Added delay before unloading plugin module after last reference to that module outside plugin manager is gone

src/common/classes/ImplementHelper.h

@@ -211,7 +211,6 @@ public:
 		{
 			PluginManagerInterfacePtr pi;
 			pi->unregisterModule(this);
-			pi->moduleUnloaded();
 
 			flagOsUnload = false;
 		}

src/include/FirebirdPluginApi.h

@@ -172,7 +172,9 @@ public:
 	// Pay attention - this should be called at plugin-regsiter time!
 	// Only at this moment manager knows, which module sets his cleanup
 	virtual void FB_CARG registerModule(IPluginModule* cleanup) = 0;
-	// Remove registered before cleanup routine
+	// Remove registered before cleanup routine.
+	// This method must be called by module which detects that it's unloaded,
+	// but not notified prior to it by PluginManager via IPluginModule.
 	virtual void FB_CARG unregisterModule(IPluginModule* cleanup) = 0;
 	// Main function called to access plugins registered in plugins manager
 	// Has front-end in GetPlugins.h - template GetPlugins
@@ -189,9 +191,6 @@ public:
 	// Plugins must be released using this function - use of plugin's release()
 	// will cause resources leak
 	virtual void FB_CARG releasePlugin(IPluginBase* plugin) = 0;
-	// This method must be called by module which detects that it's unloaded,
-	// but not notified prior to it by PluginManager via IPluginModule.
-	virtual void FB_CARG moduleUnloaded() = 0;
 };
 
 typedef void PluginEntrypoint(IMaster* masterInterface);

src/jrd/jrd.cpp

@@ -283,18 +283,10 @@ int JService::release()
 	return 0;
 }
 
-static AtomicCounter shutdownCounter;
-
 int JProvider::release()
 {
 	if (--refCounter == 0)
 	{
-		if (--shutdownCounter == 0)
-		{
-			LocalStatus status;
-			shutdown(&status, 5000, fb_shutrsn_no_connection);
-		}
-
 		delete this;
 		return 0;
 	}
@@ -302,7 +294,23 @@ int JProvider::release()
 	return 1;
 }
 
-static Firebird::UnloadDetector unloadDetector;
+static UnloadDetector unloadDetector;
+
+
+class ShutdownBeforeUnload
+{
+public:
+	ShutdownBeforeUnload(Firebird::MemoryPool&)
+	{ }
+	~ShutdownBeforeUnload()
+	{
+		LocalStatus status;
+		currentProvider()->shutdown(&status, 0, fb_shutrsn_exit_called);
+	}
+};
+
+static GlobalPtr<ShutdownBeforeUnload, InstanceControl::PRIORITY_DETECT_UNLOAD> shutdownBeforeUnload;
+
 
 class EngineFactory : public StackIface<IPluginFactory>
 {
@@ -315,7 +323,7 @@ public:
 			return NULL;
 		}
 
-		++shutdownCounter;
+		//++shutdownCounter;
 		IPluginBase* p = new JProvider(factoryParameter);
 		p->addRef();
 		return p;
@@ -3825,7 +3833,7 @@ private:
 };
 
 
-void JProvider::shutdown(IStatus* status, unsigned int timeout, const int /*reason*/)
+void JProvider::shutdown(IStatus* status, unsigned int timeout, const int reason)
 {
 /**************************************
  *
@@ -3857,6 +3865,15 @@ void JProvider::shutdown(IStatus* status, unsigned int timeout, const int /*reas
 				attach_count, database_count, svc_count);
 		}
 
+		if (reason == fb_shutrsn_exit_called)
+		{
+			// Starting threads may fail when task is going to close.
+			// This happens at least with some microsoft C runtimes.
+			// If people wish to have timeout, they should better call fb_shutdown() themselves.
+			// Therefore:
+			timeout = 0;
+		}
+
 		if (timeout)
 		{
 			Semaphore shutdown_semaphore;

src/yvalve/MasterImplementation.cpp

@@ -484,6 +484,8 @@ public:
 		if (stopThread)
 		{
 			// ignore an attempt to start timer - anyway thread to make it fire is down
+			timer->addRef();
+			timer->release();
 			return;
 		}
 

src/yvalve/PluginManager.cpp

@@ -89,6 +89,7 @@ namespace
 		file += newExt;
 	}
 
+	// Holds a reference to plugins.conf file
 	class StaticConfHolder
 	{
 	public:
@@ -236,7 +237,9 @@ namespace
 		return NULL;
 	}
 
