Fix serverlist query allocating a large amount of memory when a large…

… amount of servers are pending
Facepunch · Aug 13, 2024 · d18086a · d18086a
1 parent 4463739
commit d18086a
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Showing 3 changed files with 33 additions and 7 deletions.
diff --git a/Facepunch.Steamworks/Generated/Interfaces/ISteamMatchmakingServers.cs b/Facepunch.Steamworks/Generated/Interfaces/ISteamMatchmakingServers.cs
@@ -106,7 +106,24 @@ internal gameserveritem_t GetServerDetails( HServerListRequest hRequest, int iSe
 			var returnValue = _GetServerDetails( Self, hRequest, iServer );
 			return returnValue.ToType<gameserveritem_t>();
 		}
-
+
+		/// <summary>
+		/// Read gameserveritem_t.m_bHadSuccessfulResponse without allocating the struct on the heap
+		/// </summary>
+		/// <param name="hRequest"></param>
+		/// <param name="iServer"></param>
+		/// <returns></returns>
+		internal bool HasServerResponded( HServerListRequest hRequest, int iServer )
+		{
+			IntPtr returnValue = _GetServerDetails( Self, hRequest, iServer );
+
+			// Return false if steam returned null
+			if ( returnValue == IntPtr.Zero ) return false;
+
+			// first 8 bytes is IPAddress, next 4 bytes is ping, next 1 byte is m_bHadSuccessfulResponse
+			return Marshal.ReadByte( IntPtr.Add( returnValue, 12 ) ) == 1;
+		}
+
 		#region FunctionMeta
 		[DllImport( Platform.LibraryName, EntryPoint = "SteamAPI_ISteamMatchmakingServers_CancelQuery", CallingConvention = Platform.CC)]
 		private static extern void _CancelQuery( IntPtr self, HServerListRequest hRequest );

diff --git a/Facepunch.Steamworks/Generated/SteamStructs.cs b/Facepunch.Steamworks/Generated/SteamStructs.cs
@@ -25,14 +25,17 @@ internal partial struct servernetadr_t
 		internal uint IP; // m_unIP uint32
 
 	}
-	
+
 	[StructLayout( LayoutKind.Sequential, Pack = Platform.StructPackSize )]
 	internal partial struct gameserveritem_t
 	{
 		internal servernetadr_t NetAdr; // m_NetAdr servernetadr_t
 		internal int Ping; // m_nPing int
+
+		// NOTE: If you add fields above this you must change offset inISteamMatchmakingServers.HasServerResponded()
 		[MarshalAs(UnmanagedType.I1)]
 		internal bool HadSuccessfulResponse; // m_bHadSuccessfulResponse bool
+
 		[MarshalAs(UnmanagedType.I1)]
 		internal bool DoNotRefresh; // m_bDoNotRefresh bool
 		internal string GameDirUTF8() => System.Text.Encoding.UTF8.GetString( GameDir, 0, System.Array.IndexOf<byte>( GameDir, 0 ) );

diff --git a/Facepunch.Steamworks/ServerList/Base.cs b/Facepunch.Steamworks/ServerList/Base.cs
@@ -161,11 +161,17 @@ public void UpdateResponsive()
 		{
 			watchList.RemoveAll( x =>
 			{
-				var info = Internal.GetServerDetails( request, x );
-				if ( info.HadSuccessfulResponse )
+				// First check if the server has responded without allocating server info
+				bool hasResponded = Internal.HasServerResponded( request, x );
+				if ( hasResponded )
 				{
-					OnServer( ServerInfo.From( info ), info.HadSuccessfulResponse );
-					return true;
+					// Now get all server info
+					var info = Internal.GetServerDetails( request, x );
+					if ( info.HadSuccessfulResponse )
+					{
+						OnServer( ServerInfo.From( info ), info.HadSuccessfulResponse );
+						return true;
+					}
 				}
 
 				return false;
@@ -194,4 +200,4 @@ private void OnServer( ServerInfo serverInfo, bool responded )
 			Unresponsive.Add( serverInfo );
 		}
 	}
-}
+}