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mongo/db/commands/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 "pch.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"
#include "../queryoptimizer.h"
#include "../matcher.h"
#include "../clientcursor.h"
#include "../replpair.h"
#include "../../s/d_chunk_manager.h"
#include "../../s/d_logic.h"
#include "mr.h"
namespace mongo {
namespace mr {
AtomicUInt Config::JOB_NUMBER;
JSFunction::JSFunction( string type , const BSONElement& e ) {
_type = type;
_code = e._asCode();
if ( e.type() == CodeWScope )
_wantedScope = e.codeWScopeObject();
}
void JSFunction::init( State * state ) {
_scope = state->scope();
assert( _scope );
_scope->init( &_wantedScope );
_func = _scope->createFunction( _code.c_str() );
uassert( 13598 , str::stream() << "couldn't compile code for: " << _type , _func );
}
void JSMapper::init( State * state ) {
_func.init( state );
_params = state->config().mapParams;
}
/**
* Applies the map function to an object, which should internally call emit()
*/
void JSMapper::map( const BSONObj& o ) {
Scope * s = _func.scope();
assert( s );
s->setThis( &o );
if ( s->invoke( _func.func() , _params , 0 , true ) )
throw UserException( 9014, str::stream() << "map invoke failed: " + s->getError() );
}
/**
* Applies the finalize function to a tuple obj (key, val)
* Returns tuple obj {_id: key, value: newval}
*/
BSONObj JSFinalizer::finalize( const BSONObj& o ) {
Scope * s = _func.scope();
Scope::NoDBAccess no = s->disableDBAccess( "can't access db inside finalize" );
s->invokeSafe( _func.func() , o );
// don't want to use o.objsize() to size b
// since there are many cases where the point of finalize
// is converting many fields to 1
BSONObjBuilder b;
b.append( o.firstElement() );
s->append( b , "value" , "return" );
return b.obj();
}
/**
* Reduces a list of tuple objects (key, value) to a single tuple {"0": key, "1": value}
*/
BSONObj JSReducer::reduce( const BSONList& tuples ) {
if (tuples.size() <= 1)
return tuples[0];
BSONObj key;
int endSizeEstimate = 16;
_reduce( tuples , key , endSizeEstimate );
BSONObjBuilder b(endSizeEstimate);
b.appendAs( key.firstElement() , "0" );
_func.scope()->append( b , "1" , "return" );
return b.obj();
}
/**
* Reduces a list of tuple object (key, value) to a single tuple {_id: key, value: val}
* Also applies a finalizer method if present.
*/
BSONObj JSReducer::finalReduce( const BSONList& tuples , Finalizer * finalizer ) {
BSONObj res;
BSONObj key;
if (tuples.size() == 1) {
// 1 obj, just use it
key = tuples[0];
BSONObjBuilder b(key.objsize());
BSONObjIterator it(key);
b.appendAs( it.next() , "_id" );
b.appendAs( it.next() , "value" );
res = b.obj();
}
else {
// need to reduce
int endSizeEstimate = 16;
_reduce( tuples , key , endSizeEstimate );
BSONObjBuilder b(endSizeEstimate);
b.appendAs( key.firstElement() , "_id" );
_func.scope()->append( b , "value" , "return" );
res = b.obj();
}
if ( finalizer ) {
res = finalizer->finalize( res );
}
return res;
}
/**
* actually applies a reduce, to a list of tuples (key, value).
