open compound lib in read-only mode, unless explicitly stated

avoids dead-locking when several processes try to open the
compound lib at the same time.

modules/conop/pymod/export_compound.cc

@@ -51,7 +51,7 @@ void export_Compound() {
   register_ptr_to_python<CompoundPtr>();  
   
   class_<CompoundLib>("CompoundLib", no_init)
-    .def("Load", &CompoundLib::Load).staticmethod("Load")
+    .def("Load", &CompoundLib::Load, arg("readonly")=true).staticmethod("Load")
     .def("FindCompound", &CompoundLib::FindCompound)
     .def("ClearCache", &CompoundLib::ClearCache)
   ;

modules/conop/src/compound_lib.cc

@@ -237,10 +237,11 @@ CompoundLibPtr CompoundLib::Create(const String& database)
 }
 
 
-CompoundLibPtr CompoundLib::Load(const String& database) 
+CompoundLibPtr CompoundLib::Load(const String& database, bool readonly) 
 {
+  int flags=readonly ? SQLITE_OPEN_READONLY : SQLITE_OPEN_READWRITE;
   CompoundLibPtr lib(new CompoundLib);
-  int retval=sqlite3_open(database.c_str(), &lib->conn_);
+  int retval=sqlite3_open_v2(database.c_str(), &lib->conn_, flags, NULL);
   if (SQLITE_OK==retval) {
     return lib;
   }

modules/conop/src/compound_lib.hh

@@ -37,7 +37,7 @@ typedef std::map<String, CompoundPtr> CompoundMap;
 
 class DLLEXPORT_OST_CONOP CompoundLib {
 public:
-  static CompoundLibPtr Load(const String& database);
+  static CompoundLibPtr Load(const String& database, bool readonly=true);
   static CompoundLibPtr Create(const String& database);
   ~CompoundLib();