java-topology/defects/celery/unit/ResultSetAlgorithm.java

package unit;

import java.util.ArrayList;
import java.util.LinkedHashMap;
import java.util.List;
import java.util.Map;

/**
 * celery-0001: ResultSet.update() / ResultSet.add()
 *
 * Defect: self.results is a plain list. The expression
 *   'r not in self.results'  (Python)
 * becomes an O(N) scan on each of M elements in update() → O(M*N) total.
 *
 * Fix: maintain a parallel dict keyed by result ID for O(1) membership.
 *
 * Op counting: each comparison during the list scan counts as one op.
 * For hash lookup we count 1 op per lookup.
 */
public class ResultSetAlgorithm {

    // --- Slow path: simulate list.contains() with explicit scan counting ---

    static long slowUpdate(int existingCount, int newCount) {
        long ops = 0;
        List<String> results = new ArrayList<>();

        for (int i = 0; i < existingCount; i++) {
            results.add("result-" + i);
        }

        // simulate: self.results.extend(r for r in results if r not in self.results)
        for (int i = existingCount; i < existingCount + newCount; i++) {
            String r = "result-" + i;
            // Scan the list: worst case is a full pass (item not found)
            for (String existing : results) {
                ops++; // each comparison costs 1 op
                if (existing.equals(r)) break;
            }
            // Item not in list, add it
            results.add(r);
        }
        return ops;
    }

    // --- Fast path: LinkedHashMap (id→result) simulation ---

    static long fastUpdate(int existingCount, int newCount) {
        long ops = 0;
        Map<String, String> resultMap = new LinkedHashMap<>();

        for (int i = 0; i < existingCount; i++) {
            String r = "result-" + i;
            resultMap.put(r, r);
        }

        for (int i = existingCount; i < existingCount + newCount; i++) {
            String r = "result-" + i;
            ops++; // O(1) hash lookup counted as 1 op
            if (!resultMap.containsKey(r)) {
                resultMap.put(r, r);
            }
        }
        return ops;
    }

    // --- Slow path: add() pattern ---
    // Simulates: if result not in self.results: self.results.append(result)
    // Called N times for sequential task completions in a chord group.

    static long slowAdd(int N) {
        long ops = 0;
        List<String> results = new ArrayList<>();

        for (int i = 0; i < N; i++) {
            String r = "result-" + i;
            // Scan entire list for membership check
            for (String existing : results) {
                ops++;
                if (existing.equals(r)) break;
            }
            // Not found → append (all N items are unique, so full scan each time)
            results.add(r);
        }
        return ops;
    }

    // --- Fast path: add() pattern ---

    static long fastAdd(int N) {
        long ops = 0;
        Map<String, String> resultMap = new LinkedHashMap<>();

        for (int i = 0; i < N; i++) {
            String r = "result-" + i;
            ops++; // O(1) lookup
            resultMap.putIfAbsent(r, r);
        }
        return ops;
    }

    static void runTest(String label, int N, long slowOps, long fastOps) {
        double ratio = (double) slowOps / fastOps;
        boolean pass = ratio >= 10.0;
        System.out.printf("  %-14s N=%-5d slow=%,8d fast=%,5d ratio=%6.1fx  %s%n",
                label, N, slowOps, fastOps, ratio, pass ? "PASS" : "FAIL");
        if (!pass) {
            throw new AssertionError("Ratio " + ratio + " < 10x threshold at N=" + N);
        }
    }

    public static void main(String[] args) {
        System.out.println("celery-0001: ResultSetAlgorithm");
        System.out.println("  Defect: list.contains() per element in update()/add() → O(N²)");
        System.out.println("  Fix:    dict/map key lookup → O(N)");
        System.out.println();

        int[] sizes = {200, 500, 1000};
        int passed = 0;
        int total = sizes.length * 2;

        for (int N : sizes) {
            // Test update(): merge N new results into N existing
            long slowU = slowUpdate(N, N);
            long fastU = fastUpdate(N, N);
            try {
                runTest("update", N, slowU, fastU);
                passed++;
            } catch (AssertionError e) {
                System.out.println("  FAIL update: " + e.getMessage());
            }

            // Test add(): add N items one at a time (each unique)
            long slowA = slowAdd(N);
            long fastA = fastAdd(N);
            try {
                runTest("add", N, slowA, fastA);
                passed++;
            } catch (AssertionError e) {
                System.out.println("  FAIL add: " + e.getMessage());
            }
        }

        System.out.println();
        System.out.println(passed + "/" + total + " PASS");
        if (passed < total) {
            System.exit(1);
        }
    }
}