Introduce CLogger::ScopedReplacement and FileLogger

Comments By: @sera, @vladislavbelov, @Stan
Differential Revision: https://code.wildfiregames.com/D5167
This was SVN commit r27953.

source/main.cpp

@@ -643,6 +643,14 @@ static void RunGameOrAtlas(const PS::span<const char* const> argv)
 	{
 		g_Shutdown = ShutdownType::None;
 
+		// Do this as soon as possible, because it chdirs and will mess up the error reporting if
+		// anything crashes before the working directory is set.
+		InitVfs(args);
+
+		// This must come after VFS init, which sets the current directory (required for finding our
+		// output log files).
+		FileLogger logger;
+
 		if (!Init(args, flags))
 		{
 			flags &= ~INIT_MODS;

source/ps/CLogger.cpp

@@ -1,4 +1,4 @@
-/* Copyright (C) 2022 Wildfire Games.
+/* Copyright (C) 2023 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -34,6 +34,7 @@
 #include <ctime>
 #include <fstream>
 #include <iostream>
+#include <utility>
 
 #include <boost/algorithm/string/replace.hpp>
 
@@ -310,31 +311,30 @@ void CLogger::CleanupRenderQueue()
 		m_RenderMessages.erase(m_RenderMessages.begin(), m_RenderMessages.end() - RENDER_LIMIT);
 }
 
-TestLogger::TestLogger()
-{
-	m_OldLogger = g_Logger;
-	g_Logger = new CLogger(&m_Stream, &blackHoleStream, false, false);
-}
+CLogger::ScopedReplacement::ScopedReplacement() :
+	m_OldLogger{std::exchange(g_Logger, &m_ThisLogger)}
+{}
 
-TestLogger::~TestLogger()
+CLogger::ScopedReplacement::ScopedReplacement(std::ostream* mainLog, std::ostream* interestingLog,
+	const bool takeOwnership, const bool useDebugPrintf) :
+	m_ThisLogger{mainLog, interestingLog, takeOwnership, useDebugPrintf},
+	m_OldLogger{std::exchange(g_Logger, &m_ThisLogger)}
+{}
+
+CLogger::ScopedReplacement::~ScopedReplacement()
 {
-	delete g_Logger;
 	g_Logger = m_OldLogger;
 }
 
+TestLogger::TestLogger() :
+	m_ScopedReplacement{&m_Stream, &blackHoleStream, false, false}
+{}
+
 std::string TestLogger::GetOutput()
 {
 	return m_Stream.str();
 }
 
-TestStdoutLogger::TestStdoutLogger()
-{
-	m_OldLogger = g_Logger;
-	g_Logger = new CLogger(&std::cout, &blackHoleStream, false, false);
-}
-
-TestStdoutLogger::~TestStdoutLogger()
-{
-	delete g_Logger;
-	g_Logger = m_OldLogger;
-}
+TestStdoutLogger::TestStdoutLogger() :
+	m_ScopedReplacement{&std::cout, &blackHoleStream, false, false}
+{}

source/ps/CLogger.h

@@ -1,4 +1,4 @@
-/* Copyright (C) 2022 Wildfire Games.
+/* Copyright (C) 2023 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -47,6 +47,8 @@ class CLogger
 {
 	NONCOPYABLE(CLogger);
 public:
+	class ScopedReplacement;
+
 	enum ELogMethod
 	{
 		Normal,
@@ -109,19 +111,48 @@ private:
 };
 
 /**
- * Helper class for unit tests - captures all log output while it is in scope,
- * and returns it as a single string.
+ * Replaces `g_Logger` for as long as it's in scope.
+ */
+class CLogger::ScopedReplacement
+{
+public:
+	ScopedReplacement();
+	ScopedReplacement(std::ostream* mainLog, std::ostream* interestingLog, const bool takeOwnership,
+		const bool useDebugPrintf);
+
+	ScopedReplacement(const ScopedReplacement&) = delete;
+	ScopedReplacement& operator=(const ScopedReplacement&) = delete;
+	ScopedReplacement(ScopedReplacement&&) = delete;
+	ScopedReplacement& operator=(ScopedReplacement&&) = delete;
+	~ScopedReplacement();
+
+private:
+	CLogger m_ThisLogger;
+	CLogger* m_OldLogger;
+};
+
+/**
+ * This is used in the engine to log the messages to the logfiles.
+ */
+class FileLogger
+{
+private:
+	CLogger::ScopedReplacement m_ScopedReplacement;
+};
+
+/**
+ * Helper class for unit tests - captures all log output, and returns it as a
+ * single string.
  */
 class TestLogger
 {
-	NONCOPYABLE(TestLogger);
 public:
 	TestLogger();
-	~TestLogger();
+
 	std::string GetOutput();
 private:
-	CLogger* m_OldLogger;
 	std::stringstream m_Stream;
+	CLogger::ScopedReplacement m_ScopedReplacement;
 };
 
