java-topology/defects/blender/unit/BlenderTest.java

import java.util.*;

/**
 * CWE-407 simulation tests for Blender defects.
 *
 * blender-0001: node_runtime.cc socket chain cycle detection Vector.contains() O(D^2)
 * blender-0002: usd_skel_convert.cc used_indices dedup std::find O(J^2)
 * blender-0003: shader_tool.cc visited_files std::find O(D*V)
 */
public class BlenderTest {

    // ========== blender-0001: socket chain cycle detection ==========

    /** Simulates find_logical_origins_for_socket_recursive with Vector.contains cycle check */
    static int traceSocketChainDefective(Map<Integer, List<Integer>> links, int start) {
        List<Integer> chain = new ArrayList<>();
        return traceRecursiveDefective(links, start, chain);
    }

    static int traceRecursiveDefective(Map<Integer, List<Integer>> links, int socket, List<Integer> chain) {
        // Defect: linear scan for cycle detection
        if (chain.contains(socket)) {
            return 0; // cycle detected
        }
        chain.add(socket);
        int count = 1;
        for (int linked : links.getOrDefault(socket, Collections.emptyList())) {
            count += traceRecursiveDefective(links, linked, chain);
        }
        chain.remove(chain.size() - 1);
        return count;
    }

    /** Fixed: HashSet for O(1) cycle detection */
    static int traceSocketChainFixed(Map<Integer, List<Integer>> links, int start) {
        List<Integer> chain = new ArrayList<>();
        Set<Integer> chainSet = new HashSet<>();
        return traceRecursiveFixed(links, start, chain, chainSet);
    }

    static int traceRecursiveFixed(Map<Integer, List<Integer>> links, int socket,
                                    List<Integer> chain, Set<Integer> chainSet) {
        if (chainSet.contains(socket)) {
            return 0;
        }
        chain.add(socket);
        chainSet.add(socket);
        int count = 1;
        for (int linked : links.getOrDefault(socket, Collections.emptyList())) {
            count += traceRecursiveFixed(links, linked, chain, chainSet);
        }
        chain.remove(chain.size() - 1);
        chainSet.remove(socket);
        return count;
    }

    static boolean testSocketChainCycleDetection() {
        // Build a long reroute chain: 0 -> 1 -> 2 -> ... -> D-1
        int D = 2000;
        Map<Integer, List<Integer>> links = new HashMap<>();
        for (int i = 0; i < D - 1; i++) {
            links.put(i, List.of(i + 1));
        }
        links.put(D - 1, Collections.emptyList());

        // Warmup
        for (int i = 0; i < 3; i++) {
            traceSocketChainDefective(links, 0);
            traceSocketChainFixed(links, 0);
        }

        long t0 = System.nanoTime();
        for (int i = 0; i < 5; i++) traceSocketChainDefective(links, 0);
        long defective = System.nanoTime() - t0;

        t0 = System.nanoTime();
        for (int i = 0; i < 5; i++) traceSocketChainFixed(links, 0);
        long fixed = System.nanoTime() - t0;

        double ratio = (double) defective / fixed;
        System.out.printf("  blender-0001 socket chain cycle: defective=%dms fixed=%dms ratio=%.1fx%n",
                defective / 1_000_000, fixed / 1_000_000, ratio);
        return ratio > 2.0;
    }

    // ========== blender-0002: USD skel used_indices dedup ==========

    /** Defective: std::find on vector for dedup */
    static List<Integer> collectUsedIndicesDefective(int[] jointIndices) {
        List<Integer> usedIndices = new ArrayList<>();
        for (int index : jointIndices) {
            if (!usedIndices.contains(index)) {
                usedIndices.add(index);
            }
        }
        return usedIndices;
    }

