// Filename: vertexDataPage.I
// Created by:  drose (04Jun07)
//
////////////////////////////////////////////////////////////////////
//
// 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."
//
////////////////////////////////////////////////////////////////////


////////////////////////////////////////////////////////////////////
//     Function: VertexDataPage::get_ram_class
//       Access: Published
//  Description: Returns the current ram class of the array.  If this
//               is other than RC_resident, the array data is not
//               resident in memory.
////////////////////////////////////////////////////////////////////
INLINE VertexDataPage::RamClass VertexDataPage::
get_ram_class() const {
  MutexHolder holder(_lock);
  return _ram_class;
}

////////////////////////////////////////////////////////////////////
//     Function: VertexDataPage::get_pending_ram_class
//       Access: Published
//  Description: Returns the pending ram class of the array.  If this
//               is different from get_ram_class(), this page has been
//               queued to be processed by the thread.  Eventually the
//               page will be set to this ram class.
////////////////////////////////////////////////////////////////////
INLINE VertexDataPage::RamClass VertexDataPage::
get_pending_ram_class() const {
  MutexHolder holder(_lock);
  return _pending_ram_class;
}

////////////////////////////////////////////////////////////////////
//     Function: VertexDataPage::request_resident
//       Access: Published
//  Description: Ensures that the page will become resident soon.
//               Future calls to get_page_data() will eventually
//               return non-NULL.
////////////////////////////////////////////////////////////////////
INLINE void VertexDataPage::
request_resident() {
  MutexHolder holder(_lock);
  if (_ram_class != RC_resident) {
    request_ram_class(RC_resident);
  }
}

////////////////////////////////////////////////////////////////////
//     Function: VertexDataPage::alloc
//       Access: Published
//  Description: Allocates a new block.  Returns NULL if a block of the
//               requested size cannot be allocated.
//
//               To free the allocated block, call block->free(), or
//               simply delete the block pointer.
////////////////////////////////////////////////////////////////////
INLINE VertexDataBlock *VertexDataPage::
alloc(size_t size) {
  MutexHolder holder(_lock);
  return do_alloc(size);
}

////////////////////////////////////////////////////////////////////
//     Function: VertexDataPage::get_first_block
//       Access: Published
//  Description: Returns a pointer to the first allocated block, or
//               NULL if there are no allocated blocks.
////////////////////////////////////////////////////////////////////
INLINE VertexDataBlock *VertexDataPage::
get_first_block() const {
  MutexHolder holder(_lock);
  return (VertexDataBlock *)SimpleAllocator::get_first_block();
}

////////////////////////////////////////////////////////////////////
//     Function: VertexDataPage::get_book
//       Access: Published
//  Description: Returns a pointer to the book that owns this page.
////////////////////////////////////////////////////////////////////
INLINE VertexDataBook *VertexDataPage::
get_book() const {
  return _book;
}

////////////////////////////////////////////////////////////////////
//     Function: VertexDataPage::get_global_lru
//       Access: Published, Static
//  Description: Returns a pointer to the global LRU object that
//               manages the VertexDataPage's with the indicated
//               RamClass.
////////////////////////////////////////////////////////////////////
INLINE SimpleLru *VertexDataPage::
get_global_lru(RamClass rclass) {
  nassertr(rclass >= 0 && rclass < RC_end_of_list, NULL);
  return _global_lru[rclass];
}

////////////////////////////////////////////////////////////////////
//     Function: VertexDataPage::get_pending_lru
//       Access: Published, Static
//  Description: Returns a pointer to the global LRU object that
//               manages the VertexDataPage's that are pending
//               processing by the thread.
////////////////////////////////////////////////////////////////////
INLINE SimpleLru *VertexDataPage::
get_pending_lru() {
  return &_pending_lru;
}

////////////////////////////////////////////////////////////////////
//     Function: VertexDataPage::get_save_file
//       Access: Published, Static
//  Description: Returns the global VertexDataSaveFile that will be
//               used to save vertex data buffers to disk when
//               necessary.
////////////////////////////////////////////////////////////////////
INLINE VertexDataSaveFile *VertexDataPage::
get_save_file() {
  if (_save_file == (VertexDataSaveFile *)NULL) {
    make_save_file();
  }
  return _save_file;
}

