Fix non-asyncio nested async IO (#610)

* Fix non-asyncio nested async IO

* Add redis init ping

backend/utils/_asyncio.py

@@ -0,0 +1,69 @@
+#!/usr/bin/env python3
+# -*- coding: utf-8 -*-
+import asyncio
+import atexit
+import threading
+import weakref
+
+from typing import Awaitable, Callable, TypeVar
+
+T = TypeVar('T')
+
+
+class _TaskRunner:
+    """A task runner that runs an asyncio event loop on a background thread."""
+
+    def __init__(self):
+        self.__loop: asyncio.AbstractEventLoop | None = None
+        self.__thread: threading.Thread | None = None
+        self.__lock = threading.Lock()
+        atexit.register(self.close)
+
+    def close(self):
+        """关闭事件循环"""
+        if self.__loop:
+            self.__loop.stop()
+
+    def _target(self):
+        """后台线程目标"""
+        loop = self.__loop
+        try:
+            loop.run_forever()
+        finally:
+            loop.close()
+
+    def run(self, coro):
+        """在后台线程上同步运行协程"""
+        with self.__lock:
+            name = f'{threading.current_thread().name} - runner'
+            if self.__loop is None:
+                self.__loop = asyncio.new_event_loop()
+                self.__thread = threading.Thread(target=self._target, daemon=True, name=name)
+                self.__thread.start()
+        fut = asyncio.run_coroutine_threadsafe(coro, self.__loop)
+        return fut.result(None)
+
+
+_runner_map = weakref.WeakValueDictionary()
+
+
+def run_await(coro: Callable[..., Awaitable[T]]) -> Callable[..., T]:
+    """将协程包装在一个函数中，该函数会阻塞，直到它执行完为止"""
+
+    def wrapped(*args, **kwargs):
+        name = threading.current_thread().name
+        inner = coro(*args, **kwargs)
+        try:
+            # 如果当前此线程中正在运行循环
+            # 使用任务运行程序
+            asyncio.get_running_loop()
+            if name not in _runner_map:
+                _runner_map[name] = _TaskRunner()
+            return _runner_map[name].run(inner)
+        except RuntimeError:
+            # 如果没有，请创建一个新的事件循环
+            loop = asyncio.get_event_loop()
+            return loop.run_until_complete(inner)
+
+    wrapped.__doc__ = coro.__doc__
+    return wrapped