java-topology/defects/podman/unit/RunningPodsAlgorithm.java

package unit;

import java.util.*;

/**
 * CWE-407 unit test: podman GetRunningPods
 * File: libpod/runtime_pod.go:147 — GetRunningPods
 *
 * Slow: for each container, scan pods []string via slices.Contains → O(n²)
 * Fast: use map[string]bool for seen set → O(n)
 *
 * Run: javac -d . RunningPodsAlgorithm.java && java -ea unit.RunningPodsAlgorithm
 */
public class RunningPodsAlgorithm {

    // ── Slow implementation (mirrors defective Go code) ───────────────────────
    static class SlowGetRunningPods {
        final long ops;
        final List<String> podIDs;

        SlowGetRunningPods(List<String> containerPodIDs) {
            long count = 0;
            List<String> pods = new ArrayList<>();
            for (String podID : containerPodIDs) {
                // slices.Contains(pods, podID) — O(n) scan
                boolean found = false;
                for (String existing : pods) {
                    count++;
                    if (existing.equals(podID)) { found = true; break; }
                }
                if (!found) {
                    pods.add(podID);
                }
            }
            this.ops = count;
            this.podIDs = pods;
        }
    }

    // ── Fast implementation (proposed fix) ────────────────────────────────────
    static class FastGetRunningPods {
        final long ops;
        final List<String> podIDs;

        FastGetRunningPods(List<String> containerPodIDs) {
            long count = 0;
            Map<String, Boolean> seen = new HashMap<>(containerPodIDs.size() * 2);
            List<String> pods = new ArrayList<>();
            for (String podID : containerPodIDs) {
                count++;                               // O(1) map lookup
                if (!seen.getOrDefault(podID, false)) {
                    seen.put(podID, true);
                    pods.add(podID);
                }
            }
            this.ops = count;
            this.podIDs = pods;
        }
    }

    // ── Node / Result types ───────────────────────────────────────────────────
    static class Node {
        final String containerID;
        final String podID;
        Node(String containerID, String podID) {
            this.containerID = containerID;
            this.podID = podID;
        }
    }

    static class Result {
        final long slowOps;
        final long fastOps;
        final List<String> slowPods;
        final List<String> fastPods;

        Result(long slowOps, long fastOps, List<String> slowPods, List<String> fastPods) {
            this.slowOps = slowOps;
            this.fastOps = fastOps;
            this.slowPods = slowPods;
            this.fastPods = fastPods;
        }
    }

    // ── test infrastructure ───────────────────────────────────────────────────
    static int passed = 0, total = 0;

    static void test(String name, boolean condition) {
        total++;
        if (condition) { passed++; System.out.println("PASS: " + name); }
        else            { System.out.println("FAIL: " + name); }
    }

    /**
     * Build a workload: nContainers containers spread across nPods pods.
     * containersPerPod = nContainers / nPods (worst case for dedup).
     */
    static Result run(int nContainers, int nPods) {
        List<String> containerPodIDs = new ArrayList<>(nContainers);
        for (int i = 0; i < nContainers; i++) {
            containerPodIDs.add("pod-" + (i % nPods));
        }

        SlowGetRunningPods slow = new SlowGetRunningPods(containerPodIDs);
        FastGetRunningPods fast = new FastGetRunningPods(containerPodIDs);
        return new Result(slow.ops, fast.ops, slow.podIDs, fast.podIDs);
    }

    public static void main(String[] args) {
        // T1: 1000 containers, 100 pods (10 containers per pod)
        {
            Result r = run(1000, 100);
            // Slow: each of 1000 containers scans growing pods list — sum ~0+1+2+... per batch
            // Fast: 1000 O(1) lookups
            test("T1-slow-is-quadratic [N=1000,pods=100]",
                r.slowOps > 1000);  // definitely more than linear
            test("T1-fast-is-linear [N=1000,pods=100]",
                r.fastOps <= 1000 + 5);
            double speedup = (double) r.slowOps / r.fastOps;
            test("T1-speedup>=10x", speedup >= 10.0);
            System.out.printf("     slow=%d ops, fast=%d ops, speedup=%.1fx%n",
                r.slowOps, r.fastOps, speedup);
            List<String> ss = new ArrayList<>(r.slowPods); Collections.sort(ss);
            List<String> fs = new ArrayList<>(r.fastPods); Collections.sort(fs);
            test("T1-results-match", ss.equals(fs));
        }

        // T2: 5000 containers, 500 pods (10 per pod)
        {
            Result r = run(5000, 500);
            double speedup = (double) r.slowOps / r.fastOps;
            test("T2-slow-quadratic [N=5000,pods=500]", r.slowOps > 5000);
            test("T2-fast-linear [N=5000]", r.fastOps <= 5000 + 5);
            test("T2-speedup>=10x", speedup >= 10.0);
            System.out.printf("     slow=%d ops, fast=%d ops, speedup=%.1fx%n",
                r.slowOps, r.fastOps, speedup);
            List<String> ss = new ArrayList<>(r.slowPods); Collections.sort(ss);
            List<String> fs = new ArrayList<>(r.fastPods); Collections.sort(fs);
            test("T2-results-match", ss.equals(fs));
        }

        // T3: 100 containers, all different pods (max dedup overhead)
        {
            Result r = run(100, 100);
            // Each container requires full scan of growing pods list
            // Total: 0+1+2+...+99 = 4950 ops for slow
            test("T3-slow-sum-series [N=100,pods=100]", r.slowOps >= 100L * 99 / 2);
            test("T3-fast-linear [N=100]", r.fastOps <= 100 + 5);
            double speedup = (double) r.slowOps / r.fastOps;
            test("T3-speedup>=40x [N=100]", speedup >= 40.0);
            System.out.printf("     slow=%d ops, fast=%d ops, speedup=%.1fx%n",
                r.slowOps, r.fastOps, speedup);
        }

        // T4: Correctness — single pod, many containers
        {
            Result r = run(50, 1);
            test("T4-single-pod-result", r.fastPods.size() == 1);
            test("T4-single-pod-results-match",
                r.slowPods.equals(r.fastPods));
        }

        System.out.println();
        System.out.printf("%d/%d PASS%n", passed, total);
        if (passed != total) System.exit(1);
    }
}