 /**
@@ -129,12 +160,10 @@ private:
  */
 class TestStdoutLogger
 {
-	NONCOPYABLE(TestStdoutLogger);
 public:
 	TestStdoutLogger();
-	~TestStdoutLogger();
 private:
-	CLogger* m_OldLogger;
+	CLogger::ScopedReplacement m_ScopedReplacement;
 };
 
 #endif

source/ps/GameSetup/GameSetup.cpp

@@ -155,12 +155,10 @@ void MountMods(const Paths& paths, const std::vector<CStr>& mods)
 	g_VFS->Mount(L"", modUserPath / "user" / "", userFlags, InDevelopmentCopy() ? 0 : priority + 1);
 }
 
-static void InitVfs(const CmdLineArgs& args, int flags)
+void InitVfs(const CmdLineArgs& args)
 {
 	TIMER(L"InitVfs");
 
-	const bool setup_error = (flags & INIT_HAVE_DISPLAY_ERROR) == 0;
-
 	const Paths paths(args);
 
 	OsPath logs(paths.Logs());
@@ -172,8 +170,7 @@ static void InitVfs(const CmdLineArgs& args, int flags)
 	AppHooks hooks = {0};
 	hooks.bundle_logs = psBundleLogs;
 	hooks.get_log_dir = psLogDir;
-	if (setup_error)
-		hooks.display_error = psDisplayError;
+	hooks.display_error = psDisplayError;
 	app_hooks_update(&hooks);
 
 	g_VFS = CreateVfs();
@@ -407,7 +404,6 @@ from_config:
 		CNetHost::Deinitialize();
 
 		// should be last, since the above use them
-		SAFE_DELETE(g_Logger);
 		delete &g_Profiler;
 		delete &g_ProfileViewer;
 
@@ -523,15 +519,6 @@ bool AutostartVisualReplay(const std::string& replayFile);
 
 bool Init(const CmdLineArgs& args, int flags)
 {
-	// Do this as soon as possible, because it chdirs
-	// and will mess up the error reporting if anything
-	// crashes before the working directory is set.
-	InitVfs(args, flags);
-
-	// This must come after VFS init, which sets the current directory
-	// (required for finding our output log files).
-	g_Logger = new CLogger;
-
 	new CProfileViewer;
 	new CProfileManager;	// before any script code
 

source/ps/GameSetup/GameSetup.h

@@ -44,10 +44,6 @@ enum InitFlags
 	// needed by map editor because it uses its own GUI.
 	INIT_NO_GUI = 2,
 
-	// avoid setting display_error app hook
-	// needed by map editor because it has its own wx error display
-	INIT_HAVE_DISPLAY_ERROR = 4,
-
 	// initialize the mod folders from command line parameters
 	INIT_MODS = 8,
 
@@ -72,6 +68,8 @@ extern const std::vector<CStr>& GetMods(const CmdLineArgs& args, int flags);
  */
 extern void MountMods(const Paths& paths, const std::vector<CStr>& mods);
 
+void InitVfs(const CmdLineArgs& args);
+
 /**
  * Returns true if successful, false if Init is aborted early (for instance if
  * mods changed, or if we are using -dumpSchema).

source/tools/atlas/GameInterface/Handlers/GraphicsSetupHandlers.cpp

@@ -1,4 +1,4 @@
-/* Copyright (C) 2022 Wildfire Games.
+/* Copyright (C) 2023 Wildfire Games.
  * This file is part of 0 A.D.
  *
  * 0 A.D. is free software: you can redistribute it and/or modify
@@ -43,6 +43,8 @@
 #include "renderer/Renderer.h"
 #include "renderer/SceneRenderer.h"
 
+#include <optional>
+
 #if OS_WIN
 // We don't include wutil header directly to prevent including Windows headers.
 extern void wutil_SetAppWindow(void* hwnd);
@@ -50,7 +52,8 @@ extern void wutil_SetAppWindow(void* hwnd);
 
 namespace AtlasMessage
 {
-
+namespace
+{
 InputProcessor g_Input;
 
 // This keeps track of the last in-game user input.
@@ -60,12 +63,19 @@ double last_user_activity;
 // see comment in GameLoop.cpp about ah_display_error before using INIT_HAVE_DISPLAY_ERROR
 const int g_InitFlags = INIT_HAVE_VMODE | INIT_NO_GUI;
 
+// This isn't used directly. When it's emplaced and when it's reset it does mutate `g_Logger`.
+std::optional<FileLogger> g_FileLogger;
+}
+
 MESSAGEHANDLER(Init)
 {
 	UNUSED2(msg);
 
 	g_Quickstart = true;
 
+	InitVfs(g_AtlasGameLoop->args);
+	g_FileLogger.emplace();
+
 	// Mount mods if there are any specified as command line parameters
 	if (!Init(g_AtlasGameLoop->args, g_InitFlags | INIT_MODS| INIT_MODS_PUBLIC))
 	{
@@ -138,6 +148,7 @@ MESSAGEHANDLER(Shutdown)
 
 	int flags = 0;
 	Shutdown(flags);
+	g_FileLogger.reset();
 }