Replace lambdas with function calls

Replace lambdas with function calls. This was done either by extracting a lambda into a function or method, or by replacing it with a library function call.

Minor code changes:

The `u` prefix was removed from strings.

Instead of using the `%` operator with strings or concatenating multiple of them, f-strings were used.

Replaced complex one-like if-else chains with dicts and calls to `dict.get`.

Instead of creating lists and adding them (which returns a new list), a list is created from the get-go by extending it via the star operator during its creation.

Change according to code review

In test_download_manager.py, I replaced lambdas with `MagicMock` and `AsyncMock` as appropriate. I also rearranged mock methods inside tests.

In `dispatcher.py`, I rewrote lambda as an internal callback function.

In `conf.py`, I extracted a lambda into a function.

In `gigachannel_community.py`, I extracted two repeated lambdas into a single module-internal function.

.sonar/analyse.py

@@ -13,7 +13,7 @@
 # These env varialble should be set by Jenkins.
 SERVER_URL = os.environ.get('SONAR_SERVER_URL', "https://sonarcloud.io")
 PROJECT_KEY = os.environ.get('PROJECT_KEY', "org.sonarqube:tribler")
-PR_COMMIT = os.environ.get('ghprbActualCommit', u'')
+PR_COMMIT = os.environ.get('ghprbActualCommit', '')
 TASK_PATH = os.path.join(os.environ.get('WORKSPACE', os.getcwd()), '.scannerwork', 'report-task.txt')
 
 task_status_url = None
@@ -56,12 +56,12 @@
     json_response = requests.get(pr_analysis_url)
     data = json.loads(json_response.text)
 
-    for pull_request in data[u'pullRequests']:
-        print("Matching analysis:", pull_request[u'key'], PR_COMMIT, pull_request[u'key'] == PR_COMMIT)
+    for pull_request in data['pullRequests']:
+        print("Matching analysis:", pull_request['key'], PR_COMMIT, pull_request['key'] == PR_COMMIT)
         # If there is analysis result for the PR commit with status OK, then exit with success status (0)
-        if pull_request[u'key'] == PR_COMMIT:
-            print("Quality Gate:", pull_request[u'status'])
-            if pull_request[u'status'][u'qualityGateStatus'] == u'OK':
+        if pull_request['key'] == PR_COMMIT:
+            print("Quality Gate:", pull_request['status'])
+            if pull_request['status']['qualityGateStatus'] == 'OK':
                 print("Status: OK")
                 break
             else:

doc/conf.py

@@ -24,8 +24,6 @@
 logging.basicConfig(level=logging.INFO)
 logging.info('Start to execute conf.py')
 
-# root_dir = Path(__file__).parent.parent
-
 root_dir = os.path.abspath(os.path.join(os.path.dirname(__name__), '..'))
 tribler_source_dirs = [
     os.path.join(root_dir, "src"),
@@ -48,9 +46,12 @@
 with patch_import(modules):
     from tribler.core.components.restapi.rest.root_endpoint import RootEndpoint
 
-    add_endpoint = RootEndpoint.add_endpoint
-    RootEndpoint.add_endpoint = lambda self, path, ep: add_endpoint(self, path, ep) \
-        if path not in ['/ipv8', '/market', '/wallets'] else None
+    original_add_endpoint = RootEndpoint.add_endpoint
+    def _add_endpoint(self, path, ep):
+        if path in {'/ipv8', '/market', '/wallets'}:
+            return None
+        return original_add_endpoint(self, path, ep)
+    RootEndpoint.add_endpoint = _add_endpoint
 
     # Extract Swagger docs
     from extract_swagger import extract_swagger
@@ -93,18 +94,18 @@
 master_doc = 'index'
 
 # General information about the project.
-project = u'Tribler'
-copyright = u'2020, Tribler devs'
-author = u'Tribler devs'
+project = 'Tribler'
+copyright = '2020, Tribler devs'
+author = 'Tribler devs'
 
 # The version info for the project you're documenting, acts as replacement for
 # |version| and |release|, also used in various other places throughout the
 # built documents.
 #
 # The short X.Y version.
-version = u'7.5'
+version = '7.5'
 # The full version, including alpha/beta/rc tags.
-release = u'7.5.0'
+release = '7.5.0'
 
 # The language for content autogenerated by Sphinx. Refer to documentation
 # for a list of supported languages.
@@ -177,7 +178,7 @@
 # The name for this set of Sphinx documents.
 # "<project> v<release> documentation" by default.
 #
-# html_title = u'Tribler v6.6'
+# html_title = 'Tribler v6.6'
 
