refactor: optimize structure, stability and runtime performance

database.py

@@ -120,7 +120,7 @@ config = get_config()
 DB_FILE = config.DB_FILE
 
 # 数据库版本 (用于迁移管理)
-DB_VERSION = 17
+DB_VERSION = 18
 
 
 # ==================== 系统配置缓存（P1 / O-03） ====================
@@ -142,6 +142,37 @@ def invalidate_system_config_cache() -> None:
         _system_config_cache_loaded_at = 0.0
 
 
+def _normalize_system_config_value(value) -> dict:
+    try:
+        return dict(value or {})
+    except Exception:
+        return {}
+
+
+def _is_system_config_cache_valid(now_ts: float) -> bool:
+    if _system_config_cache_value is None:
+        return False
+    if _SYSTEM_CONFIG_CACHE_TTL_SECONDS <= 0:
+        return True
+    return (now_ts - _system_config_cache_loaded_at) < _SYSTEM_CONFIG_CACHE_TTL_SECONDS
+
+
+def _read_system_config_cache(now_ts: float, *, ignore_ttl: bool = False) -> Optional[dict]:
+    with _system_config_cache_lock:
+        if _system_config_cache_value is None:
+            return None
+        if (not ignore_ttl) and (not _is_system_config_cache_valid(now_ts)):
+            return None
+        return dict(_system_config_cache_value)
+
+
+def _write_system_config_cache(value: dict, now_ts: float) -> None:
+    global _system_config_cache_value, _system_config_cache_loaded_at
+    with _system_config_cache_lock:
+        _system_config_cache_value = dict(value)
+        _system_config_cache_loaded_at = now_ts
+
+
 def init_database():
     """初始化数据库表结构 + 迁移（入口统一）。"""
     db_pool.init_pool(DB_FILE, pool_size=config.DB_POOL_SIZE)
@@ -165,19 +196,21 @@ def migrate_database():
 
 def get_system_config():
     """获取系统配置（带进程内缓存）。"""
-    global _system_config_cache_value, _system_config_cache_loaded_at
-
     now_ts = time.time()
-    with _system_config_cache_lock:
-        if _system_config_cache_value is not None:
-            if _SYSTEM_CONFIG_CACHE_TTL_SECONDS <= 0 or (now_ts - _system_config_cache_loaded_at) < _SYSTEM_CONFIG_CACHE_TTL_SECONDS:
-                return dict(_system_config_cache_value)
 
-    value = _get_system_config_raw()
+    cached_value = _read_system_config_cache(now_ts)
+    if cached_value is not None:
+        return cached_value
 
-    with _system_config_cache_lock:
-        _system_config_cache_value = dict(value)
-        _system_config_cache_loaded_at = now_ts
+    try:
+        value = _normalize_system_config_value(_get_system_config_raw())
+    except Exception:
+        fallback_value = _read_system_config_cache(now_ts, ignore_ttl=True)
+        if fallback_value is not None:
+            return fallback_value
+        raise
+
+    _write_system_config_cache(value, now_ts)
     return dict(value)