whitepaper: 352/169 — wave4 MEDIUM (hadoop/hbase/nova/neutron/openstack) + fix odl-0002 dup

defects/substrate/unit/IsMemberAlgorithm.java

@@ -0,0 +1,71 @@
+package unit;
+
+import java.util.*;
+
+/**
+ * substrate-0002: CWE-407 Aura/BABE/BEEFY is_member linear authority scan
+ *
+ * Simulates:
+ *   Slow: authorities.iter().any(|id| id == authority_id)  — O(A)
+ *   Fast: authorities.binary_search(authority_id).is_ok()  — O(log A)
+ */
+public class IsMemberAlgorithm {
+
+    static class Result {
+        final long ops;
+        final boolean found;
+        Result(long ops, boolean found) { this.ops = ops; this.found = found; }
+    }
+
+    /** Slow: linear scan. Mirrors .iter().any() */
+    static Result slowIsMember(int[] authorities, int target) {
+        long ops = 0;
+        for (int id : authorities) {
+            ops++;
+            if (id == target) return new Result(ops, true);
+        }
+        return new Result(ops, false);
+    }
+
+    /** Fast: binary search. Mirrors .binary_search() on sorted BoundedVec */
+    static Result fastIsMember(int[] sortedAuthorities, int target) {
+        int lo = 0, hi = sortedAuthorities.length - 1;
+        long ops = 0;
+        while (lo <= hi) {
+            ops++;
+            int mid = (lo + hi) >>> 1;
+            if (sortedAuthorities[mid] == target) return new Result(ops, true);
+            else if (sortedAuthorities[mid] < target) lo = mid + 1;
+            else hi = mid - 1;
+        }
+        return new Result(ops, false);
+    }
+
+    static void bench() {
+        int N_AUTH = 1000;
+        int[] authorities = new int[N_AUTH];
+        for (int i = 0; i < N_AUTH; i++) authorities[i] = i * 2; // even IDs, sorted
+
+        // Worst case: target not present (or last element)
+        int target = N_AUTH * 2 - 1; // odd, not in list → full scan
+
+        Result slow = slowIsMember(authorities, target);
+        Result fast = fastIsMember(authorities, target);
+
+        System.out.println("is_member N_AUTH=" + N_AUTH);
+        System.out.println("  slow ops: " + slow.ops + "  found=" + slow.found);
+        System.out.println("  fast ops: " + fast.ops + "  found=" + fast.found);
+
+        double speedup = (double) slow.ops / fast.ops;
+        System.out.printf("  speedup:  %.1fx%n", speedup);
+
+        assert slow.found == fast.found : "result mismatch";
+        assert slow.ops > fast.ops * 10 : "expected >10x speedup, got " + speedup;
+
+        System.out.println("1/1 PASS");
+    }
+
+    public static void main(String[] args) {
+        bench();
+    }
+}