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// delete.cpp
/**
* Copyright (C) 2008 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 "delete.h"
#include "../queryoptimizer.h"
#include "../oplog.h"
namespace mongo {
// Just try to identify best plan.
class DeleteOp : public MultiCursor::CursorOp {
public:
DeleteOp( bool justOne, int& bestCount, int orClauseIndex = -1 ) :
justOne_( justOne ),
count_(),
bestCount_( bestCount ),
_nscanned(),
_orClauseIndex( orClauseIndex ) {
}
virtual void _init() {
c_ = qp().newCursor();
}
virtual bool prepareToYield() {
if ( _orClauseIndex > 0 ) {
return false;
}
if ( ! _cc ) {
_cc.reset( new ClientCursor( QueryOption_NoCursorTimeout , c_ , qp().ns() ) );
}
return _cc->prepareToYield( _yieldData );
}
virtual void recoverFromYield() {
if ( !ClientCursor::recoverFromYield( _yieldData ) ) {
_cc.reset();
c_.reset();
massert( 13340, "cursor dropped during delete", false );
}
}
virtual long long nscanned() {
return c_.get() ? c_->nscanned() : _nscanned;
}
virtual void next() {
if ( !c_->ok() ) {
setComplete();
return;
}
DiskLoc rloc = c_->currLoc();
if ( matcher( c_ )->matchesCurrent(c_.get()) ) {
if ( !c_->getsetdup(rloc) )
++count_;
}
c_->advance();
_nscanned = c_->nscanned();
if ( _orClauseIndex > 0 && _nscanned >= 100 ) {
setComplete();
return;
}
if ( count_ > bestCount_ )
bestCount_ = count_;
if ( count_ > 0 ) {
if ( justOne_ )
setComplete();
else if ( _nscanned >= 100 && count_ == bestCount_ )
setComplete();
}
}
virtual bool mayRecordPlan() const { return !justOne_; }
virtual QueryOp *_createChild() const {
bestCount_ = 0; // should be safe to reset this in contexts where createChild() is called
return new DeleteOp( justOne_, bestCount_, _orClauseIndex + 1 );
}
virtual shared_ptr<Cursor> newCursor() const { return qp().newCursor(); }
private:
bool justOne_;
int count_;
int &bestCount_;
long long _nscanned;
shared_ptr<Cursor> c_;
ClientCursor::CleanupPointer _cc;
ClientCursor::YieldData _yieldData;
// Avoid yielding in the MultiPlanScanner when not the first $or clause - just a temporary implementaiton for now.
int _orClauseIndex;
};
/* ns: namespace, e.g. <database>.<collection>
pattern: the "where" clause / criteria
justOne: stop after 1 match
god: allow access to system namespaces, and don't yield
*/
long long deleteObjects(const char *ns, BSONObj pattern, bool justOneOrig, bool logop, bool god, RemoveSaver * rs ) {
if( !god ) {
if ( strstr(ns, ".system.") ) {
/* note a delete from system.indexes would corrupt the db
if done here, as there are pointers into those objects in
NamespaceDetails.
*/
uassert(12050, "cannot delete from system namespace", legalClientSystemNS( ns , true ) );
}
if ( strchr( ns , '$' ) ) {
log() << "cannot delete from collection with reserved $ in name: " << ns << endl;
uassert( 10100 , "cannot delete from collection with reserved $ in name", strchr(ns, '$') == 0 );
}
}
{
NamespaceDetails *d = nsdetails( ns );
if ( ! d )
return 0;
uassert( 10101 , "can't remove from a capped collection" , ! d->capped );
}
long long nDeleted = 0;
int best = 0;
shared_ptr< MultiCursor::CursorOp > opPtr( new DeleteOp( justOneOrig, best ) );
shared_ptr< MultiCursor > creal( new MultiCursor( ns, pattern, BSONObj(), opPtr, !god ) );
if( !creal->ok() )
return nDeleted;
shared_ptr< Cursor > cPtr = creal;
auto_ptr<ClientCursor> cc( new ClientCursor( QueryOption_NoCursorTimeout, cPtr, ns) );
cc->setDoingDeletes( true );
CursorId id = cc->cursorid();
bool justOne = justOneOrig;
bool canYield = !god && !creal->matcher()->docMatcher().atomic();
do {
// TODO: we can generalize this I believe
//
bool willNeedRecord = creal->matcher()->needRecord() || pattern.isEmpty() || isSimpleIdQuery( pattern );
if ( ! willNeedRecord ) {
// TODO: this is a total hack right now
// check if the index full encompasses query
if ( pattern.nFields() == 1 &&
str::equals( pattern.firstElement().fieldName() , creal->indexKeyPattern().firstElement().fieldName() ) )
willNeedRecord = true;
}
if ( canYield && ! cc->yieldSometimes( willNeedRecord ? ClientCursor::WillNeed : ClientCursor::MaybeCovered ) ) {
cc.release(); // has already been deleted elsewhere
// TODO should we assert or something?
break;
}
if ( !cc->ok() ) {
break; // if we yielded, could have hit the end
}
// this way we can avoid calling updateLocation() every time (expensive)
// as well as some other nuances handled
cc->setDoingDeletes( true );
DiskLoc rloc = cc->currLoc();
BSONObj key = cc->currKey();
// NOTE Calling advance() may change the matcher, so it's important
// to try to match first.
bool match = creal->matcher()->matchesCurrent(creal.get());
if ( ! cc->advance() )
justOne = true;
if ( ! match )
continue;
assert( !cc->c()->getsetdup(rloc) ); // can't be a dup, we deleted it!
if ( !justOne ) {
/* NOTE: this is SLOW. this is not good, noteLocation() was designed to be called across getMore
blocks. here we might call millions of times which would be bad.
*/
cc->c()->noteLocation();
}
if ( logop ) {
BSONElement e;
if( BSONObj( rloc.rec() ).getObjectID( e ) ) {
BSONObjBuilder b;
b.append( e );
bool replJustOne = true;
logOp( "d", ns, b.done(), 0, &replJustOne );
}
else {
problem() << "deleted object without id, not logging" << endl;
}
}
if ( rs )
rs->goingToDelete( rloc.obj() /*cc->c->current()*/ );
theDataFileMgr.deleteRecord(ns, rloc.rec(), rloc);
nDeleted++;
if ( justOne ) {
break;
}
cc->c()->checkLocation();
if( !god )
getDur().commitIfNeeded();
if( debug && god && nDeleted == 100 )
log() << "warning high number of deletes with god=true which could use significant memory" << endl;
}
while ( cc->ok() );
if ( cc.get() && ClientCursor::find( id , false ) == 0 ) {
// TODO: remove this and the id declaration above if this doesn't trigger
// if it does, then i'm very confused (ERH 06/2011)
error() << "this should be impossible" << endl;
printStackTrace();
cc.release();
}
return nDeleted;
}
}
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