* After the call, tuples will hold a single tuple {"0": key, "1": value}
*/
void JSReducer::_reduce( const BSONList& tuples , BSONObj& key , int& endSizeEstimate ) {
uassert( 10074 , "need values" , tuples.size() );
int sizeEstimate = ( tuples.size() * tuples.begin()->getField( "value" ).size() ) + 128;
// need to build the reduce args: ( key, [values] )
BSONObjBuilder reduceArgs( sizeEstimate );
boost::scoped_ptr<BSONArrayBuilder> valueBuilder;
int sizeSoFar = 0;
unsigned n = 0;
for ( ; n<tuples.size(); n++ ) {
BSONObjIterator j(tuples[n]);
BSONElement keyE = j.next();
if ( n == 0 ) {
reduceArgs.append( keyE );
key = keyE.wrap();
sizeSoFar = 5 + keyE.size();
valueBuilder.reset(new BSONArrayBuilder( reduceArgs.subarrayStart( "tuples" ) ));
}
BSONElement ee = j.next();
uassert( 13070 , "value too large to reduce" , ee.size() < ( BSONObjMaxUserSize / 2 ) );
if ( sizeSoFar + ee.size() > BSONObjMaxUserSize ) {
assert( n > 1 ); // if not, inf. loop
break;
}
valueBuilder->append( ee );
sizeSoFar += ee.size();
}
assert(valueBuilder);
valueBuilder->done();
BSONObj args = reduceArgs.obj();
Scope * s = _func.scope();
s->invokeSafe( _func.func() , args );
if ( s->type( "return" ) == Array ) {
uasserted( 10075 , "reduce -> multiple not supported yet");
return;
}
endSizeEstimate = key.objsize() + ( args.objsize() / tuples.size() );
if ( n == tuples.size() )
return;
// the input list was too large, add the rest of elmts to new tuples and reduce again
// note: would be better to use loop instead of recursion to avoid stack overflow
BSONList x;
for ( ; n < tuples.size(); n++ ) {
x.push_back( tuples[n] );
}
BSONObjBuilder temp( endSizeEstimate );
temp.append( key.firstElement() );
s->append( temp , "1" , "return" );
x.push_back( temp.obj() );
_reduce( x , key , endSizeEstimate );
}
Config::Config( const string& _dbname , const BSONObj& cmdObj ) {
dbname = _dbname;
ns = dbname + "." + cmdObj.firstElement().valuestr();
verbose = cmdObj["verbose"].trueValue();
uassert( 13602 , "outType is no longer a valid option" , cmdObj["outType"].eoo() );
if ( cmdObj["out"].type() == String ) {
finalShort = cmdObj["out"].String();
outType = REPLACE;
}
else if ( cmdObj["out"].type() == Object ) {
BSONObj o = cmdObj["out"].embeddedObject();
BSONElement e = o.firstElement();
string t = e.fieldName();
if ( t == "normal" || t == "replace" ) {
outType = REPLACE;
finalShort = e.String();
}
else if ( t == "merge" ) {
outType = MERGE;
finalShort = e.String();
}
else if ( t == "reduce" ) {
outType = REDUCE;
finalShort = e.String();
}
else if ( t == "inline" ) {
outType = INMEMORY;
}
else {
uasserted( 13522 , str::stream() << "unknown out specifier [" << t << "]" );
}
if (o.hasElement("db")) {
outDB = o["db"].String();
}
}
else {
uasserted( 13606 , "'out' has to be a string or an object" );
}
if ( outType != INMEMORY ) { // setup names
tempLong = str::stream() << (outDB.empty() ? dbname : outDB) << ".tmp.mr." << cmdObj.firstElement().String() << "_" << finalShort << "_" << JOB_NUMBER++;
incLong = tempLong + "_inc";
finalLong = str::stream() << (outDB.empty() ? dbname : outDB) << "." << finalShort;
}
{
// scope and code
if ( cmdObj["scope"].type() == Object )
scopeSetup = cmdObj["scope"].embeddedObjectUserCheck();
mapper.reset( new JSMapper( cmdObj["map"] ) );
reducer.reset( new JSReducer( cmdObj["reduce"] ) );
if ( cmdObj["finalize"].type() && cmdObj["finalize"].trueValue() )
finalizer.reset( new JSFinalizer( cmdObj["finalize"] ) );
