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query.cpp
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query.cpp
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// query.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 "query.h"
#include "pdfile.h"
#include "jsobjmanipulator.h"
#include "../bson/util/builder.h"
#include <time.h>
#include "introspect.h"
#include "btree.h"
#include "../util/lruishmap.h"
#include "json.h"
#include "repl.h"
#include "replpair.h"
#include "scanandorder.h"
#include "security.h"
#include "curop.h"
#include "commands.h"
#include "queryoptimizer.h"
#include "lasterror.h"
#include "../s/d_logic.h"
#include "repl_block.h"
namespace mongo {
/* We cut off further objects once we cross this threshold; thus, you might get
a little bit more than this, it is a threshold rather than a limit.
*/
const int MaxBytesToReturnToClientAtOnce = 4 * 1024 * 1024;
//ns->query->DiskLoc
// LRUishMap<BSONObj,DiskLoc,5> lrutest(123);
extern bool useCursors;
extern bool useHints;
// Just try to identify best plan.
class DeleteOp : public MultiCursor::CursorOp {
public:
DeleteOp( bool justOne, int& bestCount ) :
justOne_( justOne ),
count_(),
bestCount_( bestCount ),
_nscanned() {
}
virtual void _init() {
c_ = qp().newCursor();
}
virtual bool prepareToYield() {
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() {
assert( c_.get() );
return c_->nscanned();
}
virtual void next() {
if ( !c_->ok() ) {
setComplete();
return;
}
DiskLoc rloc = c_->currLoc();
if ( matcher()->matches(c_->currKey(), rloc ) ) {
if ( !c_->getsetdup(rloc) )
++count_;
}
c_->advance();
_nscanned = c_->nscanned();
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_ );
}
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;
};
/* 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) {
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, true ) );
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 {
if ( canYield && ! cc->yieldSometimes() ){
cc.release(); // has already been deleted elsewhere
// TODO should we assert or something?
break;
}
if ( !cc->c->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->c->currLoc();
BSONObj key = cc->c->currKey();
// NOTE Calling advance() may change the matcher, so it's important
// to try to match first.
bool match = creal->matcher()->matches( key , rloc );
if ( ! cc->c->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;
}
}
theDataFileMgr.deleteRecord(ns, rloc.rec(), rloc);
nDeleted++;
if ( justOne ) {
break;
}
cc->c->checkLocation();
} while ( cc->c->ok() );
if ( cc.get() && ClientCursor::find( id , false ) == 0 ){
cc.release();
}
return nDeleted;
}
int otherTraceLevel = 0;
int initialExtentSize(int len);
bool runCommands(const char *ns, BSONObj& jsobj, CurOp& curop, BufBuilder &b, BSONObjBuilder& anObjBuilder, bool fromRepl, int queryOptions) {
try {
return _runCommands(ns, jsobj, b, anObjBuilder, fromRepl, queryOptions);
}
catch ( AssertionException& e ) {
e.getInfo().append( anObjBuilder , "assertion" , "assertionCode" );
}
curop.debug().str << " assertion ";
anObjBuilder.append("errmsg", "db assertion failure");
anObjBuilder.append("ok", 0.0);
BSONObj x = anObjBuilder.done();
b.appendBuf((void*) x.objdata(), x.objsize());
return true;
}
int nCaught = 0;
void killCursors(int n, long long *ids) {
int k = 0;
for ( int i = 0; i < n; i++ ) {
if ( ClientCursor::erase(ids[i]) )
k++;
}
if ( logLevel > 0 || k != n ){
log( k == n ) << "killcursors: found " << k << " of " << n << endl;
}
}
BSONObj id_obj = fromjson("{\"_id\":1}");
BSONObj empty_obj = fromjson("{}");
//int dump = 0;
/* empty result for error conditions */
QueryResult* emptyMoreResult(long long cursorid) {
BufBuilder b(32768);
b.skip(sizeof(QueryResult));
QueryResult *qr = (QueryResult *) b.buf();
qr->cursorId = 0; // 0 indicates no more data to retrieve.
