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// fts_search.cpp
/**
* Copyright (C) 2012 10gen Inc.
*
* This program is free software: you can redistribute it and/or modify
* it under the terms of the GNU Affero General Public License, version 3,
* as published by the Free Software Foundation.
*
* 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 Affero General Public License for more details.
*
* You should have received a copy of the GNU Affero General Public License
* along with this program. If not, see <http://www.gnu.org/licenses/>.
*/
#include "mongo/pch.h"
#include "mongo/db/btreecursor.h"
#include "mongo/db/fts/fts_index_format.h"
#include "mongo/db/fts/fts_search.h"
#include "mongo/db/kill_current_op.h"
#include "mongo/db/pdfile.h"
namespace mongo {
namespace fts {
/*
* Constructor generates query and term dictionaries
* @param ns, namespace
* @param idxNum, index number
* @param search, query string
* @param language, language of the query
* @param filter, filter object
*/
FTSSearch::FTSSearch( IndexDescriptor* descriptor,
const FTSSpec& ftsSpec,
const BSONObj& indexPrefix,
const FTSQuery& query,
const BSONObj& filter )
: _descriptor(descriptor),
_ftsSpec(ftsSpec),
_indexPrefix( indexPrefix ),
_query( query ),
_ftsMatcher(query, ftsSpec) {
if ( !filter.isEmpty() )
_matcher.reset( new CoveredIndexMatcher( filter, _descriptor->keyPattern() ) );
_keysLookedAt = 0;
_objectsLookedAt = 0;
}
bool FTSSearch::_ok( Record* record ) const {
if ( !_query.hasNonTermPieces() )
return true;
return _ftsMatcher.matchesNonTerm( BSONObj::make( record ) );
}
/*
* GO: sets the tree cursors on each term in terms, processes the terms by advancing
* the terms cursors and storing the partial
* results and lastly calculates the top results
* @param results, the priority queue containing the top results
* @param limit, number of results in the priority queue
*/
void FTSSearch::go(Results* results, unsigned limit ) {
vector< shared_ptr<BtreeCursor> > cursors;
for ( unsigned i = 0; i < _query.getTerms().size(); i++ ) {
const string& term = _query.getTerms()[i];
BSONObj min = FTSIndexFormat::getIndexKey( MAX_WEIGHT, term, _indexPrefix );
BSONObj max = FTSIndexFormat::getIndexKey( 0, term, _indexPrefix );
shared_ptr<BtreeCursor> c( BtreeCursor::make(
nsdetails(_descriptor->parentNS().c_str()),
_descriptor->getOnDisk(),
min, max, true, -1 ) );
cursors.push_back( c );
}
while ( !inShutdown() ) {
bool gotAny = false;
for ( unsigned i = 0; i < cursors.size(); i++ ) {
if ( cursors[i]->eof() )
continue;
gotAny = true;
_process( cursors[i].get() );
cursors[i]->advance();
}
if ( !gotAny )
break;
RARELY killCurrentOp.checkForInterrupt();
}
// priority queue using a compare that grabs the lowest of two ScoredLocations by score.
for ( Scores::iterator i = _scores.begin(); i != _scores.end(); ++i ) {
if ( i->second < 0 )
continue;
// priority queue
if ( results->size() < limit ) { // case a: queue unfilled
if ( !_ok( i->first ) )
continue;
results->push( ScoredLocation( i->first, i->second ) );
}
else if ( i->second > results->top().score ) { // case b: queue filled
if ( !_ok( i->first ) )
continue;
results->pop();
results->push( ScoredLocation( i->first, i->second ) );
}
else {
// else do nothing (case c)
}
}
}
/*
* Takes a cursor and updates the partial score for said cursor in _scores map
* @param cursor, btree cursor pointing to the current document to be scored
*/
void FTSSearch::_process( BtreeCursor* cursor ) {
_keysLookedAt++;
BSONObj key = cursor->currKey();
BSONObjIterator i( key );
for ( unsigned j = 0; j < _ftsSpec.numExtraBefore(); j++)
i.next();
i.next(); // move past indexToken
BSONElement scoreElement = i.next();
double score = scoreElement.number();
double& cur = _scores[(cursor->currLoc()).rec()];
if ( cur < 0 ) {
// already been rejected
return;
}
if ( cur == 0 && _matcher.get() ) {
// we haven't seen this before and we have a matcher
MatchDetails d;
if ( !_matcher->matchesCurrent( cursor, &d ) ) {
cur = -1;
}
if ( d.hasLoadedRecord() )
_objectsLookedAt++;
if ( cur == -1 )
return;
}
if ( cur )
cur += score * (1 + 1 / score);
else
cur += score;
}
}
}
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