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// query.h
/**
* 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/>.
*/
#pragma once
#include "../../pch.h"
#include "../../util/net/message.h"
#include "../dbmessage.h"
#include "../jsobj.h"
#include "../diskloc.h"
#include "../projection.h"
// struct QueryOptions, QueryResult, QueryResultFlags in:
#include "../../client/dbclient.h"
namespace mongo {
extern const int MaxBytesToReturnToClientAtOnce;
QueryResult* processGetMore(const char *ns, int ntoreturn, long long cursorid , CurOp& op, int pass, bool& exhaust);
const char * runQuery(Message& m, QueryMessage& q, CurOp& curop, Message &result);
/* This is for languages whose "objects" are not well ordered (JSON is well ordered).
[ { a : ... } , { b : ... } ] -> { a : ..., b : ... }
*/
inline BSONObj transformOrderFromArrayFormat(BSONObj order) {
/* note: this is slow, but that is ok as order will have very few pieces */
BSONObjBuilder b;
char p[2] = "0";
while ( 1 ) {
BSONObj j = order.getObjectField(p);
if ( j.isEmpty() )
break;
BSONElement e = j.firstElement();
uassert( 10102 , "bad order array", !e.eoo());
uassert( 10103 , "bad order array [2]", e.isNumber());
b.append(e);
(*p)++;
uassert( 10104 , "too many ordering elements", *p <= '9');
}
return b.obj();
}
/**
* this represents a total user query
* includes fields from the query message, both possible query levels
* parses everything up front
*/
class ParsedQuery : boost::noncopyable {
public:
ParsedQuery( QueryMessage& qm )
: _ns( qm.ns ) , _ntoskip( qm.ntoskip ) , _ntoreturn( qm.ntoreturn ) , _options( qm.queryOptions ) {
init( qm.query );
initFields( qm.fields );
}
ParsedQuery( const char* ns , int ntoskip , int ntoreturn , int queryoptions , const BSONObj& query , const BSONObj& fields )
: _ns( ns ) , _ntoskip( ntoskip ) , _ntoreturn( ntoreturn ) , _options( queryoptions ) {
init( query );
initFields( fields );
}
const char * ns() const { return _ns; }
bool isLocalDB() const { return strncmp(_ns, "local.", 6) == 0; }
const BSONObj& getFilter() const { return _filter; }
Projection* getFields() const { return _fields.get(); }
shared_ptr<Projection> getFieldPtr() const { return _fields; }
int getSkip() const { return _ntoskip; }
int getNumToReturn() const { return _ntoreturn; }
bool wantMore() const { return _wantMore; }
int getOptions() const { return _options; }
bool hasOption( int x ) const { return x & _options; }
bool isExplain() const { return _explain; }
bool isSnapshot() const { return _snapshot; }
bool returnKey() const { return _returnKey; }
bool showDiskLoc() const { return _showDiskLoc; }
const BSONObj& getMin() const { return _min; }
const BSONObj& getMax() const { return _max; }
const BSONObj& getOrder() const { return _order; }
const BSONElement& getHint() const { return _hint; }
int getMaxScan() const { return _maxScan; }
bool couldBeCommand() const {
/* we assume you are using findOne() for running a cmd... */
return _ntoreturn == 1 && strstr( _ns , ".$cmd" );
}
bool hasIndexSpecifier() const {
return ! _hint.eoo() || ! _min.isEmpty() || ! _max.isEmpty();
}
/* if ntoreturn is zero, we return up to 101 objects. on the subsequent getmore, there
is only a size limit. The idea is that on a find() where one doesn't use much results,
we don't return much, but once getmore kicks in, we start pushing significant quantities.
The n limit (vs. size) is important when someone fetches only one small field from big
objects, which causes massive scanning server-side.
*/
bool enoughForFirstBatch( int n , int len ) const {
if ( _ntoreturn == 0 )
return ( len > 1024 * 1024 ) || n >= 101;
return n >= _ntoreturn || len > MaxBytesToReturnToClientAtOnce;
}
bool enough( int n ) const {
if ( _ntoreturn == 0 )
return false;
return n >= _ntoreturn;
}
private:
void init( const BSONObj& q ) {
_reset();
uassert( 10105 , "bad skip value in query", _ntoskip >= 0);
if ( _ntoreturn < 0 ) {
/* _ntoreturn greater than zero is simply a hint on how many objects to send back per
"cursor batch".
A negative number indicates a hard limit.
*/
_wantMore = false;
_ntoreturn = -_ntoreturn;
}
BSONElement e = q["query"];
if ( ! e.isABSONObj() )
e = q["$query"];
if ( e.isABSONObj() ) {
_filter = e.embeddedObject();
_initTop( q );
}
else {
_filter = q;
}
}
void _reset() {
_wantMore = true;
_explain = false;
_snapshot = false;
_returnKey = false;
_showDiskLoc = false;
_maxScan = 0;
}
void _initTop( const BSONObj& top ) {
BSONObjIterator i( top );
while ( i.more() ) {
BSONElement e = i.next();
const char * name = e.fieldName();
if ( strcmp( "$orderby" , name ) == 0 ||
strcmp( "orderby" , name ) == 0 ) {
if ( e.type() == Object ) {
_order = e.embeddedObject();
}
else if ( e.type() == Array ) {
_order = transformOrderFromArrayFormat( _order );
}
else {
uasserted(13513, "sort must be an object or array");
}
continue;
}
if( *name == '$' ) {
name++;
if ( strcmp( "explain" , name ) == 0 )
_explain = e.trueValue();
else if ( strcmp( "snapshot" , name ) == 0 )
_snapshot = e.trueValue();
else if ( strcmp( "min" , name ) == 0 )
_min = e.embeddedObject();
else if ( strcmp( "max" , name ) == 0 )
_max = e.embeddedObject();
else if ( strcmp( "hint" , name ) == 0 )
_hint = e;
else if ( strcmp( "returnKey" , name ) == 0 )
_returnKey = e.trueValue();
else if ( strcmp( "maxScan" , name ) == 0 )
_maxScan = e.numberInt();
else if ( strcmp( "showDiskLoc" , name ) == 0 )
_showDiskLoc = e.trueValue();
else if ( strcmp( "comment" , name ) == 0 ) {
; // no-op
}
}
}
if ( _snapshot ) {
uassert( 12001 , "E12001 can't sort with $snapshot", _order.isEmpty() );
uassert( 12002 , "E12002 can't use hint with $snapshot", _hint.eoo() );
}
}
void initFields( const BSONObj& fields ) {
if ( fields.isEmpty() )
return;
_fields.reset( new Projection() );
_fields->init( fields );
}
const char * const _ns;
const int _ntoskip;
int _ntoreturn;
BSONObj _filter;
BSONObj _order;
const int _options;
shared_ptr< Projection > _fields;
bool _wantMore;
bool _explain;
bool _snapshot;
bool _returnKey;
bool _showDiskLoc;
BSONObj _min;
BSONObj _max;
BSONElement _hint;
int _maxScan;
};
} // namespace mongo
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