adding locking for userset weight writes as it is on demand

[yissellokta]

Description

What problem is being solved?

How is it being solved?

What changes are made to solve it?

References

Review Checklist

• I have clicked on "allow edits by maintainers".
• I have added documentation for new/changed functionality in this PR or in a PR to openfga.dev [Provide a link to any relevant PRs in the references section above]
• The correct base branch is being used, if not main
• I have added tests to validate that the change in functionality is working as expected

Summary by CodeRabbit

Release Notes

• Tests

  • Added comprehensive concurrent testing suite to validate thread-safe behavior across multiple concurrent scenarios.

• Bug Fixes

  • Enhanced thread-safety for concurrent weight operations to prevent potential race conditions.

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Walkthrough

Adds thread-safety to weighted graph userset weight mutations by introducing per-node and per-edge sync.RWMutex instances stored in global sync.Map caches, with helper functions to lazily retrieve mutexes and synchronization wrapping around weight-setting operations.

Changes

Cohort / File(s)	Summary
Concurrency protection implementation pkg/go/graph/weighted_graph.go	Adds sync.Map caches (nodeUsersetMutexes, edgeUsersetMutexes) for node and edge-level mutexes; introduces helper functions getUsersetNodeMutex and getUsersetEdgeMutex for lazy mutex retrieval; wraps setUsersetWeightToNode and setUsersetWeightToEdge with per-node/edge mutex acquire-release; imports sync package.
Concurrent test suite pkg/go/graph/weighted_graph_concurrent_test.go	Adds TestConcurrentUsersetWeights covering five scenarios: concurrent writes to node, concurrent writes to edge, concurrent same-key writes, parallel node-and-edge writes, and interleaved read-write patterns; validates thread-safe behavior and final state consistency across all goroutines.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~12 minutes

• Areas requiring attention:
  • Verify the lazy mutex initialization pattern in helper functions is thread-safe (double-checked locking in sync.Map)
  • Ensure mutex granularity (per-node, per-edge) is appropriate and doesn't introduce bottlenecks
  • Validate test coverage adequately exercises race conditions for both node and edge weight mutations
  • Confirm test assertions correctly verify final state under mutex protection

Possibly related PRs

• add userset weights #505: The main PR directly builds on the userset-weight implementation by adding per-node/per-edge mutexes and wrapping previously added weight-setting methods with synchronization for thread-safety.

Suggested reviewers

• adriantam
• elbuo8

Pre-merge checks and finishing touches

✅ Passed checks (3 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 mutex locking for concurrent userset weight write operations in the weighted graph implementation.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.

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Actionable comments posted: 2

🧹 Nitpick comments (1)

pkg/go/graph/weighted_graph_concurrent_test.go (1)

1-252: Concurrent tests are solid; consider minor cleanups

The subtests cover several important patterns (disjoint keys, shared key, node+edge in parallel, interleaved read/write) and exercise the new locking paths well. This is a good level of stress for the usersetWeights behavior.

Two small, optional tweaks:

• In the verification loops (e.g., Lines 47–60, 86–99, 169–197, 229–238), you can fetch the mutex once per loop, outside the inner body, to avoid repeated sync.Map lookups via getUsersetNodeMutex/getUsersetEdgeMutex.
• Since all subtests share the same node/edge, keep in mind future additions: if a new subtest depends on a “clean” state, it may need to reset or use a fresh graph. Right now the keys are disjoint enough that there’s no interference.

These are purely polish; the tests as written are functionally fine.

📜 Review details

Configuration used: CodeRabbit UI

Review profile: CHILL

Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between a2fbf9d and 7381c39.

📒 Files selected for processing (2)

• pkg/go/graph/weighted_graph.go (3 hunks)
• pkg/go/graph/weighted_graph_concurrent_test.go (1 hunks)

🧰 Additional context used

🧬 Code graph analysis (2)

pkg/go/graph/weighted_graph.go (2)

pkg/go/graph/weighted_graph_node.go (1)

• WeightedAuthorizationModelNode (18-27)

pkg/go/graph/weighted_graph_edge.go (1)

• WeightedAuthorizationModelEdge (58-76)

pkg/go/graph/weighted_graph_concurrent_test.go (3)

pkg/go/graph/weighted_graph.go (1)

• NewWeightedAuthorizationModelGraph (56-61)

pkg/go/graph/weighted_graph_node.go (1)

• SpecificTypeAndRelation (7-7)

pkg/go/graph/weighted_graph_edge.go (2)

• DirectEdge (11-11)
• NoCond (55-55)

⏰ Context from checks skipped due to timeout of 90000ms. You can increase the timeout in your CodeRabbit configuration to a maximum of 15 minutes (900000ms). (1)

• GitHub Check: Analyze (go)