qr->startingFrom = 0;
qr->len = b.len();
qr->setOperation(opReply);
qr->nReturned = 0;
b.decouple();
return qr;
}
QueryResult* processGetMore(const char *ns, int ntoreturn, long long cursorid , CurOp& curop, int pass, bool& exhaust ) {
// log() << "TEMP GETMORE " << ns << ' ' << cursorid << ' ' << pass << endl;
exhaust = false;
ClientCursor::Pointer p(cursorid);
ClientCursor *cc = p._c;
int bufSize = 512;
if ( cc ){
bufSize += sizeof( QueryResult );
bufSize += ( ntoreturn ? 4 : 1 ) * 1024 * 1024;
}
BufBuilder b( bufSize );
b.skip(sizeof(QueryResult));
int resultFlags = ResultFlag_AwaitCapable;
int start = 0;
int n = 0;
if ( !cc ) {
log() << "getMore: cursorid not found " << ns << " " << cursorid << endl;
cursorid = 0;
resultFlags = ResultFlag_CursorNotFound;
}
else {
if ( pass == 0 )
cc->updateSlaveLocation( curop );
int queryOptions = cc->_queryOptions;
if( pass == 0 ) {
StringBuilder& ss = curop.debug().str;
ss << " getMore: " << cc->query.toString() << " ";
}
start = cc->pos;
Cursor *c = cc->c.get();
c->checkLocation();
DiskLoc last;
while ( 1 ) {
if ( !c->ok() ) {
// log() << "TEMP Tailable : " << c->tailable() << ' ' << (queryOptions & QueryOption_AwaitData) << endl;
if ( c->tailable() ) {
/* when a tailable cursor hits "EOF", ok() goes false, and current() is null. however
advance() can still be retries as a reactivation attempt. when there is new data, it will
return true. that's what we are doing here.
*/
if ( c->advance() )
continue;
if( n == 0 && (queryOptions & QueryOption_AwaitData) && pass < 1000 ) {
throw GetMoreWaitException();
}
break;
}
p.release();
bool ok = ClientCursor::erase(cursorid);
assert(ok);
cursorid = 0;
cc = 0;
break;
}
// in some cases (clone collection) there won't be a matcher
if ( c->matcher() && !c->matcher()->matches(c->currKey(), c->currLoc() ) ) {
}
/*
TODO
else if ( _chunkMatcher && ! _chunkMatcher->belongsToMe( c->currKey(), c->currLoc() ) ){
cout << "TEMP skipping un-owned chunk: " << c->current() << endl;
}
*/
else {
if( c->getsetdup(c->currLoc()) ) {
//out() << " but it's a dup \n";
}
else {
last = c->currLoc();
BSONObj js = c->current();
// show disk loc should be part of the main query, not in an $or clause, so this should be ok
fillQueryResultFromObj(b, cc->fields.get(), js, ( cc->pq.get() && cc->pq->showDiskLoc() ? &last : 0));
n++;
if ( (ntoreturn>0 && (n >= ntoreturn || b.len() > MaxBytesToReturnToClientAtOnce)) ||
(ntoreturn==0 && b.len()>1*1024*1024) ) {
c->advance();
cc->pos += n;
break;
}
}
}
c->advance();
}
if ( cc ) {
cc->updateLocation();
cc->mayUpgradeStorage();
cc->storeOpForSlave( last );
exhaust = cc->_queryOptions & QueryOption_Exhaust;
}
}
QueryResult *qr = (QueryResult *) b.buf();
qr->len = b.len();
qr->setOperation(opReply);
qr->_resultFlags() = resultFlags;
qr->cursorId = cursorid;
qr->startingFrom = start;
qr->nReturned = n;
b.decouple();
return qr;
}
class CountOp : public QueryOp {
public:
CountOp( const string& ns , const BSONObj &spec ) :
_ns(ns), count_(),
skip_( spec["skip"].numberLong() ),
limit_( spec["limit"].numberLong() ),
bc_(){
}
virtual void _init() {
c_ = qp().newCursor();
if ( qp().exactKeyMatch() && ! matcher()->needRecord() ) {
query_ = qp().simplifiedQuery( qp().indexKey() );
bc_ = dynamic_cast< BtreeCursor* >( c_.get() );
bc_->forgetEndKey();
}
}
virtual long long nscanned() {
assert( c_.get() );
return c_->nscanned();
}
virtual bool prepareToYield() {
if ( ! _cc ) {
_cc.reset( new ClientCursor( QueryOption_NoCursorTimeout , c_ , _ns.c_str() ) );
}
return _cc->prepareToYield( _yieldData );
}
virtual void recoverFromYield() {
if ( !ClientCursor::recoverFromYield( _yieldData ) ) {
c_.reset();
_cc.reset();
massert( 13337, "cursor dropped during count", false );
// TODO maybe we want to prevent recording the winning plan as well?
