java-topology/defects/telegraf/unit/TelegrafTest.java

import java.util.*;

/**
 * CWE-407 unit test for Telegraf dedup processor defect.
 *
 * telegraf-0001: Dedup Apply() calls GetField(key) O(F) inside field loop → O(F²)
 *
 * Simulates the defect (linear field scan per field) vs the fix (hash map lookup).
 */
public class TelegrafTest {

    // --- telegraf-0001: Dedup GetField quadratic ---

    /** Simulate metric fields as a list (Go slice of *Field). */
    static List<String[]> makeFields(int n) {
        List<String[]> fields = new ArrayList<>(n);
        for (int i = 0; i < n; i++) {
            fields.add(new String[]{"field_" + i, "value_" + i});
        }
        return fields;
    }

    /** DEFECTIVE: linear scan for each field lookup, O(F) per call. */
    static Object getFieldLinear(List<String[]> fields, String key) {
        for (String[] f : fields) {
            if (f[0].equals(key)) {
                return f[1];
            }
        }
        return null;
    }

    /** DEFECTIVE: dedup comparison using linear GetField — O(F²). */
    static long dedupCompareDefective(List<String[]> incoming, List<String[]> cached) {
        long ops = 0;
        for (String[] f : incoming) {
            // Linear scan of cached fields
            for (String[] cf : cached) {
                ops++;
                if (cf[0].equals(f[0])) {
                    break;
                }
            }
        }
        return ops;
    }

    /** FIXED: build hash map first, then O(1) lookup — O(F). */
    static long dedupCompareFixed(List<String[]> incoming, List<String[]> cached) {
        long ops = 0;
        Map<String, String> cachedMap = new HashMap<>(cached.size());
        for (String[] cf : cached) {
            cachedMap.put(cf[0], cf[1]);
            ops++;
        }
        for (String[] f : incoming) {
            cachedMap.get(f[0]); // O(1) amortized
            ops++;
        }
        return ops;
    }

    static boolean testDedupGetField() {
        System.out.println("=== telegraf-0001: Dedup GetField O(F²) → O(F) ===");
        boolean pass = true;

        int[] sizes = {10, 50, 100, 500};
        for (int n : sizes) {
            List<String[]> incoming = makeFields(n);
            List<String[]> cached = makeFields(n);

            long defectOps = dedupCompareDefective(incoming, cached);
            long fixedOps = dedupCompareFixed(incoming, cached);
            double ratio = (double) defectOps / fixedOps;

            System.out.printf("  F=%d: defect=%d ops, fixed=%d ops, ratio=%.1fx%n",
                    n, defectOps, fixedOps, ratio);

            // At F=100: defect ~5050 ops (sum 1..100), fixed ~200 ops, ratio ~25x
            // At F=500: defect ~125250 ops, fixed ~1000 ops, ratio ~125x
            if (n >= 50 && ratio < 2.0) {
                System.out.printf("  FAIL: expected ratio >= 2.0 at F=%d, got %.1f%n", n, ratio);
                pass = false;
            }
        }

        // Verify correctness: both should find the same matches
        List<String[]> a = makeFields(20);
        List<String[]> b = makeFields(20);
        for (String[] f : a) {
            Object linearResult = getFieldLinear(b, f[0]);
            if (linearResult == null || !linearResult.equals(f[1])) {
                System.out.println("  FAIL: linear lookup returned wrong result for " + f[0]);
                pass = false;
            }
        }

        System.out.println("  " + (pass ? "PASS" : "FAIL"));
        return pass;
    }

    // --- Main ---

    public static void main(String[] args) {
        boolean allPass = true;

        allPass &= testDedupGetField();

        System.out.println();
        System.out.println(allPass ? "ALL TESTS PASSED" : "SOME TESTS FAILED");
        System.exit(allPass ? 0 : 1);
    }
}