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      1 /***************************************************************************/
      2 /*                                                                         */
      3 /*  ftccache.c                                                             */
      4 /*                                                                         */
      5 /*    The FreeType internal cache interface (body).                        */
      6 /*                                                                         */
      7 /*  Copyright 2000-2015 by                                                 */
      8 /*  David Turner, Robert Wilhelm, and Werner Lemberg.                      */
      9 /*                                                                         */
     10 /*  This file is part of the FreeType project, and may only be used,       */
     11 /*  modified, and distributed under the terms of the FreeType project      */
     12 /*  license, LICENSE.TXT.  By continuing to use, modify, or distribute     */
     13 /*  this file you indicate that you have read the license and              */
     14 /*  understand and accept it fully.                                        */
     15 /*                                                                         */
     16 /***************************************************************************/
     17 
     18 
     19 #include <ft2build.h>
     20 #include "ftcmanag.h"
     21 #include FT_INTERNAL_OBJECTS_H
     22 #include FT_INTERNAL_DEBUG_H
     23 
     24 #include "ftccback.h"
     25 #include "ftcerror.h"
     26 
     27 #undef  FT_COMPONENT
     28 #define FT_COMPONENT  trace_cache
     29 
     30 
     31 #define FTC_HASH_MAX_LOAD  2
     32 #define FTC_HASH_MIN_LOAD  1
     33 #define FTC_HASH_SUB_LOAD  ( FTC_HASH_MAX_LOAD - FTC_HASH_MIN_LOAD )
     34 
     35   /* this one _must_ be a power of 2! */
     36 #define FTC_HASH_INITIAL_SIZE  8
     37 
     38 
     39   /*************************************************************************/
     40   /*************************************************************************/
     41   /*****                                                               *****/
     42   /*****                   CACHE NODE DEFINITIONS                      *****/
     43   /*****                                                               *****/
     44   /*************************************************************************/
     45   /*************************************************************************/
     46 
     47   /* add a new node to the head of the manager's circular MRU list */
     48   static void
     49   ftc_node_mru_link( FTC_Node     node,
     50                      FTC_Manager  manager )
     51   {
     52     void  *nl = &manager->nodes_list;
     53 
     54 
     55     FTC_MruNode_Prepend( (FTC_MruNode*)nl,
     56                          (FTC_MruNode)node );
     57     manager->num_nodes++;
     58   }
     59 
     60 
     61   /* remove a node from the manager's MRU list */
     62   static void
     63   ftc_node_mru_unlink( FTC_Node     node,
     64                        FTC_Manager  manager )
     65   {
     66     void  *nl = &manager->nodes_list;
     67 
     68 
     69     FTC_MruNode_Remove( (FTC_MruNode*)nl,
     70                         (FTC_MruNode)node );
     71     manager->num_nodes--;
     72   }
     73 
     74 
     75 #ifndef FTC_INLINE
     76 
     77   /* move a node to the head of the manager's MRU list */
     78   static void
     79   ftc_node_mru_up( FTC_Node     node,
     80                    FTC_Manager  manager )
     81   {
     82     FTC_MruNode_Up( (FTC_MruNode*)&manager->nodes_list,
     83                     (FTC_MruNode)node );
     84   }
     85 
     86 
     87   /* get a top bucket for specified hash from cache,
     88    * body for FTC_NODE__TOP_FOR_HASH( cache, hash )
     89    */
     90   FT_LOCAL_DEF( FTC_Node* )
     91   ftc_get_top_node_for_hash( FTC_Cache  cache,
     92                              FT_Offset  hash )
     93   {
     94     FTC_Node*  pnode;
     95     FT_Offset  idx;
     96 
     97 
     98     idx = hash & cache->mask;
     99     if ( idx < cache->p )
    100       idx = hash & ( 2 * cache->mask + 1 );
    101     pnode = cache->buckets + idx;
    102     return pnode;
    103   }
    104 
    105 #endif /* !FTC_INLINE */
    106 
    107 
    108   /* Note that this function cannot fail.  If we cannot re-size the
    109    * buckets array appropriately, we simply degrade the hash table's
    110    * performance!