}
}
virtual void next() {
if ( !c_->ok() ) {
setComplete();
return;
}
if ( bc_ ) {
if ( firstMatch_.isEmpty() ) {
firstMatch_ = bc_->currKeyNode().key;
// if not match
if ( query_.woCompare( firstMatch_, BSONObj(), false ) ) {
setComplete();
return;
}
_gotOne();
} else {
if ( !firstMatch_.woEqual( bc_->currKeyNode().key ) ) {
setComplete();
return;
}
_gotOne();
}
}
else {
if ( !matcher()->matches(c_->currKey(), c_->currLoc() ) ) {
}
else if( !c_->getsetdup(c_->currLoc()) ) {
_gotOne();
}
}
c_->advance();
}
virtual QueryOp *_createChild() const {
CountOp *ret = new CountOp( _ns , BSONObj() );
ret->count_ = count_;
ret->skip_ = skip_;
ret->limit_ = limit_;
return ret;
}
long long count() const { return count_; }
virtual bool mayRecordPlan() const { return true; }
private:
void _gotOne(){
if ( skip_ ){
skip_--;
return;
}
if ( limit_ > 0 && count_ >= limit_ ){
setStop();
return;
}
count_++;
}
string _ns;
long long count_;
long long skip_;
long long limit_;
shared_ptr<Cursor> c_;
BSONObj query_;
BtreeCursor *bc_;
BSONObj firstMatch_;
ClientCursor::CleanupPointer _cc;
ClientCursor::YieldData _yieldData;
};
/* { count: "collectionname"[, query: <query>] }
returns -1 on ns does not exist error.
*/
long long runCount( const char *ns, const BSONObj &cmd, string &err ) {
Client::Context cx(ns);
NamespaceDetails *d = nsdetails( ns );
if ( !d ) {
err = "ns missing";
return -1;
}
BSONObj query = cmd.getObjectField("query");
// count of all objects
if ( query.isEmpty() ){
return applySkipLimit( d->nrecords , cmd );
}
MultiPlanScanner mps( ns, query, BSONObj(), 0, true, BSONObj(), BSONObj(), false, true );
CountOp original( ns , cmd );
shared_ptr< CountOp > res = mps.runOp( original );
if ( !res->complete() ) {
log() << "Count with ns: " << ns << " and query: " << query
<< " failed with exception: " << res->exception()
<< endl;
return 0;
}
return res->count();
}
class ExplainBuilder {
public:
ExplainBuilder() : _i() {}
void ensureStartScan() {
if ( !_a.get() ) {
_a.reset( new BSONArrayBuilder() );
}
}
void noteCursor( Cursor *c ) {
BSONObjBuilder b( _a->subobjStart() );
b << "cursor" << c->toString() << "indexBounds" << c->prettyIndexBounds();
b.done();
}
void noteScan( Cursor *c, long long nscanned, long long nscannedObjects, int n, bool scanAndOrder, int millis, bool hint ) {
if ( _i == 1 ) {
_c.reset( new BSONArrayBuilder() );
*_c << _b->obj();
}
if ( _i == 0 ) {
_b.reset( new BSONObjBuilder() );
} else {
_b.reset( new BSONObjBuilder( _c->subobjStart() ) );
}
*_b << "cursor" << c->toString();
_b->appendNumber( "nscanned", nscanned );
_b->appendNumber( "nscannedObjects", nscannedObjects );
*_b << "n" << n;
if ( scanAndOrder )
*_b << "scanAndOrder" << true;
*_b << "millis" << millis;
*_b << "indexBounds" << c->prettyIndexBounds();
if ( !hint ) {
*_b << "allPlans" << _a->arr();
}
if ( _i != 0 ) {
_b->done();
}
_a.reset( 0 );
++_i;
}
BSONObj finishWithSuffix( long long nscanned, long long nscannedObjects, int n, int millis, const BSONObj &suffix ) {
if ( _i > 1 ) {
BSONObjBuilder b;
b << "clauses" << _c->arr();
b.appendNumber( "nscanned", nscanned );
b.appendNumber( "nscanneObjects", nscannedObjects );
b << "n" << n;
b << "millis" << millis;
b.appendElements( suffix );
return b.obj();
} else {
_b->appendElements( suffix );
return _b->obj();
}
}
private:
auto_ptr< BSONArrayBuilder > _a;
auto_ptr< BSONObjBuilder > _b;
auto_ptr< BSONArrayBuilder > _c;
int _i;
};
// Implements database 'query' requests using the query optimizer's QueryOp interface
class UserQueryOp : public QueryOp {
public:
UserQueryOp( const ParsedQuery& pq, Message &response, ExplainBuilder &eb, CurOp &curop ) :
_buf( 32768 ) , // TODO be smarter here
_pq( pq ) ,
_ntoskip( pq.getSkip() ) ,
_nscanned(0), _oldNscanned(0), _nscannedObjects(0), _oldNscannedObjects(0),
_n(0),
_oldN(0),
_chunkMatcher(shardingState.getChunkMatcher(pq.ns())),
_inMemSort(false),
_saveClientCursor(false),
_wouldSaveClientCursor(false),
_oplogReplay( pq.hasOption( QueryOption_OplogReplay) ),
_response( response ),
_eb( eb ),
_curop( curop )
{}
virtual void _init() {
// only need to put the QueryResult fields there if we're building the first buffer in the message.
