ftccache.c

一个Xpdf应用的例子

    2734867,
    4102283,
    6153409,
    9230113,
    13845163,
  };


  static FT_UFast
  ftc_prime_closest( FT_UFast  num )
  {
    FT_UInt  i;


    for ( i = 0; i < sizeof ( ftc_primes ) / sizeof ( ftc_primes[0] ); i++ )
      if ( ftc_primes[i] > num )
        return ftc_primes[i];

    return FTC_PRIMES_MAX;
  }


#define FTC_CACHE_RESIZE_TEST( c )       \
          ( (c)->nodes*3 < (c)->size  || \
            (c)->size*3  < (c)->nodes )


  static void
  ftc_cache_resize( FTC_Cache  cache )
  {
    FT_UFast  new_size;


    new_size = ftc_prime_closest( cache->nodes );
    if ( new_size != cache->size )
    {
      FT_Memory  memory = cache->memory;
      FT_Error   error;
      FTC_Node*  new_buckets ;
      FT_ULong   i;


      /* no need to report an error; we'll simply keep using the same */
      /* buckets number / size                                        */
      if ( ALLOC_ARRAY( new_buckets, new_size, FTC_Node ) )
        return;

      for ( i = 0; i < cache->size; i++ )
      {
        FTC_Node   node, next, *pnode;
        FT_UFast   hash;


        node = cache->buckets[i];
        while ( node )
        {
          next  = node->link;
          hash  = node->hash % new_size;
          pnode = new_buckets + hash;

          node->link = pnode[0];
          pnode[0]   = node;

          node = next;
        }
      }

      if ( cache->buckets )
        FREE( cache->buckets );

      cache->buckets = new_buckets;
      cache->size    = new_size;
    }
  }


  FT_EXPORT_DEF( FT_Error )
  ftc_cache_init( FTC_Cache  cache )
  {
    FT_Memory        memory = cache->memory;
    FTC_Cache_Class  clazz  = cache->clazz;
    FT_Error         error;


    cache->nodes = 0;
    cache->size  = FTC_PRIMES_MIN;

    if ( ALLOC_ARRAY( cache->buckets, cache->size, FTC_Node ) )
      goto Exit;

    /* now, initialize the lru list of families for this cache */
    if ( clazz->family_size > 0 )
    {
      FT_LruList_ClassRec*  lru_class = &cache->family_class;


      lru_class->list_size = sizeof( FT_LruListRec );
      lru_class->list_init = NULL;
      lru_class->list_done = NULL;

      lru_class->node_size    = clazz->family_size;
      lru_class->node_init    = (FT_LruNode_InitFunc)   clazz->family_init;
      lru_class->node_done    = (FT_LruNode_DoneFunc)   clazz->family_done;
      lru_class->node_flush   = (FT_LruNode_FlushFunc)  NULL;
      lru_class->node_compare = (FT_LruNode_CompareFunc)clazz->family_compare;

      error = FT_LruList_New( (FT_LruList_Class) lru_class,
                              0,    /* max items == 0 => unbounded list */
                              cache,
                              memory,
                              &cache->families );
      if ( error )
        FREE( cache->buckets );
    }

  Exit:
    return error;
  }


  FT_EXPORT_DEF( void )
  ftc_cache_clear( FTC_Cache  cache )
  {
    if ( cache )
    {
      FT_Memory        memory  = cache->memory;
      FTC_Cache_Class  clazz   = cache->clazz;
      FTC_Manager      manager = cache->manager;
      FT_UFast         i;


      for ( i = 0; i < cache->size; i++ )
      {
        FTC_Node  *pnode = cache->buckets + i, next, node = *pnode;


        while ( node )
        {
          next        = node->link;
          node->link  = NULL;

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

          /* now finalize it */
          manager->cur_weight -= clazz->node_weight( node, cache );

          if ( clazz->node_done )
            clazz->node_done( node, cache );

          FREE( node );
          node = next;
        }
        cache->buckets[i] = NULL;
      }

      cache->nodes = 0;

      /* destroy the families */
      if ( cache->families )
        FT_LruList_Reset( cache->families );
    }
  }


  FT_EXPORT_DEF( void )
  ftc_cache_done( FTC_Cache  cache )
  {
    if ( cache )
    {
      FT_Memory  memory = cache->memory;


      ftc_cache_clear( cache );

      FREE( cache->buckets );
      cache->size = 0;

      if ( cache->families )
      {
        FT_LruList_Destroy( cache->families );
        cache->families = NULL;
      }
    }
  }


  /* Look up a node in "top" of its cache's hash table. */
  /* If not found, create a new node.                   */
  /*                                                    */
  FT_EXPORT_DEF( FT_Error )
  ftc_cache_lookup( FTC_Cache   cache,
                    FTC_Query   query,
                    FTC_Node   *anode )
  {
    FT_Error    error;
    FT_LruNode  lru;


    /* some argument checks are delayed to ftc_glyph_cache_lookup */
    if ( !cache || !query || !anode )
      return FTC_Err_Invalid_Argument;

    *anode = NULL;

    query->hash   = 0;
    query->family = NULL;

    error = FT_LruList_Lookup( cache->families, query, &lru );
    if ( !error )
    {
      FTC_Family  family = (FTC_Family) lru;
      FT_UFast    hash    = query->hash;
      FTC_Node*   bucket  = cache->buckets + (hash % cache->size);


      if ( query->family     != family                        ||
           family->fam_index >= cache->manager->families.size )
      {
        FT_ERROR((
          "ftc_cache_lookup: invalid query (bad 'family' field)\n" ));
        return FT_Err_Invalid_Argument;
      }

      if ( *bucket )
      {
        FTC_Node*             pnode   = bucket;
        FTC_Node_CompareFunc  compare = cache->clazz->node_compare;


        for ( ;; )
        {
          FTC_Node  node;


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

          if ( (FT_UInt)node->fam_index == family->fam_index &&
               compare( node, query, cache ) )
          {
            /* move to head of bucket list */
            if ( pnode != bucket )
            {
              *pnode     = node->link;
              node->link = *bucket;
              *bucket    = node;
            }

            /* move to head of MRU list */
            if ( node != cache->manager->nodes_list )
              ftc_node_mru_up( node, cache->manager );

            *anode = node;
            goto Exit;
          }

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

      /* didn't find a node, create a new one */
      {
        FTC_Cache_Class  clazz   = cache->clazz;
        FTC_Manager      manager = cache->manager;
        FT_Memory        memory  = cache->memory;
        FTC_Node         node;


        if ( ALLOC( node, clazz->node_size ) )
          goto Exit;

        node->fam_index = (FT_UShort) family->fam_index;
        node->hash      = query->hash;
        node->ref_count = 0;

        error = clazz->node_init( node, query, cache );
        if ( error )
        {
          FREE( node );
          goto Exit;
        }

        ftc_node_hash_link( node, cache );
        ftc_node_mru_link( node, cache->manager );

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

        /* now try to compress the node pool when necessary */
        if ( manager->cur_weight >= manager->max_weight )
        {
          node->ref_count++;
          FTC_Manager_Compress( manager );
          node->ref_count--;
        }

        /* try to resize the hash table if appropriate */
        if ( FTC_CACHE_RESIZE_TEST( cache ) )
          ftc_cache_resize( cache );

        *anode = node;
      }
    }

  Exit:
    return error;
  }


/* END */