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mr.cpp
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mr.cpp
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// mr.cpp
/**
*
* 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 "stdafx.h"
#include "db.h"
#include "instance.h"
#include "commands.h"
#include "../scripting/engine.h"
#include "../client/dbclient.h"
#include "../client/connpool.h"
#include "../client/parallel.h"
namespace mongo {
namespace mr {
class MyCmp {
public:
MyCmp(){}
bool operator()( const BSONObj &l, const BSONObj &r ) const {
return l.firstElement().woCompare( r.firstElement() ) < 0;
}
};
typedef pair<BSONObj,BSONObj> Data;
//typedef list< Data > InMemory;
typedef map< BSONObj,list<BSONObj>,MyCmp > InMemory;
BSONObj reduceValues( list<BSONObj>& values , Scope * s , ScriptingFunction reduce , bool final , ScriptingFunction finalize ){
uassert( "need values" , values.size() );
int sizeEstimate = ( values.size() * values.begin()->getField( "value" ).size() ) + 128;
BSONObj key;
BSONObjBuilder reduceArgs( sizeEstimate );
BSONObjBuilder valueBuilder( sizeEstimate );
int n = 0;
for ( list<BSONObj>::iterator i=values.begin(); i!=values.end(); i++){
BSONObj o = *i;
BSONObjIterator j(o);
BSONElement keyE = j.next();
if ( n == 0 ){
reduceArgs.append( keyE );
BSONObjBuilder temp;
temp.append( keyE );
key = temp.obj();
}
valueBuilder.appendAs( j.next() , BSONObjBuilder::numStr( n++ ).c_str() );
}
reduceArgs.appendArray( "values" , valueBuilder.obj() );
BSONObj args = reduceArgs.obj();
s->invokeSafe( reduce , args );
if ( s->type( "return" ) == Array ){
uassert("reduce -> multiple not supported yet",0);
return BSONObj();
}
if ( finalize ){
BSONObjBuilder b;
b.appendAs( key.firstElement() , "_id" );
s->append( b , "value" , "return" );
s->invokeSafe( finalize , b.obj() );
}
BSONObjBuilder b;
b.appendAs( key.firstElement() , final ? "_id" : "0" );
s->append( b , final ? "value" : "1" , "return" );
return b.obj();
}
class MRSetup {
public:
MRSetup( const string& _dbname , const BSONObj& cmdObj , bool markAsTemp = true ){
static int jobNumber = 1;
dbname = _dbname;
ns = dbname + "." + cmdObj.firstElement().valuestr();
verbose = cmdObj["verbose"].trueValue();
keeptemp = cmdObj["keeptemp"].trueValue();
{ // setup names
stringstream ss;
if ( ! keeptemp )
ss << "tmp.";
ss << "mr." << cmdObj.firstElement().fieldName() << "_" << time(0) << "_" << jobNumber++;
tempShort = ss.str();
tempLong = dbname + "." + tempShort;
incLong = tempLong + "_inc";
if ( ! keeptemp && markAsTemp )
cc().addTempCollection( tempLong );
if ( cmdObj["out"].type() == String )
finalShort = cmdObj["out"].valuestr();
else
finalShort = tempShort;
finalLong = dbname + "." + finalShort;
}
{ // code
mapCode = cmdObj["map"].ascode();
reduceCode = cmdObj["reduce"].ascode();
if ( cmdObj["finalize"].type() ){
finalizeCode = cmdObj["finalize"].ascode();
}
if ( cmdObj["mapparams"].type() == Array ){
mapparams = cmdObj["mapparams"].embeddedObjectUserCheck();
}
if ( cmdObj["scope"].type() == Object ){
scopeSetup = cmdObj["scope"].embeddedObjectUserCheck();
}
}
{ // query options
if ( cmdObj["query"].type() == Object ){
filter = cmdObj["query"].embeddedObjectUserCheck();
q = filter;
}
if ( cmdObj["sort"].type() == Object )
q.sort( cmdObj["sort"].embeddedObjectUserCheck() );
if ( cmdObj["limit"].isNumber() )
limit = cmdObj["limit"].numberLong();
else
limit = 0;
}
}
/**
@return number objects in collection
*/
long long renameIfNeeded( DBDirectClient& db ){
if ( finalLong != tempLong ){
db.dropCollection( finalLong );
if ( db.count( tempLong ) ){
BSONObj info;
uassert( "rename failed" , db.runCommand( "admin" , BSON( "renameCollection" << tempLong << "to" << finalLong ) , info ) );
}
}
return db.count( finalLong );
}
string dbname;
string ns;
// options
bool verbose;
bool keeptemp;
// query options
BSONObj filter;
Query q;
long long limit;
// functions
string mapCode;
string reduceCode;
string finalizeCode;
BSONObj mapparams;
BSONObj scopeSetup;
// output tables
string incLong;
string tempShort;
string tempLong;
string finalShort;
string finalLong;
}; // end MRsetup
class MRState {
public:
MRState( MRSetup& s ) : setup(s){