if ( cmdObj["mapparams"].type() == Array ) {
mapParams = cmdObj["mapparams"].embeddedObjectUserCheck();
}
}
{
// query options
BSONElement q = cmdObj["query"];
if ( q.type() == Object )
filter = q.embeddedObjectUserCheck();
else
uassert( 13608 , "query has to be blank or an Object" , ! q.trueValue() );
BSONElement s = cmdObj["sort"];
if ( s.type() == Object )
sort = s.embeddedObjectUserCheck();
else
uassert( 13609 , "sort has to be blank or an Object" , ! s.trueValue() );
if ( cmdObj["limit"].isNumber() )
limit = cmdObj["limit"].numberLong();
else
limit = 0;
}
}
/**
* Create temporary collection, set up indexes
*/
void State::prepTempCollection() {
if ( ! _onDisk )
return;
_db.dropCollection( _config.tempLong );
{
// create
writelock lock( _config.tempLong.c_str() );
Client::Context ctx( _config.tempLong.c_str() );
string errmsg;
if ( ! userCreateNS( _config.tempLong.c_str() , BSONObj() , errmsg , true ) ) {
uasserted( 13630 , str::stream() << "userCreateNS failed for mr tempLong ns: " << _config.tempLong << " err: " << errmsg );
}
}
{
// copy indexes
auto_ptr<DBClientCursor> idx = _db.getIndexes( _config.finalLong );
while ( idx->more() ) {
BSONObj i = idx->next();
BSONObjBuilder b( i.objsize() + 16 );
b.append( "ns" , _config.tempLong );
BSONObjIterator j( i );
while ( j.more() ) {
BSONElement e = j.next();
if ( str::equals( e.fieldName() , "_id" ) ||
str::equals( e.fieldName() , "ns" ) )
continue;
b.append( e );
}
BSONObj indexToInsert = b.obj();
insert( Namespace( _config.tempLong.c_str() ).getSisterNS( "system.indexes" ).c_str() , indexToInsert );
}
}
}
/**
* For inline mode, appends results to output object.
* Makes sure (key, value) tuple is formatted as {_id: key, value: val}
*/
void State::appendResults( BSONObjBuilder& final ) {
if ( _onDisk )
return;
uassert( 13604 , "too much data for in memory map/reduce" , _size < ( BSONObjMaxUserSize / 2 ) );
BSONArrayBuilder b( (int)(_size * 1.2) ); // _size is data size, doesn't count overhead and keys
for ( InMemory::iterator i=_temp->begin(); i!=_temp->end(); ++i ) {
BSONObj key = i->first;
BSONList& all = i->second;
assert( all.size() == 1 );
BSONObjIterator vi( all[0] );
vi.next();
BSONObjBuilder temp( b.subobjStart() );
temp.appendAs( key.firstElement() , "_id" );
temp.appendAs( vi.next() , "value" );
temp.done();
}
BSONArray res = b.arr();
uassert( 13605 , "too much data for in memory map/reduce" , res.objsize() < ( BSONObjMaxUserSize * 2 / 3 ) );
final.append( "results" , res );
}
/**
* Does post processing on output collection.
* This may involve replacing, merging or reducing.
*/
long long State::postProcessCollection() {
if ( _onDisk == false || _config.outType == Config::INMEMORY )
return _temp->size();
dblock lock;
if ( _config.finalLong == _config.tempLong )
return _db.count( _config.finalLong );
if ( _config.outType == Config::REPLACE || _db.count( _config.finalLong ) == 0 ) {
// replace: just rename from temp to final collection name, dropping previous collection
_db.dropCollection( _config.finalLong );
BSONObj info;
uassert( 10076 , "rename failed" ,
_db.runCommand( "admin" , BSON( "renameCollection" << _config.tempLong << "to" << _config.finalLong ) , info ) );
_db.dropCollection( _config.tempLong );
}
else if ( _config.outType == Config::MERGE ) {
// merge: upsert new docs into old collection
auto_ptr<DBClientCursor> cursor = _db.query( _config.tempLong , BSONObj() );
while ( cursor->more() ) {
