rabbitmq-0001/0002: fifo service-queue O(C) member→O(1) map; blocked O(B) member→O(1) map

defects/rabbitmq/unit/RabbitMQTest.java

@@ -0,0 +1,109 @@
+import java.util.*;
+
+/**
+ * CWE-407 unit tests for RabbitMQ rabbit_fifo.erl defects.
+ *
+ * rabbitmq-0001: deps/rabbit/src/rabbit_fifo.erl maybe_queue_consumer()
+ *   priority_queue:member(Key, ServiceQueue) — O(C) linear scan per message dispatch.
+ *   Called from update_or_remove_con after checkout_one pops the consumer;
+ *   the consumer is NEVER in SQ1 at that point — the scan is 100% wasted work.
+ *   Fix: maintain a shadow map #{consumer_key => true} for O(1) maps:is_key().
+ *
+ * rabbitmq-0002: deps/rabbit/src/rabbit_queue_consumers.erl is_blocked()
+ *   priority_queue:member(Consumer, BlockedConsumers) — O(B) per delivery attempt
+ *   in single-active-consumer mode.
+ *   Fix: shadow set #{consumer => true} in #cr{} for O(1) maps:is_key().
+ */
+public class RabbitMQTest {
+
+    // --- rabbitmq-0001 ---
+    // Benchmark the core operation: O(C) scan vs O(1) map lookup for member check.
+    // In the post-checkout path the consumer is NEVER in the service queue —
+    // the scan always does a full traversal and returns false (100% wasted).
+
+    static boolean pqMember_scan(List<Integer> pq, int key) {
+        for (int k : pq) {    // O(C) — defect: full scan, always false post-checkout
+            if (k == key) return true;
+        }
+        return false;
+    }
+
+    static boolean pqMember_map(Set<Integer> sqSet, int key) {
+        return sqSet.contains(key);   // O(1) — fix
+    }
+
+    static void testRabbitMQ0001() throws Exception {
+        int C = 500;   // consumers in service queue
+        List<Integer> sq = new ArrayList<>(C);
+        Set<Integer> sqSet = new HashSet<>(C);
+        for (int i = 1; i <= C; i++) { sq.add(i); sqSet.add(i); }
+
+        // The post-checkout consumer key (0) is NOT in the queue — always false
+        int popped = 0;
+
+        assert !pqMember_scan(sq, popped) : "popped consumer must not be in SQ";
+        assert !pqMember_map(sqSet, popped) : "popped consumer must not be in SQ";
+
+        // performance: simulate MSG dispatch cycles — member check fires once per message
+        int MSG = 500_000;
+        long t0 = System.nanoTime();
+        for (int m = 0; m < MSG; m++) pqMember_scan(sq, popped);
+        long tScan = System.nanoTime() - t0;
+
+        t0 = System.nanoTime();
+        for (int m = 0; m < MSG; m++) pqMember_map(sqSet, popped);
+        long tMap = System.nanoTime() - t0;
+
+        double ratio = (double) tScan / tMap;
+        System.out.printf("rabbitmq-0001: scan=%.3fs map=%.3fs ratio=%.1f×%n",
+                tScan / 1e9, tMap / 1e9, ratio);
+        assert ratio > 10 : "Expected >10× speedup, got " + ratio;
+        System.out.println("PASS rabbitmq-0001");
+    }
+
+    // --- rabbitmq-0002 ---
+
+    static boolean isBlocked_pqMember(List<Integer> blocked, int consumer) {
+        return blocked.contains(consumer);    // O(B) — defect
+    }
+
+    static boolean isBlocked_mapKey(Set<Integer> blockedSet, int consumer) {
+        return blockedSet.contains(consumer); // O(1) — fix
+    }
+
+    static void testRabbitMQ0002() throws Exception {
+        int B = 300;   // blocked consumers (high-prefetch setup)
+        int MSG = 100_000;
+
+        List<Integer> blocked = new ArrayList<>(B);
+        Set<Integer> blockedSet = new HashSet<>(B);
+        for (int i = 0; i < B; i++) { blocked.add(i); blockedSet.add(i); }
+
+        // target near end (worst case)
+        int target = B - 1;
+
+        // correctness
+        assert isBlocked_pqMember(blocked, target) == isBlocked_mapKey(blockedSet, target);
+        assert !isBlocked_pqMember(blocked, B + 99) && !isBlocked_mapKey(blockedSet, B + 99);
+
+        long t0 = System.nanoTime();
+        for (int r = 0; r < MSG; r++) isBlocked_pqMember(blocked, target);
+        long tMember = System.nanoTime() - t0;
+
+        t0 = System.nanoTime();
+        for (int r = 0; r < MSG; r++) isBlocked_mapKey(blockedSet, target);
+        long tMap = System.nanoTime() - t0;
+
+        double ratio = (double) tMember / tMap;
+        System.out.printf("rabbitmq-0002: member=%.3fs map=%.3fs ratio=%.1f×%n",
+                tMember / 1e9, tMap / 1e9, ratio);
+        assert ratio > 5 : "Expected >5× speedup, got " + ratio;
+        System.out.println("PASS rabbitmq-0002");
+    }
+
+    public static void main(String[] args) throws Exception {
+        testRabbitMQ0001();
+        testRabbitMQ0002();
+        System.out.println("ALL PASS");
+    }
+}