Don't use server commands to flush plugin unloads.

bridge/include/IProviderCallbacks.h

@@ -35,6 +35,9 @@ class IProviderCallbacks
 public:
 	// Called when a log message is printed. Return true to supercede.
 	virtual bool OnLogPrint(const char *msg) = 0;
+
+	// Called each frame tick.
+	virtual void OnThink(bool simulating) = 0;
 };
 
 } // namespace SourceMod

core/logic/AMBuilder

@@ -80,6 +80,7 @@ binary.sources += [
   'LibrarySys.cpp',
   'RootConsoleMenu.cpp',
   'CDataPack.cpp',
+  'frame_tasks.cpp',
 ]
 if builder.target_platform == 'windows':
   binary.sources += ['thread/WinThreads.cpp']

core/logic/PluginSys.cpp

@@ -43,6 +43,7 @@
 #include "common_logic.h"
 #include "Translator.h"
 #include "Logger.h"
+#include "frame_tasks.h"
 #include <am-string.h>
 #include <bridge/include/IVEngineServerBridge.h>
 #include <bridge/include/CoreProvider.h>
@@ -54,6 +55,7 @@ IdentityType_t g_PluginIdent = 0;
 CPlugin::CPlugin(const char *file)
  : m_serial(0),
    m_status(Plugin_Uncompiled),
+   m_WaitingToUnload(false),
    m_SilentFailure(false),
    m_FakeNativesMissing(false),
    m_LibraryMissing(false),
@@ -1422,7 +1424,13 @@ void CPluginManager::TryRefreshDependencies(CPlugin *pPlugin)
 
 bool CPluginManager::UnloadPlugin(IPlugin *plugin)
 {
-	return ScheduleUnload((CPlugin *)plugin);
+	CPlugin *pPlugin = (CPlugin *)plugin;
+
+	// If we're already in the unload queue, just wait.
+	if (pPlugin->WaitingToUnload())
+		return false;
+
+	return ScheduleUnload(pPlugin);
 }
 
 bool CPluginManager::ScheduleUnload(CPlugin *pPlugin)
@@ -1431,11 +1439,12 @@ bool CPluginManager::ScheduleUnload(CPlugin *pPlugin)
 	assert(m_plugins.find(pPlugin) != m_plugins.end());
 
 	IPluginContext *pContext = pPlugin->GetBaseContext();
-	if (pContext && pContext->IsInExec())
-	{
-		char buffer[255];
-		ke::SafeSprintf(buffer, sizeof(buffer), "sm plugins unload %s\n", pPlugin->GetFilename());
-		engine->ServerCommand(buffer);
+	if (pContext && pContext->IsInExec()) {
+		ke::Lambda<void()> callback = [this, pPlugin]() {
+			this->ScheduleUnload(pPlugin);
+		};
+		pPlugin->SetWaitingToUnload();
+		ScheduleTaskForNextFrame(ke::Move(callback));
 		return false;
 	}
 

core/logic/PluginSys.h

@@ -222,29 +222,29 @@ public:
 	 */
 	IPhraseCollection *GetPhrases();
 public:
-	/**
-	 * Returns the modification time during last plugin load.
-	 */
+	// Returns the modification time during last plugin load.
 	time_t GetTimeStamp();
 
-	/**
-	 * Returns the current modification time of the plugin file.
-	 */
+	// Returns the current modification time of the plugin file.
 	time_t GetFileTimeStamp();
 
-	/** 
-	 * Returns true if the plugin was running, but is now invalid.
-	 */
+	// Returns true if the plugin was running, but is now invalid.
 	bool WasRunning();
 
+	bool WaitingToUnload() const {
+		return m_WaitingToUnload;
+	}
+	void SetWaitingToUnload() {
+		m_WaitingToUnload = true;
+	}
+
 	Handle_t GetMyHandle();
 
 	bool AddFakeNative(IPluginFunction *pFunc, const char *name, SPVM_FAKENATIVE_FUNC func);
 	void AddConfig(bool autoCreate, const char *cfg, const char *folder);
 	size_t GetConfigCount();
 	AutoConfig *GetConfig(size_t i);
-	inline void AddLibrary(const char *name)
-	{
+	inline void AddLibrary(const char *name) {
 		m_Libraries.push_back(name);
 	}
 	void LibraryActions(LibraryAction action);
@@ -260,6 +260,7 @@ private:
 	unsigned int m_serial;
 
 	PluginStatus m_status;
+	bool m_WaitingToUnload;
 
 	// Statuses that are set during failure.
 	bool m_SilentFailure;

core/logic/common_logic.cpp

@@ -51,6 +51,7 @@
 #include "AdminCache.h"
 #include "ProfileTools.h"
 #include "Logger.h"
+#include "frame_tasks.h"
 #include "sprintf.h"
 #include "LibrarySys.h"
 #include "RootConsoleMenu.h"
@@ -137,6 +138,9 @@ public:
 	bool OnLogPrint(const char *msg) override {
 		return ::OnLogPrint(msg);
 	}
+	void OnThink(bool simulating) override {
+		RunScheduledFrameTasks(simulating);
+	}
 } sProviderCallbackListener;
 