BSONObj o = cursor->next();
Helpers::upsert( _config.finalLong , o );
getDur().commitIfNeeded();
}
_db.dropCollection( _config.tempLong );
}
else if ( _config.outType == Config::REDUCE ) {
// reduce: apply reduce op on new result and existing one
BSONList values;
auto_ptr<DBClientCursor> cursor = _db.query( _config.tempLong , BSONObj() );
while ( cursor->more() ) {
BSONObj temp = cursor->next();
BSONObj old;
bool found;
{
Client::Context tx( _config.finalLong );
found = Helpers::findOne( _config.finalLong.c_str() , temp["_id"].wrap() , old , true );
}
if ( found ) {
// need to reduce
values.clear();
values.push_back( temp );
values.push_back( old );
Helpers::upsert( _config.finalLong , _config.reducer->finalReduce( values , _config.finalizer.get() ) );
}
else {
Helpers::upsert( _config.finalLong , temp );
}
getDur().commitIfNeeded();
}
_db.dropCollection( _config.tempLong );
}
return _db.count( _config.finalLong );
}
/**
* Insert doc in collection
*/
void State::insert( const string& ns , BSONObj& o ) {
assert( _onDisk );
writelock l( ns );
Client::Context ctx( ns );
theDataFileMgr.insertAndLog( ns.c_str() , o , false );
}
/**
* Insert doc into the inc collection
*/
void State::_insertToInc( BSONObj& o ) {
assert( _onDisk );
theDataFileMgr.insertWithObjMod( _config.incLong.c_str() , o , true );
getDur().commitIfNeeded();
}
State::State( const Config& c ) : _config( c ), _size(0), _numEmits(0) {
_temp.reset( new InMemory() );
_onDisk = _config.outType != Config::INMEMORY;
}
bool State::sourceExists() {
return _db.exists( _config.ns );
}
long long State::incomingDocuments() {
return _db.count( _config.ns , _config.filter , QueryOption_SlaveOk , (unsigned) _config.limit );
}
State::~State() {
if ( _onDisk ) {
try {
_db.dropCollection( _config.tempLong );
_db.dropCollection( _config.incLong );
}
catch ( std::exception& e ) {
error() << "couldn't cleanup after map reduce: " << e.what() << endl;
}
}
}
/**
* Initialize the mapreduce operation, creating the inc collection
*/
void State::init() {
// setup js
_scope.reset(globalScriptEngine->getPooledScope( _config.dbname ).release() );
_scope->localConnect( _config.dbname.c_str() );
if ( ! _config.scopeSetup.isEmpty() )
_scope->init( &_config.scopeSetup );
_config.mapper->init( this );
_config.reducer->init( this );
if ( _config.finalizer )
_config.finalizer->init( this );
_scope->injectNative( "emit" , fast_emit );
if ( _onDisk ) {
// clear temp collections
_db.dropCollection( _config.tempLong );
_db.dropCollection( _config.incLong );
// create the inc collection and make sure we have index on "0" key
{
writelock l( _config.incLong );
Client::Context ctx( _config.incLong );
string err;
if ( ! userCreateNS( _config.incLong.c_str() , BSON( "autoIndexId" << 0 ) , err , false ) ) {
uasserted( 13631 , str::stream() << "userCreateNS failed for mr incLong ns: " << _config.incLong << " err: " << err );
}
}
BSONObj sortKey = BSON( "0" << 1 );
_db.ensureIndex( _config.incLong , sortKey );
}
}
/**
* Applies last reduce and finalize on a list of tuples (key, val)
* Inserts single result {_id: key, value: val} into temp collection
*/
void State::finalReduce( BSONList& values ) {
if ( !_onDisk || values.size() == 0 )
return;
BSONObj res = _config.reducer->finalReduce( values , _config.finalizer.get() );
insert( _config.tempLong , res );
}
/**
* Applies last reduce and finalize.
* After calling this method, the temp collection will be completed.
