Improve performance under load of OnDataReady and remove C-isms.

Re-use variables initialized within loop, const-ify config variables
accessed repeatedly, remove eol_found label.

Merges #1451.

diff --git a/src/users.cpp b/src/users.cpp
index 5ddd98defa6809b967babd8e65681e7d29c392f3..7f56994d4e8fb4d8c19aedf73ad644999551a620 100644 (file)
--- a/src/users.cpp
+++ b/src/users.cpp
@@ -227,37 +227,56 @@ void UserIOHandler::OnDataReady()
                        user->nick.c_str(), (unsigned long)recvq.length(), user->MyClass->GetRecvqMax());
                return;
        }
+
        unsigned long sendqmax = ULONG_MAX;
        if (!user->HasPrivPermission("users/flood/increased-buffers"))
                sendqmax = user->MyClass->GetSendqSoftMax();
+
        unsigned long penaltymax = ULONG_MAX;
        if (!user->HasPrivPermission("users/flood/no-fakelag"))
                penaltymax = user->MyClass->GetPenaltyThreshold() * 1000;
 
+       // The maximum size of an IRC message minus the terminating CR+LF.
+       const size_t maxmessage = ServerInstance->Config->Limits.MaxLine - 2;
+       std::string line;
+       line.reserve(maxmessage);
+
+       bool eol_found;
+       std::string::size_type qpos;
+
        while (user->CommandFloodPenalty < penaltymax && getSendQSize() < sendqmax)
        {
-               std::string line;
-               line.reserve(ServerInstance->Config->Limits.MaxLine);
-               std::string::size_type qpos = 0;
-               while (qpos < recvq.length())
+               qpos = 0;
+               eol_found = false;
+
+               const size_t qlen = recvq.length();
+               while (qpos < qlen)
                {
                        char c = recvq[qpos++];
                        switch (c)
                        {
-                       case '\0':
-                               c = ' ';
-                               break;
-                       case '\r':
-                               continue;
-                       case '\n':
-                               goto eol_found;
+                               case '\0':
+                                       c = ' ';
+                                       break;
+                               case '\r':
+                                       continue;
+                               case '\n':
+                                       eol_found = true;
+                                       break;
                        }
-                       if (line.length() < ServerInstance->Config->Limits.MaxLine - 2)
+
+                       if (eol_found)
+                               break;
+
+                       if (line.length() < maxmessage)
                                line.push_back(c);
                }
-               // if we got here, the recvq ran out before we found a newline
-               return;
-eol_found:
+
+               // if we return here, we haven't found a newline and make no modifications to recvq
+               // so we can wait for more data
+               if (!eol_found)
+                       return;
+
                // just found a newline. Terminate the string, and pull it out of recvq
                recvq.erase(0, qpos);
 
@@ -269,7 +288,11 @@ eol_found:
                ServerInstance->Parser.ProcessBuffer(line, user);
                if (user->quitting)
                        return;
+
+               // clear() does not reclaim memory associated with the string, so our .reserve() call is safe
+               line.clear();
        }
+
        if (user->CommandFloodPenalty >= penaltymax && !user->MyClass->fakelag)
                ServerInstance->Users->QuitUser(user, "Excess Flood");
 }