java-topology/defects/grafana/unit/GrafanaTest.java

package unit;

import java.util.*;

/**
 * Standalone unit test for grafana-0001: CWE-407.
 *
 * grafana-0001: dfs() visited-array Array.includes — O(n²) on time-range refresh
 *   slow() uses a List<String> for visited; contains() is O(V) per node visit.
 *         DFS over N nodes with average degree d: O(N * V_avg) ≈ O(N²).
 *   fast() uses a HashSet<String>; contains() is O(1) per visit.
 *         DFS over N nodes: O(N + E) where E = total edges.
 *   Assert: slowOps > fastOps * 10x for N=200 variables in a chain graph.
 */
public class GrafanaTest {

    /** Simulate the DFS with List<String> visited — O(V) membership test per node. */
    static long slowDfs(List<List<Integer>> adj, int start, int N) {
        long ops = 0;
        List<Integer> visited = new ArrayList<>();
        Deque<Integer> stack = new ArrayDeque<>();
        stack.push(start);
        while (!stack.isEmpty()) {
            int node = stack.pop();
            // visited.includes(node) — O(V) scan
            boolean seen = false;
            for (int v : visited) {
                ops++;
                if (v == node) { seen = true; break; }
            }
            if (seen) continue;
            visited.add(node);  // push(node.name)
            for (int child : adj.get(node)) {
                // !visited.includes(child) — another O(V) per edge
                boolean childSeen = false;
                for (int v : visited) {
                    ops++;
                    if (v == child) { childSeen = true; break; }
                }
                if (!childSeen) {
                    stack.push(child);
                }
            }
        }
        return ops;
    }

    /** Simulate the DFS with Set<String> visited — O(1) membership test per node. */
    static long fastDfs(List<List<Integer>> adj, int start, int N) {
        long ops = 0;
        Set<Integer> visited = new HashSet<>();
        Deque<Integer> stack = new ArrayDeque<>();
        stack.push(start);
        while (!stack.isEmpty()) {
            int node = stack.pop();
            ops++;  // O(1) hash lookup
            if (visited.contains(node)) continue;
            visited.add(node);
            for (int child : adj.get(node)) {
                ops++;  // O(1) hash lookup
                if (!visited.contains(child)) {
                    stack.push(child);
                }
            }
        }
        return ops;
    }

    static void testDfsVisited() {
        int N = 200;  // variable count
        // Build a chain graph: 0→1→2→…→N-1 (worst-case for visited growth)
        List<List<Integer>> adj = new ArrayList<>(N);
        for (int i = 0; i < N; i++) adj.add(new ArrayList<>());
        for (int i = 0; i < N - 1; i++) adj.get(i).add(i + 1);

        long sOps = slowDfs(adj, 0, N);
        long fOps = fastDfs(adj, 0, N);

        int Nx = 10;
        boolean pass = sOps > fOps * Nx;
        System.out.printf("grafana-0001 [N=%d chain]: slow=%d fast=%d ratio=%.1fx — %s%n",
                N, sOps, fOps, (double) sOps / fOps, pass ? "PASS" : "FAIL");
        if (!pass) throw new AssertionError("grafana-0001 FAIL: slow=" + sOps + " fast=" + fOps);
    }

    public static void main(String[] args) {
        testDfsVisited();
        System.out.println("1/1 PASS");
    }
}