* If inline, the results will be in the in memory map
*/
void State::finalReduce( CurOp * op , ProgressMeterHolder& pm ) {
if ( ! _onDisk ) {
// all data has already been reduced, just finalize
if ( _config.finalizer ) {
long size = 0;
for ( InMemory::iterator i=_temp->begin(); i!=_temp->end(); ++i ) {
BSONObj key = i->first;
BSONList& all = i->second;
assert( all.size() == 1 );
BSONObj res = _config.finalizer->finalize( all[0] );
all.clear();
all.push_back( res );
size += res.objsize();
}
_size = size;
}
return;
}
// use index on "0" to pull sorted data
assert( _temp->size() == 0 );
BSONObj sortKey = BSON( "0" << 1 );
{
bool foundIndex = false;
auto_ptr<DBClientCursor> idx = _db.getIndexes( _config.incLong );
while ( idx.get() && idx->more() ) {
BSONObj x = idx->next();
if ( sortKey.woCompare( x["key"].embeddedObject() ) == 0 ) {
foundIndex = true;
break;
}
}
assert( foundIndex );
}
readlock rl( _config.incLong.c_str() );
Client::Context ctx( _config.incLong );
BSONObj prev;
BSONList all;
assert( pm == op->setMessage( "m/r: (3/3) final reduce to collection" , _db.count( _config.incLong, BSONObj(), QueryOption_SlaveOk ) ) );
shared_ptr<Cursor> temp = bestGuessCursor( _config.incLong.c_str() , BSONObj() , sortKey );
auto_ptr<ClientCursor> cursor( new ClientCursor( QueryOption_NoCursorTimeout , temp , _config.incLong.c_str() ) );
// iterate over all sorted objects
while ( cursor->ok() ) {
BSONObj o = cursor->current().getOwned();
cursor->advance();
pm.hit();
if ( o.woSortOrder( prev , sortKey ) == 0 ) {
// object is same as previous, add to array
all.push_back( o );
if ( pm->hits() % 1000 == 0 ) {
if ( ! cursor->yield() ) {
cursor.release();
break;
}
killCurrentOp.checkForInterrupt();
}
continue;
}
ClientCursor::YieldLock yield (cursor.get());
// reduce an finalize array
finalReduce( all );
all.clear();
prev = o;
all.push_back( o );
if ( ! yield.stillOk() ) {
cursor.release();
break;
}
killCurrentOp.checkForInterrupt();
}
// we need to release here since we temp release below
cursor.release();
{
dbtempreleasecond tl;
if ( ! tl.unlocked() )
log( LL_WARNING ) << "map/reduce can't temp release" << endl;
// reduce and finalize last array
finalReduce( all );
}
pm.finished();
}
/**
* Attempts to reduce objects in the memory map.
* A new memory map will be created to hold the results.
* If applicable, objects with unique key may be dumped to inc collection.
* Input and output objects are both {"0": key, "1": val}
*/
void State::reduceInMemory() {
auto_ptr<InMemory> n( new InMemory() ); // for new data
long nSize = 0;
long dupCount = 0;
for ( InMemory::iterator i=_temp->begin(); i!=_temp->end(); ++i ) {
BSONObj key = i->first;
BSONList& all = i->second;
if ( all.size() == 1 ) {
// only 1 value for this key
if ( _onDisk ) {
// this key has low cardinality, so just write to collection
writelock l(_config.incLong);
Client::Context ctx(_config.incLong.c_str());
_insertToInc( *(all.begin()) );
}
else {
// add to new map
_add( n.get() , all[0] , nSize, dupCount );
}
}
else if ( all.size() > 1 ) {
// several values, reduce and add to map
BSONObj res = _config.reducer->reduce( all );
_add( n.get() , res , nSize, dupCount );
}
}
// swap maps
_temp.reset( n.release() );
_size = nSize;
_dupCount = dupCount;
}
/**
* Dumps the entire in memory map to the inc collection.
*/
void State::dumpToInc() {
if ( ! _onDisk )
return;
writelock l(_config.incLong);
Client::Context ctx(_config.incLong);
for ( InMemory::iterator i=_temp->begin(); i!=_temp->end(); i++ ) {
BSONList& all = i->second;
if ( all.size() < 1 )
continue;
for ( BSONList::iterator j=all.begin(); j!=all.end(); j++ )
_insertToInc( *j );
}
_temp->clear();
_size = 0;
}
/**
* Adds object to in memory map
*/
void State::emit( const BSONObj& a ) {
_numEmits++;
_add( _temp.get() , a , _size, _dupCount );
}
void State::_add( InMemory* im, const BSONObj& a , long& size, long& dupCount ) {
BSONList& all = (*im)[a];
all.push_back( a );
size += a.objsize() + 16;
if (all.size() > 1)
++dupCount;
}
/**
* this method checks the size of in memory map and potentially flushes to disk
