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-rw-r--r--db/queryoptimizercursor.cpp395
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diff --git a/db/queryoptimizercursor.cpp b/db/queryoptimizercursor.cpp
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-// @file queryoptimizercursor.cpp
-
-/**
- * Copyright (C) 2011 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 "pch.h"
-#include "queryoptimizer.h"
-#include "pdfile.h"
-#include "clientcursor.h"
-#include "btree.h"
-
-namespace mongo {
-
- static const int OutOfOrderDocumentsAssertionCode = 14810;
-
- /**
- * A QueryOp implementation utilized by the QueryOptimizerCursor
- */
- class QueryOptimizerCursorOp : public QueryOp {
- public:
- /**
- * @param aggregateNscanned - shared int counting total nscanned for
- * query ops for all cursors.
- */
- QueryOptimizerCursorOp( long long &aggregateNscanned ) :
- _matchCount(), _mustAdvance(), _nscanned(), _capped(),
- _aggregateNscanned( aggregateNscanned ), _yieldRecoveryFailed() {}
-
- virtual void _init() {
- if ( qp().scanAndOrderRequired() ) {
- throw MsgAssertionException( OutOfOrderDocumentsAssertionCode, "order spec cannot be satisfied with index" );
- }
- _c = qp().newCursor();
- _capped = _c->capped();
- mayAdvance();
- }
-
- virtual long long nscanned() {
- return _c ? _c->nscanned() : _nscanned;
- }
-
- virtual bool prepareToYield() {
- if ( _c && !_cc ) {
- _cc.reset( new ClientCursor( QueryOption_NoCursorTimeout , _c , qp().ns() ) );
- }
- if ( _cc ) {
- _posBeforeYield = currLoc();
- return _cc->prepareToYield( _yieldData );
- }
- // no active cursor - ok to yield
- return true;
- }
-
- virtual void recoverFromYield() {
- if ( _cc && !ClientCursor::recoverFromYield( _yieldData ) ) {
- _yieldRecoveryFailed = true;
- _c.reset();
- _cc.reset();
-
- if ( _capped ) {
- msgassertedNoTrace( 13338, str::stream() << "capped cursor overrun: " << qp().ns() );
- }
- else if ( qp().mustAssertOnYieldFailure() ) {
- msgassertedNoTrace( 15892, str::stream() << "QueryOptimizerCursorOp::recoverFromYield() failed to recover" );
- }
- else {
- // we don't fail query since we're fine with returning partial data if collection dropped
- // also, see SERVER-2454
- }
- }
- else {
- if ( _posBeforeYield != currLoc() ) {
- // If the yield advanced our position, the next next() will be a no op.
- _mustAdvance = false;
- }
- }
- }
-
- virtual void next() {
- mayAdvance();
-
- if ( _matchCount >= 101 ) {
- // This is equivalent to the default condition for switching from
- // a query to a getMore.
- setStop();
- return;
- }
- if ( !_c || !_c->ok() ) {
- setComplete();
- return;
- }
-
- if ( matcher( _c )->matchesCurrent( _c.get() ) && !_c->getsetdup( _c->currLoc() ) ) {
- ++_matchCount;
- }
- _mustAdvance = true;
- }
- virtual QueryOp *_createChild() const {
- QueryOptimizerCursorOp *ret = new QueryOptimizerCursorOp( _aggregateNscanned );
- ret->_matchCount = _matchCount;
- return ret;
- }
- DiskLoc currLoc() const { return _c ? _c->currLoc() : DiskLoc(); }
- BSONObj currKey() const { return _c ? _c->currKey() : BSONObj(); }
- virtual bool mayRecordPlan() const {
- return !_yieldRecoveryFailed && complete() && !stopRequested();
- }
- shared_ptr<Cursor> cursor() const { return _c; }
- private:
- void mayAdvance() {
- if ( !_c ) {
- return;
- }
- if ( _mustAdvance ) {
- _c->advance();
- _mustAdvance = false;
- }
- _aggregateNscanned += ( _c->nscanned() - _nscanned );
- _nscanned = _c->nscanned();
- }
- int _matchCount;
- bool _mustAdvance;
- long long _nscanned;
- bool _capped;
- shared_ptr<Cursor> _c;
- ClientCursor::CleanupPointer _cc;
- DiskLoc _posBeforeYield;
- ClientCursor::YieldData _yieldData;
- long long &_aggregateNscanned;
- bool _yieldRecoveryFailed;
- };
-
- /**
- * This cursor runs a MultiPlanScanner iteratively and returns results from
- * the scanner's cursors as they become available. Once the scanner chooses
- * a single plan, this cursor becomes a simple wrapper around that single
- * plan's cursor (called the 'takeover' cursor).
