index.c

空间数据库系统中著名的索引R-tree 源码

#include <stdio.h>
#include <malloc.h>
#include "assert.h"
#include "index.h"
#include "card.h"


// Make a new index, empty.  Consists of a single node.
//
struct Node * RTreeNewIndex()
{
	struct Node *x;
	x = RTreeNewNode();
	x->level = 0; /* leaf */
	return x;
}



// Search in an index tree or subtree for all data retangles that
// overlap the argument rectangle.
// Return the number of qualifying data rects.
//
int RTreeSearch(struct Node *N, struct Rect *R, SearchHitCallback shcb, void* cbarg)
{
	register struct Node *n = N;
	register struct Rect *r = R; // NOTE: Suspected bug was R sent in as Node* and cast to Rect* here. Fix not yet tested.
	register int hitCount = 0;
	register int i;

	assert(n);
	assert(n->level >= 0);
	assert(r);

	if (n->level > 0) /* this is an internal node in the tree */
	{
		for (i=0; i<NODECARD; i++)
			if (n->branch[i].child &&
			    RTreeOverlap(r,&n->branch[i].rect))
			{
				hitCount += RTreeSearch(n->branch[i].child, R, shcb, cbarg);
			}
	}
	else /* this is a leaf node */
	{
		for (i=0; i<LEAFCARD; i++)
			if (n->branch[i].child &&
			    RTreeOverlap(r,&n->branch[i].rect))
			{
				hitCount++;
				if(shcb) // call the user-provided callback
					if( ! shcb((int)n->branch[i].child, cbarg))
						return hitCount; // callback wants to terminate search early
			}
	}
	return hitCount;
}



// Inserts a new data rectangle into the index structure.
// Recursively descends tree, propagates splits back up.
// Returns 0 if node was not split.  Old node updated.
// If node was split, returns 1 and sets the pointer pointed to by
// new_node to point to the new node.  Old node updated to become one of two.
// The level argument specifies the number of steps up from the leaf
// level to insert; e.g. a data rectangle goes in at level = 0.
//
static int RTreeInsertRect2(struct Rect *r,
		int tid, struct Node *n, struct Node **new_node, int level)
{
/*
	register struct Rect *r = R;
	register int tid = Tid;
	register struct Node *n = N, **new_node = New_node;
	register int level = Level;
*/

	register int i;
	struct Branch b;
	struct Node *n2;

	assert(r && n && new_node);
	assert(level >= 0 && level <= n->level);

	// Still above level for insertion, go down tree recursively
	//
	if (n->level > level)
	{
		i = RTreePickBranch(r, n);
		if (!RTreeInsertRect2(r, tid, n->branch[i].child, &n2, level))
		{
			// child was not split
			//
			n->branch[i].rect =
				RTreeCombineRect(r,&(n->branch[i].rect));
			return 0;
		}
		else    // child was split
		{
			n->branch[i].rect = RTreeNodeCover(n->branch[i].child);
			b.child = n2;
			b.rect = RTreeNodeCover(n2);
			return RTreeAddBranch(&b, n, new_node);
		}
	}

	// Have reached level for insertion. Add rect, split if necessary
	//
	else if (n->level == level)
	{
		b.rect = *r;
		b.child = (struct Node *) tid;
		/* child field of leaves contains tid of data record */
		return RTreeAddBranch(&b, n, new_node);
	}
	else
	{
		/* Not supposed to happen */
		assert (FALSE);
		return 0;
	}
}



// Insert a data rectangle into an index structure.
// RTreeInsertRect provides for splitting the root;
// returns 1 if root was split, 0 if it was not.
// The level argument specifies the number of steps up from the leaf
// level to insert; e.g. a data rectangle goes in at level = 0.
// RTreeInsertRect2 does the recursion.
//
int RTreeInsertRect(struct Rect *R, int Tid, struct Node **Root, int Level)
{
	register struct Rect *r = R;
	register int tid = Tid;
	register struct Node **root = Root;
	register int level = Level;
	register int i;
	register struct Node *newroot;
	struct Node *newnode;
	struct Branch b;
	int result;

	assert(r && root);
	assert(level >= 0 && level <= (*root)->level);
	for (i=0; i<NUMDIMS; i++)
		assert(r->boundary[i] <= r->boundary[NUMDIMS+i]);

