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