class_loader_core.hpp

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#ifndef CLASS_LOADER__CLASS_LOADER_CORE_HPP_
#define CLASS_LOADER__CLASS_LOADER_CORE_HPP_
 
#include <boost/thread/recursive_mutex.hpp>
#include <cstddef>
#include <cstdio>
#include <map>
#include <string>
#include <typeinfo>
#include <utility>
#include <vector>
 
#include "class_loader/exceptions.hpp"
#include "class_loader/meta_object.hpp"
#include "class_loader/visibility_control.hpp"
 
// forward declaration
namespace Poco
{
  class SharedLibrary;
}  // namespace Poco
 
namespace class_loader
{
 
class ClassLoader;  // Forward declaration
 
namespace impl
{
 
// Typedefs
typedef std::string LibraryPath;
typedef std::string ClassName;
typedef std::string BaseClassName;
typedef std::map<ClassName, impl::AbstractMetaObjectBase *> FactoryMap;
typedef std::map<BaseClassName, FactoryMap> BaseToFactoryMapMap;
typedef std::pair<LibraryPath, Poco::SharedLibrary *> LibraryPair;
typedef std::vector<LibraryPair> LibraryVector;
typedef std::vector<AbstractMetaObjectBase *> MetaObjectVector;
 
// Debug
CLASS_LOADER_PUBLIC
void printDebugInfoToScreen();
 
// Global storage
 
CLASS_LOADER_PUBLIC
BaseToFactoryMapMap & getGlobalPluginBaseToFactoryMapMap();
 
CLASS_LOADER_PUBLIC
LibraryVector & getLoadedLibraryVector();
 
CLASS_LOADER_PUBLIC
std::string getCurrentlyLoadingLibraryName();
 
CLASS_LOADER_PUBLIC
void setCurrentlyLoadingLibraryName(const std::string & library_name);
 
 
CLASS_LOADER_PUBLIC
ClassLoader * getCurrentlyActiveClassLoader();
 
CLASS_LOADER_PUBLIC
void setCurrentlyActiveClassLoader(ClassLoader * loader);
 
 
CLASS_LOADER_PUBLIC
FactoryMap & getFactoryMapForBaseClass(const std::string & typeid_base_class_name);
 
template<typename Base>
FactoryMap & getFactoryMapForBaseClass()
{
  return getFactoryMapForBaseClass(typeid(Base).name());
}
 
CLASS_LOADER_PUBLIC
boost::recursive_mutex & getLoadedLibraryVectorMutex();
CLASS_LOADER_PUBLIC
boost::recursive_mutex & getPluginBaseToFactoryMapMapMutex();
 
CLASS_LOADER_PUBLIC
bool hasANonPurePluginLibraryBeenOpened();
 
CLASS_LOADER_PUBLIC
void hasANonPurePluginLibraryBeenOpened(bool hasIt);
 
// Plugin Functions
 
template<typename Derived, typename Base>
void registerPlugin(const std::string & class_name, const std::string & base_class_name)
{
  // Note: This function will be automatically invoked when a dlopen() call
  // opens a library. Normally it will happen within the scope of loadLibrary(),
  // but that may not be guaranteed.
  CONSOLE_BRIDGE_logDebug(
    "class_loader.impl: "
    "Registering plugin factory for class = %s, ClassLoader* = %p and library name %s.",
    class_name.c_str(), getCurrentlyActiveClassLoader(),
    getCurrentlyLoadingLibraryName().c_str());
 
  if (nullptr == getCurrentlyActiveClassLoader()) {
    CONSOLE_BRIDGE_logDebug("%s",
      "class_loader.impl: ALERT!!! "
      "A library containing plugins has been opened through a means other than through the "
      "class_loader or pluginlib package. "
      "This can happen if you build plugin libraries that contain more than just plugins "
      "(i.e. normal code your app links against). "
      "This inherently will trigger a dlopen() prior to main() and cause problems as class_loader "
      "is not aware of plugin factories that autoregister under the hood. "
      "The class_loader package can compensate, but you may run into namespace collision problems "
      "(e.g. if you have the same plugin class in two different libraries and you load them both "
      "at the same time). "
      "The biggest problem is that library can now no longer be safely unloaded as the "
      "ClassLoader does not know when non-plugin code is still in use. "
      "In fact, no ClassLoader instance in your application will be unable to unload any library "
      "once a non-pure one has been opened. "
      "Please refactor your code to isolate plugins into their own libraries.");
    hasANonPurePluginLibraryBeenOpened(true);
  }
 
  // Create factory
  impl::AbstractMetaObject<Base> * new_factory =
    new impl::MetaObject<Derived, Base>(class_name, base_class_name);
  new_factory->addOwningClassLoader(getCurrentlyActiveClassLoader());
  new_factory->setAssociatedLibraryPath(getCurrentlyLoadingLibraryName());
 
