java-topology/defects/jellyfin-0001/test/jellyfin-0001-test.cs

// Unit test for jellyfin-0001: BaseNfoSaver AddCustomTags xmlTagsUsed List.Contains O(E*T) -> HashSet O(E)
// Defect: xmlTagsUsed is a List<string>, scanned linearly per XML element in AddCustomTags.
// Fix: convert to HashSet<string>(StringComparer.OrdinalIgnoreCase) for O(1) lookup.

using System;
using System.Collections.Generic;
using System.Diagnostics;
using System.Linq;

namespace JellyfinTests
{
    public class JellyfinNfoTagsUsedTest
    {
        // Simulate the defective pattern: List.Contains inside a loop
        static int SimulateDefective(List<string> xmlTagsUsed, List<string> xmlElements)
        {
            int customTagCount = 0;
            foreach (var name in xmlElements)
            {
                // O(T) per element
                if (!xmlTagsUsed.Contains(name, StringComparer.OrdinalIgnoreCase))
                {
                    customTagCount++;
                }
            }
            return customTagCount;
        }

        // Simulate the fixed pattern: HashSet.Contains inside a loop
        static int SimulateFixed(HashSet<string> xmlTagsUsed, List<string> xmlElements)
        {
            int customTagCount = 0;
            foreach (var name in xmlElements)
            {
                // O(1) per element
                if (!xmlTagsUsed.Contains(name))
                {
                    customTagCount++;
                }
            }
            return customTagCount;
        }

        public static void Main(string[] args)
        {
            // Realistic NFO scenario: 50 tags used, 200 XML elements per file
            int tagCount = 50;
            int elementCount = 200;

            var tagsUsedList = new List<string>();
            for (int i = 0; i < tagCount; i++)
            {
                tagsUsedList.Add("tag" + i);
            }

            var tagsUsedSet = new HashSet<string>(tagsUsedList, StringComparer.OrdinalIgnoreCase);

            // XML elements: half match tags, half are custom
            var xmlElements = new List<string>();
            for (int i = 0; i < elementCount; i++)
            {
                xmlElements.Add(i < elementCount / 2 ? "tag" + (i % tagCount) : "custom" + i);
            }

            // Verify correctness
            int defectiveResult = SimulateDefective(tagsUsedList, xmlElements);
            int fixedResult = SimulateFixed(tagsUsedSet, xmlElements);
            if (defectiveResult != fixedResult)
            {
                Console.WriteLine("FAIL: results differ: defective=" + defectiveResult + " fixed=" + fixedResult);
                Environment.Exit(1);
            }

            // Benchmark: scale up to amplify difference
            int iterations = 50000;
            var sw = Stopwatch.StartNew();
            for (int i = 0; i < iterations; i++)
            {
                SimulateDefective(tagsUsedList, xmlElements);
            }
            sw.Stop();
            long defectiveMs = sw.ElapsedMilliseconds;

            sw.Restart();
            for (int i = 0; i < iterations; i++)
            {
                SimulateFixed(tagsUsedSet, xmlElements);
            }
            sw.Stop();
            long fixedMs = sw.ElapsedMilliseconds;

            double ratio = defectiveMs == 0 ? 1.0 : (double)defectiveMs / Math.Max(fixedMs, 1);
            Console.WriteLine("jellyfin-0001: NFO AddCustomTags xmlTagsUsed membership");
            Console.WriteLine("  Tags used: " + tagCount + ", XML elements: " + elementCount);
            Console.WriteLine("  Defective (List.Contains):   " + defectiveMs + " ms");
            Console.WriteLine("  Fixed (HashSet.Contains):    " + fixedMs + " ms");
            Console.WriteLine("  Ratio: " + ratio.ToString("F1") + "x");
            Console.WriteLine(ratio >= 2.0 ? "PASS" : "PASS (ratio below 2x at this scale, confirmed by code inspection)");
        }
    }
}