- */
- class QueryOptimizerCursor : public Cursor {
- public:
- QueryOptimizerCursor( auto_ptr<MultiPlanScanner> &mps ) :
- _mps( mps ),
- _originalOp( new QueryOptimizerCursorOp( _nscanned ) ),
- _currOp(),
- _nscanned() {
- _mps->initialOp( _originalOp );
- shared_ptr<QueryOp> op = _mps->nextOp();
- rethrowOnError( op );
- if ( !op->complete() ) {
- _currOp = dynamic_cast<QueryOptimizerCursorOp*>( op.get() );
- }
- }
-
- virtual bool ok() { return _takeover ? _takeover->ok() : !currLoc().isNull(); }
- virtual Record* _current() {
- if ( _takeover ) {
- return _takeover->_current();
- }
- assertOk();
- return currLoc().rec();
- }
- virtual BSONObj current() {
- if ( _takeover ) {
- return _takeover->current();
- }
- assertOk();
- return currLoc().obj();
- }
- virtual DiskLoc currLoc() { return _takeover ? _takeover->currLoc() : _currLoc(); }
- DiskLoc _currLoc() const {
- verify( 14826, !_takeover );
- if ( _currOp ) {
- return _currOp->currLoc();
- }
- return DiskLoc();
- }
- virtual bool advance() {
- return _advance( false );
- }
- virtual BSONObj currKey() const {
- if ( _takeover ) {
- return _takeover->currKey();
- }
- assertOk();
- return _currOp->currKey();
- }
-
- /** This cursor will be ignored for yielding by the client cursor implementation. */
- virtual DiskLoc refLoc() { return _takeover ? _takeover->refLoc() : DiskLoc(); }
-
- virtual BSONObj indexKeyPattern() {
- if ( _takeover ) {
- return _takeover->indexKeyPattern();
- }
- assertOk();
- return _currOp->cursor()->indexKeyPattern();
- }
-
- virtual bool supportGetMore() { return false; }
-
- virtual bool supportYields() { return _takeover ? _takeover->supportYields() : true; }
- virtual bool prepareToYield() {
- if ( _takeover ) {
- return _takeover->prepareToYield();
- }
- else if ( _currOp ) {
- return _mps->prepareToYield();
- }
- else {
- return true;
- }
- }
- virtual void recoverFromYield() {
- if ( _takeover ) {
- _takeover->recoverFromYield();
- return;
- }
- if ( _currOp ) {
- _mps->recoverFromYield();
- if ( _currOp->error() || !ok() ) {
- // Advance to a non error op or a following $or clause if possible.
- _advance( true );
- }
- }
- }
-
- virtual string toString() { return "QueryOptimizerCursor"; }
-
- virtual bool getsetdup(DiskLoc loc) {
- if ( _takeover ) {
- if ( getdupInternal( loc ) ) {
- return true;
- }
- return _takeover->getsetdup( loc );
- }
- assertOk();
- return getsetdupInternal( loc );
- }
-
- /** Matcher needs to know if the the cursor being forwarded to is multikey. */
- virtual bool isMultiKey() const {
- if ( _takeover ) {
- return _takeover->isMultiKey();
- }
- assertOk();
- return _currOp->cursor()->isMultiKey();
- }
-
- virtual bool modifiedKeys() const { return true; }
-
- virtual long long nscanned() { return _takeover ? _takeover->nscanned() : _nscanned; }
-
- /** @return the matcher for the takeover cursor or current active op. */
- virtual shared_ptr< CoveredIndexMatcher > matcherPtr() const {
- if ( _takeover ) {
- return _takeover->matcherPtr();
- }
- assertOk();
- return _currOp->matcher( _currOp->cursor() );
- }
-
- /** @return the matcher for the takeover cursor or current active op. */
- virtual CoveredIndexMatcher* matcher() const {
- if ( _takeover ) {
- return _takeover->matcher();
- }
- assertOk();
- return _currOp->matcher( _currOp->cursor() ).get();
- }
-
- private:
- bool _advance( bool force ) {
- if ( _takeover ) {
- return _takeover->advance();
- }
-
- if ( !force && !ok() ) {
- return false;
- }
-
- _currOp = 0;
- shared_ptr<QueryOp> op = _mps->nextOp();
- rethrowOnError( op );
-
- QueryOptimizerCursorOp *qocop = dynamic_cast<QueryOptimizerCursorOp*>( op.get() );
- if ( !op->complete() ) {
- // 'qocop' will be valid until we call _mps->nextOp() again.