	if (RTreeInsertRect2(r, tid, *root, &newnode, level))  /* root split */
	{
		newroot = RTreeNewNode();  /* grow a new root, & tree taller */
		newroot->level = (*root)->level + 1;
		b.rect = RTreeNodeCover(*root);
		b.child = *root;
		RTreeAddBranch(&b, newroot, NULL);
		b.rect = RTreeNodeCover(newnode);
		b.child = newnode;
		RTreeAddBranch(&b, newroot, NULL);
		*root = newroot;
		result = 1;
	}
	else
		result = 0;

	return result;
}




// Allocate space for a node in the list used in DeletRect to
// store Nodes that are too empty.
//
static struct ListNode * RTreeNewListNode()
{
	return (struct ListNode *) malloc(sizeof(struct ListNode));
	//return new ListNode;
}


static void RTreeFreeListNode(struct ListNode *p)
{
	free(p);
	//delete(p);
}



// Add a node to the reinsertion list.  All its branches will later
// be reinserted into the index structure.
//
static void RTreeReInsert(struct Node *n, struct ListNode **ee)
{
	register struct ListNode *l;

	l = RTreeNewListNode();
	l->node = n;
	l->next = *ee;
	*ee = l;
}


// Delete a rectangle from non-root part of an index structure.
// Called by RTreeDeleteRect.  Descends tree recursively,
// merges branches on the way back up.
// Returns 1 if record not found, 0 if success.
//
static int
RTreeDeleteRect2(struct Rect *R, int Tid, struct Node *N, struct ListNode **Ee)
{
	register struct Rect *r = R;
	register int tid = Tid;
	register struct Node *n = N;
	register struct ListNode **ee = Ee;
	register int i;

	assert(r && n && ee);
	assert(tid >= 0);
	assert(n->level >= 0);

	if (n->level > 0)  // not a leaf node
	{
	    for (i = 0; i < NODECARD; i++)
	    {
		if (n->branch[i].child && RTreeOverlap(r, &(n->branch[i].rect)))
		{
			if (!RTreeDeleteRect2(r, tid, n->branch[i].child, ee))
			{
				if (n->branch[i].child->count >= MinNodeFill)
					n->branch[i].rect = RTreeNodeCover(
						n->branch[i].child);
				else
				{
					// not enough entries in child,
					// eliminate child node
					//
					RTreeReInsert(n->branch[i].child, ee);
					RTreeDisconnectBranch(n, i);
				}
				return 0;
			}
		}
	    }
	    return 1;
	}
	else  // a leaf node
	{
		for (i = 0; i < LEAFCARD; i++)
		{
			if (n->branch[i].child &&
			    n->branch[i].child == (struct Node *) tid)
			{
				RTreeDisconnectBranch(n, i);
				return 0;
			}
		}
		return 1;
	}
}



// Delete a data rectangle from an index structure.
// Pass in a pointer to a Rect, the tid of the record, ptr to ptr to root node.
// Returns 1 if record not found, 0 if success.
// RTreeDeleteRect provides for eliminating the root.
//
int RTreeDeleteRect(struct Rect *R, int Tid, struct Node**Nn)
{
	register struct Rect *r = R;
	register int tid = Tid;
	register struct Node **nn = Nn;
	register int i;
	register struct Node *tmp_nptr;
	struct ListNode *reInsertList = NULL;
	register struct ListNode *e;

	assert(r && nn);
	assert(*nn);
	assert(tid >= 0);

	if (!RTreeDeleteRect2(r, tid, *nn, &reInsertList))
	{
		/* found and deleted a data item */

		/* reinsert any branches from eliminated nodes */
		while (reInsertList)
		{
			tmp_nptr = reInsertList->node;
			for (i = 0; i < MAXKIDS(tmp_nptr); i++)
			{
				if (tmp_nptr->branch[i].child)
				{
					RTreeInsertRect(
						&(tmp_nptr->branch[i].rect),
						(int)tmp_nptr->branch[i].child,
						nn,
						tmp_nptr->level);
				}
			}
			e = reInsertList;
			reInsertList = reInsertList->next;
			RTreeFreeNode(e->node);
			RTreeFreeListNode(e);
		}
		
		/* check for redundant root (not leaf, 1 child) and eliminate
		*/
		if ((*nn)->count == 1 && (*nn)->level > 0)
		{
			for (i = 0; i < NODECARD; i++)
			{
				tmp_nptr = (*nn)->branch[i].child;
				if(tmp_nptr)
					break;
			}
			assert(tmp_nptr);
			RTreeFreeNode(*nn);
			*nn = tmp_nptr;
		}
		return 0;
	}
	else
	{
		return 1;
	}
}