ref: 52f911a12d1c552b9fad3a2fb33b9e04ff2d92ee
dir: /src/cache/ftccache.c/
/***************************************************************************/
/* */
/* 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;
}
FT_EXPORT_DEF( void )
ftc_family_done( FTC_Family family )
{
if ( family && family->cache )
{
FTC_Manager manager = family->cache->manager;
/* remove from manager's family table */
ftc_family_table_free( &manager->families, family->fam_index );
}
}
/*************************************************************************/
/*************************************************************************/
/***** *****/
/***** ABSTRACT CACHE CLASS *****/
/***** *****/
/*************************************************************************/
/*************************************************************************/
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->p = 0;
cache->mask = FTC_HASH_INITIAL_SIZE - 1;
cache->slack = FTC_HASH_INITIAL_SIZE * FTC_HASH_MAX_LOAD;
if ( FT_NEW_ARRAY( cache->buckets, FTC_HASH_INITIAL_SIZE * 2 ) )
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 )
FT_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;
FT_UInt count;
count = cache->p + cache->mask + 1;
for ( i = 0; i < count; 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 );
FT_FREE( node );
node = next;
}
cache->buckets[i] = NULL;
}
cache->p = 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 );
FT_FREE( cache->buckets );
cache->mask = 0;
cache->slack = 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 = FTC_Err_Ok;
FTC_Manager manager;
FT_LruNode lru;
FT_UInt free_count = 0;
if ( !cache || !query || !anode )
return FTC_Err_Invalid_Argument;
*anode = NULL;
query->hash = 0;
query->family = NULL;
manager = cache->manager;
/* here's a small note explaining what's happening in the code below.
*
* We need to deal intelligently with out-of-memory (OOM) conditions
* when trying to create a new family or cache node during the lookup.
*
* When an OOM is detected, we try to free one or more "old" nodes
* from the cache, then try again. It may be necessary to do that
* several times, so a loop is needed.
*
* The local variable "free_count" holds the number of "old" nodes to
* discard on each attempt. It starts at 1 and doubles on each
* iteration. The loop stops when:
*
* - a non-OOM error is detected
* - a succesful lookup is performed
* - there are no more unused nodes in the cache
*
* For the record, remember that all used nodes appear _before_
* unused ones in the manager's MRU node list.
*/
for (;;)
{
{
/* first of all, find the relevant family */
FT_LruList list = cache->families;
FT_LruNode fam, *pfam;
FT_LruNode_CompareFunc compare = list->clazz->node_compare;
pfam = &list->nodes;
for (;;)
{
fam = *pfam;
if ( fam == NULL )
{
error = FT_LruList_Lookup( list, query, &lru );
if ( error )
goto Fail;
goto Skip;
}
if ( compare( fam, query, list->data ) )
break;
pfam = &fam->next;
}
FT_ASSERT( fam != NULL );
/* move to top of list when needed */
if ( fam != list->nodes )
{
*pfam = fam->next;
fam->next = list->nodes;
list->nodes = fam;
}
lru = fam;
Skip:
;
}
{
FTC_Family family = (FTC_Family) lru;
FT_UFast hash = query->hash;
FTC_Node* bucket;
FT_UInt idx;
idx = hash & cache->mask;
if ( idx < cache->p )
idx = hash & ( cache->mask * 2 + 1 );
bucket = cache->buckets + idx;
if ( query->family != family ||
family->fam_index >= manager->families.size )
{
FT_ERROR((
"ftc_cache_lookup: invalid query (bad 'family' field)\n" ));
error = FTC_Err_Invalid_Argument;
goto Exit;
}
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 ( node->hash == hash &&
(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 != manager->nodes_list )
ftc_node_mru_up( node, manager );
*anode = node;
goto Exit;
}
pnode = &node->link;
}
}
/* didn't find a node, create a new one */
{
FTC_Cache_Class clazz = cache->clazz;
FT_Memory memory = cache->memory;
FTC_Node node;
if ( FT_ALLOC( node, clazz->node_size ) )
goto Fail;
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 )
{
FT_FREE( node );
goto Fail;
}
error = ftc_node_hash_link( node, cache );
if ( error )
{
clazz->node_done( node, cache );
FT_FREE( node );
goto Fail;
}
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--;
}
*anode = node;
}
/* all is well, exit now
*/
goto Exit;
}
Fail:
if ( error != FTC_Err_Out_Of_Memory )
goto Exit;
/* There is not enough memory; try to release some unused nodes
* from the cache to make room for a new one.
*/
{
FT_UInt new_count;
new_count = 1 + free_count * 2;
/* check overflow and bounds */
if ( new_count < free_count || free_count > manager->num_nodes )
goto Exit;
free_count = new_count;
/* try to remove "new_count" nodes from the list */
{
FTC_Node first = manager->nodes_list;
FTC_Node node;
if ( first == NULL ) /* empty list! */
goto Exit;
/* go to last node - it's a circular list */
node = first->mru_prev;
for ( ; node && new_count > 0; new_count-- )
{
FTC_Node prev = node->mru_prev;
/* Used nodes always appear before unused one in the MRU
* list. If we find one here, we'd better stop right now
* our iteration.
*/
if ( node->ref_count > 0 )
{
/* if there are no unused nodes in the list, we'd better exit */
if ( new_count == free_count )
goto Exit;
break;
}
ftc_node_destroy( node, manager );
if ( node == first )
break;
node = prev;
}
}
}
}
Exit:
return error;
}
/* END */