    111    */
    112   static void
    113   ftc_cache_resize( FTC_Cache  cache )
    114   {
    115     for (;;)
    116     {
    117       FTC_Node  node, *pnode;
    118       FT_UFast  p     = cache->p;
    119       FT_UFast  mask  = cache->mask;
    120       FT_UFast  count = mask + p + 1;    /* number of buckets */
    121 
    122 
    123       /* do we need to shrink the buckets array? */
    124       if ( cache->slack < 0 )
    125       {
    126         FTC_Node  new_list = NULL;
    127 
    128 
    129         /* try to expand the buckets array _before_ splitting
    130          * the bucket lists
    131          */
    132         if ( p >= mask )
    133         {
    134           FT_Memory  memory = cache->memory;
    135           FT_Error   error;
    136 
    137 
    138           /* if we can't expand the array, leave immediately */
    139           if ( FT_RENEW_ARRAY( cache->buckets,
    140                                ( mask + 1 ) * 2, ( mask + 1 ) * 4 ) )
    141             break;
    142         }
    143 
    144         /* split a single bucket */
    145         pnode = cache->buckets + p;
    146 
    147         for (;;)
    148         {
    149           node = *pnode;
    150           if ( node == NULL )
    151             break;
    152 
    153           if ( node->hash & ( mask + 1 ) )
    154           {
    155             *pnode     = node->link;
    156             node->link = new_list;
    157             new_list   = node;
    158           }
    159           else
    160             pnode = &node->link;
    161         }
    162 
    163         cache->buckets[p + mask + 1] = new_list;
    164 
    165         cache->slack += FTC_HASH_MAX_LOAD;
    166 
    167         if ( p >= mask )
    168         {
    169           cache->mask = 2 * mask + 1;
    170           cache->p    = 0;
    171         }
    172         else
    173           cache->p = p + 1;
    174       }
    175 
    176       /* do we need to expand the buckets array? */
    177       else if ( cache->slack > (FT_Long)count * FTC_HASH_SUB_LOAD )
    178       {
    179         FT_UFast   old_index = p + mask;
    180         FTC_Node*  pold;
    181 
    182 
    183         if ( old_index + 1 <= FTC_HASH_INITIAL_SIZE )
    184           break;
    185 
    186         if ( p == 0 )
    187         {
    188           FT_Memory  memory = cache->memory;
    189           FT_Error   error;
    190 
    191 
    192           /* if we can't shrink the array, leave immediately */
    193           if ( FT_RENEW_ARRAY( cache->buckets,
    194                                ( mask + 1 ) * 2, mask + 1 ) )
    195             break;
    196 
    197           cache->mask >>= 1;
    198           p             = cache->mask;
    199         }
    200         else
    201           p--;
    202 
    203         pnode = cache->buckets + p;
    204         while ( *pnode )
    205           pnode = &(*pnode)->link;
    206 
    207         pold   = cache->buckets + old_index;
    208         *pnode = *pold;
    209         *pold  = NULL;
    210 
    211         cache->slack -= FTC_HASH_MAX_LOAD;
    212         cache->p      = p;
    213       }
    214 
    215       /* otherwise, the hash table is balanced */
    216       else
    217         break;
    218     }
    219   }
    220 
    221 
    222   /* remove a node from its cache's hash table */
    223   static void
    224   ftc_node_hash_unlink( FTC_Node   node0,
