/**
 * 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 glBufferContext_src.cxx
 * @author rdb
 * @date 2016-12-12
 */

TypeHandle CLP(BufferContext)::_type_handle;

/**
 * Evicts the page from the LRU.  Called internally when the LRU determines
 * that it is full.  May also be called externally when necessary to
 * explicitly evict the page.
 *
 * It is legal for this method to either evict the page as requested, do
 * nothing (in which case the eviction will be requested again at the next
 * epoch), or requeue itself on the tail of the queue (in which case the
 * eviction will be requested again much later).
 */
void CLP(BufferContext)::
evict_lru() {
  dequeue_lru();

  // Make sure the buffer is unbound before we delete it.
  if (_glgsg->_current_ibuffer_index == _index) {
    if (GLCAT.is_debug() && gl_debug_buffers) {
      GLCAT.debug()
        << "unbinding index buffer\n";
    }
    _glgsg->_glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
    _glgsg->_current_ibuffer_index = 0;
  }

  // Free the buffer.
  _glgsg->_glDeleteBuffers(1, &_index);

  // We still need a valid index number, though, in case we want to re-load
  // the buffer later.
  _glgsg->_glGenBuffers(1, &_index);

  update_data_size_bytes(0);
  set_resident(false);
}