/*********************************************************************
* *
* Copyright (c) 1997,1998, 1999 *
* Multimedia DB Group and DEIS - CSITE-CNR, *
* University of Bologna, Bologna, ITALY. *
* *
* All Rights Reserved. *
* *
* Permission to use, copy, and distribute this software and its *
* documentation for NON-COMMERCIAL purposes and without fee is *
* hereby granted provided that this copyright notice appears in *
* all copies. *
* *
* THE AUTHORS MAKE NO REPRESENTATIONS OR WARRANTIES ABOUT THE *
* SUITABILITY OF THE SOFTWARE, EITHER EXPRESS OR IMPLIED, INCLUDING *
* BUT NOT LIMITED TO THE IMPLIED WARRANTIES OF MERCHANTABILITY, *
* FITNESS FOR A PARTICULAR PURPOSE, OR NON-INFRINGEMENT. THE AUTHOR *
* SHALL NOT BE LIABLE FOR ANY DAMAGES SUFFERED BY LICENSEE AS A *
* RESULT OF USING, MODIFYING OR DISTRIBUTING THIS SOFTWARE OR ITS *
* DERIVATIVES. *
* *
*********************************************************************/
#include <stdlib.h>
#include "list.h"
#include "MT.h"
#include "MTpredicate.h"
#include "MTcursor.h"
#ifdef _WIN32 // these functions are defined under UNIX
void srandom(int seed) { srand(seed); }
int random() { return rand(); }
#endif
TruePredicate truePredicate;
int
PickRandom(int from, int to)
{
return (random()%(to-from))+from;
}
MTnode *
MT::ParentNode(MTnode *node)
{
GiSTpath path=node->Path();
MTnode *parentnode;
path.MakeParent();
parentnode=(MTnode *)ReadNode(path);
return parentnode; // parentnode should be destroyed by the caller
}
void
MT::CollectStats()
{
/*#if defined(_DEBUG)
CMemoryState msOld, msNew, msDif;
msOld.Checkpoint();
#endif */
GiSTpath path;
GiSTnode *node;
path.MakeRoot();
node=ReadNode(path);
if(!node->IsLeaf()) {
TruePredicate truePredicate;
GiSTlist<GiSTentry*> list=node->Search(truePredicate); // retrieve all the children
double *areas, *radii, totarea=0;
int *n, maxn=node->Level(), totn=1, i;
areas=new double[maxn];
radii=new double[maxn];
n=new int[maxn];
for(i=0; i<maxn; i++) {
n[i]=0;
areas[i]=0;
radii[i]=0;
}
delete node;
while(!list.IsEmpty()) {
GiSTentry *e=list.RemoveFront();
GiSTlist<GiSTentry*> newlist;
path.MakeChild(e->Ptr());
node=ReadNode(path);
n[node->Level()]++;
areas[node->Level()]+=((MTkey *)e->Key())->area();
radii[node->Level()]+=((MTkey *)e->Key())->maxradius();
if(!node->IsLeaf()) newlist=node->Search(truePredicate); // recurse to next level
while(!newlist.IsEmpty()) list.Append(newlist.RemoveFront());
path.MakeParent();
delete e;
delete node;
}
// output the results
cout << "Level:\tPages:\tRadius:\tArea:\n";
for(i=maxn-1; i>=0; i--) {
totn+=n[i];
totarea+=areas[i];
cout << i << ":\t" << n[i] << "\t" << radii[i]/n[i] << "\t" << areas[i]/n[i] << endl;
}
cout << "tot:\t" << totn << "\t" << totarea << endl;
delete []areas;
delete []radii;
delete []n;
}
else delete node;
/* #if defined(_DEBUG)
msNew.Checkpoint();
msDif.Difference(msOld, msNew);
msDif.DumpStatistics();
#endif */
}
BOOL
MT::CheckNode(GiSTpath path, MTentry *e)
{
MTnode *node=(MTnode *)ReadNode(path);
BOOL ret=TRUE;
for(int i=0; (i<node->NumEntries())&&ret; i++) {
MTentry *child=(MTentry *)(*node)[i].Ptr();
if((e!=NULL)&&(((child->Key()->distance+child->maxradius())>e->maxradius())||(child->object().distance(e->object())!=child->Key()->distance))) {
cout << "Error with entry " << child << "in " << node;
ret=FALSE;
}
path.MakeChild(child->Ptr());
if(!node->IsLeaf()) ret&=CheckNode(path, child);
path.MakeParent();
}
delete node;
return ret;
}
GiSTlist<MTentry *>
