src/cache/ftccache.h

   1 /****************************************************************************
   2  *
   3  * ftccache.h
   4  *
   5  *   FreeType internal cache interface (specification).
   6  *
   7  * Copyright (C) 2000-2020 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 #ifndef FTCCACHE_H_
  20 #define FTCCACHE_H_
  21
  22 #include <freetype/internal/compiler-macros.h>
  23 #include "ftcmru.h"
  24
  25 FT_BEGIN_HEADER
  26
  27 #define FTC_FACE_ID_HASH( i )                                  \
  28          ( ( (FT_Offset)(i) >> 3 ) ^ ( (FT_Offset)(i) << 7 ) )
  29
  30   /* handle to cache object */
  31   typedef struct FTC_CacheRec_*  FTC_Cache;
  32
  33   /* handle to cache class */
  34   typedef const struct FTC_CacheClassRec_*  FTC_CacheClass;
  35
  36
  37   /*************************************************************************/
  38   /*************************************************************************/
  39   /*****                                                               *****/
  40   /*****                   CACHE NODE DEFINITIONS                      *****/
  41   /*****                                                               *****/
  42   /*************************************************************************/
  43   /*************************************************************************/
  44
  45   /**************************************************************************
  46    *
  47    * Each cache controls one or more cache nodes.  Each node is part of
  48    * the global_lru list of the manager.  Its `data' field however is used
  49    * as a reference count for now.
  50    *
  51    * A node can be anything, depending on the type of information held by
  52    * the cache.  It can be an individual glyph image, a set of bitmaps
  53    * glyphs for a given size, some metrics, etc.
  54    *
  55    */
  56
  57   /* structure size should be 20 bytes on 32-bits machines */
  58   typedef struct  FTC_NodeRec_
  59   {
  60     FTC_MruNodeRec  mru;          /* circular mru list pointer           */
  61     FTC_Node        link;         /* used for hashing                    */
  62     FT_Offset       hash;         /* used for hashing too                */
  63     FT_UShort       cache_index;  /* index of cache the node belongs to  */
  64     FT_Short        ref_count;    /* reference count for this node       */
  65
  66   } FTC_NodeRec;
  67
  68
  69 #define FTC_NODE( x )    ( (FTC_Node)(x) )
  70 #define FTC_NODE_P( x )  ( (FTC_Node*)(x) )
  71
  72 #define FTC_NODE_NEXT( x )  FTC_NODE( (x)->mru.next )
  73 #define FTC_NODE_PREV( x )  FTC_NODE( (x)->mru.prev )
  74
  75 #ifdef FTC_INLINE
  76 #define FTC_NODE_TOP_FOR_HASH( cache, hash )                      \
  77         ( ( cache )->buckets +                                    \
  78             ( ( ( ( hash ) &   ( cache )->mask ) < ( cache )->p ) \
  79               ? ( ( hash ) & ( ( cache )->mask * 2 + 1 ) )        \
  80               : ( ( hash ) &   ( cache )->mask ) ) )
  81 #else
  82   FT_LOCAL( FTC_Node* )
  83   ftc_get_top_node_for_hash( FTC_Cache  cache,
  84                              FT_Offset  hash );
  85 #define FTC_NODE_TOP_FOR_HASH( cache, hash )             \
  86         ftc_get_top_node_for_hash( ( cache ), ( hash ) )
  87 #endif
  88
  89
  90   /*************************************************************************/
  91   /*************************************************************************/
  92   /*****                                                               *****/
  93   /*****                       CACHE DEFINITIONS                       *****/
  94   /*****                                                               *****/
  95   /*************************************************************************/
  96   /*************************************************************************/
  97
  98   /* initialize a new cache node */
  99   typedef FT_Error
 100   (*FTC_Node_NewFunc)( FTC_Node    *pnode,
 101                        FT_Pointer   query,
 102                        FTC_Cache    cache );
 103
 104   typedef FT_Offset
 105   (*FTC_Node_WeightFunc)( FTC_Node   node,
 106                           FTC_Cache  cache );
 107
 108   /* compare a node to a given key pair */
 109   typedef FT_Bool
 110   (*FTC_Node_CompareFunc)( FTC_Node    node,
 111                            FT_Pointer  key,
 112                            FTC_Cache   cache,
 113                            FT_Bool*    list_changed );
 114
 115
 116   typedef void
 117   (*FTC_Node_FreeFunc)( FTC_Node   node,
 118                         FTC_Cache  cache );
 119
 120   typedef FT_Error
 121   (*FTC_Cache_InitFunc)( FTC_Cache  cache );
 122
 123   typedef void
 124   (*FTC_Cache_DoneFunc)( FTC_Cache  cache );
 125
 126
 127   typedef struct  FTC_CacheClassRec_
 128   {
 129     FTC_Node_NewFunc      node_new;
 130     FTC_Node_WeightFunc   node_weight;
 131     FTC_Node_CompareFunc  node_compare;
 132     FTC_Node_CompareFunc  node_remove_faceid;
 133     FTC_Node_FreeFunc     node_free;
 134
 135     FT_Offset             cache_size;
 136     FTC_Cache_InitFunc    cache_init;
 137     FTC_Cache_DoneFunc    cache_done;
 138
 139   } FTC_CacheClassRec;
 140
 141
 142   /* each cache really implements a dynamic hash table to manage its nodes */
 143   typedef struct  FTC_CacheRec_
 144   {
 145     FT_UFast           p;
 146     FT_UFast           mask;
