From e1054e684ad464ef1270ae4604184c0447a3b1e2 Mon Sep 17 00:00:00 2001
From: "2569718930@qq.com" <2569718930@qq.com>
Date: Mon, 8 Jun 2026 01:20:59 +0800
Subject: [PATCH] Return stale cache for duplicate force refresh

---
 tests/test_web_observability.py | 63 +++++++++++++++++++++++++++++++++
 web/services/city_api.py        | 17 +++++++--
 2 files changed, 77 insertions(+), 3 deletions(-)

diff --git a/tests/test_web_observability.py b/tests/test_web_observability.py
index 60b306ad..4516d3c3 100644
--- a/tests/test_web_observability.py
+++ b/tests/test_web_observability.py
@@ -1339,6 +1339,69 @@ def test_force_refresh_panel_returns_cached_payload_when_refresh_is_slow(monkeyp
     assert refresh_calls == 1
 
 
+def test_force_refresh_panel_returns_cached_payload_when_refresh_already_running(monkeypatch):
+    import asyncio
+
+    refresh_calls = 0
+
+    class FakeCache:
+        def get_city_cache(self, kind, city):
+            assert kind == "panel"
+            assert city == "paris"
+            return {
+                "payload": {
+                    "name": "paris",
+                    "deb": {"prediction": 20.0},
+                    "from_cache": True,
+                },
+            }
+
+    async def fake_run_in_threadpool(fn, *args, **kwargs):
+        if fn is city_api.legacy_routes._refresh_city_panel_cache:
+            await asyncio.sleep(0.08)
+        return fn(*args, **kwargs)
+
+    def refresh_panel(city, force_refresh):
+        nonlocal refresh_calls
+        refresh_calls += 1
+        return {"name": city, "deb": {"prediction": 21.0}, "from_cache": False}
+
+    city_api._CITY_FORCE_REFRESH_INFLIGHT.clear()
+
+    monkeypatch.setenv("POLYWEATHER_CITY_FORCE_REFRESH_TIMEOUT_SEC", "0.5")
+    monkeypatch.setattr(city_api, "run_in_threadpool", fake_run_in_threadpool)
+    monkeypatch.setattr(city_api.legacy_routes, "_normalize_city_or_404", lambda name: name.strip().lower())
+    monkeypatch.setattr(city_api.legacy_routes, "_CACHE_DB", FakeCache())
+    monkeypatch.setattr(city_api.legacy_routes, "_overlay_latest_wunderground_current", lambda city, payload: payload)
+    monkeypatch.setattr(city_api.legacy_routes, "_refresh_city_panel_cache", refresh_panel)
+
+    async def run_requests():
+        first_task = asyncio.create_task(
+            city_api.get_city_detail_payload(
+                object(),
+                "Paris",
+                force_refresh=True,
+                depth="panel",
+            )
+        )
+        await asyncio.sleep(0.01)
+        second = await city_api.get_city_detail_payload(
+            object(),
+            "Paris",
+            force_refresh=True,
+            depth="panel",
+        )
+        first = await first_task
+        return first, second
+
+    first_result, second_result = asyncio.run(run_requests())
+
+    assert first_result["from_cache"] is False
+    assert second_result["from_cache"] is True
+    assert second_result["deb"]["prediction"] == 20.0
+    assert refresh_calls == 1
+
+
 def test_stale_panel_returns_cached_payload_while_refreshing(monkeypatch):
     import asyncio
 
diff --git a/web/services/city_api.py b/web/services/city_api.py
index 691272cf..38a25143 100644
--- a/web/services/city_api.py
+++ b/web/services/city_api.py
@@ -86,12 +86,14 @@ async def _get_cached_city_payload(city: str, kind: str) -> Dict[str, Any]:
 async def _get_or_start_city_force_refresh_task(
     key: str,
     refresh_factory: Callable[[], Awaitable[Dict[str, Any]]],
-) -> "asyncio.Task[Dict[str, Any]]":
+) -> Tuple["asyncio.Task[Dict[str, Any]]", bool]:
     async with _CITY_FORCE_REFRESH_LOCK:
         task = _CITY_FORCE_REFRESH_INFLIGHT.get(key)
+        started = False
         if task is None or task.done():
             task = asyncio.create_task(refresh_factory())
             _CITY_FORCE_REFRESH_INFLIGHT[key] = task
+            started = True
 
             def _cleanup(done: "asyncio.Task[Dict[str, Any]]") -> None:
                 if _CITY_FORCE_REFRESH_INFLIGHT.get(key) is done:
@@ -102,7 +104,7 @@ async def _get_or_start_city_force_refresh_task(
                     logger.warning("city force refresh failed key={}: {}", key, exc)
 
             task.add_done_callback(_cleanup)
-        return task
+        return task, started
 
 
 async def _refresh_city_payload_with_stale_timeout(
@@ -110,7 +112,16 @@ async def _refresh_city_payload_with_stale_timeout(
     kind: str,
     refresh_factory: Callable[[], Awaitable[Dict[str, Any]]],
 ) -> Dict[str, Any]:
-    task = await _get_or_start_city_force_refresh_task(f"{kind}:{city}", refresh_factory)
+    task, started = await _get_or_start_city_force_refresh_task(f"{kind}:{city}", refresh_factory)
+    if not started:
+        cached_payload = await _get_cached_city_payload(city, kind)
+        if cached_payload:
+            logger.warning(
+                "city force refresh already running city={} kind={}; returning stale cache",
+                city,
+                kind,
+            )
+            return await _overlay_cached_wunderground(city, cached_payload)
     timeout_sec = _city_force_refresh_timeout_sec()
     try:
         return await asyncio.wait_for(asyncio.shield(task), timeout=timeout_sec)