~drizzle-trunk/drizzle/development

/* Copyright (C) 2000 MySQL AB

   This program is free software; you can redistribute it and/or modify

   it under the terms of the GNU General Public License as published by

   the Free Software Foundation; version 2 of the License.

   This program is distributed in the hope that it will be useful,

   but WITHOUT ANY WARRANTY; without even the implied warranty of

   MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the

   GNU General Public License for more details.

   You should have received a copy of the GNU General Public License

   along with this program; if not, write to the Free Software

   Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA  02110-1301  USA */

/*

  Code for handling red-black (balanced) binary trees.

  key in tree is allocated accrding to following:

  1) If size < 0 then tree will not allocate keys and only a pointer to

     each key is saved in tree.

     compare and search functions uses and returns key-pointer

  2) If size == 0 then there are two options:

       - key_size != 0 to tree_insert: The key will be stored in the tree.

       - key_size == 0 to tree_insert:  A pointer to the key is stored.

     compare and search functions uses and returns key-pointer.

  3) if key_size is given to init_tree then each node will continue the

     key and calls to insert_key may increase length of key.

     if key_size > sizeof(pointer) and key_size is a multiple of 8 (double

     allign) then key will be put on a 8 alligned adress. Else

     the key will be on adress (element+1). This is transparent for user

     compare and search functions uses a pointer to given key-argument.

  - If you use a free function for tree-elements and you are freeing

    the element itself, you should use key_size = 0 to init_tree and

    tree_search

  The actual key in TREE_ELEMENT is saved as a pointer or after the

  TREE_ELEMENT struct.

  If one uses only pointers in tree one can use tree_set_pointer() to

  change address of data.

  Implemented by monty.

*/

/*

  NOTE:

  tree->compare function should be ALWAYS called as

    (*tree->compare)(custom_arg, ELEMENT_KEY(tree,element), key)

  and not other way around, as

    (*tree->compare)(custom_arg, key, ELEMENT_KEY(tree,element))

*/

#include <config.h>

#include <drizzled/tree.h>

#include <drizzled/internal/my_sys.h>

#include <drizzled/internal/m_string.h>

#include <drizzled/memory/root.h>

#define BLACK		1

#define RED		0

#define DEFAULT_ALLOC_SIZE 8192

#define DEFAULT_ALIGN_SIZE 8192

#define ELEMENT_KEY(tree,element)\

(tree->offset_to_key ? (void*)((unsigned char*) element+tree->offset_to_key) :\

			*((void**) (element+1)))

#define ELEMENT_CHILD(element, offs) (*(TREE_ELEMENT**)((char*)element + offs))

namespace drizzled

{

static void delete_tree_element(TREE *,TREE_ELEMENT *);

static int tree_walk_left_root_right(TREE *,TREE_ELEMENT *,

				     tree_walk_action,void *);

static int tree_walk_right_root_left(TREE *,TREE_ELEMENT *,

				     tree_walk_action,void *);

static void left_rotate(TREE_ELEMENT **parent,TREE_ELEMENT *leaf);

static void right_rotate(TREE_ELEMENT **parent, TREE_ELEMENT *leaf);

static void rb_insert(TREE *tree,TREE_ELEMENT ***parent,

		      TREE_ELEMENT *leaf);

void init_tree(TREE *tree, size_t default_alloc_size, uint32_t memory_limit,

               uint32_t size, qsort_cmp2 compare, bool with_delete,

	       tree_element_free free_element, void *custom_arg)

{

  if (default_alloc_size < DEFAULT_ALLOC_SIZE)

    default_alloc_size= DEFAULT_ALLOC_SIZE;

  default_alloc_size= MY_ALIGN(default_alloc_size, DEFAULT_ALIGN_SIZE);

  memset(&tree->null_element, 0, sizeof(tree->null_element));

  tree->root= &tree->null_element;

  tree->compare= compare;

  tree->size_of_element= size > 0 ? (uint32_t) size : 0;

  tree->memory_limit= memory_limit;

  tree->free= free_element;

  tree->allocated= 0;

  tree->elements_in_tree= 0;

  tree->custom_arg = custom_arg;

  tree->null_element.colour= BLACK;

  tree->null_element.left=tree->null_element.right= 0;

  tree->flag= 0;

  if (!free_element &&

      (size <= sizeof(void*) || ((uint32_t) size & (sizeof(void*)-1))))

  {

    /*

      We know that the data doesn't have to be aligned (like if the key

      contains a double), so we can store the data combined with the

      TREE_ELEMENT.

