feat(epp): order all requestcontrol hooks by data-dependency DAG by chethanuk · Pull Request #15 · chethanuk/llm-d-router

chethanuk · 2026-07-17T12:17:13Z

User description

What type of PR is this?
/kind bug
/kind feature

What this PR does / why we need it:

ValidateAndOrderDataDependencies already built a topological order of requestcontrol plugins, but only DataProducer plugins were reordered. The other five hook lists (PreRequest, RequestHeader, Admission, ResponseReceived, ResponseStreaming) kept the map-iteration order from GetAllPlugins, so a consumer could run before its producer after a restart (the llm-d#1856 class of bug).

This PR:

Makes TopologicalSort deterministic with a largest-ready Kahn tie-break (so the existing reverse yields ascending name ties).
Replaces OrderDataProducerPlugins with OrderPlugins, which reorders all six requestcontrol hook lists by the DAG rank while retaining unranked plugins (stable append by name).
Documents that Consumes/Produces govern every requestcontrol extension point.

Not a duplicate of llm-d#1421 / PR llm-d#1876: that work ordered plugin instantiation in the config loader; this orders hook execution in requestcontrol.

Which issue(s) this PR fixes:
Fixes llm-d#2040

How to test:

make test-filter PATTERN=TestConfig_OrderPlugins_AllHookLists TYPE=epp epp_TEST_PACKAGES='./pkg/epp/requestcontrol/' — 6 subtests PASS (all six lists ordered; unranked retained)
make test-filter PATTERN=TestTopologicalSort_Deterministic TYPE=epp epp_TEST_PACKAGES='./pkg/epp/util/' — PASS
make test-filter PATTERN=TestDAGAndTopologicalOrder TYPE=epp epp_TEST_PACKAGES='./pkg/epp/datalayer/' — PASS
make test-filter PATTERN='TestPluginsWithDependencies|TestFilterExecutionOrderFromYAML' TYPE=epp epp_TEST_PACKAGES='./pkg/epp/config/loader/' — PASS (2nd TopologicalSort caller / instantiation order)
make lint — 0 issues
make build — epp + sidecar
make test-unit-epp (excl. pre-existing pkg/kvcache/kvblock full-suite load flake; package green in isolation) + make test-unit-sidecar

Release note (write NONE if no user-facing change):

Requestcontrol plugins on every extension point (not only DataProducer) now run in data-dependency DAG order: producers before consumers, with a deterministic tie-break. Removes restart-dependent PreRequest/header/response hook ordering.

CodeAnt-AI Description

Order every request hook by data dependencies

What Changed

Plugins that depend on other data now run after their producers across all request hook paths, not just the main data-producing path.
Unranked plugins are still kept, and they now appear in a stable name order instead of changing between runs.
Dependency ordering is now repeatable, so the same plugin graph produces the same execution order every time.
Added coverage for the ordering rules across all hook lists and for edge cases like empty configs and missing names.

Impact

✅ Fewer cases where a consumer runs before its producer
✅ Stable hook order after restart
✅ More predictable request processing

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Summary by CodeRabbit

Improvements
- Plugin execution now consistently follows declared data dependencies across request, admission, and response processing stages.
- Plugin ordering is deterministic, including plugins without declared dependencies.
- Dependency-based ordering now handles ties consistently for predictable results.
Bug Fixes
- Corrected configuration ordering so all applicable plugin types follow the computed dependency order.

ValidateAndOrderDataDependencies already produced a topological order, but only DataProducer plugins were reordered. Other extension points kept the map-iteration order from GetAllPlugins, so PreRequest (and related hooks) could run consumers before producers across restarts (llm-d#1856 class of bug). Make TopologicalSort deterministic via a largest-ready tie-break (so the existing reverse yields ascending name ties), apply that order to all six requestcontrol hook lists while retaining unranked plugins, and document that Consumes/Produces govern every requestcontrol extension point. Signed-off-by: ChethanUK <chethanuk@outlook.com>

codeant-ai · 2026-07-17T12:17:17Z

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coderabbitai · 2026-07-17T12:17:45Z

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Review details

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: 1af0c45c-3f7e-4bc3-9ee9-ff4c0e613f3a

📥 Commits

Reviewing files that changed from the base of the PR and between c965fd1 and 4e93151.

📒 Files selected for processing (2)

pkg/epp/framework/interface/plugin/plugins.go
pkg/epp/requestcontrol/request_control_config_test.go

📝 Walkthrough

Walkthrough

The request-control configuration now orders all hook plugins from the dependency DAG, with deterministic handling for ties and unranked plugins. Topological sorting receives deterministic tie-breaking, and tests cover hook-list ordering, edge cases, dependency shapes, and cycle detection.

Changes

Request-control plugin ordering

Layer / File(s)	Summary
Deterministic dependency graph ordering `pkg/epp/util/utils.go`, `pkg/epp/util/utils_test.go`	`TopologicalSort` deterministically resolves ready-node ties, with tests covering dependency graphs and cycle errors.
All-hook plugin ordering `pkg/epp/requestcontrol/request_control_config.go`, `pkg/epp/requestcontrol/request_control_config_test.go`, `pkg/epp/framework/interface/plugin/plugins.go`	`OrderPlugins` applies DAG ranks across request-control hook lists, sorts unranked plugins by typed name, and tests ranked, unranked, missing, and empty inputs.
Configuration phase integration `cmd/epp/runner/runner.go`	Configuration phase two invokes `OrderPlugins` with the computed dependency order.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Suggested reviewers: shmuelk

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly matches the main change: applying the data-dependency DAG to all requestcontrol hooks.
Docstring Coverage	✅ Passed	Docstring coverage is 100.00% which is sufficient. The required threshold is 80.00%.
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.

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Commit unit tests in branch fix/issue-2040-feat-order-all-plugin-hook-lists

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gemini-code-assist

Code Review

This pull request updates the plugin ordering mechanism to ensure deterministic execution across all request control extension points, addressing potential order-dependency issues. It introduces a unified OrderPlugins method, refactors the topological sort utility to break ties deterministically, and adds comprehensive unit tests. The reviewer provided valuable feedback on performance optimizations: first, to avoid sorting the entire queue in Kahn's algorithm by finding the maximum element in linear time; and second, to cache plugin names and ranks prior to sorting in orderByName to eliminate redundant string formatting and map lookups.

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codeant-ai · 2026-07-17T12:21:37Z

CodeAnt AI finished reviewing your PR.

The whole point of ordering every hook list by the data-dependency DAG is that the result must not depend on Go's randomized map iteration in GetAllPlugins. The existing tests fed a single input order, so a regression that reintroduced input-order sensitivity could pass. Drive several fixed permutations of the same plugin set and assert every hook list comes out identical. Signed-off-by: ChethanUK <chethanuk@outlook.com>

Ordering every requestcontrol hook list by the data-dependency DAG makes execution deterministic, which is the goal. The producer-before-consumer direction is right for the request-path hooks, but for ResponseHeader and ResponseBody a producer may release the state a consumer reads, so the correct direction there is not established. Document it as unsettled rather than asserting producer-first is canonical for response hooks. Signed-off-by: ChethanUK <chethanuk@outlook.com>

github-actions Bot added the size/L label Jul 17, 2026

codeant-ai Bot added the size:L This PR changes 100-499 lines, ignoring generated files label Jul 17, 2026

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feat(epp): order all requestcontrol hooks by data-dependency DAG#15

feat(epp): order all requestcontrol hooks by data-dependency DAG#15
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