/***************************************************************************/

/*                                                                         */

/*  ftccache.c                                                             */

/*                                                                         */

/*    The FreeType internal cache interface (body).                        */

/*                                                                         */

/*  Copyright 2000-2001, 2002, 2003, 2004, 2005, 2006, 2007, 2009, 2010,   */

/*            2011 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 "ftcmanag.h"

#include FT_INTERNAL_OBJECTS_H

#include FT_INTERNAL_DEBUG_H

#include "ftccback.h"

#include "ftcerror.h"

#undef  FT_COMPONENT

#define FT_COMPONENT  trace_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_PtrDist  hash )

  {

    FTC_Node*  pnode;

    FT_UInt    idx;

    idx = (FT_UInt)( hash & cache->mask );

    if ( idx < cache->p )

      idx = (FT_UInt)( 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 == 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 )

        {

          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 == NULL )

      {

        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 */

#ifdef FT_CONFIG_OPTION_OLD_INTERNALS

  FT_BASE_DEF( void )

#else

  FT_LOCAL_DEF( void )

#endif

  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 == NULL )

    {

      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_PtrDist 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_PtrDist  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_PtrDist  hash,

                    FT_Pointer  query,

                    FTC_Node   *anode )

  {

    FTC_Node*  bucket;

    FTC_Node*  pnode;

    FTC_Node   node;

    FT_Error   error        = FTC_Err_Ok;

    FT_Bool    list_changed = FALSE;

    FTC_Node_CompareFunc  compare = cache->clazz.node_compare;

    if ( cache == NULL || anode == NULL )

      return FTC_Err_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 == NULL )

        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 */