*/
void State::checkSize() {
if ( _size < 1024 * 50 )
return;
// attempt to reduce in memory map, if we've seen duplicates
if ( _dupCount > 0) {
long before = _size;
reduceInMemory();
log(1) << " mr: did reduceInMemory " << before << " -->> " << _size << endl;
}
if ( ! _onDisk || _size < 1024 * 100 )
return;
dumpToInc();
log(1) << " mr: dumping to db" << endl;
}
boost::thread_specific_ptr<State*> _tl;
/**
* emit that will be called by js function
*/
BSONObj fast_emit( const BSONObj& args ) {
uassert( 10077 , "fast_emit takes 2 args" , args.nFields() == 2 );
uassert( 13069 , "an emit can't be more than half max bson size" , args.objsize() < ( BSONObjMaxUserSize / 2 ) );
(*_tl)->emit( args );
return BSONObj();
}
/**
* This class represents a map/reduce command executed on a single server
*/
class MapReduceCommand : public Command {
public:
MapReduceCommand() : Command("mapReduce", false, "mapreduce") {}
virtual bool slaveOk() const { return !replSet; }
virtual bool slaveOverrideOk() { return true; }
virtual void help( stringstream &help ) const {
help << "Run a map/reduce operation on the server.\n";
help << "Note this is used for aggregation, not querying, in MongoDB.\n";
help << "http://www.mongodb.org/display/DOCS/MapReduce";
}
virtual LockType locktype() const { return NONE; }
bool run(const string& dbname , BSONObj& cmd, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
Timer t;
Client::GodScope cg;
Client& client = cc();
CurOp * op = client.curop();
Config config( dbname , cmd );
log(1) << "mr ns: " << config.ns << endl;
bool shouldHaveData = false;
long long num = 0;
long long inReduce = 0;
BSONObjBuilder countsBuilder;
BSONObjBuilder timingBuilder;
State state( config );
if ( ! state.sourceExists() ) {
errmsg = "ns doesn't exist";
return false;
}
if (replSet && state.isOnDisk()) {
// this means that it will be doing a write operation, make sure we are on Master
// ideally this check should be in slaveOk(), but at that point config is not known
if (!isMaster(dbname.c_str())) {
errmsg = "not master";
return false;
}
}
try {
state.init();
{
State** s = new State*();
s[0] = &state;
_tl.reset( s );
}
wassert( config.limit < 0x4000000 ); // see case on next line to 32 bit unsigned
ProgressMeterHolder pm( op->setMessage( "m/r: (1/3) emit phase" , state.incomingDocuments() ) );
long long mapTime = 0;
{
readlock lock( config.ns );
Client::Context ctx( config.ns );
ShardChunkManagerPtr chunkManager;
if ( shardingState.needShardChunkManager( config.ns ) ) {
chunkManager = shardingState.getShardChunkManager( config.ns );
}
// obtain cursor on data to apply mr to, sorted
shared_ptr<Cursor> temp = bestGuessCursor( config.ns.c_str(), config.filter, config.sort );
auto_ptr<ClientCursor> cursor( new ClientCursor( QueryOption_NoCursorTimeout , temp , config.ns.c_str() ) );
Timer mt;
// go through each doc
while ( cursor->ok() ) {
// make sure we dont process duplicates in case data gets moved around during map
if ( cursor->currentIsDup() ) {
cursor->advance();
continue;
}
if ( ! cursor->currentMatches() ) {
cursor->advance();
continue;
}
BSONObj o = cursor->current();
cursor->advance();
// check to see if this is a new object we don't own yet
// because of a chunk migration
if ( chunkManager && ! chunkManager->belongsToMe( o ) )
continue;
// do map
if ( config.verbose ) mt.reset();
config.mapper->map( o );
if ( config.verbose ) mapTime += mt.micros();
num++;
if ( num % 100 == 0 ) {
// try to yield lock regularly
ClientCursor::YieldLock yield (cursor.get());
Timer t;
// check if map needs to be dumped to disk
state.checkSize();
inReduce += t.micros();
if ( ! yield.stillOk() ) {
cursor.release();
break;
}
killCurrentOp.checkForInterrupt();
}
pm.hit();
if ( config.limit && num >= config.limit )
break;
}
}
pm.finished();
killCurrentOp.checkForInterrupt();
// update counters
countsBuilder.appendNumber( "input" , num );
countsBuilder.appendNumber( "emit" , state.numEmits() );
if ( state.numEmits() )
shouldHaveData = true;
timingBuilder.append( "mapTime" , mapTime / 1000 );
timingBuilder.append( "emitLoop" , t.millis() );
