From 65766ec9aca3a21eac7243ec834fd71f19521747 Mon Sep 17 00:00:00 2001
From: NIC619 <twedusuck@gmail.com>
Date: Tue, 17 Dec 2019 17:36:15 +0800
Subject: [PATCH] Change type of local peers var from list to set

---
 libp2p/pubsub/gossipsub.py | 29 ++++++++++++++++-------------
 1 file changed, 16 insertions(+), 13 deletions(-)

diff --git a/libp2p/pubsub/gossipsub.py b/libp2p/pubsub/gossipsub.py
index 7ef1372d..61287940 100644
--- a/libp2p/pubsub/gossipsub.py
+++ b/libp2p/pubsub/gossipsub.py
@@ -213,7 +213,7 @@ class GossipSub(IPubsubRouter):
         :param origin: peer id of the peer the message originate from.
         :return: a generator of the peer ids who we send data to.
         """
-        send_to: List[ID] = []
+        send_to: Set[ID] = set()
         for topic in topic_ids:
             if topic not in self.pubsub.peer_topics:
                 continue
@@ -221,14 +221,15 @@ class GossipSub(IPubsubRouter):
             # floodsub peers
             # FIXME: `gossipsub.peers_floodsub` can be changed to `gossipsub.peers` in go.
             #   This will improve the efficiency when searching for a peer's protocol id.
-            floodsub_peers: List[ID] = [
+            floodsub_peers: Set[ID] = set(
                 peer_id
                 for peer_id in self.pubsub.peer_topics[topic]
                 if peer_id in self.peers_floodsub
-            ]
+            )
+            send_to.update(floodsub_peers)
 
             # gossipsub peers
-            gossipsub_peers: List[ID] = []
+            gossipsub_peers: Set[ID] = set()
             if topic in self.mesh:
                 gossipsub_peers = self.mesh[topic]
             else:
@@ -236,21 +237,23 @@ class GossipSub(IPubsubRouter):
                 # `self.degree` number of peers who have subscribed to the topic and add them
                 # as our `fanout` peers.
                 topic_in_fanout: bool = topic in self.fanout
-                fanout_peers: List[ID] = self.fanout[topic] if topic_in_fanout else []
+                fanout_peers: Set[ID] = self.fanout[topic] if topic_in_fanout else set()
                 fanout_size = len(fanout_peers)
                 if not topic_in_fanout or (
                     topic_in_fanout and fanout_size < self.degree
                 ):
                     if topic in self.pubsub.peer_topics:
                         # Combine fanout peers with selected peers
-                        fanout_peers += self._get_in_topic_gossipsub_peers_from_minus(
-                            topic, self.degree - fanout_size, fanout_peers
+                        fanout_peers.update(
+                            self._get_in_topic_gossipsub_peers_from_minus(
+                                topic, self.degree - fanout_size, fanout_peers
+                            )
                         )
-                self.fanout[topic] = set(fanout_peers)
+                self.fanout[topic] = fanout_peers
                 gossipsub_peers = fanout_peers
-            send_to.extend(floodsub_peers + gossipsub_peers)
+            send_to.update(gossipsub_peers)
         # Excludes `msg_forwarder` and `origin`
-        yield from set(send_to).difference([msg_forwarder, origin])
+        yield from send_to.difference([msg_forwarder, origin])
 
     async def join(self, topic: str) -> None:
         """
@@ -264,10 +267,10 @@ class GossipSub(IPubsubRouter):
         if topic in self.mesh:
             return
         # Create mesh[topic] if it does not yet exist
-        self.mesh[topic] = []
+        self.mesh[topic] = set()
 
         topic_in_fanout: bool = topic in self.fanout
-        fanout_peers: List[ID] = self.fanout[topic] if topic_in_fanout else []
+        fanout_peers: Set[ID] = self.fanout[topic] if topic_in_fanout else set()
         fanout_size = len(fanout_peers)
         if not topic_in_fanout or (topic_in_fanout and fanout_size < self.degree):
             # There are less than D peers (let this number be x)
@@ -278,7 +281,7 @@ class GossipSub(IPubsubRouter):
                     topic, self.degree - fanout_size, fanout_peers
                 )
                 # Combine fanout peers with selected peers
-                fanout_peers += selected_peers
+                fanout_peers.update(selected_peers)
 
         # Add fanout peers to mesh and notifies them with a GRAFT(topic) control message.
         for peer in fanout_peers: