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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 "../replutil.h"
#include "../../s/d_chunk_manager.h"
#include "../../s/d_logic.h"
#include "../../s/grid.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 );
// install in JS scope so that it can be called in JS mode
_scope->setFunction(_type.c_str(), _code.c_str());
}
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 );
if ( s->invoke( _func.func() , &_params, &o , 0 , true, false, 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, 0 );
// 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();
}
void JSReducer::init( State * state ) {
_func.init( state );
}
/**
* 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, 0, 0, false, true, true );
++numReduces;
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();
jsMode = cmdObj["jsMode"].trueValue();
splitInfo = 0;
if (cmdObj.hasField("splitInfo"))
splitInfo = cmdObj["splitInfo"].Int();
jsMaxKeys = 500000;
reduceTriggerRatio = 10.0;
maxInMemSize = 500 * 1024;
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();
}
if (o.hasElement("nonAtomic")) {
outNonAtomic = o["nonAtomic"].Bool();
if (outNonAtomic)
uassert( 15895 , "nonAtomic option cannot be used with this output type", (outType == REDUCE || outType == MERGE) );
}
}
else {
uasserted( 13606 , "'out' has to be a string or an object" );
}
shardedFirstPass = false;
if (cmdObj.hasField("shardedFirstPass") && cmdObj["shardedFirstPass"].trueValue()){
massert(16054, "shardedFirstPass should only use replace outType", outType == REPLACE);
shardedFirstPass = true;
}
if ( outType != INMEMORY ) { // setup names
tempLong = str::stream() << (outDB.empty() ? dbname : outDB) << ".tmp.mr." << cmdObj.firstElement().String() << "_" << 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;
if (_config.incLong != _config.tempLong) {
// create the inc collection and make sure we have index on "0" key
_db.dropCollection( _config.incLong );
{
writelock l( _config.incLong );
Client::Context ctx( _config.incLong );
string err;
if ( ! userCreateNS( _config.incLong.c_str() , BSON( "autoIndexId" << 0 << "temp" << true ) , 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 );
}
// create temp collection
_db.dropCollection( _config.tempLong );
{
writelock lock( _config.tempLong.c_str() );
Client::Context ctx( _config.tempLong.c_str() );
string errmsg;
if ( ! userCreateNS( _config.tempLong.c_str() , BSON("temp" << true) , 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 ) {
if (!_config.outDB.empty()) {
BSONObjBuilder loc;
if ( !_config.outDB.empty())
loc.append( "db" , _config.outDB );
if ( !_config.finalShort.empty() )
loc.append( "collection" , _config.finalShort );
final.append("result", loc.obj());
}
else {
if ( !_config.finalShort.empty() )
final.append( "result" , _config.finalShort );
}
if ( _config.splitInfo > 0 ) {
// add split points, used for shard
BSONObj res;
BSONObj idKey = BSON( "_id" << 1 );
if ( ! _db.runCommand( "admin" , BSON( "splitVector" << _config.finalLong << "keyPattern" << idKey << "maxChunkSizeBytes" << _config.splitInfo ) , res ) ) {
uasserted( 15921 , str::stream() << "splitVector failed: " << res );
}
if ( res.hasField( "splitKeys" ) )
final.append( res.getField( "splitKeys" ) );
}
return;
}
if (_jsMode) {
ScriptingFunction getResult = _scope->createFunction("var map = _mrMap; var result = []; for (key in map) { result.push({_id: key, value: map[key]}) } return result;");
_scope->invoke(getResult, 0, 0, 0, false);
BSONObj obj = _scope->getObject("return");
final.append("results", BSONArray(obj));
return;
}
uassert( 13604 , "too much data for in memory map/reduce" , _size < BSONObjMaxUserSize );
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();
final.append( "results" , res );
}
/**
* Does post processing on output collection.
* This may involve replacing, merging or reducing.
*/
long long State::postProcessCollection(CurOp* op, ProgressMeterHolder& pm) {
if ( _onDisk == false || _config.outType == Config::INMEMORY )
return _temp->size();
if (_config.outNonAtomic)
return postProcessCollectionNonAtomic(op, pm);
writelock lock;
return postProcessCollectionNonAtomic(op, pm);
}
long long State::postProcessCollectionNonAtomic(CurOp* op, ProgressMeterHolder& pm) {
if ( _config.finalLong == _config.tempLong )
return _db.count( _config.finalLong );
if ( _config.outType == Config::REPLACE || _db.count( _config.finalLong ) == 0 ) {
writelock lock;
// replace: just rename from temp to final collection name, dropping previous collection
_db.dropCollection( _config.finalLong );
BSONObj info;
if ( ! _db.runCommand( "admin"
, BSON( "renameCollection" << _config.tempLong <<
"to" << _config.finalLong <<
"stayTemp" << _config.shardedFirstPass )
, info ) ) {
uasserted( 10076 , str::stream() << "rename failed: " << info );
}
_db.dropCollection( _config.tempLong );
}
else if ( _config.outType == Config::MERGE ) {
// merge: upsert new docs into old collection
op->setMessage( "m/r: merge post processing" , _db.count( _config.tempLong, BSONObj() ) );
auto_ptr<DBClientCursor> cursor = _db.query( _config.tempLong , BSONObj() );
while ( cursor->more() ) {
writelock lock;
BSONObj o = cursor->next();
Helpers::upsert( _config.finalLong , o );
getDur().commitIfNeeded();
pm.hit();
}
_db.dropCollection( _config.tempLong );
pm.finished();
}
else if ( _config.outType == Config::REDUCE ) {
// reduce: apply reduce op on new result and existing one
BSONList values;
op->setMessage( "m/r: reduce post processing" , _db.count( _config.tempLong, BSONObj() ) );
auto_ptr<DBClientCursor> cursor = _db.query( _config.tempLong , BSONObj() );
while ( cursor->more() ) {
writelock lock;
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();
pm.hit();
}
_db.dropCollection( _config.tempLong );
pm.finished();
}
return _db.count( _config.finalLong );
}
/**
* Insert doc in collection
*/
void State::insert( const string& ns , const BSONObj& o ) {
assert( _onDisk );
writelock l( ns );
Client::Context ctx( ns );
theDataFileMgr.insertAndLog( ns.c_str() , o , false );
}
/**
* Insert doc into the inc collection, taking proper lock
*/
void State::insertToInc( BSONObj& o ) {
writelock l(_config.incLong);
Client::Context ctx(_config.incLong);
_insertToInc(o);
}
/**
* 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), _dupCount(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;
}
}
if (_scope) {
// cleanup js objects
ScriptingFunction cleanup = _scope->createFunction("delete _emitCt; delete _keyCt; delete _mrMap;");
_scope->invoke(cleanup, 0, 0, 0, true);
}
}
/**
* 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->setBoolean("_doFinal", _config.finalizer);
// by default start in JS mode, will be faster for small jobs
_jsMode = _config.jsMode;
// _jsMode = true;
switchMode(_jsMode);
// global JS map/reduce hashmap
// we use a standard JS object which means keys are only simple types
// we could also add a real hashmap from a library, still we need to add object comparison methods
// _scope->setObject("_mrMap", BSONObj(), false);
ScriptingFunction init = _scope->createFunction("_emitCt = 0; _keyCt = 0; _dupCt = 0; _redCt = 0; if (typeof(_mrMap) === 'undefined') { _mrMap = {}; }");
_scope->invoke(init, 0, 0, 0, true);
// js function to run reduce on all keys
// redfunc = _scope->createFunction("for (var key in hashmap) { print('Key is ' + key); list = hashmap[key]; ret = reduce(key, list); print('Value is ' + ret); };");
_reduceAll = _scope->createFunction("var map = _mrMap; var list, ret; for (var key in map) { list = map[key]; if (list.length != 1) { ret = _reduce(key, list); map[key] = [ret]; ++_redCt; } } _dupCt = 0;");
_reduceAndEmit = _scope->createFunction("var map = _mrMap; var list, ret; for (var key in map) { list = map[key]; if (list.length == 1) { ret = list[0]; } else { ret = _reduce(key, list); ++_redCt; } emit(key, ret); }; delete _mrMap;");
_reduceAndFinalize = _scope->createFunction("var map = _mrMap; var list, ret; for (var key in map) { list = map[key]; if (list.length == 1) { if (!_doFinal) {continue;} ret = list[0]; } else { ret = _reduce(key, list); ++_redCt; }; if (_doFinal){ ret = _finalize(key, ret); } map[key] = ret; }");
_reduceAndFinalizeAndInsert = _scope->createFunction("var map = _mrMap; var list, ret; for (var key in map) { list = map[key]; if (list.length == 1) { ret = list[0]; } else { ret = _reduce(key, list); ++_redCt; }; if (_doFinal){ ret = _finalize(key, ret); } _nativeToTemp({_id: key, value: ret}); }");
}
void State::switchMode(bool jsMode) {
