Checker: change image check

In the master branch, the checker starts to stream the response
and cut the connection. However it creates a lot of read error,
which are false negative. I don't know how to fix the issue.

This commit change the checker to download the whole image.
The error reporting is also changed to report only one line,
instead of the whole stacktrace.

Also, if a timeout occurs, the checker waits for one second
before retry.

Do note that I have not test the checker running in background.
This feature seems forgotten and lack of interrest despite the
initial move few years ago.

searx/search/checker/impl.py

@@ -1,11 +1,11 @@
 # SPDX-License-Identifier: AGPL-3.0-or-later
 
 import gc
+import time
 import typing
 import types
 import functools
 import itertools
-from time import time
 from timeit import default_timer
 from urllib.parse import urlparse
 
@@ -65,15 +65,15 @@ def _download_and_check_if_image(image_url: str) -> bool:
     This function should not be called directly: use _is_url_image
     otherwise the cache of functools.lru_cache contains data: URL which might be huge.
     """
-    retry = 2
+    retry = 3
 
     while retry > 0:
-        a = time()
+        a = default_timer()
         try:
             # use "image_proxy" (avoid HTTP/2)
+            network.set_timeout_for_thread(2)
             network.set_context_network_name('image_proxy')
-            r, stream = network.stream(
-                'GET',
+            r = network.get(
                 image_url,
                 timeout=10.0,
                 allow_redirects=True,
@@ -89,19 +89,20 @@ def _download_and_check_if_image(image_url: str) -> bool:
                     'Cache-Control': 'max-age=0',
                 },
             )
-            r.close()
             if r.status_code == 200:
                 is_image = r.headers.get('content-type', '').startswith('image/')
             else:
                 is_image = False
             del r
-            del stream
             return is_image
         except httpx.TimeoutException:
-            logger.error('Timeout for %s: %i', image_url, int(time() - a))
+            logger.error('Timeout for %s: %i', image_url, int(default_timer() - a))
+            time.sleep(1)
             retry -= 1
-        except httpx.HTTPError:
-            logger.exception('Exception for %s', image_url)
+        except httpx.HTTPStatusError as e:
+            logger.error('Exception for %s: HTTP status=%i', image_url, e.response.status_code)
+        except httpx.HTTPError as e:
+            logger.error('Exception for %s: %s, %s', image_url, e.__class__.__name__, ",".join(e.args))
             return False
     return False