ftccache.c

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/***************************************************************************/
/*                                                                         */
/*  ftccache.c                                                             */
/*                                                                         */
/*    The FreeType internal cache interface (body).                        */
/*                                                                         */
/*  Copyright 2000-2001, 2002, 2003 by                                     */
/*  David Turner, Robert Wilhelm, and Werner Lemberg.                      */
/*                                                                         */
/*  This file is part of the FreeType project, and may only be used,       */
/*  modified, and distributed under the terms of the FreeType project      */
/*  license, LICENSE.TXT.  By continuing to use, modify, or distribute     */
/*  this file you indicate that you have read the license and              */
/*  understand and accept it fully.                                        */
/*                                                                         */
/***************************************************************************/


#include <ft2build.h>
#include FT_CACHE_MANAGER_H
#include FT_INTERNAL_OBJECTS_H
#include FT_INTERNAL_DEBUG_H

#include "ftcerror.h"


#define FTC_HASH_MAX_LOAD  2
#define FTC_HASH_MIN_LOAD  1
#define FTC_HASH_SUB_LOAD  ( FTC_HASH_MAX_LOAD - FTC_HASH_MIN_LOAD )

/* this one _must_ be a power of 2! */
#define FTC_HASH_INITIAL_SIZE  8


  /*************************************************************************/
  /*************************************************************************/
  /*****                                                               *****/
  /*****                   CACHE NODE DEFINITIONS                      *****/
  /*****                                                               *****/
  /*************************************************************************/
  /*************************************************************************/

  FT_EXPORT_DEF( void )
  ftc_node_done( FTC_Node   node,
                 FTC_Cache  cache )
  {
    FTC_Family       family;
    FTC_FamilyEntry  entry;


    entry  = cache->manager->families.entries + node->fam_index;
    family = entry->family;

    /* remove from parent set table - eventually destroy the set */
    if ( --family->num_nodes == 0 )
      FT_LruList_Remove( cache->families, (FT_LruNode) family );
  }


  /* add a new node to the head of the manager's circular MRU list */
  static void
  ftc_node_mru_link( FTC_Node     node,
                     FTC_Manager  manager )
  {
    FTC_Node  first = manager->nodes_list;


    if ( first )
    {
      FTC_Node  last = first->mru_prev;


      FT_ASSERT( last->mru_next == first );

      node->mru_prev = last;
      node->mru_next = first;

      last->mru_next  = node;
      first->mru_prev = node;
    }
    else
    {
      FT_ASSERT( manager->num_nodes == 0 );

      node->mru_next = node;
      node->mru_prev = node;
    }

    manager->nodes_list = node;
    manager->num_nodes++;
  }


  /* remove a node from the manager's MRU list */
  static void
  ftc_node_mru_unlink( FTC_Node     node,
                       FTC_Manager  manager )
  {
    FTC_Node  first = manager->nodes_list;
    FTC_Node  prev  = node->mru_prev;
    FTC_Node  next  = node->mru_next;


    FT_ASSERT( first != NULL && manager->num_nodes > 0 );
    FT_ASSERT( next->mru_prev == node );
    FT_ASSERT( prev->mru_next == node );

    next->mru_prev = prev;
    prev->mru_next = next;

    if ( node == first )
    {
      /* this is the last node in the list; update its head pointer */
      if ( node == next )
        manager->nodes_list = NULL;
      else
        manager->nodes_list = next;
    }

    node->mru_next = NULL;
    node->mru_prev = NULL;
    manager->num_nodes--;
  }


  /* move a node to the head of the manager's MRU list */
  static void
  ftc_node_mru_up( FTC_Node     node,
                   FTC_Manager  manager )
  {
    FTC_Node  first = manager->nodes_list;


    if ( node != first )
    {
      FTC_Node  prev = node->mru_prev;
      FTC_Node  next = node->mru_next;
      FTC_Node  last;


      prev->mru_next = next;
      next->mru_prev = prev;

      last            = first->mru_prev;
      node->mru_next  = first;
      node->mru_prev  = last;
      first->mru_prev = node;
      last->mru_next  = node;

      manager->nodes_list = node;
    }
  }


  /* remove a node from its cache's hash table */
  static FT_Error
  ftc_node_hash_unlink( FTC_Node   node,
                        FTC_Cache  cache )
  {
    FT_Error   error = 0;
    FTC_Node  *pnode;
    FT_UInt    idx, num_buckets;


    idx = (FT_UInt)( node->hash & cache->mask );
    if ( idx < cache->p )
      idx = (FT_UInt)( node->hash & ( 2 * cache->mask + 1 ) );

    pnode = cache->buckets + idx;

    for (;;)
    {
      if ( *pnode == NULL )
      {
        FT_ERROR(( "ftc_node_hash_unlink: unknown node!\n" ));
        return FTC_Err_Ok;
      }

      if ( *pnode == node )
      {
        *pnode     = node->link;
        node->link = NULL;
        break;
      }

      pnode = &(*pnode)->link;
    }

    num_buckets = ( cache->p + cache->mask + 1 );