scope = globalScriptEngine->getPooledScope( setup.dbname );
scope->localConnect( setup.dbname.c_str() );
map = scope->createFunction( setup.mapCode.c_str() );
reduce = scope->createFunction( setup.reduceCode.c_str() );
if ( setup.finalizeCode.size() )
finalize = scope->createFunction( setup.finalizeCode.c_str() );
else
finalize = 0;
if ( ! setup.scopeSetup.isEmpty() )
scope->init( &setup.scopeSetup );
db.dropCollection( setup.tempLong );
db.dropCollection( setup.incLong );
writelock l( setup.incLong );
string err;
assert( userCreateNS( setup.incLong.c_str() , BSON( "autoIndexId" << 0 ) , err , false ) );
}
void finalReduce( list<BSONObj>& values ){
if ( values.size() == 0 )
return;
BSONObj key = values.begin()->firstElement().wrap( "_id" );
BSONObj res = reduceValues( values , scope.get() , reduce , 1 , finalize );
writelock l( setup.tempLong );
theDataFileMgr.insertAndLog( setup.tempLong.c_str() , res , false );
}
MRSetup& setup;
auto_ptr<Scope> scope;
DBDirectClient db;
ScriptingFunction map;
ScriptingFunction reduce;
ScriptingFunction finalize;
};
class MRTL {
public:
MRTL( MRState& state ) : _state( state ){
_temp = new InMemory();
_size = 0;
numEmits = 0;
}
~MRTL(){
delete _temp;
}
void reduceInMemory(){
InMemory * old = _temp;
InMemory * n = new InMemory();
_temp = n;
_size = 0;
for ( InMemory::iterator i=old->begin(); i!=old->end(); i++ ){
BSONObj key = i->first;
list<BSONObj>& all = i->second;
if ( all.size() == 1 ){
// this key has low cardinality, so just write to db
writelock l(_state.setup.incLong);
write( *(all.begin()) );
}
else if ( all.size() > 1 ){
BSONObj res = reduceValues( all , _state.scope.get() , _state.reduce , false , 0 );
insert( res );
}
}
delete( old );
}
void dump(){
writelock l(_state.setup.incLong);
for ( InMemory::iterator i=_temp->begin(); i!=_temp->end(); i++ ){
list<BSONObj>& all = i->second;
if ( all.size() < 1 )
continue;
for ( list<BSONObj>::iterator j=all.begin(); j!=all.end(); j++ )
write( *j );
}
_temp->clear();
_size = 0;
}
void insert( const BSONObj& a ){
list<BSONObj>& all = (*_temp)[a];
all.push_back( a );
_size += a.objsize() + 16;
}
void checkSize(){
if ( _size < 1024 * 5 )
return;
long before = _size;
reduceInMemory();
log(1) << " mr: did reduceInMemory " << before << " -->> " << _size << endl;
if ( _size < 1024 * 15 )
return;
dump();
log(1) << " mr: dumping to db" << endl;
}
private:
void write( BSONObj& o ){
theDataFileMgr.insert( _state.setup.incLong.c_str() , o , true );
}
MRState& _state;
InMemory * _temp;
long _size;
public:
long long numEmits;
};
boost::thread_specific_ptr<MRTL> _tlmr;
BSONObj fast_emit( const BSONObj& args ){
uassert( "fast_emit takes 2 args" , args.nFields() == 2 );
_tlmr->insert( args );
_tlmr->numEmits++;
return BSONObj();
}
class MapReduceCommand : public Command {
public:
MapReduceCommand() : Command("mapreduce"){}
virtual bool slaveOk() { return true; }
virtual void help( stringstream &help ) const {
help << "see http://www.mongodb.org/display/DOCS/MapReduce";
}
bool run(const char *dbname, BSONObj& cmd, string& errmsg, BSONObjBuilder& result, bool fromRepl ){
Timer t;
Client::GodScope cg;
MRSetup mr( cc().database()->name , cmd );
log(1) << "mr ns: " << mr.ns << endl;
if ( ! db.exists( mr.ns ) ){
errmsg = "ns doesn't exist";
return false;
}
bool shouldHaveData = false;
long long num = 0;
long long inReduce = 0;
BSONObjBuilder countsBuilder;
BSONObjBuilder timingBuilder;
try {
dbtemprelease temprlease;
MRState state( mr );
state.scope->injectNative( "emit" , fast_emit );
MRTL * mrtl = new MRTL( state );
_tlmr.reset( mrtl );
ProgressMeter pm( db.count( mr.ns , mr.filter ) );
auto_ptr<DBClientCursor> cursor = db.query( mr.ns , mr.q );
long long mapTime = 0;
Timer mt;
while ( cursor->more() ){
BSONObj o = cursor->next();
if ( mr.verbose ) mt.reset();
state.scope->setThis( &o );
if ( state.scope->invoke( state.map , state.setup.mapparams , 0 , true ) )
throw UserException( (string)"map invoke failed: " + state.scope->getError() );
if ( mr.verbose ) mapTime += mt.micros();
num++;
if ( num % 100 == 0 ){
Timer t;
mrtl->checkSize();
inReduce += t.micros();
}
pm.hit();
if ( mr.limit && num >= mr.limit )
break;
}
countsBuilder.append( "input" , num );