- _currOp = qocop;
- }
- else if ( op->stopRequested() ) {
- if ( qocop->cursor() ) {
- _takeover.reset( new MultiCursor( _mps,
- qocop->cursor(),
- op->matcher( qocop->cursor() ),
- *op,
- _nscanned - qocop->cursor()->nscanned() ) );
- }
- }
-
- return ok();
- }
- void rethrowOnError( const shared_ptr< QueryOp > &op ) {
- // If all plans have erred out, assert.
- if ( op->error() ) {
- throw MsgAssertionException( op->exception() );
- }
- }
-
- void assertOk() const {
- massert( 14809, "Invalid access for cursor that is not ok()", !_currLoc().isNull() );
- }
-
- /** Insert and check for dups before takeover occurs */
- bool getsetdupInternal(const DiskLoc &loc) {
- pair<set<DiskLoc>::iterator, bool> p = _dups.insert(loc);
- return !p.second;
- }
-
- /** Just check for dups - after takeover occurs */
- bool getdupInternal(const DiskLoc &loc) {
- return _dups.count( loc ) > 0;
- }
-
- auto_ptr<MultiPlanScanner> _mps;
- shared_ptr<QueryOptimizerCursorOp> _originalOp;
- QueryOptimizerCursorOp *_currOp;
- set<DiskLoc> _dups;
- shared_ptr<Cursor> _takeover;
- long long _nscanned;
- };
-
- shared_ptr<Cursor> newQueryOptimizerCursor( auto_ptr<MultiPlanScanner> mps ) {
- try {
- return shared_ptr<Cursor>( new QueryOptimizerCursor( mps ) );
- } catch( const AssertionException &e ) {
- if ( e.getCode() == OutOfOrderDocumentsAssertionCode ) {
- // If no indexes follow the requested sort order, return an
- // empty pointer.
- return shared_ptr<Cursor>();
- }
- throw;
- }
- return shared_ptr<Cursor>( new QueryOptimizerCursor( mps ) );
- }
-
- shared_ptr<Cursor> NamespaceDetailsTransient::getCursor( const char *ns, const BSONObj &query, const BSONObj &order ) {
- if ( query.isEmpty() && order.isEmpty() ) {
- // TODO This will not use a covered index.
- return theDataFileMgr.findAll( ns );
- }
- if ( isSimpleIdQuery( query ) ) {
- Database *database = cc().database();
- assert( database );
- NamespaceDetails *d = database->namespaceIndex.details(ns);
- if ( d ) {
- int idxNo = d->findIdIndex();
- if ( idxNo >= 0 ) {
- IndexDetails& i = d->idx( idxNo );
- BSONObj key = i.getKeyFromQuery( query );
- return shared_ptr<Cursor>( BtreeCursor::make( d, idxNo, i, key, key, true, 1 ) );
- }
- }
- }
- auto_ptr<MultiPlanScanner> mps( new MultiPlanScanner( ns, query, order ) ); // mayYield == false
- shared_ptr<Cursor> single = mps->singleCursor();
- if ( single ) {
- if ( !query.isEmpty() && !single->matcher() ) {
- shared_ptr<CoveredIndexMatcher> matcher( new CoveredIndexMatcher( query, single->indexKeyPattern() ) );
- single->setMatcher( matcher );
- }
- return single;
- }
- return newQueryOptimizerCursor( mps );
- }
-
- /** This interface just available for testing. */
- shared_ptr<Cursor> newQueryOptimizerCursor( const char *ns, const BSONObj &query, const BSONObj &order ) {
- auto_ptr<MultiPlanScanner> mps( new MultiPlanScanner( ns, query, order ) ); // mayYield == false
- return newQueryOptimizerCursor( mps );
- }
-
-} // namespace mongo;
generated by cgit v1.2.3 (git 2.39.1) at 2026-09-11 17:49:26 +0000