feat(api): Human Input Node (backend part) (#31646)

The backend part of the human in the loop (HITL) feature and relevant architecture / workflow engine changes.

Signed-off-by: yihong0618 <zouzou0208@gmail.com>
Co-authored-by: autofix-ci[bot] <114827586+autofix-ci[bot]@users.noreply.github.com>
Co-authored-by: -LAN- <laipz8200@outlook.com>
Co-authored-by: 盐粒 Yanli <yanli@dify.ai>
Co-authored-by: CrabSAMA <40541269+CrabSAMA@users.noreply.github.com>
Co-authored-by: Stephen Zhou <38493346+hyoban@users.noreply.github.com>
Co-authored-by: Copilot <175728472+Copilot@users.noreply.github.com>
Co-authored-by: yihong <zouzou0208@gmail.com>
Co-authored-by: Joel <iamjoel007@gmail.com>

api/tests/unit_tests/libs/test_rate_limiter.py

@@ -0,0 +1,68 @@
+from unittest.mock import MagicMock
+
+from libs import helper as helper_module
+
+
+class _FakeRedis:
+    def __init__(self) -> None:
+        self._zsets: dict[str, dict[str, float]] = {}
+        self._expiry: dict[str, int] = {}
+
+    def zadd(self, key: str, mapping: dict[str, float]) -> int:
+        zset = self._zsets.setdefault(key, {})
+        for member, score in mapping.items():
+            zset[str(member)] = float(score)
+        return len(mapping)
+
+    def zremrangebyscore(self, key: str, min_score: str | float, max_score: str | float) -> int:
+        zset = self._zsets.get(key, {})
+        min_value = float("-inf") if min_score == "-inf" else float(min_score)
+        max_value = float("inf") if max_score == "+inf" else float(max_score)
+        to_delete = [member for member, score in zset.items() if min_value <= score <= max_value]
+        for member in to_delete:
+            del zset[member]
+        return len(to_delete)
+
+    def zcard(self, key: str) -> int:
+        return len(self._zsets.get(key, {}))
+
+    def expire(self, key: str, ttl: int) -> bool:
+        self._expiry[key] = ttl
+        return True
+
+
+def test_rate_limiter_counts_attempts_within_same_second(monkeypatch):
+    fake_redis = _FakeRedis()
+    monkeypatch.setattr(helper_module.time, "time", lambda: 1000)
+
+    limiter = helper_module.RateLimiter(
+        prefix="test_rate_limit",
+        max_attempts=2,
+        time_window=60,
+        redis_client=fake_redis,
+    )
+
+    limiter.increment_rate_limit("203.0.113.10")
+    limiter.increment_rate_limit("203.0.113.10")
+
+    assert limiter.is_rate_limited("203.0.113.10") is True
+
+
+def test_rate_limiter_uses_injected_redis(monkeypatch):
+    redis_client = MagicMock()
+    redis_client.zcard.return_value = 1
+    monkeypatch.setattr(helper_module.time, "time", lambda: 1000)
+
+    limiter = helper_module.RateLimiter(
+        prefix="test_rate_limit",
+        max_attempts=1,
+        time_window=60,
+        redis_client=redis_client,
+    )
+
+    limiter.increment_rate_limit("203.0.113.10")
+    limiter.is_rate_limited("203.0.113.10")
+
+    assert redis_client.zadd.called is True
+    assert redis_client.zremrangebyscore.called is True
+    assert redis_client.zcard.called is True