russell@unturf.com
32cbeb5dcb
tomcat-0001: WebSocket getNegotiatedSubprotocol List.contains O(R×S) MEDIUM 52x hibernate-orm-0001: FK ordering buildRecursiveOrderedFkSecondPasses List.contains O(N²) HIGH 2.8x netty-0001: ALPN select/selected List.contains O(S×P) MEDIUM 26x netty-0002: DnsResolveContext dedup ArrayList.contains O(R²) MEDIUM 30x All 4/4 unit tests PASS.
90 lines
3.6 KiB
Java
90 lines
3.6 KiB
Java
import java.util.*;
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/**
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* Unit test for netty-0002: DnsResolveContext
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* ArrayList.contains() dedup O(R²) → companion HashSet O(R).
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*/
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public class Netty0002Test {
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// --- BEFORE: O(R²) ArrayList dedup ---
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static List<String> resolveBefore(List<String> records, boolean duplicateAllowed) {
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List<String> finalResult = null;
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for (String record : records) {
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if (finalResult == null) {
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finalResult = new ArrayList<>(8);
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finalResult.add(record);
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} else if (duplicateAllowed || !finalResult.contains(record)) { // O(R)
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finalResult.add(record);
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}
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}
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return finalResult != null ? finalResult : Collections.emptyList();
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}
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// --- AFTER: O(R) companion HashSet dedup ---
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static List<String> resolveAfter(List<String> records, boolean duplicateAllowed) {
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List<String> finalResult = null;
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Set<String> finalResultSet = null;
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for (String record : records) {
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if (finalResult == null) {
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finalResult = new ArrayList<>(8);
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finalResultSet = new HashSet<>(8);
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finalResult.add(record);
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finalResultSet.add(record);
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} else if (duplicateAllowed || !finalResultSet.contains(record)) { // O(1)
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finalResult.add(record);
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finalResultSet.add(record);
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}
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}
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return finalResult != null ? finalResult : Collections.emptyList();
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}
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public static void main(String[] args) {
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// Correctness with duplicates
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List<String> records = Arrays.asList("1.2.3.4", "5.6.7.8", "1.2.3.4", "9.10.11.12", "5.6.7.8");
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List<String> beforeResult = resolveBefore(records, false);
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List<String> afterResult = resolveAfter(records, false);
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assert beforeResult.equals(afterResult) : "Dedup results must match: " + beforeResult + " vs " + afterResult;
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assert beforeResult.size() == 3 : "Expected 3 unique, got " + beforeResult.size();
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System.out.println("PASS correctness dedup: " + beforeResult);
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// Correctness with duplicates allowed
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List<String> beforeDup = resolveBefore(records, true);
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List<String> afterDup = resolveAfter(records, true);
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assert beforeDup.equals(afterDup) : "Dup-allowed results must match";
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assert beforeDup.size() == 5 : "Expected 5 with dups, got " + beforeDup.size();
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System.out.println("PASS correctness dup-allowed: " + beforeDup);
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// Performance: R=1000 records, 50% duplicates
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int R = 1000;
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List<String> bigRecords = new ArrayList<>();
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for (int i = 0; i < R; i++) {
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bigRecords.add("10.0." + (i % (R / 2)) / 256 + "." + (i % (R / 2)) % 256);
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}
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// Warmup
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for (int w = 0; w < 500; w++) {
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resolveBefore(bigRecords, false);
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resolveAfter(bigRecords, false);
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}
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int iterations = 3000;
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long t0 = System.nanoTime();
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for (int i = 0; i < iterations; i++) {
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resolveBefore(bigRecords, false);
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}
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long beforeNs = System.nanoTime() - t0;
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t0 = System.nanoTime();
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for (int i = 0; i < iterations; i++) {
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resolveAfter(bigRecords, false);
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}
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long afterNs = System.nanoTime() - t0;
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double ratio = (double) beforeNs / afterNs;
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System.out.printf("PASS performance: before=%dms after=%dms ratio=%.1fx (R=%d)%n",
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beforeNs / 1_000_000, afterNs / 1_000_000, ratio, R);
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assert ratio > 2.0 : "Expected at least 2x speedup, got " + ratio;
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System.out.println("PASS all tests for netty-0002");
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}
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}
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