    */

    tree->offset_to_key= sizeof(TREE_ELEMENT); /* Put key after element */

    /* Fix allocation size so that we don't lose any memory */

    default_alloc_size/= (sizeof(TREE_ELEMENT)+size);

    if (!default_alloc_size)

      default_alloc_size= 1;

    default_alloc_size*= (sizeof(TREE_ELEMENT)+size);

  }

  else

  {

    tree->offset_to_key= 0;		/* use key through pointer */

    tree->size_of_element+= sizeof(void*);

  }

  if (! (tree->with_delete= with_delete))

  {

    tree->mem_root.init(default_alloc_size);

    tree->mem_root.min_malloc= (sizeof(TREE_ELEMENT)+tree->size_of_element);

  }

}

static void free_tree(TREE *tree, myf free_flags)

{

  if (tree->root)				/* If initialized */

  {

    if (tree->with_delete)

      delete_tree_element(tree,tree->root);

    else

    {

      if (tree->free)

      {

        if (tree->memory_limit)

          (*tree->free)(NULL, free_init, tree->custom_arg);

	delete_tree_element(tree,tree->root);

        if (tree->memory_limit)

          (*tree->free)(NULL, free_end, tree->custom_arg);

      }

      tree->mem_root.free_root(free_flags);

    }

  }

  tree->root= &tree->null_element;

  tree->elements_in_tree= 0;

  tree->allocated= 0;

}

void delete_tree(TREE* tree)

{

  free_tree(tree, MYF(0)); /* free() mem_root if applicable */

}

void reset_tree(TREE* tree)

{

  /* do not free mem_root, just mark blocks as free */

  free_tree(tree, MYF(memory::MARK_BLOCKS_FREE));

}

static void delete_tree_element(TREE *tree, TREE_ELEMENT *element)

{

  if (element != &tree->null_element)

  {

    delete_tree_element(tree,element->left);

    if (tree->free)

      (*tree->free)(ELEMENT_KEY(tree,element), free_free, tree->custom_arg);

    delete_tree_element(tree,element->right);

    if (tree->with_delete)

      free((char*) element);

  }

}

/*

  insert, search and delete of elements

  The following should be true:

    parent[0] = & parent[-1][0]->left ||

    parent[0] = & parent[-1][0]->right

*/

TREE_ELEMENT *tree_insert(TREE *tree, void *key, uint32_t key_size,

                          void* custom_arg)

{

  int cmp;

  TREE_ELEMENT *element,***parent;

  parent= tree->parents;

  *parent = &tree->root; element= tree->root;

  for (;;)

  {

    if (element == &tree->null_element ||

	(cmp = (*tree->compare)(custom_arg, ELEMENT_KEY(tree,element),

                                key)) == 0)

      break;

    if (cmp < 0)

    {

      *++parent= &element->right; element= element->right;

    }

    else

    {

      *++parent = &element->left; element= element->left;

    }

  }

  if (element == &tree->null_element)

  {

    size_t alloc_size= sizeof(TREE_ELEMENT)+key_size+tree->size_of_element;

    tree->allocated+= alloc_size;

    if (tree->memory_limit && tree->elements_in_tree

                           && tree->allocated > tree->memory_limit)

    {

      reset_tree(tree);

      return tree_insert(tree, key, key_size, custom_arg);

    }

    key_size+= tree->size_of_element;

    if (tree->with_delete)

      element= (TREE_ELEMENT *) malloc(alloc_size);

    else

      element= (TREE_ELEMENT *) tree->mem_root.alloc(alloc_size);

    **parent= element;

    element->left= element->right= &tree->null_element;

    if (!tree->offset_to_key)

    {

      if (key_size == sizeof(void*))		 /* no length, save pointer */

	*((void**) (element+1))= key;

      else

      {

	*((void**) (element+1))= (void*) ((void **) (element+1)+1);

	memcpy(*((void **) (element+1)),key, key_size - sizeof(void*));