 147     FT_Long            slack;
 148     FTC_Node*          buckets;
 149
 150     FTC_CacheClassRec  clazz;       /* local copy, for speed  */
 151
 152     FTC_Manager        manager;
 153     FT_Memory          memory;
 154     FT_UInt            index;       /* in manager's table     */
 155
 156     FTC_CacheClass     org_class;   /* original class pointer */
 157
 158   } FTC_CacheRec;
 159
 160
 161 #define FTC_CACHE( x )    ( (FTC_Cache)(x) )
 162 #define FTC_CACHE_P( x )  ( (FTC_Cache*)(x) )
 163
 164
 165   /* default cache initialize */
 166   FT_LOCAL( FT_Error )
 167   FTC_Cache_Init( FTC_Cache  cache );
 168
 169   /* default cache finalizer */
 170   FT_LOCAL( void )
 171   FTC_Cache_Done( FTC_Cache  cache );
 172
 173   /* Call this function to look up the cache.  If no corresponding
 174    * node is found, a new one is automatically created.  This function
 175    * is capable of flushing the cache adequately to make room for the
 176    * new cache object.
 177    */
 178
 179 #ifndef FTC_INLINE
 180   FT_LOCAL( FT_Error )
 181   FTC_Cache_Lookup( FTC_Cache   cache,
 182                     FT_Offset   hash,
 183                     FT_Pointer  query,
 184                     FTC_Node   *anode );
 185 #endif
 186
 187   FT_LOCAL( FT_Error )
 188   FTC_Cache_NewNode( FTC_Cache   cache,
 189                      FT_Offset   hash,
 190                      FT_Pointer  query,
 191                      FTC_Node   *anode );
 192
 193   /* Remove all nodes that relate to a given face_id.  This is useful
 194    * when un-installing fonts.  Note that if a cache node relates to
 195    * the face_id but is locked (i.e., has `ref_count > 0'), the node
 196    * will _not_ be destroyed, but its internal face_id reference will
 197    * be modified.
 198    *
 199    * The final result will be that the node will never come back
 200    * in further lookup requests, and will be flushed on demand from
 201    * the cache normally when its reference count reaches 0.
 202    */
 203   FT_LOCAL( void )
 204   FTC_Cache_RemoveFaceID( FTC_Cache   cache,
 205                           FTC_FaceID  face_id );
 206
 207
 208 #ifdef FTC_INLINE
 209
 210 #define FTC_CACHE_LOOKUP_CMP( cache, nodecmp, hash, query, node, error ) \
 211   FT_BEGIN_STMNT                                                         \
 212     FTC_Node             *_bucket, *_pnode, _node;                       \
 213     FTC_Cache             _cache   = FTC_CACHE(cache);                   \
 214     FT_Offset             _hash    = (FT_Offset)(hash);                  \
 215     FTC_Node_CompareFunc  _nodcomp = (FTC_Node_CompareFunc)(nodecmp);    \
 216     FT_Bool               _list_changed = FALSE;                         \
 217                                                                          \
 218                                                                          \
 219     error = FT_Err_Ok;                                                   \
 220     node  = NULL;                                                        \
 221                                                                          \
 222     /* Go to the `top' node of the list sharing same masked hash */      \
 223     _bucket = _pnode = FTC_NODE_TOP_FOR_HASH( _cache, _hash );           \
 224                                                                          \
 225     /* Look up a node with identical hash and queried properties.    */  \
 226     /* NOTE: _nodcomp() may change the linked list to reduce memory. */  \
 227     for (;;)                                                             \
 228     {                                                                    \
 229       _node = *_pnode;                                                   \
 230       if ( !_node )                                                      \
 231         goto NewNode_;                                                   \
 232                                                                          \
 233       if ( _node->hash == _hash                             &&           \
 234            _nodcomp( _node, query, _cache, &_list_changed ) )            \
 235         break;                                                           \
 236                                                                          \
 237       _pnode = &_node->link;                                             \
 238     }                                                                    \
 239                                                                          \
 240     if ( _list_changed )                                                 \
 241     {                                                                    \
 242       /* Update _bucket by possibly modified linked list */              \
 243       _bucket = _pnode = FTC_NODE_TOP_FOR_HASH( _cache, _hash );         \
 244                                                                          \
 245       /* Update _pnode by possibly modified linked list */               \
 246       while ( *_pnode != _node )                                         \
 247       {                                                                  \
 248         if ( !*_pnode )                                                  \
 249         {                                                                \
 250           FT_ERROR(( "FTC_CACHE_LOOKUP_CMP: oops!!! node missing\n" ));  \
 251           goto NewNode_;                                                 \