 static sm_logic_t logic =

core/logic/frame_tasks.cpp

@@ -0,0 +1,55 @@
+// vim: set ts=4 sw=4 tw=99 noet :
+// =============================================================================
+// SourceMod
+// Copyright (C) 2004-2008 AlliedModders LLC.  All rights reserved.
+// =============================================================================
+
+// This program is free software; you can redistribute it and/or modify it under
+// the terms of the GNU General Public License, version 3.0, as published by the
+// Free Software Foundation.
+// 
+// This program is distributed in the hope that it will be useful, but WITHOUT
+// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+// FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+// details.
+
+// You should have received a copy of the GNU General Public License along with
+// this program.  If not, see <http://www.gnu.org/licenses/>.
+
+// As a special exception, AlliedModders LLC gives you permission to link the
+// code of this program (as well as its derivative works) to "Half-Life 2," the
+// "Source Engine," the "SourcePawn JIT," and any Game MODs that run on software
+// by the Valve Corporation.  You must obey the GNU General Public License in
+// all respects for all other code used.  Additionally, AlliedModders LLC grants
+// this exception to all derivative works.  AlliedModders LLC defines further
+// exceptions, found in LICENSE.txt (as of this writing, version JULY-31-2007),
+// or <http://www.sourcemod.net/license.php>.
+#include "frame_tasks.h"
+#include <am-vector.h>
+
+using namespace SourceMod;
+
+ke::Vector<ke::Lambda<void()>> sNextTasks;
+ke::Vector<ke::Lambda<void()>> sWorkTasks;
+
+void
+SourceMod::ScheduleTaskForNextFrame(ke::Lambda<void()>&& task)
+{
+	sNextTasks.append(ke::Forward<decltype(task)>(task));
+}
+
+void
+SourceMod::RunScheduledFrameTasks(bool simulating)
+{
+	if (sNextTasks.empty())
+		return;
+
+	// Swap.
+	ke::Vector<ke::Lambda<void()>> temp(ke::Move(sNextTasks));
+	sNextTasks = ke::Move(sWorkTasks);
+	sWorkTasks = ke::Move(temp);
+
+	for (size_t i = 0; i < sWorkTasks.length(); i++)
+		sWorkTasks[i]();
+	sWorkTasks.clear();
+}

core/logic/frame_tasks.h

@@ -0,0 +1,40 @@
+// vim: set ts=4 sw=4 tw=99 noet :
+// =============================================================================
+// SourceMod
+// Copyright (C) 2004-2008 AlliedModders LLC.  All rights reserved.
+// =============================================================================
+
+// This program is free software; you can redistribute it and/or modify it under
+// the terms of the GNU General Public License, version 3.0, as published by the
+// Free Software Foundation.
+// 
+// This program is distributed in the hope that it will be useful, but WITHOUT
+// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
+// FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
+// details.
+
+// You should have received a copy of the GNU General Public License along with
+// this program.  If not, see <http://www.gnu.org/licenses/>.
+
+// As a special exception, AlliedModders LLC gives you permission to link the
+// code of this program (as well as its derivative works) to "Half-Life 2," the
+// "Source Engine," the "SourcePawn JIT," and any Game MODs that run on software
+// by the Valve Corporation.  You must obey the GNU General Public License in
+// all respects for all other code used.  Additionally, AlliedModders LLC grants
+// this exception to all derivative works.  AlliedModders LLC defines further
+// exceptions, found in LICENSE.txt (as of this writing, version JULY-31-2007),
+// or <http://www.sourcemod.net/license.php>.
+#ifndef _include_sourcemod_logic_frame_tasks_h_
+#define _include_sourcemod_logic_frame_tasks_h_
+
+#include <am-function.h>
+
+namespace SourceMod {
+
+void ScheduleTaskForNextFrame(ke::Lambda<void()>&& task);
+
+void RunScheduledFrameTasks(bool simulating);
+
+}
+
+#endif // _include_sourcemod_logic_frame_tasks_h_

core/sourcemod.cpp

@@ -46,11 +46,13 @@
 #include <amtl/os/am-path.h>
 #include <bridge/include/IExtensionBridge.h>
 #include <bridge/include/IScriptManager.h>
+#include <bridge/include/IProviderCallbacks.h>
 #include <bridge/include/ILogger.h>
 
 SH_DECL_HOOK6(IServerGameDLL, LevelInit, SH_NOATTRIB, false, bool, const char *, const char *, const char *, const char *, bool, bool);
 SH_DECL_HOOK0_void(IServerGameDLL, LevelShutdown, SH_NOATTRIB, false);
 SH_DECL_HOOK1_void(IServerGameDLL, GameFrame, SH_NOATTRIB, false, bool);
+SH_DECL_HOOK1_void(IServerGameDLL, Think, SH_NOATTRIB, false, bool);
 SH_DECL_HOOK1_void(IVEngineServer, ServerCommand, SH_NOATTRIB, false, const char *);
 
 SourceModBase g_SourceMod;
@@ -322,6 +324,8 @@ void SourceModBase::StartSourceMod(bool late)
 	{
 		g_pSourcePawn2->InstallWatchdogTimer(atoi(timeout) * 1000);
 	}
+
+	SH_ADD_HOOK(IServerGameDLL, Think, gamedll, SH_MEMBER(logicore.callbacks, &IProviderCallbacks::OnThink), false);
 }
 
 static bool g_LevelEndBarrier = false;
@@ -539,6 +543,7 @@ void SourceModBase::ShutdownServices()
 
 	SH_REMOVE_HOOK(IServerGameDLL, LevelShutdown, gamedll, SH_MEMBER(this, &SourceModBase::LevelShutdown), false);
 	SH_REMOVE_HOOK(IServerGameDLL, GameFrame, gamedll, SH_MEMBER(&g_Timers, &TimerSystem::GameFrame), false);
+	SH_REMOVE_HOOK(IServerGameDLL, Think, gamedll, SH_MEMBER(logicore.callbacks, &IProviderCallbacks::OnThink), false);
 }
 
 void SourceModBase::LogMessage(IExtension *pExt, const char *format, ...)