/****************************************************************************
*
* ftccache.c
*
* The FreeType internal cache interface (body).
*
* Copyright (C) 2000-2021 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 "ftcmanag.h"
#include <freetype/internal/ftobjs.h>
#include <freetype/internal/ftdebug.h>
#include "ftccback.h"
#include "ftcerror.h"
#undef FT_COMPONENT
#define FT_COMPONENT cache
#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 *****/
/***** *****/
/*************************************************************************/
/*************************************************************************/
/* 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 )
{
void *nl = &manager->nodes_list;
FTC_MruNode_Prepend( (FTC_MruNode*)nl,
(FTC_MruNode)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 )
{
void *nl = &manager->nodes_list;
FTC_MruNode_Remove( (FTC_MruNode*)nl,
(FTC_MruNode)node );
manager->num_nodes--;
}
#ifndef FTC_INLINE
/* 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_MruNode_Up( (FTC_MruNode*)&manager->nodes_list,
(FTC_MruNode)node );
}
/* get a top bucket for specified hash from cache,
* body for FTC_NODE_TOP_FOR_HASH( cache, hash )
*/
FT_LOCAL_DEF( FTC_Node* )
ftc_get_top_node_for_hash( FTC_Cache cache,
FT_Offset hash )
{
FTC_Node* pnode;
FT_Offset idx;
idx = hash & cache->mask;
if ( idx < cache->p )
idx = hash & ( 2 * cache->mask + 1 );
pnode = cache->buckets + idx;
return pnode;
}
#endif /* !FTC_INLINE */
/* Note that this function cannot fail. If we cannot re-size the
* buckets array appropriately, we simply degrade the hash table's
* performance!
*/
static void
ftc_cache_resize( FTC_Cache cache )
{
for (;;)
{
FTC_Node node, *pnode;
FT_UFast p = cache->p;
FT_UFast mask = cache->mask;
FT_UFast count = mask + p + 1; /* number of buckets */
/* do we need to shrink the buckets array? */
if ( cache->slack < 0 )
{
FTC_Node new_list = NULL;
/* try to expand the buckets array _before_ splitting
* the bucket lists
*/
if ( p >= mask )
{
FT_Memory memory = cache->memory;
FT_Error error;
/* if we can't expand the array, leave immediately */
if ( FT_RENEW_ARRAY( cache->buckets,
( mask + 1 ) * 2, ( mask + 1 ) * 4 ) )
break;
}
/* split a single bucket */
pnode = cache->buckets + p;
for (;;)
{
node = *pnode;
if ( !node )
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 )
{
cache->mask = 2 * mask + 1;
cache->p = 0;
}
else
cache->p = p + 1;
}
/* do we need to expand the buckets array? */
else if ( cache->slack > (FT_Long)count * FTC_HASH_SUB_LOAD )
{
FT_UFast old_index = p + mask;
FTC_Node* pold;
if ( old_index + 1 <= FTC_HASH_INITIAL_SIZE )
break;
if ( p == 0 )
{
FT_Memory memory = cache->memory;
FT_Error error;
/* if we can't shrink the array, leave immediately */
if ( FT_RENEW_ARRAY( cache->buckets,
( mask + 1 ) * 2, mask + 1 ) )
break;
cache->mask >>= 1;
p = cache->mask;
}
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;
}
/* otherwise, the hash table is balanced */
else
break;
}
}
/* remove a node from its cache's hash table */
static void
ftc_node_hash_unlink( FTC_Node node0,
FTC_Cache cache )
{
FTC_Node *pnode = FTC_NODE_TOP_FOR_HASH( cache, node0->hash );
for (;;)
{
FTC_Node node = *pnode;
if ( !node )
{
FT_TRACE0(( "ftc_node_hash_unlink: unknown node\n" ));
return;
}
if ( node == node0 )
break;
pnode = &(*pnode)->link;
}
*pnode = node0->link;
node0->link = NULL;
cache->slack++;
ftc_cache_resize( cache );
}
/* add a node to the `top' of its cache's hash table */
static void
ftc_node_hash_link( FTC_Node node,
FTC_Cache cache )
{
FTC_Node *pnode = FTC_NODE_TOP_FOR_HASH( cache, node->hash );
node->link = *pnode;
*pnode = node;
cache->slack--;
ftc_cache_resize( cache );
}
/* remove a node from the cache manager */
FT_LOCAL_DEF( void )
ftc_node_destroy( FTC_Node node,
FTC_Manager manager )
{
FTC_Cache cache;
#ifdef FT_DEBUG_ERROR
/* find node's cache */
if ( node->cache_index >= manager->num_caches )
{
FT_TRACE0(( "ftc_node_destroy: invalid node handle\n" ));
return;
}
#endif
cache = manager->caches[node->cache_index];
#ifdef FT_DEBUG_ERROR
if ( !cache )
{
FT_TRACE0(( "ftc_node_destroy: invalid node handle\n" ));
return;
}
#endif
manager->cur_weight -= cache->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 */
cache->clazz.node_free( node, cache );
#if 0
/* check, just in case of general corruption :-) */
if ( manager->num_nodes == 0 )
FT_TRACE0(( "ftc_node_destroy: invalid cache node count (%d)\n",
manager->num_nodes ));
#endif
}
/*************************************************************************/
/*************************************************************************/
/***** *****/
/***** ABSTRACT CACHE CLASS *****/
/***** *****/