    225                         FTC_Cache  cache )
    226   {
    227     FTC_Node  *pnode = FTC_NODE__TOP_FOR_HASH( cache, node0->hash );
    228 
    229 
    230     for (;;)
    231     {
    232       FTC_Node  node = *pnode;
    233 
    234 
    235       if ( node == NULL )
    236       {
    237         FT_TRACE0(( "ftc_node_hash_unlink: unknown node\n" ));
    238         return;
    239       }
    240 
    241       if ( node == node0 )
    242         break;
    243 
    244       pnode = &(*pnode)->link;
    245     }
    246 
    247     *pnode      = node0->link;
    248     node0->link = NULL;
    249 
    250     cache->slack++;
    251     ftc_cache_resize( cache );
    252   }
    253 
    254 
    255   /* add a node to the `top' of its cache's hash table */
    256   static void
    257   ftc_node_hash_link( FTC_Node   node,
    258                       FTC_Cache  cache )
    259   {
    260     FTC_Node  *pnode = FTC_NODE__TOP_FOR_HASH( cache, node->hash );
    261 
    262 
    263     node->link = *pnode;
    264     *pnode     = node;
    265 
    266     cache->slack--;
    267     ftc_cache_resize( cache );
    268   }
    269 
    270 
    271   /* remove a node from the cache manager */
    272   FT_LOCAL_DEF( void )
    273   ftc_node_destroy( FTC_Node     node,
    274                     FTC_Manager  manager )
    275   {
    276     FTC_Cache  cache;
    277 
    278 
    279 #ifdef FT_DEBUG_ERROR
    280     /* find node's cache */
    281     if ( node->cache_index >= manager->num_caches )
    282     {
    283       FT_TRACE0(( "ftc_node_destroy: invalid node handle\n" ));
    284       return;
    285     }
    286 #endif
    287 
    288     cache = manager->caches[node->cache_index];
    289 
    290 #ifdef FT_DEBUG_ERROR
    291     if ( cache == NULL )
    292     {
    293       FT_TRACE0(( "ftc_node_destroy: invalid node handle\n" ));
    294       return;
    295     }
    296 #endif
    297 
    298     manager->cur_weight -= cache->clazz.node_weight( node, cache );
    299 
    300     /* remove node from mru list */
    301     ftc_node_mru_unlink( node, manager );
    302 
    303     /* remove node from cache's hash table */
    304     ftc_node_hash_unlink( node, cache );
    305 
    306     /* now finalize it */
    307     cache->clazz.node_free( node, cache );
    308 
    309 #if 0
    310     /* check, just in case of general corruption :-) */
    311     if ( manager->num_nodes == 0 )
    312       FT_TRACE0(( "ftc_node_destroy: invalid cache node count (%d)\n",
    313                   manager->num_nodes ));
    314 #endif
    315   }
    316 
    317 
    318   /*************************************************************************/
    319   /*************************************************************************/
    320   /*****                                                               *****/
    321   /*****                    ABSTRACT CACHE CLASS                       *****/
    322   /*****                                                               *****/
    323   /*************************************************************************/
    324   /*************************************************************************/
    325 
    326 
    327   FT_LOCAL_DEF( FT_Error )
    328   FTC_Cache_Init( FTC_Cache  cache )
    329   {
    330     return ftc_cache_init( cache );
    331   }
    332 
    333 
    334   FT_LOCAL_DEF( FT_Error )
    335   ftc_cache_init( FTC_Cache  cache )
