[fix] searx.network: fix rare cases where LOOP is None

* searx.network.client.LOOP is initialized in a thread
* searx.network.__init__ imports LOOP which may happen
  before the thread has initialized LOOP

This commit adds a new function "searx.network.client.get_loop()"
to fix this issue

searx/network/__init__.py

@@ -9,7 +9,7 @@ import httpx
 import h2.exceptions
 
 from .network import get_network, initialize
-from .client import LOOP
+from .client import get_loop
 from .raise_for_httperror import raise_for_httperror
 
 # queue.SimpleQueue: Support Python 3.6
@@ -98,7 +98,7 @@ def request(method, url, **kwargs):
     network = get_context_network()
 
     # do request
-    future = asyncio.run_coroutine_threadsafe(network.request(method, url, **kwargs), LOOP)
+    future = asyncio.run_coroutine_threadsafe(network.request(method, url, **kwargs), get_loop())
     try:
         response = future.result(timeout)
     except concurrent.futures.TimeoutError as e:
@@ -179,7 +179,7 @@ def stream(method, url, **kwargs):
     """
     q = SimpleQueue()
     future = asyncio.run_coroutine_threadsafe(stream_chunk_to_queue(get_network(), q, method, url, **kwargs),
-                                              LOOP)
+                                              get_loop())
     chunk_or_exception = q.get()
     while chunk_or_exception is not None:
         if isinstance(chunk_or_exception, Exception):

searx/network/client.py

@@ -120,7 +120,6 @@ class AsyncHTTPTransportFixed(httpx.AsyncHTTPTransport):
 
 
 def get_transport_for_socks_proxy(verify, http2, local_address, proxy_url, limit, retries):
-    global LOOP, TRANSPORT_KWARGS
     # support socks5h (requests compatibility):
     # https://requests.readthedocs.io/en/master/user/advanced/#socks
     # socks5://   hostname is resolved on client side
@@ -136,7 +135,7 @@ def get_transport_for_socks_proxy(verify, http2, local_address, proxy_url, limit
     return AsyncProxyTransportFixed(proxy_type=proxy_type, proxy_host=proxy_host, proxy_port=proxy_port,
                                     username=proxy_username, password=proxy_password,
                                     rdns=rdns,
-                                    loop=LOOP,
+                                    loop=get_loop(),
                                     verify=verify,
                                     http2=http2,
                                     local_address=local_address,
@@ -192,6 +191,11 @@ def new_client(enable_http, verify, enable_http2,
     return httpx.AsyncClient(transport=transport, mounts=mounts, max_redirects=max_redirects)
 
 
+def get_loop():
+    global LOOP
+    return LOOP
+
+
 def init():
     # log
     for logger_name in ('hpack.hpack', 'hpack.table'):

searx/network/network.py

@@ -7,7 +7,7 @@ from itertools import cycle
 
 import httpx
 
-from .client import new_client, LOOP
+from .client import new_client, get_loop
 
 
 DEFAULT_NAME = '__DEFAULT__'
@@ -291,8 +291,9 @@ def done():
     So Network.aclose is called here using atexit.register
     """
     try:
-        if LOOP:
-            future = asyncio.run_coroutine_threadsafe(Network.aclose_all(), LOOP)
+        loop = get_loop()
+        if loop:
+            future = asyncio.run_coroutine_threadsafe(Network.aclose_all(), loop)
             # wait 3 seconds to close the HTTP clients
             future.result(3)
     finally: