Allow multiple clients running WebView on a singular machine. (#5947)

* Multiple CEF instances on a single machine

* remove unused

* meh implementation

* cefextension

* me when partials, race conditions and extractiion of methods exists

* Change remote debugging handling

It now defaults to 9222 again. This doesn't seem to cause any issues when launching 3 clients. The debug port can be reconfigured via CVar if desired.

Also disabled debugging by default outside dev builds.

* Lower MaxAttempts to 15

100 was way too much and gave me anxiety idk.

* Fix non-TOOLS default of remote debug port

* Rewrite locking implementation.

It is much smaller, less complicated and probably more robust too. Should be fully atomic (the previous one wasn't).

* Undo unnecessary style changes

---------

Co-authored-by: PJB3005 <pieterjan.briers+git@gmail.com>

Robust.Client.WebView/Cef/WebViewManagerCef.Lock.cs

@@ -0,0 +1,51 @@
+using System;
+using System.IO;
+using Robust.Client.Utility;
+
+namespace Robust.Client.WebView.Cef;
+
+internal sealed partial class WebViewManagerCef
+{
+    private const string BaseCacheName = "cef_cache";
+    private const string LockFileName = "robust.lock";
+    private FileStream? _lockFileStream;
+    private const int MaxAttempts = 15; // This probably shouldn't be a cvar because the only reason you'd need it change for legit just botting the game.
+
+    private string FindAndLockCacheDirectory()
+    {
+        var rootDir = Path.Combine(UserDataDir.GetRootUserDataDir(_gameController), BaseCacheName);
+
+        for (var i = 0; i < MaxAttempts; i++)
+        {
+            var cacheDirPath = Path.Combine(rootDir, i.ToString());
+
+            if (TryLockCacheDir(i, cacheDirPath))
+                return cacheDirPath;
+        }
+
+        throw new Exception("Unable to locate available CEF cache directory!");
+    }
+
+    private bool TryLockCacheDir(int attempt, string path)
+    {
+        _sawmill.Verbose($"Trying to lock cache directory {attempt}");
+
+        // Does not fail if directory already exists.
+        Directory.CreateDirectory(path);
+
+        var lockFilePath = Path.Combine(path, LockFileName);
+
+        try
+        {
+            var file = File.Open(lockFilePath, FileMode.Create, FileAccess.ReadWrite, FileShare.None);
+            _lockFileStream = file;
+            _sawmill.Debug($"Successfully locked CEF cache directory {attempt}");
+            return true;
+        }
+        catch (IOException ex)
+        {
+            _sawmill.Error($"Failed to lock cache directory {attempt}: {ex}");
+            return false;
+        }
+    }
+}

Robust.Client.WebView/Cef/WebViewManagerCef.cs

@@ -61,12 +61,9 @@ namespace Robust.Client.WebView.Cef
             if (cefResourcesPath == null)
                 throw new InvalidOperationException("Unable to locate cef_resources directory!");
 
-            var cachePath = "";
-            if (_resourceManager.UserData is WritableDirProvider userData)
-            {
-                var rootDir = UserDataDir.GetRootUserDataDir(_gameController);
-                cachePath = Path.Combine(rootDir, "cef_cache", "0");
-            }
+            var remoteDebugPort = _cfg.GetCVar(WCVars.WebRemoteDebugPort);
+
+            var cachePath = FindAndLockCacheDirectory();
 
             var settings = new CefSettings()
             {
@@ -76,7 +73,7 @@ namespace Robust.Client.WebView.Cef
                 BrowserSubprocessPath = subProcessPath,
                 LocalesDirPath = Path.Combine(cefResourcesPath, "locales"),
                 ResourcesDirPath = cefResourcesPath,
-                RemoteDebuggingPort = 9222,
+                RemoteDebuggingPort = remoteDebugPort,
                 CookieableSchemesList = "usr,res",
                 CachePath = cachePath,
             };

Robust.Client.WebView/WCVars.cs

@@ -26,4 +26,16 @@ public static class WCVars
     /// </summary>
     public static readonly CVarDef<bool> WebHeadless =
         CVarDef.Create("web.headless", false, CVar.CLIENTONLY);
+
+#if TOOLS
+    private const int DefaultRemoteDebugPort = 9222;
+#else
+    private const int DefaultRemoteDebugPort = 0;
+#endif
+
+    /// <summary>
+    /// If not 0, the port number used for Chromium's remote debugging.
+    /// </summary>
+    public static readonly CVarDef<int> WebRemoteDebugPort =
+        CVarDef.Create("web.remote_debug_port", DefaultRemoteDebugPort, CVar.CLIENTONLY);
 }