    if ( ++cache->slack > (FT_Long)num_buckets * FTC_HASH_SUB_LOAD )
    {
      FT_UInt    p         = cache->p;
      FT_UInt    mask      = cache->mask;
      FT_UInt    old_index = p + mask;
      FTC_Node*  pold;


      if ( old_index + 1 <= FTC_HASH_INITIAL_SIZE )
        goto Exit;

      if ( p == 0 )
      {
        FT_Memory  memory = cache->memory;


        cache->mask >>= 1;
        p             = cache->mask;

        if ( FT_RENEW_ARRAY( cache->buckets, ( mask + 1 ) * 2, (mask+1) ) )
        {
          FT_ERROR(( "ftc_node_hash_unlink: couldn't shunk buckets!\n" ));
          goto Exit;
        }
      }
      else
        p--;

      pnode = cache->buckets + p;
      while ( *pnode )
        pnode = &(*pnode)->link;

      pold   = cache->buckets + old_index;
      *pnode = *pold;
      *pold  = NULL;

      cache->slack -= FTC_HASH_MAX_LOAD;
      cache->p      = p;
    }

  Exit:
    return error;
  }



  /* add a node to the "top" of its cache's hash table */
  static FT_Error
  ftc_node_hash_link( FTC_Node   node,
                      FTC_Cache  cache )
  {
    FTC_Node  *pnode;
    FT_UInt    idx;
    FT_Error   error = 0;


    idx = (FT_UInt)( node->hash & cache->mask );
    if ( idx < cache->p )
      idx = (FT_UInt)( node->hash & (2 * cache->mask + 1 ) );

    pnode = cache->buckets + idx;

    node->link = *pnode;
    *pnode     = node;

    if ( --cache->slack < 0 )
    {
      FT_UInt    p     = cache->p;
      FT_UInt    mask  = cache->mask;
      FTC_Node   new_list;


      /* split a single bucket */
      new_list = NULL;
      pnode    = cache->buckets + p;

      for (;;)
      {
        node = *pnode;
        if ( node == NULL )
          break;

        if ( node->hash & ( mask + 1 ) )
        {
          *pnode     = node->link;
          node->link = new_list;
          new_list   = node;
        }
        else
          pnode = &node->link;
      }

      cache->buckets[p + mask + 1] = new_list;

      cache->slack += FTC_HASH_MAX_LOAD;

      if ( p >= mask )
      {
        FT_Memory  memory = cache->memory;


        if ( FT_RENEW_ARRAY( cache->buckets,
                             ( mask + 1 ) * 2, ( mask + 1 ) * 4 ) )
        {
          FT_ERROR(( "ftc_node_hash_link: couldn't expand buckets!\n" ));
          goto Exit;
        }

        cache->mask = 2 * mask + 1;
        cache->p    = 0;
      }
      else
        cache->p = p + 1;
    }

  Exit:
    return error;
  }




  /* remove a node from the cache manager */
  FT_EXPORT_DEF( void )
  ftc_node_destroy( FTC_Node     node,
                    FTC_Manager  manager )
  {
    FT_Memory        memory  = manager->library->memory;
    FTC_Cache        cache;
    FTC_FamilyEntry  entry;
    FTC_Cache_Class  clazz;


#ifdef FT_DEBUG_ERROR
    /* find node's cache */
    if ( node->fam_index >= manager->families.count )
    {
      FT_ERROR(( "ftc_node_destroy: invalid node handle\n" ));
      return;
    }
#endif

    entry = manager->families.entries + node->fam_index;
    cache = entry->cache;

#ifdef FT_DEBUG_ERROR
    if ( cache == NULL )
    {
      FT_ERROR(( "ftc_node_destroy: invalid node handle\n" ));
      return;
    }
#endif

    clazz = cache->clazz;

    manager->cur_weight -= clazz->node_weight( node, cache );

    /* remove node from mru list */
    ftc_node_mru_unlink( node, manager );

    /* remove node from cache's hash table */
    ftc_node_hash_unlink( node, cache );

    /* now finalize it */
    if ( clazz->node_done )
      clazz->node_done( node, cache );

    FT_FREE( node );

#if 0
    /* check, just in case of general corruption :-) */
    if ( manager->num_nodes == 0 )
      FT_ERROR(( "ftc_node_destroy: invalid cache node count! = %d\n",
                  manager->num_nodes ));
#endif
  }


  /*************************************************************************/
  /*************************************************************************/
  /*****                                                               *****/
  /*****                   CACHE FAMILY DEFINITIONS                    *****/
  /*****                                                               *****/
  /*************************************************************************/
  /*************************************************************************/


  FT_EXPORT_DEF( FT_Error )
  ftc_family_init( FTC_Family  family,
                   FTC_Query   query,
                   FTC_Cache   cache )
  {
    FT_Error         error;
    FTC_Manager      manager = cache->manager;
    FT_Memory        memory  = manager->library->memory;
    FTC_FamilyEntry  entry;


    family->cache     = cache;
    family->num_nodes = 0;

    /* now add to manager's family table */
    error = ftc_family_table_alloc( &manager->families, memory, &entry );
    if ( !error )
    {
      entry->cache      = cache;
      entry->family     = family;
      family->fam_index = entry->index;

      query->family = family;   /* save family in query */
    }

    return error;
  }