multi_library_class_loader.hpp

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#ifndef CLASS_LOADER__MULTI_LIBRARY_CLASS_LOADER_HPP_
#define CLASS_LOADER__MULTI_LIBRARY_CLASS_LOADER_HPP_

#include <boost/thread.hpp>
#include <map>
#include <string>
#include <vector>

#include "console_bridge/console.h"

#include "class_loader/class_loader.hpp"
#include "class_loader/console_bridge_compatibility.hpp"

// TODO(mikaelarguedas) : replace no lints with the explicit keyword in an ABI breaking release

namespace class_loader
{

typedef std::string LibraryPath;
typedef std::map<LibraryPath, class_loader::ClassLoader *> LibraryToClassLoaderMap;
typedef std::vector<ClassLoader *> ClassLoaderVector;

class MultiLibraryClassLoader
{
public:
  MultiLibraryClassLoader(bool enable_ondemand_loadunload);  // NOLINT(runtime/explicit)

  virtual ~MultiLibraryClassLoader();

  template<class Base>
  boost::shared_ptr<Base> createInstance(const std::string & class_name)
  {
    CONSOLE_BRIDGE_logDebug(
      "class_loader::MultiLibraryClassLoader: "
      "Attempting to create instance of class type %s.",
      class_name.c_str());
    ClassLoader * loader = getClassLoaderForClass<Base>(class_name);
    if (NULL == loader) {
      throw class_loader::CreateClassException(
              "MultiLibraryClassLoader: Could not create object of class type " +
              class_name +
              " as no factory exists for it. Make sure that the library exists and "
              "was explicitly loaded through MultiLibraryClassLoader::loadLibrary()");
    }

    return loader->createInstance<Base>(class_name);
  }

  template<class Base>
  boost::shared_ptr<Base>
  createInstance(const std::string & class_name, const std::string & library_path)
  {
    ClassLoader * loader = getClassLoaderForLibrary(library_path);
    if (NULL == loader) {
      throw class_loader::NoClassLoaderExistsException(
              "Could not create instance as there is no ClassLoader in "
              "MultiLibraryClassLoader bound to library " + library_path +
              " Ensure you called MultiLibraryClassLoader::loadLibrary()");
    }
    return loader->createInstance<Base>(class_name);
  }

#if __cplusplus >= 201103L

  template<class Base>
  ClassLoader::UniquePtr<Base> createUniqueInstance(const std::string & class_name)
  {
    CONSOLE_BRIDGE_logDebug(
      "class_loader::MultiLibraryClassLoader: Attempting to create instance of class type %s.",
      class_name.c_str());
    ClassLoader * loader = getClassLoaderForClass<Base>(class_name);
    if (nullptr == loader) {
      throw class_loader::CreateClassException(
              "MultiLibraryClassLoader: Could not create object of class type " + class_name +
              " as no factory exists for it. "
              "Make sure that the library exists and was explicitly loaded through "
              "MultiLibraryClassLoader::loadLibrary()");
    }
    return loader->createUniqueInstance<Base>(class_name);
  }

  template<class Base>
  ClassLoader::UniquePtr<Base>
  createUniqueInstance(const std::string & class_name, const std::string & library_path)
  {
    ClassLoader * loader = getClassLoaderForLibrary(library_path);
    if (nullptr == loader) {
      throw class_loader::NoClassLoaderExistsException(
              "Could not create instance as there is no ClassLoader in "
              "MultiLibraryClassLoader bound to library " + library_path +
              " Ensure you called MultiLibraryClassLoader::loadLibrary()");
    }
    return loader->createUniqueInstance<Base>(class_name);
  }
#endif

  template<class Base>
  Base * createUnmanagedInstance(const std::string & class_name)
  {
    ClassLoader * loader = getClassLoaderForClass<Base>(class_name);
    if (NULL == loader) {
      throw class_loader::CreateClassException(
              "MultiLibraryClassLoader: Could not create class of type " + class_name);
    }
    return loader->createUnmanagedInstance<Base>(class_name);
  }

  template<class Base>
  Base * createUnmanagedInstance(const std::string & class_name, const std::string & library_path)
  {
    ClassLoader * loader = getClassLoaderForLibrary(library_path);
    if (NULL == loader) {
      throw class_loader::NoClassLoaderExistsException(
              "Could not create instance as there is no ClassLoader in MultiLibraryClassLoader "
              "bound to library " + library_path +
              " Ensure you called MultiLibraryClassLoader::loadLibrary()");
    }
    return loader->createUnmanagedInstance<Base>(class_name);
  }

  template<class Base>
  bool isClassAvailable(const std::string & class_name)
  {
    std::vector<std::string> available_classes = getAvailableClasses<Base>();
    return available_classes.end() != std::find(
      available_classes.begin(), available_classes.end(), class_name);
  }

  bool isLibraryAvailable(const std::string & library_path);

  template<class Base>
  std::vector<std::string> getAvailableClasses()
  {
    std::vector<std::string> available_classes;
    ClassLoaderVector loaders = getAllAvailableClassLoaders();
    for (unsigned int c = 0; c < loaders.size(); c++) {
      ClassLoader * current = loaders.at(c);
      std::vector<std::string> loader_classes = current->getAvailableClasses<Base>();
      available_classes.insert(
        available_classes.end(), loader_classes.begin(), loader_classes.end());
    }
    return available_classes;
  }

  template<class Base>
  std::vector<std::string> getAvailableClassesForLibrary(const std::string & library_path)
  {
    ClassLoader * loader = getClassLoaderForLibrary(library_path);
    std::vector<std::string> available_classes;
    if (loader) {
      available_classes = loader->getAvailableClasses<Base>();
      return available_classes;
    } else {
      throw class_loader::NoClassLoaderExistsException(
              "There is no ClassLoader in MultiLibraryClassLoader bound to library " +
              library_path +
              " Ensure you called MultiLibraryClassLoader::loadLibrary()");
    }
  }

  std::vector<std::string> getRegisteredLibraries();

  void loadLibrary(const std::string & library_path);

  int unloadLibrary(const std::string & library_path);

private:
  bool isOnDemandLoadUnloadEnabled() {return enable_ondemand_loadunload_;}

  ClassLoader * getClassLoaderForLibrary(const std::string & library_path);

  template<typename Base>
  ClassLoader * getClassLoaderForClass(const std::string & class_name)
  {
    ClassLoaderVector loaders = getAllAvailableClassLoaders();
    for (ClassLoaderVector::iterator i = loaders.begin(); i != loaders.end(); ++i) {
      if (!(*i)->isLibraryLoaded()) {
        (*i)->loadLibrary();
      }
      if ((*i)->isClassAvailable<Base>(class_name)) {
        return *i;
      }
    }
    return NULL;
  }

  ClassLoaderVector getAllAvailableClassLoaders();

  void shutdownAllClassLoaders();

private:
  bool enable_ondemand_loadunload_;
  LibraryToClassLoaderMap active_class_loaders_;
  boost::mutex loader_mutex_;
};


}  // namespace class_loader
#endif  // CLASS_LOADER__MULTI_LIBRARY_CLASS_LOADER_HPP_