threadSafePointerToBase.I

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/**
 * PANDA 3D SOFTWARE
 * Copyright (c) Carnegie Mellon University.  All rights reserved.
 *
 * All use of this software is subject to the terms of the revised BSD
 * license.  You should have received a copy of this license along
 * with this source code in a file named "LICENSE."
 *
 * @file threadSafePointerToBase.I
 * @author drose
 * @date 2006-04-28
 */

/**
 *
 */
template<class T>
INLINE ThreadSafePointerToBase<T>::
ThreadSafePointerToBase(To *ptr) {
  reassign(ptr);
}

/**
 *
 */
template<class T>
INLINE ThreadSafePointerToBase<T>::
ThreadSafePointerToBase(const ThreadSafePointerToBase<T> &copy) {
  reassign(copy);
}

/**
 *
 */
template<class T>
INLINE ThreadSafePointerToBase<T>::
~ThreadSafePointerToBase() {
  reassign(nullptr);
}

/**
 * This is the main work of the ThreadSafePointerTo family.  When the pointer
 * is reassigned, decrement the old reference count and increment the new one.
 */
template<class T>
INLINE void ThreadSafePointerToBase<T>::
reassign(To *ptr) {
  To *old_ptr = (To *)AtomicAdjust::get_ptr(_void_ptr);
  if (ptr == old_ptr) {
    return;
  }

#ifdef HAVE_THREADS
  void *orig_ptr = AtomicAdjust::compare_and_exchange_ptr(_void_ptr, old_ptr, ptr);
  while (orig_ptr != old_ptr) {
    // Some other thread assigned it first.  Try again.
    old_ptr = (To *)AtomicAdjust::get_ptr(_void_ptr);
    if (ptr == old_ptr) {
      return;
    }

    orig_ptr = AtomicAdjust::compare_and_exchange_ptr(_void_ptr, old_ptr, ptr);
  }
#else  // HAVE_THREADS
  _void_ptr = ptr;
#endif  // HAVE_THREADS

  if (ptr != nullptr) {
    ptr->ref();
#ifdef DO_MEMORY_USAGE
    if (MemoryUsage::get_track_memory_usage()) {
      update_type(ptr);
    }
#endif
  }

  // Now delete the old pointer.
  if (old_ptr != nullptr) {
    unref_delete(old_ptr);
  }
}

/**
 *
 */
template<class T>
INLINE void ThreadSafePointerToBase<T>::
reassign(const ThreadSafePointerToBase<To> &copy) {
  reassign((To *)copy._void_ptr);
}

/**
 * Ensures that the MemoryUsage record for the pointer has the right type of
 * object, if we know the type ourselves.
 */
template<class T>
void ThreadSafePointerToBase<T>::
update_type(To *ptr) {
#ifdef DO_MEMORY_USAGE
  TypeHandle type = get_type_handle(To);
  if (type == TypeHandle::none()) {
    do_init_type(To);
    type = get_type_handle(To);
  }
  if (type != TypeHandle::none()) {
    MemoryUsage::update_type(ptr, type);
  }
#endif  // DO_MEMORY_USAGE
}

/**
 * A convenient way to set the ThreadSafePointerTo object to NULL. (Assignment
 * to a NULL pointer also works, of course.)
 */
template<class T>
INLINE void ThreadSafePointerToBase<T>::
clear() {
  reassign(nullptr);
}

/**
 * A handy function to output ThreadSafePointerTo's as a hex pointer followed
 * by a reference count.
 */
template<class T>
INLINE void ThreadSafePointerToBase<T>::
output(std::ostream &out) const {
  out << _void_ptr;
  if (_void_ptr != nullptr) {
    out << ":" << ((To *)_void_ptr)->get_ref_count();
  }
}