 # A shorter title for the navigation bar.  Default is the same as html_title.
 #
@@ -303,8 +304,8 @@
 # (source start file, target name, title,
 #  author, documentclass [howto, manual, or own class]).
 latex_documents = [
-    (master_doc, 'Tribler.tex', u'Tribler Documentation',
-     u'Tribler devs', 'manual'),
+    (master_doc, 'Tribler.tex', 'Tribler Documentation',
+     'Tribler devs', 'manual'),
 ]
 
 # The name of an image file (relative to this directory) to place at the top of
@@ -339,7 +340,7 @@
 # One entry per manual page. List of tuples
 # (source start file, name, description, authors, manual section).
 man_pages = [
-    (master_doc, 'tribler', u'Tribler Documentation',
+    (master_doc, 'tribler', 'Tribler Documentation',
      [author], 1)
 ]
 
@@ -354,7 +355,7 @@
 # (source start file, target name, title, author,
 #  dir menu entry, description, category)
 texinfo_documents = [
-    (master_doc, 'Tribler', u'Tribler Documentation',
+    (master_doc, 'Tribler', 'Tribler Documentation',
      author, 'Tribler', 'One line description of project.',
      'Miscellaneous'),
 ]

src/tribler/core/components/gigachannel/community/gigachannel_community.py

@@ -42,6 +42,12 @@ def __init__(self, max_peers_per_channel=10):
         # Reverse mapping from peers to channels
         self._peers_channels = defaultdict(set)
 
+    @staticmethod
+    def _peer_last_response(peer: Peer):
+        """Get the last response from a peer."""
+        return peer.last_response
+
+
     def add(self, peer: Peer, channel_pk: bytes, channel_id: int):
         id_tuple = (channel_pk, channel_id)
         channel_peers = self._channels_dict[id_tuple]
@@ -50,7 +56,7 @@ def add(self, peer: Peer, channel_pk: bytes, channel_id: int):
         self._peers_channels[peer].add(id_tuple)
 
         if len(channel_peers) > self.max_peers_per_channel:
-            removed_peer = min(channel_peers, key=lambda x: x.last_response)
+            removed_peer = min(channel_peers, key=ChannelsPeersMapping._peer_last_response)
             channel_peers.remove(removed_peer)
             # Maintain the reverse mapping
             self._peers_channels[removed_peer].remove(id_tuple)
@@ -67,7 +73,12 @@ def remove_peer(self, peer):
     def get_last_seen_peers_for_channel(self, channel_pk: bytes, channel_id: int, limit=None):
         id_tuple = (channel_pk, channel_id)
         channel_peers = self._channels_dict.get(id_tuple, [])
-        return sorted(channel_peers, key=lambda x: x.last_response, reverse=True)[0:limit]
+        last_seen_peers = sorted(
+            channel_peers,
+            key=ChannelsPeersMapping._peer_last_response,
+            reverse=True,
+        )
+        return last_seen_peers[0:limit]
 
 
 class GigaChannelCommunity(RemoteQueryCommunity):

src/tribler/core/components/libtorrent/download_manager/download_manager.py

@@ -132,12 +132,40 @@ def __init__(self,
     def libtorrent_port(self):
         return self._libtorrent_port
 
+    @staticmethod
+    def convert_rate(rate: int) -> int:
+        """
+        Rate conversion due to the fact that we had a different system with Swift
+        and the old python BitTorrent core: unlimited == 0, stop == -1, else rate in kbytes
+        """
+        if rate == 0:
+            return -1
+        elif rate == -1:
+            return 1
+        else:
+            return rate * 1024
+
+    @staticmethod
+    def reverse_convert_rate(rate: int) -> int:
+        """
+        Rate conversion due to the fact that we had a different system with Swift
+        and the old python BitTorrent core: unlimited == 0, stop == -1, else rate in kbytes
+        """
+        if rate == -1:
+            return 0
+        elif rate == 1:
+            return -1
+        else:
+            return rate // 1024
+
     async def _check_dht_ready(self, min_dht_peers=60):
-        # Checks whether we got enough DHT peers. If the number of DHT peers is low,
-        # checking for a bunch of torrents in a short period of time may result in several consecutive requests
-        # sent to the same peers. This can trigger those peers' flood protection mechanism,
-        # which results in DHT checks stuck for hours.
-        # See https://github.com/Tribler/tribler/issues/5319
+        """
+        Checks whether we got enough DHT peers. If the number of DHT peers is low,
+        checking for a bunch of torrents in a short period of time may result in several consecutive requests
+        sent to the same peers. This can trigger those peers' flood protection mechanism,
+        which results in DHT checks stuck for hours.
+        See https://github.com/Tribler/tribler/issues/5319
+        """
         while not (self.get_session() and self.get_session().status().dht_nodes > min_dht_peers):
             await asyncio.sleep(1)
 
@@ -248,11 +276,11 @@ def create_session(self, hops=0, store_listen_port=True):
         self._logger.info(f'Dummy mode: {self.dummy_mode}. Hops: {hops}.')
 