    336   {
    337     FT_Memory  memory = cache->memory;
    338     FT_Error   error;
    339 
    340 
    341     cache->p     = 0;
    342     cache->mask  = FTC_HASH_INITIAL_SIZE - 1;
    343     cache->slack = FTC_HASH_INITIAL_SIZE * FTC_HASH_MAX_LOAD;
    344 
    345     (void)FT_NEW_ARRAY( cache->buckets, FTC_HASH_INITIAL_SIZE * 2 );
    346     return error;
    347   }
    348 
    349 
    350   static void
    351   FTC_Cache_Clear( FTC_Cache  cache )
    352   {
    353     if ( cache && cache->buckets )
    354     {
    355       FTC_Manager  manager = cache->manager;
    356       FT_UFast     i;
    357       FT_UFast     count;
    358 
    359 
    360       count = cache->p + cache->mask + 1;
    361 
    362       for ( i = 0; i < count; i++ )
    363       {
    364         FTC_Node  *pnode = cache->buckets + i, next, node = *pnode;
    365 
    366 
    367         while ( node )
    368         {
    369           next        = node->link;
    370           node->link  = NULL;
    371 
    372           /* remove node from mru list */
    373           ftc_node_mru_unlink( node, manager );
    374 
    375           /* now finalize it */
    376           manager->cur_weight -= cache->clazz.node_weight( node, cache );
    377 
    378           cache->clazz.node_free( node, cache );
    379           node = next;
    380         }
    381         cache->buckets[i] = NULL;
    382       }
    383       ftc_cache_resize( cache );
    384     }
    385   }
    386 
    387 
    388   FT_LOCAL_DEF( void )
    389   ftc_cache_done( FTC_Cache  cache )
    390   {
    391     if ( cache->memory )
    392     {
    393       FT_Memory  memory = cache->memory;
    394 
    395 
    396       FTC_Cache_Clear( cache );
    397 
    398       FT_FREE( cache->buckets );
    399       cache->mask  = 0;
    400       cache->p     = 0;
    401       cache->slack = 0;
    402 
    403       cache->memory = NULL;
    404     }
    405   }
    406 
    407 
    408   FT_LOCAL_DEF( void )
    409   FTC_Cache_Done( FTC_Cache  cache )
    410   {
    411     ftc_cache_done( cache );
    412   }
    413 
    414 
    415   static void
    416   ftc_cache_add( FTC_Cache  cache,
    417                  FT_Offset  hash,
    418                  FTC_Node   node )
    419   {
    420     node->hash        = hash;
    421     node->cache_index = (FT_UInt16)cache->index;
    422     node->ref_count   = 0;
    423 
    424     ftc_node_hash_link( node, cache );
    425     ftc_node_mru_link( node, cache->manager );
    426 
    427     {
    428       FTC_Manager  manager = cache->manager;
    429 
    430 
    431       manager->cur_weight += cache->clazz.node_weight( node, cache );
    432 
    433       if ( manager->cur_weight >= manager->max_weight )
    434       {
    435         node->ref_count++;
    436         FTC_Manager_Compress( manager );
    437         node->ref_count--;
    438       }
    439     }
    440   }
    441 
    442 
    443   FT_LOCAL_DEF( FT_Error )
    444   FTC_Cache_NewNode( FTC_Cache   cache,
    445                      FT_Offset   hash,
    446                      FT_Pointer  query,
    447                      FTC_Node   *anode )
    448   {
    449     FT_Error  error;
    450     FTC_Node  node;
    451 
    452 
    453     /*
    454      * We use the FTC_CACHE_TRYLOOP macros to support out-of-memory
    455      * errors (OOM) correctly, i.e., by flushing the cache progressively
    456      * in order to make more room.