      }

    }

    else

      memcpy((unsigned char*) element + tree->offset_to_key, key, key_size);

    element->count= 1;			/* May give warning in purify */

    tree->elements_in_tree++;

    rb_insert(tree,parent,element);	/* rebalance tree */

  }

  else

  {

    if (tree->flag & TREE_NO_DUPS)

      return(NULL);

    element->count++;

    /* Avoid a wrap over of the count. */

    if (! element->count)

      element->count--;

  }

  return element;

}

void *tree_search_key(TREE *tree, const void *key,

                      TREE_ELEMENT **parents, TREE_ELEMENT ***last_pos,

                      enum ha_rkey_function flag, void *custom_arg)

{

  TREE_ELEMENT *element= tree->root;

  TREE_ELEMENT **last_left_step_parent= NULL, **last_right_step_parent= NULL;

  TREE_ELEMENT **last_equal_element= NULL;

/*

  TODO: support for HA_READ_KEY_OR_PREV, HA_READ_PREFIX flags if needed.

*/

  *parents = &tree->null_element;

  while (element != &tree->null_element)

  {

    int cmp;

    *++parents= element;

    if ((cmp= (*tree->compare)(custom_arg, ELEMENT_KEY(tree, element),

			       key)) == 0)

    {

      switch (flag) {

      case HA_READ_KEY_EXACT:

      case HA_READ_KEY_OR_NEXT:

      case HA_READ_BEFORE_KEY:

	last_equal_element= parents;

	cmp= 1;

	break;

      case HA_READ_AFTER_KEY:

	cmp= -1;

	break;

      case HA_READ_PREFIX_LAST:

      case HA_READ_PREFIX_LAST_OR_PREV:

	last_equal_element= parents;

	cmp= -1;

	break;

      default:

	return NULL;

      }

    }

    if (cmp < 0) /* element < key */

    {

      last_right_step_parent= parents;

      element= element->right;

    }

    else

    {

      last_left_step_parent= parents;

      element= element->left;

    }

  }

  switch (flag) {

  case HA_READ_KEY_EXACT:

  case HA_READ_PREFIX_LAST:

    *last_pos= last_equal_element;

    break;

  case HA_READ_KEY_OR_NEXT:

    *last_pos= last_equal_element ? last_equal_element : last_left_step_parent;

    break;

  case HA_READ_AFTER_KEY:

    *last_pos= last_left_step_parent;

    break;

  case HA_READ_PREFIX_LAST_OR_PREV:

    *last_pos= last_equal_element ? last_equal_element : last_right_step_parent;

    break;

  case HA_READ_BEFORE_KEY:

    *last_pos= last_right_step_parent;

    break;

  default:

    return NULL;

  }

  return *last_pos ? ELEMENT_KEY(tree, **last_pos) : NULL;

}

void *tree_search_next(TREE *tree, TREE_ELEMENT ***last_pos, int l_offs,

                       int r_offs)

{

  TREE_ELEMENT *x= **last_pos;

  if (ELEMENT_CHILD(x, r_offs) != &tree->null_element)

  {

    x= ELEMENT_CHILD(x, r_offs);

    *++*last_pos= x;

    while (ELEMENT_CHILD(x, l_offs) != &tree->null_element)

    {

      x= ELEMENT_CHILD(x, l_offs);

      *++*last_pos= x;

    }

    return ELEMENT_KEY(tree, x);

  }

  else

  {

    TREE_ELEMENT *y= *--*last_pos;

    while (y != &tree->null_element && x == ELEMENT_CHILD(y, r_offs))

    {

      x= y;

      y= *--*last_pos;

    }

    return y == &tree->null_element ? NULL : ELEMENT_KEY(tree, y);

  }

}

/*

  Expected that tree is fully balanced

  (each path from root to leaf has the same length)

*/

ha_rows tree_record_pos(TREE *tree, const void *key,

			enum ha_rkey_function flag, void *custom_arg)

{

  TREE_ELEMENT *element= tree->root;

  double left= 1;

  double right= tree->elements_in_tree;

  while (element != &tree->null_element)

  {

    int cmp;

    if ((cmp= (*tree->compare)(custom_arg, ELEMENT_KEY(tree, element),

			       key)) == 0)