MT::RangeSearch(const MTquery& query)
{
GiSTpath path;
path.MakeRoot();
MTnode *root=(MTnode *)ReadNode(path);
GiSTlist<MTentry *> list=root->RangeSearch(query);
delete root;
return list;
}
MTentry **
MT::TopSearch(const TopQuery& query)
{
GiSTpath path; // path for retrieving root node
MTnode *node; // next node to be examined
MTentry **results=new MTentry*[query.k]; // the results list (ordered for increasing distances)
list<dst *> queue(comparedst); // list for ordering the nodes
SimpleQuery q(query.Pred(), maxDist(), TRUE);
double *dists=new double[query.k]; // array containing the NN distances
int i;
for (i=0; i<query.k; i++) dists[i]=maxDist(); // initialization of the NN-distances array
path.MakeRoot();
node=(MTnode *)ReadNode(path); // retrieve the root node
while(node!=NULL) { // examine current node
double oldDist=q.Grade();
// search the first children to be examined
// cout << "Examining node " << node->Path() << endl;
for(unsigned int i=0; i<node->NumEntries(); i++) { // for each entry in the current node
MTentry *e=(MTentry *)((*node)[i].Ptr());
q.SetGrade(oldDist);
// cout << "range=" << q.Radius() << ", oldDist=" << q.Grade() << ": Checking " << e;
if(q.Consistent(*e)) { // check if the entry is consistent with the query
// cout << "grade=" << q.Grade() << endl;
if(e->IsLeaf()) { // object qualifies
if(dists[query.k-1]<maxDist()) delete results[query.k-1]; // delete last element of the results list
MTentry *key=(MTentry *)e->Copy();
int j=0;
key->setminradius(0);
key->setmaxradius(q.Grade()); // we insert the actual distance from the query object as the key radius
// insert dist in the results list (sorting for incr. distance)
// could be improved using binary search
while(dists[j]<q.Grade()) j++;
// cout << "\tInserted (" << q.Grade() << "<" << dists[query.k-1] << ") into list in position " << j << endl;
for(int l=query.k-1; l>j; l--) { // shift up results array
results[l]=results[l-1];
dists[l]=dists[l-1];
}
results[j]=key;
dists[j]=q.Grade();
q.SetRadius(dists[query.k-1]);
}
else { // we have to insert the child node in the priority queue
GiSTpath path=node->Path();
double dmin=q.Grade()-e->maxradius(), dmax=q.Grade()+e->maxradius(); // these are lower- and upper-bounds on the distances of the descendants of the entry from the query object
if(dmin<0) dmin=0;
// insert the node in the stack (sorting for decr. level and incr. LB on distance)
// could be improved using binary search
path.MakeChild(e->Ptr());
dst *d=new dst(path, dmin, q.Grade());
queue.Insert(d);
// cout << "\tInserted (" << dmin << "<" << dists[query.k-1] << ") into list\n";
}
}
else {
// cout << "\tPruned (" << q.Grade() << ">" << dists[query.k-1] << ") from the list\n";
// if we're in a "true" leaf node (i.e. not in the root) and last entry was pruned, we can safely prune all other entries too
// if(e->IsLeaf()&&(!e->Node()->Path().IsRoot())&&(fabs(e->Key()->distance-oldDist)>q.Grade()))) break;
}
}
// the next entry to be chosen is that whose distance from the parent is most similar to the distance between the parent and the query object
delete node; // delete examined node
if(!queue.IsEmpty()) { // retrieve next node to be examined
dst *d=queue.RemoveFirst();
if(d->Bound()>=dists[query.k-1]) { // terminate the search
while(!queue.IsEmpty())
delete queue.RemoveFirst();
node=NULL;
}
else {
node=(MTnode *)ReadNode(d->Path());
q.SetGrade(d->Dist());
}
delete d;
}
else node=NULL; // terminate the search
}
delete []dists;
return results;
}