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// extsort.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 "extsort.h"
#include "namespace-inl.h"
#include "../util/file.h"
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>
namespace mongo {
BSONObj BSONObjExternalSorter::extSortOrder;
unsigned long long BSONObjExternalSorter::_compares = 0;
BSONObjExternalSorter::BSONObjExternalSorter( const BSONObj & order , long maxFileSize )
: _order( order.getOwned() ) , _maxFilesize( maxFileSize ) ,
_arraySize(1000000), _cur(0), _curSizeSoFar(0), _sorted(0){
stringstream rootpath;
rootpath << dbpath;
if ( dbpath[dbpath.size()-1] != '/' )
rootpath << "/";
rootpath << "_tmp/esort." << time(0) << "." << rand() << "/";
_root = rootpath.str();
log(1) << "external sort root: " << _root.string() << endl;
create_directories( _root );
_compares = 0;
}
BSONObjExternalSorter::~BSONObjExternalSorter(){
if ( _cur ){
delete _cur;
_cur = 0;
}
unsigned long removed = remove_all( _root );
wassert( removed == 1 + _files.size() );
}
void BSONObjExternalSorter::_sortInMem(){
// extSortComp needs to use glbals
// qsort_r only seems available on bsd, which is what i really want to use
dblock l;
extSortOrder = _order;
_cur->sort( BSONObjExternalSorter::extSortComp );
}
void BSONObjExternalSorter::sort(){
uassert( 10048 , "already sorted" , ! _sorted );
_sorted = true;
if ( _cur && _files.size() == 0 ){
_sortInMem();
log(1) << "\t\t not using file. size:" << _curSizeSoFar << " _compares:" << _compares << endl;
return;
}
if ( _cur ){
finishMap();
}
if ( _cur ){
delete _cur;
_cur = 0;
}
if ( _files.size() == 0 )
return;
}
void BSONObjExternalSorter::add( const BSONObj& o , const DiskLoc & loc ){
uassert( 10049 , "sorted already" , ! _sorted );
if ( ! _cur ){
_cur = new InMemory( _arraySize );
}
Data& d = _cur->getNext();
d.first = o.getOwned();
d.second = loc;
long size = o.objsize();
_curSizeSoFar += size + sizeof( DiskLoc ) + sizeof( BSONObj );
if ( _cur->hasSpace() == false || _curSizeSoFar > _maxFilesize ){
finishMap();
log(1) << "finishing map" << endl;
}
}
void BSONObjExternalSorter::finishMap(){
uassert( 10050 , "bad" , _cur );
_curSizeSoFar = 0;
if ( _cur->size() == 0 )
return;
_sortInMem();
stringstream ss;
ss << _root.string() << "/file." << _files.size();
string file = ss.str();
ofstream out;
out.open( file.c_str() , ios_base::out | ios_base::binary );
assertStreamGood( 10051 , (string)"couldn't open file: " + file , out );
int num = 0;
for ( InMemory::iterator i=_cur->begin(); i != _cur->end(); ++i ){
Data p = *i;
out.write( p.first.objdata() , p.first.objsize() );
out.write( (char*)(&p.second) , sizeof( DiskLoc ) );
num++;
}
_cur->clear();
_files.push_back( file );
out.close();
log(2) << "Added file: " << file << " with " << num << "objects for external sort" << endl;
}
// ---------------------------------
BSONObjExternalSorter::Iterator::Iterator( BSONObjExternalSorter * sorter ) :
_cmp( sorter->_order ) , _in( 0 ){
for ( list<string>::iterator i=sorter->_files.begin(); i!=sorter->_files.end(); i++ ){
_files.push_back( new FileIterator( *i ) );
_stash.push_back( pair<Data,bool>( Data( BSONObj() , DiskLoc() ) , false ) );
}
if ( _files.size() == 0 && sorter->_cur ){
_in = sorter->_cur;
_it = sorter->_cur->begin();
}
}
BSONObjExternalSorter::Iterator::~Iterator(){
for ( vector<FileIterator*>::iterator i=_files.begin(); i!=_files.end(); i++ )
delete *i;
_files.clear();
}
bool BSONObjExternalSorter::Iterator::more(){
if ( _in )
return _it != _in->end();
for ( vector<FileIterator*>::iterator i=_files.begin(); i!=_files.end(); i++ )
if ( (*i)->more() )
return true;
for ( vector< pair<Data,bool> >::iterator i=_stash.begin(); i!=_stash.end(); i++ )
if ( i->second )
return true;
return false;
}
BSONObjExternalSorter::Data BSONObjExternalSorter::Iterator::next(){
if ( _in ){
Data& d = *_it;
++_it;
return d;
}
Data best;
int slot = -1;
for ( unsigned i=0; i<_stash.size(); i++ ){
if ( ! _stash[i].second ){
if ( _files[i]->more() )
_stash[i] = pair<Data,bool>( _files[i]->next() , true );
else
continue;
}
if ( slot == -1 || _cmp( best , _stash[i].first ) == 0 ){
best = _stash[i].first;
slot = i;
}
}
assert( slot >= 0 );
_stash[slot].second = false;
return best;
}
// -----------------------------------
BSONObjExternalSorter::FileIterator::FileIterator( string file ){
unsigned long long length;
_buf = (char*)_file.map( file.c_str() , length , MemoryMappedFile::SEQUENTIAL );
massert( 10308 , "mmap failed" , _buf );
assert( length == (unsigned long long) file_size( file ) );
_end = _buf + length;
}
BSONObjExternalSorter::FileIterator::~FileIterator() {}
bool BSONObjExternalSorter::FileIterator::more(){
return _buf < _end;
}
BSONObjExternalSorter::Data BSONObjExternalSorter::FileIterator::next(){
BSONObj o( _buf );
_buf += o.objsize();
DiskLoc * l = (DiskLoc*)_buf;
_buf += 8;
return Data( o , *l );
}
}
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