelationshipsGroup and any attribute-query
singleflight logic to ensure each caller gets its own copies, preventing shared
protobuf pointers from being mutated across duplicate requests.

🪄 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: defaults

Review profile: CHILL

Plan: Pro

Run ID: 74726ccc-8d17-4eb3-bb5e-08eedb224cb7

📥 Commits

Reviewing files that changed from the base of the PR and between aa3a7c6 and e783304.

📒 Files selected for processing (2)

• internal/storage/proxies/singleflight/data_reader.go
• internal/storage/proxies/singleflight/data_reader_test.go

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 74.87%. Comparing base (aa3a7c6) to head (e783304).

❌ Your project check has failed because the head coverage (74.87%) is below the target coverage (75.00%). You can increase the head coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3023      +/-   ##
==========================================
+ Coverage   74.67%   74.87%   +0.20%     
==========================================
  Files          83       83              
  Lines        9212     9281      +69     
==========================================
+ Hits         6878     6948      +70     
  Misses       1798     1798              
+ Partials      536      535       -1     

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