-	struct RegisteredPlugin		// This is POD object
+	// Plugins registered when loading pluign module
+	// This is POD object - no dtor, only simple data types inside
+	struct RegisteredPlugin
 	{
 		RegisteredPlugin(IPluginFactory* f, const char* nm, unsigned int t)
 			: factory(f), name(nm), type(t)
@@ -251,6 +254,7 @@ namespace
 		unsigned int type;
 	};
 
+	// Controls module, containing plugins
 	class PluginModule : public Firebird::RefCounted, public GlobalStorage
 	{
 	public:
@@ -310,6 +314,10 @@ namespace
 			if (cleanup == c)
 			{
 				cleanup = 0;
+				// This is called only by unregister module
+				// when current module is forced to go away by OS.
+				// Do not unload it ourself in this case.
+				addRef();
 			}
 			else if (next)
 			{
@@ -377,6 +385,8 @@ namespace
 
 	PluginModule* builtin = NULL;
 
+	// Provides most of configuration services for plugins,
+	// except per-database configuration in aliases.conf
 	class ConfiguredPlugin : public RefCounted, public GlobalStorage
 	{
 	public:
@@ -442,6 +452,34 @@ namespace
 		PathName plugName;
 	};
 
+	// Delays destruction of ConfiguredPlugin instance
+	class PluginDestroyTimer : public Firebird::StdIface<Firebird::ITimer, FB_I_TIMER_VERSION>
+	{
+	public:
+		PluginDestroyTimer(ConfiguredPlugin* cp)
+			: configuredPlugin(cp)
+		{ }
+
+		// ITimer implementation
+		void FB_CARG handler()
+		{ }
+
+		int FB_CARG release()
+		{
+			if (--refCounter == 0)
+			{
+				delete this;
+				return 0;
+			}
+
+			return 1;
+		}
+
+	private:
+		RefPtr<ConfiguredPlugin> configuredPlugin;
+	};
+
+	// Provides per-database configuration from aliases.conf
 	class FactoryParameter : public StdIface<IPluginConfig, FB_FACTORY_PARAMETER_VERSION>
 	{
 	public:
@@ -484,6 +522,12 @@ namespace
 		}
 
 	private:
+		~FactoryParameter()
+		{
+			PluginDestroyTimer* timer = new PluginDestroyTimer(configuredPlugin);
+			TimerInterfacePtr()->start(timer, 1000000);		// 1 sec
+		}
+
 		RefPtr<ConfiguredPlugin> configuredPlugin;
 		RefPtr<IFirebirdConf> firebirdConf;
 	};
@@ -586,6 +630,7 @@ namespace
 		*prev = this;
 	}
 
+	// Provides access to plugins of given type / name
 	class PluginSet : public StdIface<IPluginSet, FB_PLUGIN_SET_VERSION>
 	{
 	public:
@@ -848,9 +893,16 @@ void FB_CARG PluginManager::registerModule(IPluginModule* cleanup)
 
 void FB_CARG PluginManager::unregisterModule(IPluginModule* cleanup)
 {
-	MutexLockGuard g(plugins->mutex);
+	{	// guard scope
+		MutexLockGuard g(plugins->mutex);
+		modules->resetCleanup(cleanup);
+	}
 
-	modules->resetCleanup(cleanup);
+	// Module cleanup should be unregistered only if it's unoaded
+	// and only if it's unoaded not by PluginManager, but by OS.
+	// That means that task is closing unexpectedly - sooner of all
+	// exit() is called by client of embedded server. Shutdown ourself.
+	fb_shutdown(5000, fb_shutrsn_exit_called);
 }
 
 IPluginSet* FB_CARG PluginManager::getPlugins(unsigned int interfaceType, const char* namesList,
@@ -934,9 +986,4 @@ void PluginManager::waitForType(unsigned int typeThatMustGoAway)
 	}
 }
 
-void FB_CARG PluginManager::moduleUnloaded()
-{
-	fb_shutdown(5000, fb_shutrsn_exit_called);
-}
-
 }	// namespace Firebird

src/yvalve/PluginManager.h

@@ -51,7 +51,6 @@ public:
 	void FB_CARG releasePlugin(IPluginBase* plugin);
 	void FB_CARG registerModule(IPluginModule* cleanup);
 	void FB_CARG unregisterModule(IPluginModule* cleanup);
-	void FB_CARG moduleUnloaded();
 
 	PluginManager();