Rank channel search results by relevance, run search off the event loop

list_channel previously matched every playlist with one unranked
".*keyword.*" regex, so a specific channel name could be buried pages
behind unrelated names that merely contained the keyword mid-word.
Split matches into two tiers (word-boundary match first, then
anywhere-else) using a cheap count+skip/limit per tier so pagination
still avoids pulling every match into memory.

Also found while testing against a 1.19M-channel playlist: searching
scans an unindexed regex and can take several seconds, and it was
running synchronously inside the async handler, freezing every other
request/socket for that whole time. Moved it to run_in_executor;
verified a concurrent request now returns in ~2ms while a 3.6s search
is in flight.

Co-Authored-By: Claude Sonnet 5 <noreply@anthropic.com>

server.py

@@ -892,31 +892,44 @@ async def get_source(request):
 
 
 # List Channels
-async def list_channel(request):
+def _search_channels_sync(channel_to_search, current_page):
     MAX_RECORDS = 30
-    data = await request.post()
 
-    channel_to_search = unquote(data['keyword'])
-    current_page = int(data['num_page'])
+    escaped_keyword = re.escape(channel_to_search)
+    # Channel names are typically prefixed with a country/format tag (e.g.
+    # "AR - BEIN SPORTS 1 FHD"), so match at word boundaries rather than the
+    # start of the string to rank those above unrelated names that merely
+    # contain the keyword mid-word.
+    prefix_pattern = re.compile(r'\b' + escaped_keyword, re.IGNORECASE)
+    contains_pattern = re.compile(escaped_keyword, re.IGNORECASE)
 
-    logger.info("Search keyword='%s' page=%s", channel_to_search, current_page)
-    regex_pattern = ".*" + re.escape(channel_to_search) + ".*"
-
-    # First pass: compute totals without pulling all docs into memory
-    total_records = 0
     active_playlists = list(playlists.find({"activation": 1}))
-    per_playlist_counts = []
+
+    # Two relevance tiers, most relevant first: names starting with the keyword,
+    # then everything else that merely contains it. Counted per tier/playlist so
+    # pagination stays a cheap count+skip/limit instead of pulling every match
+    # into memory to sort it.
+    tiers = []
     for playlist in active_playlists:
         collection_channels = db_iptv['channels_' + playlist['id_playlist']]
-        count = collection_channels.count_documents({
+        prefix_filter = {'id_playlist': playlist['id_playlist'], 'Name': prefix_pattern}
+        count = collection_channels.count_documents(prefix_filter)
+        if count:
+            tiers.append((playlist, prefix_filter, count))
+    for playlist in active_playlists:
+        collection_channels = db_iptv['channels_' + playlist['id_playlist']]
+        contains_only_filter = {
             'id_playlist': playlist['id_playlist'],
-            'Name': {'$regex': regex_pattern, '$options': "i"}
-        })
-        per_playlist_counts.append((playlist, count))
-        total_records += count
+            '$and': [{'Name': contains_pattern}, {'Name': {'$not': prefix_pattern}}],
+        }
+        count = collection_channels.count_documents(contains_only_filter)
+        if count:
+            tiers.append((playlist, contains_only_filter, count))
+
+    total_records = sum(count for _, _, count in tiers)
 
     if total_records == 0:
-        return web.json_response({'num_total_page': 0, 'current_page': 1, 'data': []})
+        return {'num_total_page': 0, 'current_page': 1, 'data': []}
 
     num_total_page = max(1, (total_records + MAX_RECORDS - 1) // MAX_RECORDS)
     current_page = max(1, min(current_page, num_total_page))
@@ -926,7 +939,7 @@ async def list_channel(request):
     # Second pass: fetch only the page slice
     serialized_data = []
     offset = 0
-    for playlist, count in per_playlist_counts:
+    for playlist, mongo_filter, count in tiers:
         if remaining == 0:
             break
         if offset + count <= begin:
@@ -936,16 +949,30 @@ async def list_channel(request):
         local_skip = max(0, begin - offset)
         fetch_limit = min(remaining, count - local_skip)
         collection_channels = db_iptv['channels_' + playlist['id_playlist']]
-        cursor = collection_channels.find({
-            'id_playlist': playlist['id_playlist'],
-            'Name': {'$regex': regex_pattern, '$options': "i"}
-        }).skip(local_skip).limit(fetch_limit)
+        cursor = collection_channels.find(mongo_filter).skip(local_skip).limit(fetch_limit)
 
         serialized_data.extend(serialize_doc(doc) for doc in cursor)
         remaining = MAX_RECORDS - len(serialized_data)
         offset += count
 
-    return web.json_response({'num_total_page': num_total_page, 'current_page': current_page, 'data': serialized_data})
+    return {'num_total_page': num_total_page, 'current_page': current_page, 'data': serialized_data}
+
+
+async def list_channel(request):
+    data = await request.post()
+
+    channel_to_search = unquote(data['keyword'])
+    current_page = int(data['num_page'])
+
+    logger.info("Search keyword='%s' page=%s", channel_to_search, current_page)
+
+    # Searching can mean scanning a multi-hundred-thousand-channel collection
+    # with an unindexed regex (several seconds); run it off the event loop so
+    # it doesn't stall every other request/socket while it works.
+    result = await asyncio.get_running_loop().run_in_executor(
+        None, _search_channels_sync, channel_to_search, current_page
+    )
+    return web.json_response(result)