From aee2eefb92fbd9a6ac64dc446193703d16d26d7c Mon Sep 17 00:00:00 2001
From: Anton Popovichenko <anton.popovichenko@mendix.com>
Date: Mon, 1 Apr 2024 10:49:42 +0200
Subject: [PATCH] feat(Core/Optimization): Reduce CPU consumption by allocating
 sendBuffer only when it is needed. (#18628)

* feat(Core/Optimization): Reduce CPU consumption by allocating the sendBuffer only when it is needed.

* Remove whitespaces.
---
 src/server/game/Server/WorldSocket.cpp | 67 ++++++++++++++------------
 1 file changed, 35 insertions(+), 32 deletions(-)

diff --git a/src/server/game/Server/WorldSocket.cpp b/src/server/game/Server/WorldSocket.cpp
index 05235bc6f..2b44a26ee 100644
--- a/src/server/game/Server/WorldSocket.cpp
+++ b/src/server/game/Server/WorldSocket.cpp
@@ -161,43 +161,46 @@ void WorldSocket::CheckIpCallback(PreparedQueryResult result)
 bool WorldSocket::Update()
 {
     EncryptableAndCompressiblePacket* queued;
-    MessageBuffer buffer(_sendBufferSize);
-    while (_bufferQueue.Dequeue(queued))
+    if (_bufferQueue.Dequeue(queued))
     {
-        queued->CompressIfNeeded();
-
-        ServerPktHeader header(queued->size() + 2, queued->GetOpcode());
-        if (queued->NeedsEncryption())
-            _authCrypt.EncryptSend(header.header, header.getHeaderLength());
-
-        if (buffer.GetRemainingSpace() < queued->size() + header.getHeaderLength())
+        // Allocate buffer only when it's needed but not on every Update() call.
+        MessageBuffer buffer(_sendBufferSize);
+        do
         {
+            queued->CompressIfNeeded();
+            ServerPktHeader header(queued->size() + 2, queued->GetOpcode());
+            if (queued->NeedsEncryption())
+                _authCrypt.EncryptSend(header.header, header.getHeaderLength());
+
+            if (buffer.GetRemainingSpace() < queued->size() + header.getHeaderLength())
+            {
+                QueuePacket(std::move(buffer));
+                buffer.Resize(_sendBufferSize);
+            }
+
+            if (buffer.GetRemainingSpace() >= queued->size() + header.getHeaderLength())
+            {
+                buffer.Write(header.header, header.getHeaderLength());
+                if (!queued->empty())
+                    buffer.Write(queued->contents(), queued->size());
+            }
+            else    // single packet larger than 4096 bytes
+            {
+                MessageBuffer packetBuffer(queued->size() + header.getHeaderLength());
+                packetBuffer.Write(header.header, header.getHeaderLength());
+                if (!queued->empty())
+                    packetBuffer.Write(queued->contents(), queued->size());
+
+                QueuePacket(std::move(packetBuffer));
+            }
+
+            delete queued;
+        } while (_bufferQueue.Dequeue(queued));
+
+        if (buffer.GetActiveSize() > 0)
             QueuePacket(std::move(buffer));
-            buffer.Resize(_sendBufferSize);
-        }
-
-        if (buffer.GetRemainingSpace() >= queued->size() + header.getHeaderLength())
-        {
-            buffer.Write(header.header, header.getHeaderLength());
-            if (!queued->empty())
-                buffer.Write(queued->contents(), queued->size());
-        }
-        else    // single packet larger than 4096 bytes
-        {
-            MessageBuffer packetBuffer(queued->size() + header.getHeaderLength());
-            packetBuffer.Write(header.header, header.getHeaderLength());
-            if (!queued->empty())
-                packetBuffer.Write(queued->contents(), queued->size());
-
-            QueuePacket(std::move(packetBuffer));
-        }
-
-        delete queued;
     }
 
-    if (buffer.GetActiveSize() > 0)
-        QueuePacket(std::move(buffer));
-
     if (!BaseSocket::Update())
         return false;