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

defects/substrate/unit/IsExposedAlgorithm.java

@@ -0,0 +1,96 @@
+package unit;
+
+import java.util.*;
+
+/**
+ * substrate-0001: CWE-407 is_exposed_in_era full table scan
+ *
+ * Simulates:
+ *   Slow: iter_prefix(era).any(|(validator, exposure)| exposure.others.iter().any(|i| i.who == who))
+ *   Fast: ErasValidatorPrefs::contains_key (validator fast-path) + targeted scan
+ */
+public class IsExposedAlgorithm {
+
+    static class Result {
+        final long ops;
+        final boolean exposed;
+        Result(long ops, boolean exposed) { this.ops = ops; this.exposed = exposed; }
+    }
+
+    /**
+     * Slow: scan all validators, scan all nominators per validator.
+     * Mirrors: ErasStakers::iter_prefix(era).any(|(v, exp)| v==who || exp.others.iter().any(...))
+     */
+    static Result slowIsExposed(String who, String[] validators, Map<String, String[]> nominators) {
+        long ops = 0;
+        for (String validator : validators) {
+            ops++;
+            if (validator.equals(who)) return new Result(ops, true);
+            String[] noms = nominators.getOrDefault(validator, new String[0]);
+            for (String nom : noms) {
+                ops++;
+                if (nom.equals(who)) return new Result(ops, true);
+            }
+        }
+        return new Result(ops, false);
+    }
+
+    /**
+     * Fast: O(1) validator set check, then targeted nominator scan.
+     * Mirrors: ErasValidatorPrefs::contains_key(era, who) fast path
+     * + nominator reverse index lookup.
+     */
+    static Result fastIsExposed(String who, Set<String> validatorSet,
+                                 Map<String, String[]> nominators,
+                                 Map<String, List<String>> nominatorToValidators) {
+        long ops = 1; // O(1) set lookup
+        if (validatorSet.contains(who)) return new Result(ops, true);
+
+        // Nominator reverse-index lookup: O(K) where K = validators who nominated
+        List<String> validatorsForNominator = nominatorToValidators.getOrDefault(who, Collections.emptyList());
+        ops += validatorsForNominator.size();
+        return new Result(ops, !validatorsForNominator.isEmpty());
+    }
+
+    static void bench() {
+        int N_VALIDATORS = 300;
+        int N_NOMINATORS_PER = 256;
+        // Target nominator is the last entry of the last validator (worst case slow path)
+        String who = "nominator_" + (N_VALIDATORS - 1) + "_" + (N_NOMINATORS_PER - 1);
+
+        String[] validators = new String[N_VALIDATORS];
+        Map<String, String[]> nominators = new HashMap<>();
+        Set<String> validatorSet = new HashSet<>();
+        Map<String, List<String>> reverseIndex = new HashMap<>();
+
+        for (int v = 0; v < N_VALIDATORS; v++) {
+            validators[v] = "validator_" + v;
+            validatorSet.add(validators[v]);
+            String[] noms = new String[N_NOMINATORS_PER];
+            for (int n = 0; n < N_NOMINATORS_PER; n++) {
+                noms[n] = "nominator_" + v + "_" + n;
+                reverseIndex.computeIfAbsent(noms[n], k -> new ArrayList<>()).add(validators[v]);
+            }
+            nominators.put(validators[v], noms);
+        }
+
+        Result slow = slowIsExposed(who, validators, nominators);
+        Result fast = fastIsExposed(who, validatorSet, nominators, reverseIndex);
+
+        System.out.println("is_exposed_in_era N_VALIDATORS=" + N_VALIDATORS + " N_NOMINATORS_PER=" + N_NOMINATORS_PER);
+        System.out.println("  slow ops: " + slow.ops + "  exposed=" + slow.exposed);
+        System.out.println("  fast ops: " + fast.ops + "  exposed=" + fast.exposed);
+
+        double speedup = (double) slow.ops / fast.ops;
+        System.out.printf("  speedup:  %.1fx%n", speedup);
+
+        assert slow.exposed == fast.exposed : "result mismatch";
+        assert slow.ops > fast.ops * 100 : "expected >100x speedup, got " + speedup;
+
+        System.out.println("1/1 PASS");
+    }
+
+    public static void main(String[] args) {
+        bench();
+    }
+}