class_loader.cpp

/*
 * Copyright (c) 2012, Willow Garage, Inc.
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 *     * Redistributions of source code must retain the above copyright
 *       notice, this list of conditions and the following disclaimer.
 *     * Redistributions in binary form must reproduce the above copyright
 *       notice, this list of conditions and the following disclaimer in the
 *       documentation and/or other materials provided with the distribution.
 *     * Neither the name of the Willow Garage, Inc. nor the names of its
 *       contributors may be used to endorse or promote products derived from
 *       this software without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
 * POSSIBILITY OF SUCH DAMAGE.
 */

#include <class_loader/class_loader.h>

#include <Poco/SharedLibrary.h>

namespace class_loader
{

bool ClassLoader::has_unmananged_instance_been_created_ = false;

bool ClassLoader::hasUnmanagedInstanceBeenCreated()
{
  return ClassLoader::has_unmananged_instance_been_created_;
}

void ClassLoader::setUnmanagedInstanceBeenCreated(bool state)
{
  ClassLoader::has_unmananged_instance_been_created_ = state;
}

std::string systemLibraryPrefix()
{
#if !defined(WIN32)
  return "lib";
#endif
  return "";
}

std::string systemLibrarySuffix()
{
#if !defined(WIN32)
  return Poco::SharedLibrary::suffix();
#else
  // Return just .dll , as Poco::SharedLibrary::suffix() will return d.dll in debug mode.
  // This isn't common for our usecase (instead debug libraries are placed in a `Debug` folder).
  return ".dll";
#endif
}

std::string systemLibraryFormat(const std::string & library_name)
{
  return systemLibraryPrefix() + library_name + systemLibrarySuffix();
}

ClassLoader::ClassLoader(const std::string & library_path, bool ondemand_load_unload)
: ondemand_load_unload_(ondemand_load_unload),
  library_path_(library_path),
  load_ref_count_(0),
  plugin_ref_count_(0)
{
  CONSOLE_BRIDGE_logDebug("class_loader.ClassLoader: Constructing new ClassLoader (%p) bound to library %s.", this, library_path.c_str());
  if (!isOnDemandLoadUnloadEnabled()) {
    loadLibrary();
  }
}

ClassLoader::~ClassLoader()
{
  CONSOLE_BRIDGE_logDebug("class_loader.ClassLoader: Destroying class loader, unloading associated library...\n");
  unloadLibrary(); //TODO: while(unloadLibrary() > 0){} ??
}

const std::string & ClassLoader::getLibraryPath() const
{
  return library_path_;
}

bool ClassLoader::isLibraryLoaded() const
{
  return class_loader::impl::isLibraryLoaded(getLibraryPath(), this);
}

bool ClassLoader::isLibraryLoadedByAnyClassloader() const
{
  return class_loader::impl::isLibraryLoadedByAnybody(getLibraryPath());
}

bool ClassLoader::isOnDemandLoadUnloadEnabled() const
{
  return ondemand_load_unload_;
}

void ClassLoader::loadLibrary()
{
  if (getLibraryPath() == "") {
    // special library path for libraries linked at link-time (not dlopen-ed)
    return;
  }
  std::lock_guard<std::recursive_mutex> lock(load_ref_count_mutex_);
  ++load_ref_count_;
  class_loader::impl::loadLibrary(getLibraryPath(), this);
}

int ClassLoader::unloadLibrary()
{
  if (getLibraryPath() == "") {
    // special library path for libraries linked at link-time (not dlopen-ed)
    return 0;
  }
  return unloadLibraryInternal(true);
}

int ClassLoader::unloadLibraryInternal(bool lock_plugin_ref_count)
{
  std::lock_guard<std::recursive_mutex> load_ref_lock(load_ref_count_mutex_);
  if (lock_plugin_ref_count) {
    plugin_ref_count_mutex_.lock();
  }

  try {
    if (plugin_ref_count_ > 0) {
      CONSOLE_BRIDGE_logWarn("class_loader.ClassLoader: SEVERE WARNING!!! Attempting to unload library while objects created by this loader exist in the heap! You should delete your objects before attempting to unload the library or destroying the ClassLoader. The library will NOT be unloaded.");
    } else {
      load_ref_count_ = load_ref_count_ - 1;
      if (load_ref_count_ == 0) {
        class_loader::impl::unloadLibrary(getLibraryPath(), this);
      } else if (load_ref_count_ < 0) {
        load_ref_count_ = 0;
      }
    }
  } catch (...) {
    if (lock_plugin_ref_count) {
      plugin_ref_count_mutex_.unlock();
    }
    throw;
  }
  if (lock_plugin_ref_count) {
    plugin_ref_count_mutex_.unlock();
  }
  return load_ref_count_;
}

}  // namespace class_loader