russell@unturf.com
178d9c03db
HandBrake: libhb uses array-backed lists bounded by media metadata sizes (tracks, subtitles, chapters, presets). No user-controlled quadratic growth path found. Emacs: C core uses Fmemq/Fmember on small bounded lists (property lists, error conditions, flags). Larger lists (features ~1000, charsets ~200) only scanned in non-hot-path code. Elisp delete-dups already has hash optimization for >100 elements.
91 lines
3.1 KiB
Java
91 lines
3.1 KiB
Java
import java.util.*;
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/**
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* CWE-407 simulation tests for Neovim defects.
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*
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* neovim-0001: ins_compl_add() O(N^2) duplicate completion check
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* (inherited from Vim — same defect pattern as vim-0001)
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*/
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public class NeovimTest {
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// ========================================================================
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// neovim-0001: ins_compl_add duplicate check — linked-list scan vs hash set
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// ========================================================================
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/**
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* DEFECTIVE: O(N^2) — each insertion scans the full list for duplicates.
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* Mirrors Neovim's do { strncmp } while loop in insexpand.c line 943-958.
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*/
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static int complAddDefective(String[] candidates) {
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List<String> matches = new ArrayList<>();
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int ops = 0;
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for (String candidate : candidates) {
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// Linear scan for duplicate
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boolean found = false;
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for (String existing : matches) {
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ops++;
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if (existing.equals(candidate)) {
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found = true;
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break;
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}
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}
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if (!found) {
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matches.add(candidate);
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}
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}
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return ops;
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}
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/**
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* PATCHED: O(N) — hash set for O(1) amortised duplicate detection.
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* Uses Neovim's map infrastructure (map_defs.h) for O(1) lookup.
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*/
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static int complAddPatched(String[] candidates) {
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Set<String> seen = new HashSet<>();
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List<String> matches = new ArrayList<>();
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int ops = 0;
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for (String candidate : candidates) {
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ops++; // hash lookup
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if (seen.add(candidate)) {
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matches.add(candidate);
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}
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}
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return ops;
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}
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static void testNeovim0001() {
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System.out.println("=== neovim-0001: ins_compl_add duplicate check ===");
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int N = 1000;
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// All unique candidates — worst case for duplicate scan
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String[] candidates = new String[N];
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for (int i = 0; i < N; i++) {
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candidates[i] = "nvim_completion_" + i;
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}
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int opsDefective = complAddDefective(candidates);
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int opsPatched = complAddPatched(candidates);
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double ratio = (double) opsDefective / opsPatched;
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System.out.printf(" N=%d candidates (all unique)%n", N);
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System.out.printf(" Defective ops: %,d%n", opsDefective);
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System.out.printf(" Patched ops: %,d%n", opsPatched);
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System.out.printf(" Ratio: %.1fx%n", ratio);
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// Defective: sum(0..N-1) = N*(N-1)/2 = 499,500
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// Patched: N = 1,000
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assert opsDefective >= N * (N - 1) / 2 : "Defective should be O(N^2)";
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assert opsPatched == N : "Patched should be O(N)";
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assert ratio > 100 : "Ratio should exceed 100x, got " + ratio;
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System.out.println(" PASS");
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}
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// ========================================================================
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// Main
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// ========================================================================
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public static void main(String[] args) {
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testNeovim0001();
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System.out.println("\nAll Neovim tests PASSED.");
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}
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}
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