 
  // Add it to global factory map map
  getPluginBaseToFactoryMapMapMutex().lock();
  FactoryMap & factoryMap = getFactoryMapForBaseClass<Base>();
  if (factoryMap.find(class_name) != factoryMap.end()) {
    CONSOLE_BRIDGE_logWarn(
      "class_loader.impl: SEVERE WARNING!!! "
      "A namespace collision has occurred with plugin factory for class %s. "
      "New factory will OVERWRITE existing one. "
      "This situation occurs when libraries containing plugins are directly linked against an "
      "executable (the one running right now generating this message). "
      "Please separate plugins out into their own library or just don't link against the library "
      "and use either class_loader::ClassLoader/MultiLibraryClassLoader to open.",
      class_name.c_str());
  }
  factoryMap[class_name] = new_factory;
  getPluginBaseToFactoryMapMapMutex().unlock();
 
  CONSOLE_BRIDGE_logDebug(
    "class_loader.impl: "
    "Registration of %s complete (Metaobject Address = %p)",
    class_name.c_str(), reinterpret_cast<void *>(new_factory));
}
 
template<typename Base>
Base * createInstance(const std::string & derived_class_name, ClassLoader * loader)
{
  AbstractMetaObject<Base> * factory = nullptr;
 
  getPluginBaseToFactoryMapMapMutex().lock();
  FactoryMap & factoryMap = getFactoryMapForBaseClass<Base>();
  if (factoryMap.find(derived_class_name) != factoryMap.end()) {
    factory = dynamic_cast<impl::AbstractMetaObject<Base> *>(factoryMap[derived_class_name]);
  } else {
    CONSOLE_BRIDGE_logError(
      "class_loader.impl: No metaobject exists for class type %s.", derived_class_name.c_str());
  }
  getPluginBaseToFactoryMapMapMutex().unlock();
 
  Base * obj = nullptr;
  if (factory != nullptr && factory->isOwnedBy(loader)) {
    obj = factory->create();
  }
 
  if (nullptr == obj) {  // Was never created
    if (factory && factory->isOwnedBy(nullptr)) {
      CONSOLE_BRIDGE_logDebug("%s",
        "class_loader.impl: ALERT!!! "
        "A metaobject (i.e. factory) exists for desired class, but has no owner. "
        "This implies that the library containing the class was dlopen()ed by means other than "
        "through the class_loader interface. "
        "This can happen if you build plugin libraries that contain more than just plugins "
        "(i.e. normal code your app links against) -- that intrinsically will trigger a dlopen() "
        "prior to main(). "
        "You should isolate your plugins into their own library, otherwise it will not be "
        "possible to shutdown the library!");
 
      obj = factory->create();
    } else {
      throw class_loader::CreateClassException(
              "Could not create instance of type " + derived_class_name);
    }
  }
 
  CONSOLE_BRIDGE_logDebug(
    "class_loader.impl: Created instance of type %s and object pointer = %p",
    (typeid(obj).name()), reinterpret_cast<void *>(obj));
 
  return obj;
}
 
template<typename Base>
std::vector<std::string> getAvailableClasses(ClassLoader * loader)
{
  boost::recursive_mutex::scoped_lock lock(getPluginBaseToFactoryMapMapMutex());
 
  FactoryMap & factory_map = getFactoryMapForBaseClass<Base>();
  std::vector<std::string> classes;
  std::vector<std::string> classes_with_no_owner;
 
  for (auto & it : factory_map) {
    AbstractMetaObjectBase * factory = it.second;
    if (factory->isOwnedBy(loader)) {
      classes.push_back(it.first);
    } else if (factory->isOwnedBy(nullptr)) {
      classes_with_no_owner.push_back(it.first);
    }
  }
 
  // Added classes not associated with a class loader (Which can happen through
  // an unexpected dlopen() to the library)
  classes.insert(classes.end(), classes_with_no_owner.begin(), classes_with_no_owner.end());
  return classes;
}
 
CLASS_LOADER_PUBLIC
std::vector<std::string> getAllLibrariesUsedByClassLoader(const ClassLoader * loader);
 
CLASS_LOADER_PUBLIC
bool isLibraryLoaded(const std::string & library_path, ClassLoader * loader);
 
CLASS_LOADER_PUBLIC
bool isLibraryLoadedByAnybody(const std::string & library_path);
 
CLASS_LOADER_PUBLIC
void loadLibrary(const std::string & library_path, ClassLoader * loader);
 
CLASS_LOADER_PUBLIC
void unloadLibrary(const std::string & library_path, ClassLoader * loader);
 
}  // namespace impl
}  // namespace class_loader
 
#endif  // CLASS_LOADER__CLASS_LOADER_CORE_HPP_