findAndVerifyWindowGrace() recurses over parent GraphNodes without a visited accumulator. Kafka Streams GraphNode is a genuine DAG (addChild wires parent→child with multiple parents allowed), so a diamond topology causes 2^D recursive calls. Fix: thread an IdentityHashMap<GraphNode,Long> memo through recursion; memoize on first visit, return cached result on revisit. 8/8 unit tests PASS; D=10 defect count=3071 vs patched O(N). Diamond-recursion CLEAN markers added for: flink, neo4j, janusgraph, tinkerpop, dgraph, zookeeper, storm, ant, gradle, graal, eclipse-jdt, exposed, intellij, kotlin, scala3, hibernate-0007 (prior session work now committed).
20 lines
1.2 KiB
Markdown
20 lines
1.2 KiB
Markdown
## Diamond Recursion Scan — CLEAN
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**Scan date:** 2026-03-29
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**Pattern:** Recursive cycle/dependency check without visited set (CWE-407 diamond recursion, O(2^D))
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### Files examined
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- `subprojects/core/src/main/java/org/gradle/execution/plan/DetermineExecutionPlanAction.java` — cycle detection, `findCycles`
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- `subprojects/core/src/main/java/org/gradle/execution/plan/Node.java` — dependency node
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- `platforms/core-configuration/model-core/src/main/java/org/gradle/model/internal/registry/DefaultModelRegistry.java` — model dependency resolution
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### Findings
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**DetermineExecutionPlanAction:** Uses two `HashSet<Node>` accumulators (`visiting` and `visited`) for DFS traversal. The `findCycles` method delegates to `graphWalker.findCycles()` which uses proper SCC cycle detection. CLEAN.
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**DefaultModelRegistry:** Uses a goal state machine (`NotSeen / VisitingDependencies / Achieved`) where each goal can only be in one state at a time. Goals transition from `NotSeen` → `VisitingDependencies` → `Achieved`, preventing re-traversal. CLEAN.
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Note: `gradle-0002` covers a pre-existing CWE-407 defect in `NodeState.addIncomingEdge` ArrayList membership scan.
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### Verdict: CLEAN — no diamond recursion CWE-407 found
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