         # Elric: Strip out the -rcX, -beta, -whatever tail on the version string.
-        fingerprint = ['TL'] + [int(x) for x in version_id.split('-')[0].split('.')] + [0]
+        fingerprint = ['TL', *map(int, version_id.split('-')[0].split('.')), 0]
         if self.dummy_mode:
             from unittest.mock import Mock
             ltsession = Mock()
-            ltsession.pop_alerts = lambda: {}
+            ltsession.pop_alerts = dict
             ltsession.listen_port = lambda: 123
             ltsession.get_settings = lambda: {"peer_fingerprint": "000"}
         else:
@@ -268,10 +296,10 @@ def create_session(self, hops=0, store_listen_port=True):
             settings['enable_incoming_utp'] = enable_utp
 
             settings['prefer_rc4'] = True
-            settings["listen_interfaces"] = "0.0.0.0:%d" % libtorrent_port
+            settings["listen_interfaces"] = f"0.0.0.0:{libtorrent_port}"
 
             settings['peer_fingerprint'] = self.peer_mid
-            settings['handshake_client_version'] = 'Tribler/' + version_id + '/' + hexlify(self.peer_mid)
+            settings['handshake_client_version'] = f"Tribler/{version_id}/{hexlify(self.peer_mid)}"
         else:
             settings['enable_outgoing_utp'] = True
             settings['enable_incoming_utp'] = True
@@ -281,7 +309,7 @@ def create_session(self, hops=0, store_listen_port=True):
             settings['force_proxy'] = True
 
             # Anon listen port is never used anywhere, so we let Libtorrent set it
-            # settings["listen_interfaces"] = "0.0.0.0:%d" % anon_port
+            # settings["listen_interfaces"] = f"0.0.0.0:{anon_port}"
 
             # By default block all IPs except 1.1.1.1 (which is used to ensure libtorrent makes a connection to us)
             self.update_ip_filter(ltsession, ['1.1.1.1'])
@@ -363,7 +391,7 @@ def set_max_connections(self, conns, hops=None):
     def set_upload_rate_limit(self, rate, hops=None):
         # Rate conversion due to the fact that we had a different system with Swift
         # and the old python BitTorrent core: unlimited == 0, stop == -1, else rate in kbytes
-        libtorrent_rate = int(-1 if rate == 0 else (1 if rate == -1 else rate * 1024))
+        libtorrent_rate = self.__class__.convert_rate(rate=rate)
 
         # Pass outgoing_port and num_outgoing_ports to dict due to bug in libtorrent 0.16.18
         settings_dict = {'upload_rate_limit': libtorrent_rate, 'outgoing_port': 0, 'num_outgoing_ports': 1}
@@ -374,19 +402,19 @@ def get_upload_rate_limit(self, hops=None):
         # Rate conversion due to the fact that we had a different system with Swift
         # and the old python BitTorrent core: unlimited == 0, stop == -1, else rate in kbytes
         libtorrent_rate = self.get_session(hops).upload_rate_limit()
-        return 0 if libtorrent_rate == -1 else (-1 if libtorrent_rate == 1 else libtorrent_rate / 1024)
+        return self.__class__.reverse_convert_rate(rate=libtorrent_rate)
 
     def set_download_rate_limit(self, rate, hops=None):
-        libtorrent_rate = int(-1 if rate == 0 else (1 if rate == -1 else rate * 1024))
+        libtorrent_rate = self.__class__.convert_rate(rate=rate)
 
         # Pass outgoing_port and num_outgoing_ports to dict due to bug in libtorrent 0.16.18
         settings_dict = {'download_rate_limit': libtorrent_rate}
         for session in self.ltsessions.values():
             self.set_session_settings(session, settings_dict)
 
     def get_download_rate_limit(self, hops=0):
-        libtorrent_rate = self.get_session(hops).download_rate_limit()
-        return 0 if libtorrent_rate == -1 else (-1 if libtorrent_rate == 1 else libtorrent_rate / 1024)
+        libtorrent_rate = self.get_session(hops=hops).download_rate_limit()
+        return self.__class__.reverse_convert_rate(rate=libtorrent_rate)
 
     def process_alert(self, alert, hops=0):
         alert_type = alert.__class__.__name__
@@ -780,7 +808,7 @@ def update_trackers(self, infohash, trackers):
             old_def = download.get_def()
             old_trackers = old_def.get_trackers()
             new_trackers = list(set(trackers) - old_trackers)
-            all_trackers = list(old_trackers) + new_trackers
+            all_trackers = [*old_trackers, *new_trackers]
 
             if new_trackers:
                 # Add new trackers to the download