if ( _response.empty() ) {
_buf.skip( sizeof( QueryResult ) );
}
if ( _oplogReplay ) {
_findingStartCursor.reset( new FindingStartCursor( qp() ) );
} else {
_c = qp().newCursor( DiskLoc() , _pq.getNumToReturn() + _pq.getSkip() );
}
if ( qp().scanAndOrderRequired() ) {
_inMemSort = true;
_so.reset( new ScanAndOrder( _pq.getSkip() , _pq.getNumToReturn() , _pq.getOrder() ) );
}
if ( _pq.isExplain() ) {
_eb.noteCursor( _c.get() );
}
}
virtual bool prepareToYield() {
if ( _findingStartCursor.get() ) {
return _findingStartCursor->prepareToYield();
} else {
if ( ! _cc ) {
_cc.reset( new ClientCursor( QueryOption_NoCursorTimeout , _c , _pq.ns() ) );
}
return _cc->prepareToYield( _yieldData );
}
}
virtual void recoverFromYield() {
if ( _findingStartCursor.get() ) {
_findingStartCursor->recoverFromYield();
} else {
if ( !ClientCursor::recoverFromYield( _yieldData ) ) {
_c.reset();
_cc.reset();
massert( 13338, "cursor dropped during query", false );
// TODO maybe we want to prevent recording the winning plan as well?
}
}
}
virtual long long nscanned() {
if ( _findingStartCursor.get() ) {
return 0; // should only be one query plan, so value doesn't really matter.
}
assert( _c.get() );
return _c->nscanned();
}
virtual void next() {
if ( _findingStartCursor.get() ) {
if ( _findingStartCursor->done() ) {
_c = _findingStartCursor->cRelease();
_findingStartCursor.reset( 0 );
} else {
_findingStartCursor->next();
}
return;
}
if ( !_c->ok() ) {
finish( false );
return;
}
bool mayCreateCursor1 = _pq.wantMore() && ! _inMemSort && _pq.getNumToReturn() != 1 && useCursors;
if( 0 ) {
cout << "SCANNING this: " << this << " key: " << _c->currKey() << " obj: " << _c->current() << endl;
}
if ( _pq.getMaxScan() && _nscanned >= _pq.getMaxScan() ){
finish( true ); //?
return;
}
_nscanned = _c->nscanned();
if ( !matcher()->matches(_c->currKey(), _c->currLoc() , &_details ) ) {
// not a match, continue onward
if ( _details.loadedObject )
_nscannedObjects++;
}
else {
_nscannedObjects++;
DiskLoc cl = _c->currLoc();
if ( _chunkMatcher && ! _chunkMatcher->belongsToMe( _c->currKey(), _c->currLoc() ) ){
// cout << "TEMP skipping un-owned chunk: " << _c->current() << endl;
}
else if( _c->getsetdup(cl) ) {
// dup
}
else {
// got a match.
if ( _inMemSort ) {
// note: no cursors for non-indexed, ordered results. results must be fairly small.