op->setMessage( "m/r: (2/3) final reduce in memory" );
// do reduce in memory
// this will be the last reduce needed for inline mode
state.reduceInMemory();
// if not inline: dump the in memory map to inc collection, all data is on disk
state.dumpToInc();
state.prepTempCollection();
// final reduce
state.finalReduce( op , pm );
_tl.reset();
}
catch ( ... ) {
log() << "mr failed, removing collection" << endl;
throw;
}
long long finalCount = state.postProcessCollection();
state.appendResults( result );
timingBuilder.append( "total" , t.millis() );
if (!config.outDB.empty()) {
BSONObjBuilder loc;
if ( !config.outDB.empty())
loc.append( "db" , config.outDB );
if ( !config.finalShort.empty() )
loc.append( "collection" , config.finalShort );
result.append("result", loc.obj());
}
else {
if ( !config.finalShort.empty() )
result.append( "result" , config.finalShort );
}
result.append( "timeMillis" , t.millis() );
countsBuilder.appendNumber( "output" , finalCount );
if ( config.verbose ) result.append( "timing" , timingBuilder.obj() );
result.append( "counts" , countsBuilder.obj() );
if ( finalCount == 0 && shouldHaveData ) {
result.append( "cmd" , cmd );
errmsg = "there were emits but no data!";
return false;
}
return true;
}
} mapReduceCommand;
/**
* This class represents a map/reduce command executed on the output server of a sharded env
*/
class MapReduceFinishCommand : public Command {
public:
MapReduceFinishCommand() : Command( "mapreduce.shardedfinish" ) {}
virtual bool slaveOk() const { return !replSet; }
virtual bool slaveOverrideOk() { return true; }
virtual LockType locktype() const { return NONE; }
bool run(const string& dbname , BSONObj& cmdObj, string& errmsg, BSONObjBuilder& result, bool) {
string shardedOutputCollection = cmdObj["shardedOutputCollection"].valuestrsafe();
Config config( dbname , cmdObj.firstElement().embeddedObjectUserCheck() );
config.incLong = config.tempLong;
set<ServerAndQuery> servers;
BSONObjBuilder shardCounts;
map<string,long long> counts;
BSONObj shards = cmdObj["shards"].embeddedObjectUserCheck();
vector< auto_ptr<DBClientCursor> > shardCursors;
{
// parse per shard results
BSONObjIterator i( shards );
while ( i.more() ) {
BSONElement e = i.next();
string shard = e.fieldName();
BSONObj res = e.embeddedObjectUserCheck();
uassert( 10078 , "something bad happened" , shardedOutputCollection == res["result"].valuestrsafe() );
servers.insert( shard );
shardCounts.appendAs( res["counts"] , shard );
BSONObjIterator j( res["counts"].embeddedObjectUserCheck() );
while ( j.more() ) {
BSONElement temp = j.next();
counts[temp.fieldName()] += temp.numberLong();
}
}
}
State state(config);
state.prepTempCollection();
{
// reduce from each stream
BSONObj sortKey = BSON( "_id" << 1 );
ParallelSortClusteredCursor cursor( servers , dbname + "." + shardedOutputCollection ,
Query().sort( sortKey ) );
cursor.init();
state.init();
BSONList values;
if (!config.outDB.empty()) {
BSONObjBuilder loc;
if ( !config.outDB.empty())
loc.append( "db" , config.outDB );
if ( !config.finalShort.empty() )
loc.append( "collection" , config.finalShort );
result.append("result", loc.obj());
}
else {
if ( !config.finalShort.empty() )
result.append( "result" , config.finalShort );
}
while ( cursor.more() ) {
BSONObj t = cursor.next().getOwned();
if ( values.size() == 0 ) {
values.push_back( t );
continue;
}
if ( t.woSortOrder( *(values.begin()) , sortKey ) == 0 ) {
values.push_back( t );
continue;
}
state.emit( config.reducer->finalReduce( values , config.finalizer.get() ) );
values.clear();
values.push_back( t );
}
if ( values.size() )
state.emit( config.reducer->finalReduce( values , config.finalizer.get() ) );
}
state.dumpToInc();
state.postProcessCollection();
state.appendResults( result );
for ( set<ServerAndQuery>::iterator i=servers.begin(); i!=servers.end(); i++ ) {
ScopedDbConnection conn( i->_server );
conn->dropCollection( dbname + "." + shardedOutputCollection );
conn.done();
}
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;
}
}
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