/*************************************************************************/
/*************************************************************************/
FT_LOCAL_DEF( FT_Error )
FTC_Cache_Init( FTC_Cache cache )
{
return ftc_cache_init( cache );
}
FT_LOCAL_DEF( FT_Error )
ftc_cache_init( FTC_Cache cache )
{
FT_Memory memory = cache->memory;
FT_Error error;
cache->p = 0;
cache->mask = FTC_HASH_INITIAL_SIZE - 1;
cache->slack = FTC_HASH_INITIAL_SIZE * FTC_HASH_MAX_LOAD;
(void)FT_NEW_ARRAY( cache->buckets, FTC_HASH_INITIAL_SIZE * 2 );
return error;
}
static void
FTC_Cache_Clear( FTC_Cache cache )
{
if ( cache && cache->buckets )
{
FTC_Manager manager = cache->manager;
FT_UFast i;
FT_UFast 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 -= cache->clazz.node_weight( node, cache );
cache->clazz.node_free( node, cache );
node = next;
}
cache->buckets[i] = NULL;
}
ftc_cache_resize( cache );
}
}
FT_LOCAL_DEF( void )
ftc_cache_done( FTC_Cache cache )
{
if ( cache->memory )
{
FT_Memory memory = cache->memory;
FTC_Cache_Clear( cache );
FT_FREE( cache->buckets );
cache->mask = 0;
cache->p = 0;
cache->slack = 0;
cache->memory = NULL;
}
}
FT_LOCAL_DEF( void )
FTC_Cache_Done( FTC_Cache cache )
{
ftc_cache_done( cache );
}
static void
ftc_cache_add( FTC_Cache cache,
FT_Offset hash,
FTC_Node node )
{
node->hash = hash;
node->cache_index = (FT_UInt16)cache->index;
node->ref_count = 0;
ftc_node_hash_link( node, cache );
ftc_node_mru_link( node, cache->manager );
{
FTC_Manager manager = cache->manager;
manager->cur_weight += cache->clazz.node_weight( node, cache );
if ( manager->cur_weight >= manager->max_weight )
{
node->ref_count++;
FTC_Manager_Compress( manager );
node->ref_count--;
}
}
}
FT_LOCAL_DEF( FT_Error )
FTC_Cache_NewNode( FTC_Cache cache,
FT_Offset hash,
FT_Pointer query,
FTC_Node *anode )
{
FT_Error error;
FTC_Node node;
/*
* We use the FTC_CACHE_TRYLOOP macros to support out-of-memory
* errors (OOM) correctly, i.e., by flushing the cache progressively
* in order to make more room.
*/
FTC_CACHE_TRYLOOP( cache )
{
error = cache->clazz.node_new( &node, query, cache );
}
FTC_CACHE_TRYLOOP_END( NULL );
if ( error )
node = NULL;
else
{
/* don't assume that the cache has the same number of buckets, since
* our allocation request might have triggered global cache flushing
*/
ftc_cache_add( cache, hash, node );
}
*anode = node;
return error;
}
#ifndef FTC_INLINE
FT_LOCAL_DEF( FT_Error )
FTC_Cache_Lookup( FTC_Cache cache,
FT_Offset hash,
FT_Pointer query,
FTC_Node *anode )
{
FTC_Node* bucket;
FTC_Node* pnode;
FTC_Node node;
FT_Error error = FT_Err_Ok;
FT_Bool list_changed = FALSE;
FTC_Node_CompareFunc compare = cache->clazz.node_compare;
if ( !cache || !anode )
return FT_THROW( Invalid_Argument );
/* Go to the `top' node of the list sharing same masked hash */
bucket = pnode = FTC_NODE_TOP_FOR_HASH( cache, hash );
/* Lookup a node with exactly same hash and queried properties. */
/* NOTE: _nodcomp() may change the linked list to reduce memory. */
for (;;)
{
node = *pnode;
if ( !node )
goto NewNode;
if ( node->hash == hash &&
compare( node, query, cache, &list_changed ) )
break;
pnode = &node->link;
}
if ( list_changed )
{
/* Update bucket by modified linked list */
bucket = pnode = FTC_NODE_TOP_FOR_HASH( cache, hash );
/* Update pnode by modified linked list */
while ( *pnode != node )
{
if ( !*pnode )
{
FT_ERROR(( "FTC_Cache_Lookup: oops!!! node missing\n" ));
goto NewNode;
}
else
pnode = &((*pnode)->link);
}
}
/* Reorder the list to move the found node to the `top' */
if ( node != *bucket )
{
*pnode = node->link;
node->link = *bucket;
*bucket = node;
}
/* move to head of MRU list */
{
FTC_Manager manager = cache->manager;
if ( node != manager->nodes_list )
ftc_node_mru_up( node, manager );
}
*anode = node;
return error;
NewNode:
return FTC_Cache_NewNode( cache, hash, query, anode );
}
#endif /* !FTC_INLINE */
FT_LOCAL_DEF( void )
FTC_Cache_RemoveFaceID( FTC_Cache cache,
FTC_FaceID face_id )
{
FT_UFast i, count;
FTC_Manager manager = cache->manager;
FTC_Node frees = NULL;
count = cache->p + cache->mask + 1;
for ( i = 0; i < count; i++ )
{
FTC_Node* bucket = cache->buckets + i;
FTC_Node* pnode = bucket;
for (;;)
{
FTC_Node node = *pnode;
FT_Bool list_changed = FALSE;
if ( !node )
break;
if ( cache->clazz.node_remove_faceid( node, face_id,
cache, &list_changed ) )
{
*pnode = node->link;
node->link = frees;
frees = node;
}
else
pnode = &node->link;
}
}
/* remove all nodes in the free list */
while ( frees )
{
FTC_Node node;
node = frees;
frees = node->link;
manager->cur_weight -= cache->clazz.node_weight( node, cache );
ftc_node_mru_unlink( node, manager );
cache->clazz.node_free( node, cache );
cache->slack++;
}
ftc_cache_resize( cache );
}
/* END */