_so->add( _pq.returnKey() ? _c->currKey() : _c->current(), _pq.showDiskLoc() ? &cl : 0 );
}
else if ( _ntoskip > 0 ) {
_ntoskip--;
}
else {
if ( _pq.isExplain() ) {
_n++;
if ( n() >= _pq.getNumToReturn() && !_pq.wantMore() ) {
// .limit() was used, show just that much.
finish( true ); //?
return;
}
}
else {
if ( _pq.returnKey() ){
BSONObjBuilder bb( _buf );
bb.appendKeys( _c->indexKeyPattern() , _c->currKey() );
bb.done();
}
else {
BSONObj js = _c->current();
assert( js.isValid() );
if ( _oplogReplay ){
BSONElement e = js["ts"];
if ( e.type() == Date || e.type() == Timestamp )
_slaveReadTill = e._opTime();
}
fillQueryResultFromObj( _buf , _pq.getFields() , js , (_pq.showDiskLoc() ? &cl : 0));
}
_n++;
if ( ! _c->supportGetMore() ){
if ( _pq.enough( n() ) || _buf.len() >= MaxBytesToReturnToClientAtOnce ){
finish( true );
return;
}
}
else if ( _pq.enoughForFirstBatch( n() , _buf.len() ) ){
/* if only 1 requested, no cursor saved for efficiency...we assume it is findOne() */
if ( mayCreateCursor1 ) {
_wouldSaveClientCursor = true;
if ( _c->advance() ) {
// more...so save a cursor
_saveClientCursor = true;
}
}
finish( true );
return;
}
}
}
}
}
_c->advance();
}
// this plan won, so set data for response broadly
void finish( bool stop ) {
if ( _pq.isExplain() ) {
_n = _inMemSort ? _so->size() : _n;
}
else if ( _inMemSort ) {
_so->fill( _buf, _pq.getFields() , _n );
}
if ( _pq.hasOption( QueryOption_CursorTailable ) && _pq.getNumToReturn() != 1 )
_c->setTailable();
// If the tailing request succeeded.
if ( _c->tailable() )
_saveClientCursor = true;
if ( _pq.isExplain()) {
_eb.noteScan( _c.get(), _nscanned, _nscannedObjects, _n, scanAndOrderRequired(), _curop.elapsedMillis(), useHints && !_pq.getHint().eoo() );
} else {
_response.appendData( _buf.buf(), _buf.len() );
_buf.decouple();
}
if ( stop ) {
setStop();
} else {
setComplete();
}
}
void finishExplain( const BSONObj &suffix ) {
BSONObj obj = _eb.finishWithSuffix( totalNscanned(), nscannedObjects(), n(), _curop.elapsedMillis(), suffix);
fillQueryResultFromObj(_buf, 0, obj);
_n = 1;
_oldN = 0;
_response.appendData( _buf.buf(), _buf.len() );
_buf.decouple();
}
virtual bool mayRecordPlan() const { return _pq.getNumToReturn() != 1; }
virtual QueryOp *_createChild() const {
if ( _pq.isExplain() ) {
_eb.ensureStartScan();
}
UserQueryOp *ret = new UserQueryOp( _pq, _response, _eb, _curop );
ret->_oldN = n();
ret->_oldNscanned = totalNscanned();
ret->_oldNscannedObjects = nscannedObjects();
ret->_ntoskip = _ntoskip;
return ret;
}
bool scanAndOrderRequired() const { return _inMemSort; }
shared_ptr<Cursor> cursor() { return _c; }
int n() const { return _oldN + _n; }
long long totalNscanned() const { return _nscanned + _oldNscanned; }
long long nscannedObjects() const { return _nscannedObjects + _oldNscannedObjects; }
bool saveClientCursor() const { return _saveClientCursor; }
bool wouldSaveClientCursor() const { return _wouldSaveClientCursor; }
void finishForOplogReplay( ClientCursor * cc ){
if ( _oplogReplay && ! _slaveReadTill.isNull() )
cc->_slaveReadTill = _slaveReadTill;
}
private:
BufBuilder _buf;
const ParsedQuery& _pq;
long long _ntoskip;
long long _nscanned;
long long _oldNscanned;
long long _nscannedObjects;
long long _oldNscannedObjects;
int _n; // found so far
int _oldN;
MatchDetails _details;
ChunkMatcherPtr _chunkMatcher;
bool _inMemSort;
auto_ptr< ScanAndOrder > _so;
shared_ptr<Cursor> _c;
ClientCursor::CleanupPointer _cc;
ClientCursor::YieldData _yieldData;
bool _saveClientCursor;
bool _wouldSaveClientCursor;
bool _oplogReplay;
auto_ptr< FindingStartCursor > _findingStartCursor;
Message &_response;
ExplainBuilder &_eb;
CurOp &_curop;
OpTime _slaveReadTill;
};
/* run a query -- includes checking for and running a Command */
const char *runQuery(Message& m, QueryMessage& q, CurOp& curop, Message &result) {
StringBuilder& ss = curop.debug().str;
shared_ptr<ParsedQuery> pq_shared( new ParsedQuery(q) );
ParsedQuery& pq( *pq_shared );
int ntoskip = q.ntoskip;
BSONObj jsobj = q.query;
int queryOptions = q.queryOptions;
const char *ns = q.ns;
if( logLevel >= 2 )
log() << "query: " << ns << jsobj << endl;
ss << ns;
{
// only say ntoreturn if nonzero.
