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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 "mongo/pch.h"
#include "mongo/db/ops/delete.h"
#include "mongo/client/dbclientinterface.h"
#include "mongo/db/cc_by_loc.h"
#include "mongo/db/clientcursor.h"
#include "mongo/db/cursor.h"
#include "mongo/db/namespace_details.h"
#include "mongo/db/query_optimizer.h"
#include "mongo/db/queryutil.h"
#include "mongo/db/repl/oplog.h"
#include "mongo/util/stacktrace.h"
namespace mongo {
/* 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 justOne, bool logop, bool god) {
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->isCapped() );
}
long long nDeleted = 0;
shared_ptr< Cursor > creal = getOptimizedCursor( ns, pattern );
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 canYield = !god && !(creal->matcher() && creal->matcher()->docMatcher().atomic());
do {
// TODO: we can generalize this I believe
//
bool willNeedRecord = (creal->matcher() && 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 prepareToYield() every time (expensive)
// as well as some other nuances handled
cc->setDoingDeletes( true );
DiskLoc rloc = cc->currLoc();
BSONObj key = cc->currKey();
bool match = creal->currentMatches();
cc->advance();
if ( ! match )
continue;
// SERVER-5198 Advance past the document to be modified, but see SERVER-5725.
while( cc->ok() && rloc == cc->currLoc() ) {
cc->advance();
}
bool foundAllResults = ( justOne || !cc->ok() );
if ( !foundAllResults ) {
// NOTE: Saving and restoring a btree cursor's position was historically described
// as slow here.
cc->c()->prepareToTouchEarlierIterate();
}
if ( logop ) {
BSONElement e;
if( BSONObj::make( 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;
}
}
theDataFileMgr.deleteRecord(ns, rloc.rec(), rloc);
nDeleted++;
if ( foundAllResults ) {
break;
}
cc->c()->recoverFromTouchingEarlierIterate();
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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