// This is the only iteration method that should ever be called so it does all of the work.
bool DocumentSourceOut::eof() {
// make sure we only write out once
if (_done)
return true;
_done = true;
verify(_conn);
prepTempCollection();
verify(_tempNs.size() != 0);
for (bool haveNext = !pSource->eof(); haveNext; haveNext = pSource->advance()) {
BSONObj toInsert = pSource->getCurrent().toBson();
_conn->insert(_tempNs.ns(), toInsert);
BSONObj err = _conn->getLastErrorDetailed();
uassert(16996, str::stream() << "insert for $out failed: " << err,
DBClientWithCommands::getLastErrorString(err).empty());
}
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 true;
}
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;
}