    457      */
    458 
    459     FTC_CACHE_TRYLOOP( cache )
    460     {
    461       error = cache->clazz.node_new( &node, query, cache );
    462     }
    463     FTC_CACHE_TRYLOOP_END( NULL );
    464 
    465     if ( error )
    466       node = NULL;
    467     else
    468     {
    469      /* don't assume that the cache has the same number of buckets, since
    470       * our allocation request might have triggered global cache flushing
    471       */
    472       ftc_cache_add( cache, hash, node );
    473     }
    474 
    475     *anode = node;
    476     return error;
    477   }
    478 
    479 
    480 #ifndef FTC_INLINE
    481 
    482   FT_LOCAL_DEF( FT_Error )
    483   FTC_Cache_Lookup( FTC_Cache   cache,
    484                     FT_Offset   hash,
    485                     FT_Pointer  query,
    486                     FTC_Node   *anode )
    487   {
    488     FTC_Node*  bucket;
    489     FTC_Node*  pnode;
    490     FTC_Node   node;
    491     FT_Error   error        = FT_Err_Ok;
    492     FT_Bool    list_changed = FALSE;
    493 
    494     FTC_Node_CompareFunc  compare = cache->clazz.node_compare;
    495 
    496 
    497     if ( cache == NULL || anode == NULL )
    498       return FT_THROW( Invalid_Argument );
    499 
    500     /* Go to the `top' node of the list sharing same masked hash */
    501     bucket = pnode = FTC_NODE__TOP_FOR_HASH( cache, hash );
    502 
    503     /* Lookup a node with exactly same hash and queried properties.  */
    504     /* NOTE: _nodcomp() may change the linked list to reduce memory. */
    505     for (;;)
    506     {
    507       node = *pnode;
    508       if ( node == NULL )
    509         goto NewNode;
    510 
    511       if ( node->hash == hash                           &&
    512            compare( node, query, cache, &list_changed ) )
    513         break;
    514 
    515       pnode = &node->link;
    516     }
    517 
    518     if ( list_changed )
    519     {
    520       /* Update bucket by modified linked list */
    521       bucket = pnode = FTC_NODE__TOP_FOR_HASH( cache, hash );
    522 
    523       /* Update pnode by modified linked list */
    524       while ( *pnode != node )
    525       {
    526         if ( *pnode == NULL )
    527         {
    528           FT_ERROR(( "FTC_Cache_Lookup: oops!!!  node missing\n" ));
    529           goto NewNode;
    530         }
    531         else
    532           pnode = &((*pnode)->link);
    533       }
    534     }
    535 
    536     /* Reorder the list to move the found node to the `top' */
    537     if ( node != *bucket )
    538     {
    539       *pnode     = node->link;
    540       node->link = *bucket;
    541       *bucket    = node;
    542     }
    543 
    544     /* move to head of MRU list */
    545     {
    546       FTC_Manager  manager = cache->manager;
    547 
    548 
    549       if ( node != manager->nodes_list )
    550         ftc_node_mru_up( node, manager );
    551     }
    552     *anode = node;
    553 
    554     return error;
    555 
    556   NewNode:
    557     return FTC_Cache_NewNode( cache, hash, query, anode );
    558   }
    559 
    560 #endif /* !FTC_INLINE */
    561 
    562 
    563   FT_LOCAL_DEF( void )
    564   FTC_Cache_RemoveFaceID( FTC_Cache   cache,
    565                           FTC_FaceID  face_id )
    566   {
    567     FT_UFast     i, count;
    568     FTC_Manager  manager = cache->manager;
    569     FTC_Node     frees   = NULL;
    570 
    571 
    572     count = cache->p + cache->mask + 1;
    573     for ( i = 0; i < count; i++ )
    574     {
    575       FTC_Node*  bucket = cache->buckets + i;
    576       FTC_Node*  pnode  = bucket;
    577 
    578 
    579       for ( ;; )
    580       {
    581         FTC_Node  node = *pnode;
    582         FT_Bool   list_changed = FALSE;
    583 
    584 
    585         if ( node == NULL )
    586           break;
    587 
    588         if ( cache->clazz.node_remove_faceid( node, face_id,
    589                                               cache, &list_changed ) )
    590         {
    591           *pnode     = node->link;
    592           node->link = frees;
    593           frees      = node;
    594         }
    595         else
    596           pnode = &node->link;
    597       }
    598     }
    599 
    600     /* remove all nodes in the free list */
    601     while ( frees )
    602     {
    603       FTC_Node  node;
    604 
    605 
    606       node  = frees;
    607       frees = node->link;
    608 
    609       manager->cur_weight -= cache->clazz.node_weight( node, cache );
    610       ftc_node_mru_unlink( node, manager );
    611 
    612       cache->clazz.node_free( node, cache );
    613 
    614       cache->slack++;
    615     }
    616 
    617     ftc_cache_resize( cache );
    618   }
    619 
    620 
    621 /* END */
    622