_jsMode = jsMode;
if (jsMode) {
// emit function that stays in JS
_scope->setFunction("emit", "function(key, value) { if (typeof(key) === 'object') { _bailFromJS(key, value); return; }; ++_emitCt; var map = _mrMap; var list = map[key]; if (!list) { ++_keyCt; list = []; map[key] = list; } else { ++_dupCt; } list.push(value); }");
_scope->injectNative("_bailFromJS", _bailFromJS, this);
}
else {
// emit now populates C++ map
_scope->injectNative( "emit" , fast_emit, this );
}
}
void State::bailFromJS() {
log(1) << "M/R: Switching from JS mode to mixed mode" << endl;
// reduce and reemit into c++
switchMode(false);
_scope->invoke(_reduceAndEmit, 0, 0, 0, true);
// need to get the real number emitted so far
_numEmits = _scope->getNumberInt("_emitCt");
_config.reducer->numReduces = _scope->getNumberInt("_redCt");
}
/**
* 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 );
}
BSONObj _nativeToTemp( const BSONObj& args, void* data ) {
State* state = (State*) data;
BSONObjIterator it(args);
state->insert(state->_config.tempLong, it.next().Obj());
return BSONObj();
}
// BSONObj _nativeToInc( const BSONObj& args, void* data ) {
// State* state = (State*) data;
// BSONObjIterator it(args);
// const BSONObj& obj = it.next().Obj();
// state->_insertToInc(const_cast<BSONObj&>(obj));
// return BSONObj();
// }
/**
* 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 (_jsMode) {
// apply the reduce within JS
if (_onDisk) {
_scope->injectNative("_nativeToTemp", _nativeToTemp, this);
_scope->invoke(_reduceAndFinalizeAndInsert, 0, 0, 0, true);
return;
}
else {
_scope->invoke(_reduceAndFinalize, 0, 0, 0, true);
return;
}
}
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());
try {
// reduce a finalize array
finalReduce( all );
}
catch (...) {
yield.relock();
cursor.release();
throw;
}
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() {
if (_jsMode) {
// in js mode the reduce is applied when writing to collection
return;
}
auto_ptr<InMemory> n( new InMemory() ); // for new data
long nSize = 0;
_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 );
}
}
else if ( all.size() > 1 ) {
// several values, reduce and add to map
BSONObj res = _config.reducer->reduce( all );
_add( n.get() , res , nSize );
}
}
// swap maps
_temp.reset( n.release() );
_size = nSize;
}
/**
* 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 );
}
void State::_add( InMemory* im, const BSONObj& a , long& size ) {
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 (_jsMode) {
// try to reduce if it is beneficial
int dupCt = _scope->getNumberInt("_dupCt");
int keyCt = _scope->getNumberInt("_keyCt");
if (keyCt > _config.jsMaxKeys) {
// too many keys for JS, switch to mixed
_bailFromJS(BSONObj(), this);
// then fall through to check map size
}
else if (dupCt > (keyCt * _config.reduceTriggerRatio)) {
// reduce now to lower mem usage
Timer t;
_scope->invoke(_reduceAll, 0, 0, 0, true);
log(1) << " MR - did reduceAll: keys=" << keyCt << " dups=" << dupCt << " newKeys=" << _scope->getNumberInt("_keyCt") << " time=" << t.millis() << "ms" << endl;
return;
}
}
if (_jsMode)
return;
if (_size > _config.maxInMemSize || _dupCount > (_temp->size() * _config.reduceTriggerRatio)) {
// attempt to reduce in memory map, if memory is too high or we have many duplicates
long oldSize = _size;
Timer t;
reduceInMemory();
log(1) << " MR - did reduceInMemory: size=" << oldSize << " dups=" << _dupCount << " newSize=" << _size << " time=" << t.millis() << "ms" << endl;
// if size is still high, or values are not reducing well, dump
if ( _onDisk && (_size > _config.maxInMemSize || _size > oldSize / 2) ) {
dumpToInc();
log(1) << " MR - dumping to db" << endl;
}
}
}
/**
* emit that will be called by js function
*/
BSONObj fast_emit( const BSONObj& args, void* data ) {
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 ) );
State* state = (State*) data;
if ( args.firstElement().type() == Undefined ) {
BSONObjBuilder b( args.objsize() );
b.appendNull( "" );
BSONObjIterator i( args );
i.next();
b.append( i.next() );
state->emit( b.obj() );
}
else {
state->emit( args );
}
return BSONObj();
}
/**
* function is called when we realize we cant use js mode for m/r on the 1st key
*/
BSONObj _bailFromJS( const BSONObj& args, void* data ) {
State* state = (State*) data;
state->bailFromJS();
// emit this particular key if there is one
if (!args.isEmpty()) {
fast_emit(args, data);
}
return BSONObj();
}
/**
* This class represents a map/reduce command executed on a single server
*/
class MapReduceCommand : public Command {
public:
MapReduceCommand() : Command("mapReduce", false, "mapreduce") {}
/* why !replset ?