    /** Fixed: Set for O(1) dedup */
    static List<Integer> collectUsedIndicesFixed(int[] jointIndices) {
        Set<Integer> seen = new HashSet<>();
        List<Integer> usedIndices = new ArrayList<>();
        for (int index : jointIndices) {
            if (seen.add(index)) {
                usedIndices.add(index);
            }
        }
        return usedIndices;
    }

    static boolean testUsedIndicesDedup() {
        // Simulate a high-poly mesh with many joint weight entries
        int J = 10000;
        int numJoints = 200;
        Random rng = new Random(42);
        int[] jointIndices = new int[J];
        for (int i = 0; i < J; i++) {
            jointIndices[i] = rng.nextInt(numJoints);
        }

        // Warmup
        for (int i = 0; i < 3; i++) {
            collectUsedIndicesDefective(jointIndices);
            collectUsedIndicesFixed(jointIndices);
        }

        long t0 = System.nanoTime();
        for (int i = 0; i < 100; i++) collectUsedIndicesDefective(jointIndices);
        long defective = System.nanoTime() - t0;

        t0 = System.nanoTime();
        for (int i = 0; i < 100; i++) collectUsedIndicesFixed(jointIndices);
        long fixed = System.nanoTime() - t0;

        double ratio = (double) defective / fixed;
        System.out.printf("  blender-0002 USD skel dedup:      defective=%dms fixed=%dms ratio=%.1fx%n",
                defective / 1_000_000, fixed / 1_000_000, ratio);
        return ratio > 2.0;
    }

    // ========== blender-0003: shader_tool visited_files ==========

    /** Defective: std::find on visited vector — isolate visited membership */
    static int processShaderDepsDefective(List<String> resolvedFiles) {
        List<String> visited = new ArrayList<>();
        int processed = 0;
        for (String file : resolvedFiles) {
            // Defect: linear scan of visited list
            if (!visited.contains(file)) {
                visited.add(file);
                processed++;
            }
        }
        return processed;
    }

    /** Fixed: HashSet for visited check */
    static int processShaderDepsFixed(List<String> resolvedFiles) {
        Set<String> visitedSet = new HashSet<>();
        int processed = 0;
        for (String file : resolvedFiles) {
            if (visitedSet.add(file)) {
                processed++;
            }
        }
        return processed;
    }

    static boolean testShaderToolVisited() {
        int D = 5000;  // dependencies (many unique files to grow visited list)
        List<String> resolvedFiles = new ArrayList<>();
        Random rng = new Random(42);
        // Many unique files so visited list grows large
        for (int i = 0; i < D; i++) resolvedFiles.add("shader_" + rng.nextInt(D) + ".glsl");

        // Warmup
        for (int i = 0; i < 3; i++) {
            processShaderDepsDefective(resolvedFiles);
            processShaderDepsFixed(resolvedFiles);
        }

        long t0 = System.nanoTime();
        for (int i = 0; i < 20; i++) processShaderDepsDefective(resolvedFiles);
        long defective = System.nanoTime() - t0;

        t0 = System.nanoTime();
        for (int i = 0; i < 20; i++) processShaderDepsFixed(resolvedFiles);
        long fixed = System.nanoTime() - t0;

        double ratio = (double) defective / fixed;
        System.out.printf("  blender-0003 shader visited:      defective=%dms fixed=%dms ratio=%.1fx%n",
                defective / 1_000_000, fixed / 1_000_000, ratio);
        return ratio > 2.0;
    }

    // ========== Main ==========

    public static void main(String[] args) {
        System.out.println("Blender CWE-407 unit tests");
        System.out.println("=========================");

        boolean p1 = testSocketChainCycleDetection();
        boolean p2 = testUsedIndicesDedup();
        boolean p3 = testShaderToolVisited();

        System.out.println();
        System.out.printf("blender-0001 socket chain cycle: %s%n", p1 ? "PASS" : "FAIL");
        System.out.printf("blender-0002 USD skel dedup:     %s%n", p2 ? "PASS" : "FAIL");
        System.out.printf("blender-0003 shader visited:     %s%n", p3 ? "PASS" : "FAIL");

        if (!p1 || !p2 || !p3) {
            System.exit(1);
        }
        System.out.println("\nAll 3 tests PASS");
    }
}