countsBuilder.append( "emit" , mrtl->numEmits );
if ( mrtl->numEmits )
shouldHaveData = true;
timingBuilder.append( "mapTime" , mapTime / 1000 );
timingBuilder.append( "emitLoop" , t.millis() );
// final reduce
mrtl->reduceInMemory();
mrtl->dump();
BSONObj sortKey = BSON( "0" << 1 );
db.ensureIndex( mr.incLong , sortKey );
BSONObj prev;
list<BSONObj> all;
ProgressMeter fpm( db.count( mr.incLong ) );
cursor = db.query( mr.incLong, Query().sort( sortKey ) );
while ( cursor->more() ){
BSONObj o = cursor->next().getOwned();
if ( o.woSortOrder( prev , sortKey ) == 0 ){
all.push_back( o );
continue;
}
state.finalReduce( all );
all.clear();
prev = o;
all.push_back( o );
fpm.hit();
}
state.finalReduce( all );
_tlmr.reset( 0 );
}
catch ( ... ){
log() << "mr failed, removing collection" << endl;
db.dropCollection( mr.tempLong );
db.dropCollection( mr.incLong );
throw;
}
db.dropCollection( mr.incLong );
long long finalCount = mr.renameIfNeeded( db );
if ( finalCount == 0 && shouldHaveData ){
errmsg = "there were emits but no data!";
return false;
}
timingBuilder.append( "total" , t.millis() );
result.append( "result" , mr.finalShort );
result.append( "timeMillis" , t.millis() );
countsBuilder.append( "output" , finalCount );
if ( mr.verbose ) result.append( "timing" , timingBuilder.obj() );
result.append( "counts" , countsBuilder.obj() );
return true;
}
private:
DBDirectClient db;
} mapReduceCommand;
class MapReduceFinishCommand : public Command {
public:
MapReduceFinishCommand() : Command( "mapreduce.shardedfinish" ){}
virtual bool slaveOk() { return true; }
bool run(const char *ns, BSONObj& cmdObj, string& errmsg, BSONObjBuilder& result, bool){
dbtemprelease temprlease; // we don't touch the db directly
string dbname = cc().database()->name;
string shardedOutputCollection = cmdObj["shardedOutputCollection"].valuestrsafe();
MRSetup mr( dbname , cmdObj.firstElement().embeddedObjectUserCheck() , false );
set<ServerAndQuery> servers;
BSONObjBuilder shardCounts;
map<string,long long> counts;
BSONObj shards = cmdObj["shards"].embeddedObjectUserCheck();
vector< auto_ptr<DBClientCursor> > shardCursors;
BSONObjIterator i( shards );
while ( i.more() ){
BSONElement e = i.next();
string shard = e.fieldName();
BSONObj res = e.embeddedObjectUserCheck();
uassert( "something bad happened" , shardedOutputCollection == res["result"].valuestrsafe() );
servers.insert( shard );
shardCounts.appendAs( res["counts"] , shard.c_str() );
BSONObjIterator j( res["counts"].embeddedObjectUserCheck() );
while ( j.more() ){
BSONElement temp = j.next();
counts[temp.fieldName()] += temp.numberLong();
}
}
BSONObj sortKey = BSON( "_id" << 1 );
ParallelSortClusteredCursor cursor( servers , dbname + "." + shardedOutputCollection ,
Query().sort( sortKey ) );
auto_ptr<Scope> s = globalScriptEngine->getPooledScope( ns );
ScriptingFunction reduceFunction = s->createFunction( mr.reduceCode.c_str() );
ScriptingFunction finalizeFunction = 0;
if ( mr.finalizeCode.size() )
finalizeFunction = s->createFunction( mr.finalizeCode.c_str() );
list<BSONObj> values;
result.append( "result" , mr.finalShort );
DBDirectClient db;
while ( cursor.more() ){
BSONObj t = cursor.next();
if ( values.size() == 0 ){
values.push_back( t );
continue;
}
if ( t.woSortOrder( *(values.begin()) , sortKey ) == 0 ){
values.push_back( t );
continue;
}
db.insert( mr.tempLong , reduceValues( values , s.get() , reduceFunction , 1 , finalizeFunction ) );
values.clear();
values.push_back( t );
}
if ( values.size() )
db.insert( mr.tempLong , reduceValues( values , s.get() , reduceFunction , 1 , finalizeFunction ) );
long long finalCount = mr.renameIfNeeded( db );
log(0) << " mapreducefinishcommand " << mr.finalLong << " " << finalCount << endl;
for ( set<ServerAndQuery>::iterator i=servers.begin(); i!=servers.end(); i++ ){
ScopedDbConnection conn( i->_server );
conn->dropCollection( dbname + "." + shardedOutputCollection );
}
result.append( "shardCounts" , shardCounts.obj() );
{
BSONObjBuilder c;
for ( map<string,long long>::iterator i=counts.begin(); i!=counts.end(); i++ ){
c.append( i->first , i->second );
}
result.append( "counts" , c.obj() );
}
return 1;
}
} mapReduceFinishCommand;
}
}