bad things happen with --slave (i think because of this)
*/
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, int, string& errmsg, BSONObjBuilder& result, bool fromRepl ) {
Timer t;
Client& client = cc();
CurOp * op = client.curop();
Config config( dbname , cmd );
log(1) << "mr ns: " << config.ns << endl;
auto_ptr<ClientCursor> holdCursor;
ShardChunkManagerPtr chunkManager;
{
// Get chunk manager before we check our version, to make sure it doesn't increment
// in the meantime
if ( shardingState.needShardChunkManager( config.ns ) ) {
chunkManager = shardingState.getShardChunkManager( config.ns );
}
// Check our version immediately, to avoid migrations happening in the meantime while we do prep
readlock lock( config.ns );
Client::Context ctx( config.ns );
// Get a very basic cursor, prevents deletion of migrated data while we m/r
shared_ptr<Cursor> temp = NamespaceDetailsTransient::getCursor( config.ns.c_str(), BSONObj(), BSONObj() );
uassert( 15876, str::stream() << "could not create cursor over " << config.ns << " to hold data while prepping m/r", temp.get() );
holdCursor = auto_ptr<ClientCursor>( new ClientCursor( QueryOption_NoCursorTimeout , temp , config.ns.c_str() ) );
uassert( 15877, str::stream() << "could not create m/r holding client cursor over " << config.ns, holdCursor.get() );
}
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;
}
}
if (state.isOnDisk() && !client.getAuthenticationInfo()->isAuthorized(dbname)) {
errmsg = "read-only user cannot output mapReduce to collection, use inline instead";
return false;
}
try {
state.init();
state.prepTempCollection();
ProgressMeterHolder pm( op->setMessage( "m/r: (1/3) emit phase" , state.incomingDocuments() ) );
wassert( config.limit < 0x4000000 ); // see case on next line to 32 bit unsigned
long long mapTime = 0;
{
// We've got a cursor preventing migrations off, now re-establish our useful cursor
// Need lock and context to use it
readlock lock( config.ns );
// This context does no version check, safe b/c we checked earlier and have an
// open cursor
Client::Context ctx( config.ns, dbpath, true, false );
// obtain full cursor on data to apply mr to
shared_ptr<Cursor> temp = NamespaceDetailsTransient::getCursor( config.ns.c_str(), config.filter, config.sort );
uassert( 16052, str::stream() << "could not create cursor over " << config.ns << " for query : " << config.filter << " sort : " << config.sort, temp.get() );
auto_ptr<ClientCursor> cursor( new ClientCursor( QueryOption_NoCursorTimeout , temp , config.ns.c_str() ) );
uassert( 16053, str::stream() << "could not create client cursor over " << config.ns << " for query : " << config.filter << " sort : " << config.sort, cursor.get() );
// Cleanup our previous cursor
holdCursor.reset();
Timer mt;
// go through each doc
while ( cursor->ok() ) {
if ( ! cursor->currentMatches() ) {
cursor->advance();
continue;
}
// make sure we dont process duplicates in case data gets moved around during map
// TODO This won't actually help when data gets moved, it's to handle multikeys.
if ( cursor->currentIsDup() ) {
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 % 1000 == 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" );
Timer t;
// 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();
// final reduce
state.finalReduce( op , pm );
inReduce += t.micros();
countsBuilder.appendNumber( "reduce" , state.numReduces() );
timingBuilder.append( "reduceTime" , inReduce / 1000 );
timingBuilder.append( "mode" , state.jsMode() ? "js" : "mixed" );
long long finalCount = state.postProcessCollection(op, pm);
state.appendResults( result );
timingBuilder.append( "total" , t.millis() );
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;
}
}
catch( SendStaleConfigException& e ){
log() << "mr detected stale config, should retry" << causedBy(e) << endl;
throw e;
}
// TODO: The error handling code for queries is v. fragile,
// *requires* rethrow AssertionExceptions - should probably fix.
