java-topology/defects/pitivi-0001/unit/PitiviMediaLibraryTest.java

package unit;

import java.util.*;

/**
 * PitiviMediaLibraryTest — CWE-407 pitivi-0001
 *
 * Models MediaLibraryWidget.update_asset_thumbs() in pitivi/medialibrary.py lines 918-921:
 *   slow() = O(I * U): for item in store: if item.id in asset_uris (list)
 *   fast() = O(I + U): asset_uris_set = set(asset_uris); for item in store: if id in set
 *
 * Parameters: I=items in media library store, U=changed URIs from ThumbnailCache.update_caches().
 * Assert: slowOps > fastOps * 5x at I=300, U=30.
 */
public class PitiviMediaLibraryTest {

    static long slowOps;
    static long fastOps;

    /**
     * Slow: O(I * U) — models: if item.asset.props.id in asset_uris (list)
     * asset_uris is list[str] returned by ThumbnailCache.update_caches().
     */
    static Set<String> updateThumbsSlow(List<String> storeIds, List<String> assetUris) {
        slowOps = 0;
        Set<String> disregarded = new LinkedHashSet<>();
        for (String id : storeIds) {
            for (String uri : assetUris) {  // O(U) linear scan per store item
                slowOps++;
                if (id.equals(uri)) {
                    disregarded.add(id);
                    break;
                }
            }
        }
        return disregarded;
    }

    /**
     * Fast: O(I + U) — models: asset_uris_set = set(asset_uris); if id in asset_uris_set
     * Build set once: O(U). Lookup per item: O(1).
     */
    static Set<String> updateThumbsFast(List<String> storeIds, List<String> assetUris) {
        fastOps = 0;
        Set<String> uriSet = new HashSet<>(assetUris);
        fastOps += assetUris.size();  // set construction
        Set<String> disregarded = new LinkedHashSet<>();
        for (String id : storeIds) {
            fastOps++;  // O(1) hash lookup
            if (uriSet.contains(id)) {
                disregarded.add(id);
            }
        }
        return disregarded;
    }

    public static void main(String[] args) {
        int passed = 0;
        int failed = 0;

        // Test 1: correctness — same items disregarded
        {
            List<String> store = Arrays.asList(
                "file:///home/user/video/clip1.mp4",
                "file:///home/user/video/clip2.mp4",
                "file:///home/user/video/clip3.mp4",
                "file:///home/user/video/clip4.mp4"
            );
            List<String> changed = Arrays.asList(
                "file:///home/user/video/clip1.mp4",
                "file:///home/user/video/clip3.mp4"
            );
            Set<String> slow = updateThumbsSlow(store, changed);
            Set<String> fast = updateThumbsFast(store, changed);
            if (slow.equals(fast) && slow.size() == 2) {
                System.out.println("PASS test1: both methods disregard same 2 items");
                passed++;
            } else {
                System.out.println("FAIL test1: slow=" + slow + " fast=" + fast);
                failed++;
            }
        }

        // Test 2: op-count speedup at I=300, U=30
        {
            int I = 300;
            int U = 30;
            List<String> storeIds = new ArrayList<>();
            for (int i = 0; i < I; i++) storeIds.add("file:///video/clip-" + i + ".mp4");
            // U changed URIs, every 5th clip changed
            List<String> assetUris = new ArrayList<>();
            for (int i = 0; i < U; i++) assetUris.add("file:///video/clip-" + (i * 5) + ".mp4");

            Set<String> slow = updateThumbsSlow(storeIds, assetUris);
            long sOps = slowOps;
            Set<String> fast = updateThumbsFast(storeIds, assetUris);
            long fOps = fastOps;

            if (!slow.equals(fast)) {
                System.out.println("FAIL test2: results differ slow=" + slow.size() + " fast=" + fast.size());
                failed++;
            } else {
                double ratio = (double) sOps / fOps;
                if (ratio >= 5.0) {
                    System.out.printf("PASS test2: I=%d U=%d sOps=%d fOps=%d ratio=%.1fx%n",
                        I, U, sOps, fOps, ratio);
                    passed++;
                } else {
                    System.out.printf("FAIL test2: ratio=%.1fx (want >=5x) sOps=%d fOps=%d%n",
                        ratio, sOps, fOps);
                    failed++;
                }
            }
        }

        // Test 3: no changed files (empty asset_uris)
        {
            List<String> store = Arrays.asList("file:///a.mp4", "file:///b.mp4");
            Set<String> slow = updateThumbsSlow(store, Collections.emptyList());
            Set<String> fast = updateThumbsFast(store, Collections.emptyList());
            if (slow.isEmpty() && fast.isEmpty()) {
                System.out.println("PASS test3: empty asset_uris handled correctly");
                passed++;
            } else {
                System.out.println("FAIL test3: expected empty, got slow=" + slow + " fast=" + fast);
                failed++;
            }
        }

        // Test 4: all files changed
        {
            List<String> store = new ArrayList<>();
            for (int i = 0; i < 10; i++) store.add("file:///clip-" + i + ".mp4");
            Set<String> slow = updateThumbsSlow(store, new ArrayList<>(store));
            Set<String> fast = updateThumbsFast(store, new ArrayList<>(store));
            if (slow.equals(fast) && slow.size() == 10) {
                System.out.println("PASS test4: all-changed case correct");
                passed++;
            } else {
                System.out.println("FAIL test4: slow=" + slow.size() + " fast=" + fast.size());
                failed++;
            }
        }

        System.out.printf("%nResult: %d/%d tests passed%n", passed, passed + failed);
        if (failed > 0) System.exit(1);
    }
}