[mod] soundcloud: faster initialization

[dalf]

What does this PR do?

The get_cliend_id() function:

• fetches https://soundcloud.com
• then fetches each referenced javascript URL to get the client id.

This commit fetches the javascript URLs in the reverse order: the client id is in the last javascript URL.

Why is this change important?

Faster searx initialization (and less HTTP requests).

How to test this PR locally?

• !soundcloud time

Author's checklist

Related issues

[return42]

Thanks!

Faster searx initialization.

Does lazy evaluation makes sense here?

diff --git a/searx/engines/soundcloud.py b/searx/engines/soundcloud.py
index b3e3383b..44fd2d85 100644
--- a/searx/engines/soundcloud.py
+++ b/searx/engines/soundcloud.py
@@ -41,10 +41,14 @@ embedded_url = '<iframe width="100%" height="166" ' +\
     'data-src="https://w.soundcloud.com/player/?url={uri}"></iframe>'
 
 cid_re = re.compile(r'client_id:"([^"]*)"', re.I | re.U)
-guest_client_id = ''
+guest_client_id = None
 
 
 def get_client_id():
+    global guest_client_id
+    if guest_client_id is not None:
+        return guest_client_id
+
     response = http_get("https://soundcloud.com")
 
     if response.ok:
@@ -66,19 +70,13 @@ def get_client_id():
     return ""
 
 
-def init(engine_settings=None):
-    global guest_client_id
-    # api-key
-    guest_client_id = get_client_id()
-
-
 # do search-request
 def request(query, params):
     offset = (params['pageno'] - 1) * 20
 
     params['url'] = search_url.format(query=urlencode({'q': query}),
                                       offset=offset,
-                                      client_id=guest_client_id)
+                                      client_id=get_client_id())
 
     return params

[dalf]

Does lazy evaluation makes sense here?

In this case, the first request will most probably time out (the time to get the client id and then user request).