catch ( AssertionException& e ){
log() << "mr failed, removing collection" << causedBy(e) << endl;
throw e;
}
catch ( std::exception& e ){
log() << "mr failed, removing collection" << causedBy(e) << endl;
throw e;
}
catch ( ... ) {
log() << "mr failed for unknown reason, removing collection" << endl;
throw;
}
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, int, string& errmsg, BSONObjBuilder& result, bool) {
ShardedConnectionInfo::addHook();
// legacy name
string shardedOutputCollection = cmdObj["shardedOutputCollection"].valuestrsafe();
string inputNS = cmdObj["inputNS"].valuestrsafe();
if (inputNS.empty())
inputNS = dbname + "." + shardedOutputCollection;
Client& client = cc();
CurOp * op = client.curop();
Config config( dbname , cmdObj.firstElement().embeddedObjectUserCheck() );
State state(config);
state.init();
// no need for incremental collection because records are already sorted
config.incLong = config.tempLong;
BSONObj shardCounts = cmdObj["shardCounts"].embeddedObjectUserCheck();
BSONObj counts = cmdObj["counts"].embeddedObjectUserCheck();
ProgressMeterHolder pm( op->setMessage( "m/r: merge sort and reduce" ) );
set<ServerAndQuery> servers;
vector< auto_ptr<DBClientCursor> > shardCursors;
{
// parse per shard results
BSONObjIterator i( shardCounts );
while ( i.more() ) {
BSONElement e = i.next();
string shard = e.fieldName();
// BSONObj res = e.embeddedObjectUserCheck();
servers.insert( shard );
}
}
state.prepTempCollection();
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 );
}
// fetch result from other shards 1 chunk at a time
// it would be better to do just one big $or query, but then the sorting would not be efficient
string shardName = shardingState.getShardName();
DBConfigPtr confOut = grid.getDBConfig( dbname , false );
vector<ChunkPtr> chunks;
if ( confOut->isSharded(config.finalLong) ) {
ChunkManagerPtr cm = confOut->getChunkManager( config.finalLong );
const ChunkMap& chunkMap = cm->getChunkMap();
for ( ChunkMap::const_iterator it = chunkMap.begin(); it != chunkMap.end(); ++it ) {
ChunkPtr chunk = it->second;
if (chunk->getShard().getName() == shardName) chunks.push_back(chunk);
}
}
long long inputCount = 0;
unsigned int index = 0;
BSONObj query;
BSONArrayBuilder chunkSizes;
while (true) {
ChunkPtr chunk;
if (chunks.size() > 0) {
chunk = chunks[index];
BSONObjBuilder b;
b.appendAs(chunk->getMin().firstElement(), "$gte");
b.appendAs(chunk->getMax().firstElement(), "$lt");
query = BSON("_id" << b.obj());
// chunkSizes.append(min);
}
// reduce from each shard for a chunk
BSONObj sortKey = BSON( "_id" << 1 );
ParallelSortClusteredCursor cursor( servers , inputNS , Query( query ).sort( sortKey ) );
cursor.init();
int chunkSize = 0;
while ( cursor.more() || !values.empty() ) {
BSONObj t;
if (cursor.more()) {
t = cursor.next().getOwned();
++inputCount;
if ( values.size() == 0 ) {
values.push_back( t );
continue;
}
if ( t.woSortOrder( *(values.begin()) , sortKey ) == 0 ) {
values.push_back( t );
continue;
}
}
BSONObj res = config.reducer->finalReduce( values , config.finalizer.get());
chunkSize += res.objsize();
if (state.isOnDisk())
state.insertToInc(res);
else
state.emit(res);
values.clear();
if (!t.isEmpty())
values.push_back( t );
}
if (chunk) {
chunkSizes.append(chunk->getMin());
chunkSizes.append(chunkSize);
}
if (++index >= chunks.size())
break;
}
result.append( "chunkSizes" , chunkSizes.arr() );
long long outputCount = state.postProcessCollection(op, pm);
state.appendResults( result );
BSONObjBuilder countsB(32);
countsB.append("input", inputCount);
countsB.append("reduce", state.numReduces());
countsB.append("output", outputCount);
result.append( "counts" , countsB.obj() );
return 1;
}
} mapReduceFinishCommand;
}
}
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