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/**
* Copyright 2011 (c) 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 "mongo/pch.h"
#include "mongo/db/pipeline/document_source.h"
namespace mongo {
const char DocumentSourceOut::outName[] = "$out";
DocumentSourceOut::~DocumentSourceOut() {
DESTRUCTOR_GUARD(
// Make sure we drop the temp collection if anything goes wrong. Errors are ignored
// here because nothing can be done about them. Additionally, if this fails and the
// collection is left behind, it will be cleaned up next time the server is started.
if (_mongod && _tempNs.size())
_mongod->directClient()->dropCollection(_tempNs.ns());
)
}
const char *DocumentSourceOut::getSourceName() const {
return outName;
}
static AtomicUInt32 aggOutCounter;
void DocumentSourceOut::prepTempCollection() {
verify(_mongod);
verify(_tempNs.size() == 0);
DBClientBase* conn = _mongod->directClient();
// Fail early by checking before we do any work.
uassert(17017, str::stream() << "namespace '" << _outputNs.ns()
<< "' is sharded so it can't be used for $out'",
!_mongod->isSharded(_outputNs));
_tempNs = StringData(str::stream() << _outputNs.db()
<< ".tmp.agg_out."
<< aggOutCounter.addAndFetch(1)
);
{
BSONObj info;
bool ok =conn->runCommand(_outputNs.db().toString(),
BSON("create" << _tempNs.coll() << "temp" << true),
info);
uassert(16994, str::stream() << "failed to create temporary $out collection '"
<< _tempNs.ns() << "': " << info.toString(),
ok);
}
// copy indexes on _outputNs to _tempNs
scoped_ptr<DBClientCursor> indexes(conn->getIndexes(_outputNs));
while (indexes->more()) {
MutableDocument index(Document(indexes->nextSafe()));
index.remove("_id"); // indexes shouldn't have _ids but some existing ones do
index["ns"] = Value(_tempNs.ns());
BSONObj indexBson = index.freeze().toBson();
conn->insert(_tempNs.getSystemIndexesCollection(), indexBson);
BSONObj err = conn->getLastErrorDetailed();
uassert(16995, str::stream() << "copying index for $out failed."
<< " index: " << indexBson
<< " error: " << err,
DBClientWithCommands::getLastErrorString(err).empty());
}
}
void DocumentSourceOut::spill(DBClientBase* conn, const vector<BSONObj>& toInsert) {
conn->insert(_tempNs.ns(), toInsert);
BSONObj err = conn->getLastErrorDetailed();
uassert(16996, str::stream() << "insert for $out failed: " << err,
DBClientWithCommands::getLastErrorString(err).empty());
}
boost::optional<Document> DocumentSourceOut::getNext() {
pExpCtx->checkForInterrupt();
// make sure we only write out once
if (_done)
return boost::none;
_done = true;
verify(_mongod);
DBClientBase* conn = _mongod->directClient();
prepTempCollection();
verify(_tempNs.size() != 0);
vector<BSONObj> bufferedObjects;
int bufferedBytes = 0;
while (boost::optional<Document> next = pSource->getNext()) {
BSONObj toInsert = next->toBson();
bufferedBytes += toInsert.objsize();
if (!bufferedObjects.empty() && bufferedBytes > BSONObjMaxUserSize) {
spill(conn, bufferedObjects);
bufferedObjects.clear();
bufferedBytes = toInsert.objsize();
}
bufferedObjects.push_back(toInsert);
}
if (!bufferedObjects.empty())
spill(conn, bufferedObjects);
// Checking again to make sure we didn't become sharded while running.
uassert(17018, str::stream() << "namespace '" << _outputNs.ns()
<< "' became sharded so it can't be used for $out'",
!_mongod->isSharded(_outputNs));
BSONObj rename = BSON("renameCollection" << _tempNs.ns()
<< "to" << _outputNs.ns()
<< "dropTarget" << true
);
BSONObj info;
bool ok = conn->runCommand("admin", rename, info);
uassert(16997, str::stream() << "renameCollection for $out failed: " << info,
ok);
// We don't need to drop the temp collection in our destructor if the rename succeeded.
_tempNs = NamespaceString("");
// This "DocumentSource" doesn't produce output documents. This can change in the future
// if we support using $out in "tee" mode.
return boost::none;
}
DocumentSourceOut::DocumentSourceOut(const NamespaceString& outputNs,
const intrusive_ptr<ExpressionContext>& pExpCtx)
: SplittableDocumentSource(pExpCtx)
, _done(false)
, _tempNs("") // filled in by prepTempCollection
, _outputNs(outputNs)
{}
intrusive_ptr<DocumentSource> DocumentSourceOut::createFromBson(
BSONElement *pBsonElement,
const intrusive_ptr<ExpressionContext> &pExpCtx) {
uassert(16990, str::stream() << "$out only supports a string argument, not "
<< typeName(pBsonElement->type()),
pBsonElement->type() == String);
NamespaceString outputNs(pExpCtx->ns.db().toString() + '.' + pBsonElement->str());
return new DocumentSourceOut(outputNs, pExpCtx);
}
Value DocumentSourceOut::serialize(bool explain) const {
massert(17000, "$out shouldn't have different db than input",
_outputNs.db() == pExpCtx->ns.db());
return Value(DOC(getSourceName() << _outputNs.coll()));
}
}
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