refactor: net: avoid duplicate map lookups to mapLocalHost

src/net.cpp

@@ -190,8 +190,8 @@ CAddress GetLocalAddress(const CNetAddr *paddrPeer, ServiceFlags nLocalServices)
 static int GetnScore(const CService& addr)
 {
     LOCK(cs_mapLocalHost);
-    if (mapLocalHost.count(addr) == 0) return 0;
+    const auto it = mapLocalHost.find(addr);
-    return mapLocalHost[addr].nScore;
+    return (it != mapLocalHost.end()) ? it->second.nScore : 0;
 }
 
 // Is our peer's addrLocal potentially useful as an external IP source?
@@ -243,10 +243,10 @@ bool AddLocal(const CService& addr, int nScore)
 
     {
         LOCK(cs_mapLocalHost);
-        bool fAlready = mapLocalHost.count(addr) > 0;
+        const auto [it, is_newly_added] = mapLocalHost.emplace(addr, LocalServiceInfo());
-        LocalServiceInfo &info = mapLocalHost[addr];
+        LocalServiceInfo &info = it->second;
-        if (!fAlready || nScore >= info.nScore) {
+        if (is_newly_added || nScore >= info.nScore) {
-            info.nScore = nScore + (fAlready ? 1 : 0);
+            info.nScore = nScore + (is_newly_added ? 0 : 1);
             info.nPort = addr.GetPort();
         }
     }
@@ -288,12 +288,10 @@ bool IsReachable(const CNetAddr &addr)
 /** vote for a local address */
 bool SeenLocal(const CService& addr)
 {
-    {
+    LOCK(cs_mapLocalHost);
-        LOCK(cs_mapLocalHost);
+    const auto it = mapLocalHost.find(addr);
-        if (mapLocalHost.count(addr) == 0)
+    if (it == mapLocalHost.end()) return false;
-            return false;
+    ++it->second.nScore;
-        mapLocalHost[addr].nScore++;
-    }
     return true;
 }