 252         }                                                                \
 253         else                                                             \
 254           _pnode = &((*_pnode)->link);                                   \
 255       }                                                                  \
 256     }                                                                    \
 257                                                                          \
 258     /* Reorder the list to move the found node to the `top' */           \
 259     if ( _node != *_bucket )                                             \
 260     {                                                                    \
 261       *_pnode     = _node->link;                                         \
 262       _node->link = *_bucket;                                            \
 263       *_bucket    = _node;                                               \
 264     }                                                                    \
 265                                                                          \
 266     /* Update MRU list */                                                \
 267     {                                                                    \
 268       FTC_Manager  _manager = _cache->manager;                           \
 269       void*        _nl      = &_manager->nodes_list;                     \
 270                                                                          \
 271                                                                          \
 272       if ( _node != _manager->nodes_list )                               \
 273         FTC_MruNode_Up( (FTC_MruNode*)_nl,                               \
 274                         (FTC_MruNode)_node );                            \
 275     }                                                                    \
 276     goto Ok_;                                                            \
 277                                                                          \
 278   NewNode_:                                                              \
 279     error = FTC_Cache_NewNode( _cache, _hash, query, &_node );           \
 280                                                                          \
 281   Ok_:                                                                   \
 282     node = _node;                                                        \
 283   FT_END_STMNT
 284
 285 #else /* !FTC_INLINE */
 286
 287 #define FTC_CACHE_LOOKUP_CMP( cache, nodecmp, hash, query, node, error ) \
 288   FT_BEGIN_STMNT                                                         \
 289     error = FTC_Cache_Lookup( FTC_CACHE( cache ), hash, query,           \
 290                               (FTC_Node*)&(node) );                      \
 291   FT_END_STMNT
 292
 293 #endif /* !FTC_INLINE */
 294
 295
 296   /*
 297    * This macro, together with FTC_CACHE_TRYLOOP_END, defines a retry
 298    * loop to flush the cache repeatedly in case of memory overflows.
 299    *
 300    * It is used when creating a new cache node, or within a lookup
 301    * that needs to allocate data (e.g. the sbit cache lookup).
 302    *
 303    * Example:
 304    *
 305    * {
 306    *   FTC_CACHE_TRYLOOP( cache )
 307    *     error = load_data( ... );
 308    *   FTC_CACHE_TRYLOOP_END()
 309    * }
 310    *
 311    */
 312 #define FTC_CACHE_TRYLOOP( cache )                           \
 313   {                                                          \
 314     FTC_Manager  _try_manager = FTC_CACHE( cache )->manager; \
 315     FT_UInt      _try_count   = 4;                           \
 316                                                              \
 317                                                              \
 318     for (;;)                                                 \
 319     {                                                        \
 320       FT_UInt  _try_done;
 321
 322
 323 #define FTC_CACHE_TRYLOOP_END( list_changed )                     \
 324       if ( !error || FT_ERR_NEQ( error, Out_Of_Memory ) )         \
 325         break;                                                    \
 326                                                                   \
 327       _try_done = FTC_Manager_FlushN( _try_manager, _try_count ); \
 328       if ( _try_done > 0 && list_changed != NULL )                \
 329         *(FT_Bool*)( list_changed ) = TRUE;                       \
 330                                                                   \
 331       if ( _try_done == 0 )                                       \
 332         break;                                                    \
 333                                                                   \
 334       if ( _try_done == _try_count )                              \
 335       {                                                           \
 336         _try_count *= 2;                                          \
 337         if ( _try_count < _try_done              ||               \
 338             _try_count > _try_manager->num_nodes )                \
 339           _try_count = _try_manager->num_nodes;                   \
 340       }                                                           \
 341     }                                                             \
 342   }
 343
 344  /* */
 345
 346 FT_END_HEADER
 347
 348
 349 #endif /* FTCCACHE_H_ */
 350
 351
 352 /* END */