HA stage 2: DB-shared rate limiting + second server unit + monitor both-servers check (#52)

Co-authored-by: host <host@test.local>

cloud/tests/test_rate_limit_db.py

@@ -0,0 +1,74 @@
+"""HA 阶段 2 单测：DB 共享限流。
+
+DbRateLimiter 与内存版同接口：窗口内达到阈值即 False、窗口
+滑过去后恢复、不同 key 互不干扰；关键一条是多实例共享计数
+（两个 server 进程各建一个实例，计数仍合流——多 server 限流
+的前提）。SQLite 跑同款 SQL，Postgres 方言差异由 db.py 适配层
+覆盖（本文件不连真实 Postgres）。
+"""
+
+import os
+import sys
+import tempfile
+import unittest
+from pathlib import Path
+
+try:
+    from cloud.server import DbRateLimiter, RateLimiter
+except ImportError:
+    sys.path.insert(0, str(Path(__file__).resolve().parents[2]))
+    from cloud.server import DbRateLimiter, RateLimiter
+
+
+class DbRateLimiterTestCase(unittest.TestCase):
+    def setUp(self):
+        self.tmp = tempfile.TemporaryDirectory()
+        self.db_path = os.path.join(self.tmp.name, "control.db")
+        self.now = [1000.0]
+
+    def tearDown(self):
+        self.tmp.cleanup()
+
+    def _limiter(self, per_minute=3, window=60):
+        return DbRateLimiter(self.db_path, per_minute=per_minute,
+                             window_seconds=window,
+                             time_fn=lambda: self.now[0])
+
+    def test_allow_up_to_limit_then_false(self):
+        lim = self._limiter()
+        self.assertTrue(lim.allow("k1"))
+        self.assertTrue(lim.allow("k1"))
+        self.assertTrue(lim.allow("k1"))
+        self.assertFalse(lim.allow("k1"))
+
+    def test_window_slides_and_recovers(self):
+        lim = self._limiter()
+        for _ in range(3):
+            self.assertTrue(lim.allow("k1"))
+        self.assertFalse(lim.allow("k1"))
+        self.now[0] += 61
+        self.assertTrue(lim.allow("k1"))
+
+    def test_keys_are_independent(self):
+        lim = self._limiter()
+        for _ in range(3):
+            self.assertTrue(lim.allow("a"))
+        self.assertFalse(lim.allow("a"))
+        self.assertTrue(lim.allow("b"))
+
+    def test_two_instances_share_counts(self):
+        # 多 server 的核心性质：两个实例（两个进程）计数合流。
+        a = self._limiter()
+        b = self._limiter()
+        self.assertTrue(a.allow("shared"))
+        self.assertTrue(a.allow("shared"))
+        self.assertTrue(b.allow("shared"))
+        self.assertFalse(b.allow("shared"))
+        self.assertFalse(a.allow("shared"))
+
+    def test_memory_limiter_unchanged(self):
+        lim = RateLimiter(per_minute=2, window_seconds=60,
+                          time_fn=lambda: self.now[0])
+        self.assertTrue(lim.allow("k"))
+        self.assertTrue(lim.allow("k"))
+        self.assertFalse(lim.allow("k"))