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/**
* Copyright (C) 2013-2014 MongoDB 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/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#pragma once
#include "mongo/db/exec/plan_stage.h"
#include "mongo/db/fts/fts_index_format.h"
#include "mongo/db/fts/fts_matcher.h"
#include "mongo/db/fts/fts_query.h"
#include "mongo/db/fts/fts_spec.h"
#include "mongo/db/fts/fts_util.h"
#include "mongo/db/index/index_descriptor.h"
#include "mongo/db/jsobj.h"
#include "mongo/db/matcher/expression.h"
#include "mongo/db/record_id.h"
#include "mongo/platform/unordered_map.h"
#include <map>
#include <queue>
#include <vector>
namespace mongo {
using fts::FTSIndexFormat;
using fts::FTSMatcher;
using fts::FTSQuery;
using fts::FTSSpec;
using fts::MAX_WEIGHT;
class OperationContext;
struct TextStageParams {
TextStageParams(const FTSSpec& s) : spec(s) {}
// Text index descriptor. IndexCatalog owns this.
IndexDescriptor* index;
// Index spec.
FTSSpec spec;
// Index keys that precede the "text" index key.
BSONObj indexPrefix;
// The text query.
FTSQuery query;
};
/**
* Implements a blocking stage that returns text search results.
*
* Prerequisites: None; is a leaf node.
* Output type: LOC_AND_OBJ_UNOWNED.
*
* TODO: Should the TextStage ever generate NEED_YIELD requests for fetching MMAP v1 records?
* Right now this stage could reduce concurrency by failing to request a yield during fetch.
*/
class TextStage : public PlanStage {
public:
/**
* The text stage has a few 'states' it transitions between.
*/
enum State {
// 1. Initialize the index scans we use to retrieve term/score info.
INIT_SCANS,
// 2. Read the terms/scores from the text index.
READING_TERMS,
// 3. Return results to our parent.
RETURNING_RESULTS,
// 4. Done.
DONE,
};
TextStage(OperationContext* txn,
const TextStageParams& params,
WorkingSet* ws,
const MatchExpression* filter);
virtual ~TextStage();
virtual StageState work(WorkingSetID* out);
virtual bool isEOF();
virtual void saveState();
virtual void restoreState(OperationContext* opCtx);
virtual void invalidate(OperationContext* txn, const RecordId& dl, InvalidationType type);
virtual std::vector<PlanStage*> getChildren() const;
virtual StageType stageType() const { return STAGE_TEXT; }
PlanStageStats* getStats();
virtual const CommonStats* getCommonStats() const;
virtual const SpecificStats* getSpecificStats() const;
static const char* kStageType;
private:
/**
* Initializes sub-scanners.
*/
StageState initScans(WorkingSetID* out);
/**
* Helper for buffering results array. Returns NEED_TIME (if any results were produced),
* IS_EOF, or FAILURE.
*/
StageState readFromSubScanners(WorkingSetID* out);
/**
* Helper called from readFromSubScanners to update aggregate score with a new-found (term,
* score) pair for this document. Also rejects documents that don't match this stage's
* filter.
*/
StageState addTerm(WorkingSetID wsid, WorkingSetID* out);
/**
* Possibly return a result. FYI, this may perform a fetch directly if it is needed to
* evaluate all filters.
*/
StageState returnResults(WorkingSetID* out);
// transactional context for read locks. Not owned by us
OperationContext* _txn;
// Parameters of this text stage.
TextStageParams _params;
// Text-specific phrase and negated term matcher.
FTSMatcher _ftsMatcher;
// Working set. Not owned by us.
WorkingSet* _ws;
// Filter. Not owned by us.
const MatchExpression* _filter;
// Stats.
CommonStats _commonStats;
TextStats _specificStats;
// What state are we in? See the State enum above.
State _internalState;
// Used in INIT_SCANS and READING_TERMS. The index scans we're using to retrieve text
// terms.
OwnedPointerVector<PlanStage> _scanners;
// Which _scanners are we currently reading from?
size_t _currentIndexScanner;
// If not Null, we use this rather than asking our child what to do next.
WorkingSetID _idRetrying;
// Map each buffered record id to this data.
struct TextRecordData {
TextRecordData() : wsid(WorkingSet::INVALID_ID), score(0.0) { }
WorkingSetID wsid;
double score;
};
// Temporary score data filled out by sub-scans. Used in READING_TERMS and
// RETURNING_RESULTS.
// Maps from diskloc -> (aggregate score for doc, wsid).
typedef unordered_map<RecordId, TextRecordData, RecordId::Hasher> ScoreMap;
ScoreMap _scores;
ScoreMap::const_iterator _scoreIterator;
// Used for fetching records from the collection.
std::unique_ptr<RecordCursor> _recordCursor;
};
} // namespace mongo
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