////////////////////////////////////////////////////////////////////
//     Function: VertexDataPage::save_to_disk
//       Access: Published
//  Description: Writes the page to disk, but does not evict it from
//               memory or affect its LRU status.  If it gets evicted
//               later without having been modified, it will not need
//               to write itself to disk again.
////////////////////////////////////////////////////////////////////
INLINE bool VertexDataPage::
save_to_disk() {
  MutexHolder holder(_lock);
  return do_save_to_disk();
}

////////////////////////////////////////////////////////////////////
//     Function: VertexDataPage::get_num_threads
//       Access: Published, Static
//  Description: Returns the number of threads that have been spawned
//               to service vertex paging requests, or 0 if no threads
//               have been spawned (which may mean either that all
//               paging requests will be handled by the main thread,
//               or simply that no paging requests have yet been
//               issued).
////////////////////////////////////////////////////////////////////
INLINE int VertexDataPage::
get_num_threads() {
  MutexHolder holder(_tlock);
  if (_thread_mgr == (PageThreadManager *)NULL) {
    return 0;
  }
  return _thread_mgr->get_num_threads();
}

////////////////////////////////////////////////////////////////////
//     Function: VertexDataPage::get_num_pending_reads
//       Access: Published, Static
//  Description: Returns the number of read requests that are waiting
//               to be serviced by a thread.
////////////////////////////////////////////////////////////////////
INLINE int VertexDataPage::
get_num_pending_reads() {
  MutexHolder holder(_tlock);
  if (_thread_mgr == (PageThreadManager *)NULL) {
    return 0;
  }
  return _thread_mgr->get_num_pending_reads();
}

////////////////////////////////////////////////////////////////////
//     Function: VertexDataPage::get_num_pending_writes
//       Access: Published, Static
//  Description: Returns the number of write requests that are waiting
//               to be serviced by a thread.
////////////////////////////////////////////////////////////////////
INLINE int VertexDataPage::
get_num_pending_writes() {
  MutexHolder holder(_tlock);
  if (_thread_mgr == (PageThreadManager *)NULL) {
    return 0;
  }
  return _thread_mgr->get_num_pending_writes();
}

////////////////////////////////////////////////////////////////////
//     Function: VertexDataPage::get_page_data
//       Access: Public
//  Description: Returns a pointer to the page's data area, or NULL if
//               the page is not currently resident.  If the page is
//               not currently resident, this will implicitly request
//               it to become resident soon.
//
//               If force is true, this method will never return NULL,
//               but may block until the page is available.
////////////////////////////////////////////////////////////////////
INLINE unsigned char *VertexDataPage::
get_page_data(bool force) {
  MutexHolder holder(_lock);
  if (_ram_class != RC_resident || _pending_ram_class != RC_resident) {
    if (force) {
      make_resident_now();
    } else {
      request_ram_class(RC_resident);
      if (_ram_class != RC_resident) {
        return NULL;
      }
    }
  }

  mark_used_lru();
  nassertr(_size == _uncompressed_size, _page_data);
  return _page_data;
}

////////////////////////////////////////////////////////////////////
//     Function: VertexDataPage::operator
//       Access: Public
//  Description: This comparison method is used to order pages within
//               a book.
////////////////////////////////////////////////////////////////////
INLINE bool VertexDataPage::
operator < (const VertexDataPage &other) const {
  // We sort pages so that the pages with the smallest number of
  // available contiguous bytes come up first.  We store our best
  // estimate of continguous bytes here.
  if (_book_size != other._book_size) {
    return _book_size < other._book_size;
  }

  // For pages of equal size, we sort based on pointers, to make it
  // easy to quickly find a specific page.
  return this < &other;
}

////////////////////////////////////////////////////////////////////
//     Function: VertexDataPage::set_ram_class
//       Access: Private
//  Description: Puts the data in a new ram class.  Assumes the page
//               lock is already held.
////////////////////////////////////////////////////////////////////
INLINE void VertexDataPage::
set_ram_class(RamClass rclass) {
  _ram_class = rclass;
  mark_used_lru(_global_lru[rclass]);

  // Changing the ram class might make our effective available space 0
  // and thereby change the placement within the book.
  adjust_book_size();
}

////////////////////////////////////////////////////////////////////
//     Function: VertexDataPage::round_up
//       Access: Private
//  Description: Round page_size up to the next multiple of
//               _block_size.
////////////////////////////////////////////////////////////////////
INLINE size_t VertexDataPage::
round_up(size_t page_size) const {
  return ((page_size + _block_size - 1) / _block_size) * _block_size;
}