int n = pq.getNumToReturn();
if( n )
ss << " ntoreturn:" << n;
}
curop.setQuery(jsobj);
if ( pq.couldBeCommand() ) {
BufBuilder bb;
bb.skip(sizeof(QueryResult));
BSONObjBuilder cmdResBuf;
if ( runCommands(ns, jsobj, curop, bb, cmdResBuf, false, queryOptions) ) {
ss << " command: " << jsobj.toString();
curop.markCommand();
auto_ptr< QueryResult > qr;
qr.reset( (QueryResult *) bb.buf() );
bb.decouple();
qr->setResultFlagsToOk();
qr->len = bb.len();
ss << " reslen:" << bb.len();
qr->setOperation(opReply);
qr->cursorId = 0;
qr->startingFrom = 0;
qr->nReturned = 1;
result.setData( qr.release(), true );
}
return false;
}
/* --- regular query --- */
int n = 0;
BSONElement hint = useHints ? pq.getHint() : BSONElement();
bool explain = pq.isExplain();
bool snapshot = pq.isSnapshot();
BSONObj order = pq.getOrder();
BSONObj query = pq.getFilter();
/* The ElemIter will not be happy if this isn't really an object. So throw exception
here when that is true.
(Which may indicate bad data from client.)
*/
if ( query.objsize() == 0 ) {
out() << "Bad query object?\n jsobj:";
out() << jsobj.toString() << "\n query:";
out() << query.toString() << endl;
uassert( 10110 , "bad query object", false);
}
/* --- read lock --- */
mongolock lk(false);
Client::Context ctx( ns , dbpath , &lk );
replVerifyReadsOk(pq);
if ( pq.hasOption( QueryOption_CursorTailable ) ) {
NamespaceDetails *d = nsdetails( ns );
uassert( 13051, "tailable cursor requested on non capped collection", d && d->capped );
const BSONObj nat1 = BSON( "$natural" << 1 );
if ( order.isEmpty() ) {
order = nat1;
} else {
uassert( 13052, "only {$natural:1} order allowed for tailable cursor", order == nat1 );
}
}
BSONObj snapshotHint; // put here to keep the data in scope
if( snapshot ) {
NamespaceDetails *d = nsdetails(ns);
if ( d ){
int i = d->findIdIndex();
if( i < 0 ) {
if ( strstr( ns , ".system." ) == 0 )
log() << "warning: no _id index on $snapshot query, ns:" << ns << endl;
}
else {
/* [dm] the name of an _id index tends to vary, so we build the hint the hard way here.
probably need a better way to specify "use the _id index" as a hint. if someone is
in the query optimizer please fix this then!
*/
BSONObjBuilder b;
b.append("$hint", d->idx(i).indexName());
snapshotHint = b.obj();
hint = snapshotHint.firstElement();
}
}
}
if ( ! (explain || pq.showDiskLoc()) && isSimpleIdQuery( query ) && !pq.hasOption( QueryOption_CursorTailable ) ) {
bool nsFound = false;
bool indexFound = false;
BSONObj resObject;
Client& c = cc();
bool found = Helpers::findById( c, ns , query , resObject , &nsFound , &indexFound );
if ( nsFound == false || indexFound == true ){
BufBuilder bb(sizeof(QueryResult)+resObject.objsize()+32);
bb.skip(sizeof(QueryResult));
ss << " idhack ";
if ( found ){