    {

      switch (flag) {

      case HA_READ_KEY_EXACT:

      case HA_READ_BEFORE_KEY:

        cmp= 1;

        break;

      case HA_READ_AFTER_KEY:

        cmp= -1;

        break;

      default:

        return HA_POS_ERROR;

      }

    }

    if (cmp < 0) /* element < key */

    {

      element= element->right;

      left= (left + right) / 2;

    }

    else

    {

      element= element->left;

      right= (left + right) / 2;

    }

  }

  switch (flag) {

  case HA_READ_KEY_EXACT:

  case HA_READ_BEFORE_KEY:

    return (ha_rows) right;

  case HA_READ_AFTER_KEY:

    return (ha_rows) left;

  default:

    return HA_POS_ERROR;

  }

}

int tree_walk(TREE *tree, tree_walk_action action, void *argument, TREE_WALK visit)

{

  switch (visit) {

  case left_root_right:

    return tree_walk_left_root_right(tree,tree->root,action,argument);

  case right_root_left:

    return tree_walk_right_root_left(tree,tree->root,action,argument);

  }

  return 0;			/* Keep gcc happy */

}

static int tree_walk_left_root_right(TREE *tree, TREE_ELEMENT *element, tree_walk_action action, void *argument)

{

  int error;

  if (element->left)				/* Not null_element */

  {

    if ((error=tree_walk_left_root_right(tree,element->left,action,

					  argument)) == 0 &&

	(error=(*action)(ELEMENT_KEY(tree,element),

			  element->count,

			  argument)) == 0)

      error=tree_walk_left_root_right(tree,element->right,action,argument);

    return error;

  }

  return 0;

}

static int tree_walk_right_root_left(TREE *tree, TREE_ELEMENT *element, tree_walk_action action, void *argument)

{

  int error;

  if (element->right)				/* Not null_element */

  {

    if ((error=tree_walk_right_root_left(tree,element->right,action,

					  argument)) == 0 &&

	(error=(*action)(ELEMENT_KEY(tree,element),

			  element->count,

			  argument)) == 0)

     error=tree_walk_right_root_left(tree,element->left,action,argument);

    return error;

  }

  return 0;

}

/* Functions to fix up the tree after insert and delete */

static void left_rotate(TREE_ELEMENT **parent, TREE_ELEMENT *leaf)

{

  TREE_ELEMENT *y;

  y= leaf->right;

  leaf->right= y->left;

  parent[0]= y;

  y->left= leaf;

}

static void right_rotate(TREE_ELEMENT **parent, TREE_ELEMENT *leaf)

{

  TREE_ELEMENT *x;

  x= leaf->left;

  leaf->left= x->right;

  parent[0]= x;

  x->right= leaf;

}

static void rb_insert(TREE *tree, TREE_ELEMENT ***parent, TREE_ELEMENT *leaf)

{

  TREE_ELEMENT *y,*par,*par2;

  leaf->colour=RED;

  while (leaf != tree->root && (par=parent[-1][0])->colour == RED)

  {

    if (par == (par2=parent[-2][0])->left)

    {

      y= par2->right;

      if (y->colour == RED)

      {

	par->colour= BLACK;

	y->colour= BLACK;

	leaf= par2;

	parent-= 2;

	leaf->colour= RED;		/* And the loop continues */

      }

      else

      {

	if (leaf == par->right)

	{

	  left_rotate(parent[-1],par);

	  par= leaf;			/* leaf is now parent to old leaf */

	}

	par->colour= BLACK;

	par2->colour= RED;

	right_rotate(parent[-2],par2);

	break;

      }

    }

    else

    {

      y= par2->left;

      if (y->colour == RED)

      {

	par->colour= BLACK;

	y->colour= BLACK;

	leaf= par2;

	parent-= 2;

	leaf->colour= RED;		/* And the loop continues */

      }

      else

      {

	if (leaf == par->left)

	{

	  right_rotate(parent[-1],par);

	  par= leaf;

	}

	par->colour= BLACK;

	par2->colour= RED;

	left_rotate(parent[-2],par2);

	break;

      }

    }

  }

  tree->root->colour=BLACK;

}

} /* namespace drizzled */