[pclasses-cvs] pclasses2/include/pclasses/Plugin Plugin.h,1.10,1.11

[stephan b. <sg...@us...>]

Update of /cvsroot/pclasses/pclasses2/include/pclasses/Plugin
In directory sc8-pr-cvs1.sourceforge.net:/tmp/cvs-serv1518/include/pclasses/Plugin

Modified Files:
	Plugin.h 
Log Message:
Added caching of SharedLib lookups. Removed the NonCopyable requirement because this object no longer deletes the SharedLib objects.

Index: Plugin.h
===================================================================
RCS file: /cvsroot/pclasses/pclasses2/include/pclasses/Plugin/Plugin.h,v
retrieving revision 1.10
retrieving revision 1.11
diff -u -d -r1.10 -r1.11
--- Plugin.h	25 Dec 2004 19:56:34 -0000	1.10
+++ Plugin.h	25 Dec 2004 20:50:20 -0000	1.11
@@ -32,7 +32,7 @@
 	*/
 	template <class InterfaceT>
 	class PluginManager :
-		public ::P::NamedTypeFactory< InterfaceT >, public NonCopyable
+		public ::P::NamedTypeFactory< InterfaceT >
 	{
 	public:
 		typedef InterfaceT InterfaceType;
@@ -128,22 +128,37 @@
 		   caller does NOT own the pointer - it is owned by
 		   this class.
 
-		   @todo: if the SO is already opened, give back the
-		   existing SharedLib. We can't do this until we map names to
-		   SharedLibs, which we really have little reason to
-		   do.
+		   This function caches lookups, and calling addPlugin()
+		   multiple times with the same so_name will return the
+		   same SharedLib object.
 		*/
 		::P::System::SharedLib *
 		addPlugin( const std::string & so_name ) throw(::P::RuntimeError)
 		{
-			//CERR << "addPlugin("<<so_name<<").\n";
+			typedef typename PluginsMap::iterator IT;
+			// look for cached entry:
+			IT it = this->m_smap.find( so_name );
+			if( this->m_smap.end() != it )
+			{
+				return (*it).second;
+			}
+
+			// find a DLL file:
 			std::string fn = this->searchPath().find( so_name );
 			if( fn.empty() )
 			{
 				throw ::P::System::SystemError( 0, (std::string("No plugin found for '")+so_name+"'.").c_str(), P_SOURCEINFO );
 			}
+
+			// check for entry cached under DLL's file name:
+			it = this->m_smap.find( fn );
+			if( this->m_smap.end() != it )
+			{
+				return (*it).second;
+			}
+
+			// open DLL and, if workie, cache it:
 			::P::System::SharedLib * shl = ::P::System::openSharedLib( fn );
-			//CERR << "Opened fn="<<fn<<"\n";
 			m_smap.insert( std::make_pair( fn, shl ) );
 			return shl;
 		}
@@ -195,6 +210,11 @@
 		   lib. That said, the default lib-opening routines
 		   do not destroy SharedLibs loaded via this class
 		   until post-main().
+
+		   ACHTUNG #2: using the non-const PluginsMap together
+		   with non-const member functions, e.g. addPlugin(),
+		   from multi-threaded code is likely to Cause Greif.
+		   To be fixed, via P's mutex support.
 		*/
 		PluginsMap & loadedPlugins()
 		{
@@ -256,7 +276,7 @@
 	template <typename T>
 	::P::System::SharedLib *
 	addPlugin( const std::string & pluginname )  throw(RuntimeError)
-	{
+	{		
 		return pluginManager<T>().addPlugin( pluginname );
 	}