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/**
* Copyright (C) 2017 MongoDB 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/>.
*
* As a special exception, the copyright holders give permission to link the
* code of portions of this program with the OpenSSL library under certain
* conditions as described in each individual source file and distribute
* linked combinations including the program with the OpenSSL library. You
* must comply with the GNU Affero General Public License in all respects for
* all of the code used other than as permitted herein. If you modify file(s)
* with this exception, you may extend this exception to your version of the
* file(s), but you are not obligated to do so. If you do not wish to do so,
* delete this exception statement from your version. If you delete this
* exception statement from all source files in the program, then also delete
* it in the license file.
*/
#define MONGO_LOG_DEFAULT_COMPONENT ::mongo::logger::LogComponent::kCommand
#include "mongo/db/pipeline/document_source_change_notification.h"
#include "mongo/db/pipeline/document_source_limit.h"
#include "mongo/db/pipeline/document_source_match.h"
#include "mongo/db/pipeline/document_source_sort.h"
#include "mongo/db/pipeline/expression.h"
#include "mongo/db/pipeline/lite_parsed_document_source.h"
#include "mongo/util/log.h"
namespace mongo {
using boost::intrusive_ptr;
using std::vector;
using std::string;
constexpr StringData kNamespaceField = "ns"_sd;
constexpr StringData kTimestmapField = "ts"_sd;
constexpr StringData kOpTypeField = "op"_sd;
constexpr StringData kOField = "o"_sd;
constexpr StringData kIdField = "_id"_sd;
REGISTER_MULTI_STAGE_ALIAS(changeNotification,
DocumentSourceChangeNotification::LiteParsed::parse,
DocumentSourceChangeNotification::createFromBson);
BSONObj DocumentSourceChangeNotification::buildMatch(BSONElement elem, const NamespaceString& nss) {
auto target = nss.ns();
// 1) Supported commands that have the target db namespace (e.g. test.$cmd) in "ns" field.
auto dropDatabase = BSON("o.dropDatabase" << 1);
auto dropCollection = BSON("o.drop" << nss.coll());
auto renameCollection = BSON("o.renameCollection" << target);
// Commands that are on target db and one of the above.
auto commandsOnTargetDb =
BSON("ns" << nss.getCommandNS().ns() << "$or"
<< BSON_ARRAY(dropDatabase << dropCollection << renameCollection));
// 2) Supported commands that have arbitrary db namespaces in "ns" field.
auto renameDropTarget = BSON("o.to" << target);
// 3) All supported commands that are either (1) or (2).
auto commandMatch = BSON("op"
<< "c"
<< "$or"
<< BSON_ARRAY(commandsOnTargetDb << renameDropTarget));
// 4) Normal CRUD ops on the target collection.
auto opMatch = BSON("ns" << target);
// Match oplog entries after "start" and are either (3) supported commands or (4) CRUD ops.
auto matchFilter =
BSON("ts" << GT << Timestamp() << "$or" << BSON_ARRAY(opMatch << commandMatch));
return BSON("$match" << matchFilter);
}
vector<intrusive_ptr<DocumentSource>> DocumentSourceChangeNotification::createFromBson(
BSONElement elem, const intrusive_ptr<ExpressionContext>& expCtx) {
// TODO: Add sharding support here (SERVER-29141).
uassert(40470,
"The $changeNotification stage is not supported on sharded systems.",
!expCtx->inRouter);
uassert(40471,
"Only default collation is allowed when using a $changeNotification stage.",
!expCtx->getCollator());
BSONObj matchObj = buildMatch(elem, expCtx->ns);
BSONObj sortObj = BSON("$sort" << BSON("ts" << -1));
auto matchSource = DocumentSourceMatch::createFromBson(matchObj.firstElement(), expCtx);
auto sortSource = DocumentSourceSort::createFromBson(sortObj.firstElement(), expCtx);
auto transformSource = createTransformationStage(expCtx);
return {matchSource, sortSource, transformSource};
}
intrusive_ptr<DocumentSource> DocumentSourceChangeNotification::createTransformationStage(
const intrusive_ptr<ExpressionContext>& expCtx) {
return intrusive_ptr<DocumentSource>(new DocumentSourceSingleDocumentTransformation(
expCtx, stdx::make_unique<Transformation>(), "$changeNotification"));
}
namespace {
void checkValueType(Value v, StringData filedName, BSONType expectedType) {
uassert(40532,
str::stream() << "Oplog entry field \"" << filedName << "\" should be "
<< typeName(expectedType)
<< ", found: "
<< typeName(v.getType()),
(v.getType() == expectedType));
}
} // namespace
Document DocumentSourceChangeNotification::Transformation::applyTransformation(
const Document& input) {
MutableDocument doc;
// Extract the fields we need.
checkValueType(input[kOpTypeField], kOpTypeField, BSONType::String);
string op = input[kOpTypeField].getString();
Value ts = input[kTimestmapField];
Value ns = input[kNamespaceField];
checkValueType(ns, kNamespaceField, BSONType::String);
NamespaceString nss(ns.getString());
Value id = input.getNestedField("o._id");
// Non-replace updates have the _id in field "o2".
Value documentId = id.missing() ? input.getNestedField("o2._id") : id;
string operationType;
Value newDocument;
Value updateDescription;
// Deal with CRUD operations and commands.
if (op == "i") {
operationType = "insert";
newDocument = input[kOField];
} else if (op == "d") {
operationType = "delete";
} else if (op == "u") {
if (id.missing()) {
operationType = "update";
checkValueType(input[kOField], kOField, BSONType::Object);
Document o = input[kOField].getDocument();
Value updatedFields = o["$set"];
Value removedFields = o["$unset"];
// Extract the field names of $unset document.
vector<Value> removedFieldsVector;
if (removedFields.getType() == BSONType::Object) {
auto iter = removedFields.getDocument().fieldIterator();
while (iter.more()) {
removedFieldsVector.push_back(Value(iter.next().first));
}
}
updateDescription = Value(Document{
{"updatedFields", updatedFields.missing() ? Value(Document()) : updatedFields},
{"removedFields", removedFieldsVector}});
} else {
operationType = "replace";
newDocument = input[kOField];
}
} else if (op == "c") {
operationType = "invalidate";
// Make sure the result doesn't have a document id.
documentId = Value();
}
// Construct the result document. If document id is missing, it will not appear in the output.
doc.addField(
kIdField,
Value(Document{{kTimestmapField, ts}, {kNamespaceField, ns}, {kIdField, documentId}}));
doc.addField("operationType", Value(operationType));
// "invalidate" entry has fewer fields.
if (op == "c") {
return doc.freeze();
}
// Add fields for normal operations.
doc.addField(kNamespaceField, Value(Document{{"db", nss.db()}, {"coll", nss.coll()}}));
doc.addField("documentKey", Value(Document{{kIdField, documentId}}));
// If newDocument or updateDescription is missing, it will not be serialized.
doc.addField("newDocument", newDocument);
doc.addField("updateDescription", updateDescription);
return doc.freeze();
}
Document DocumentSourceChangeNotification::Transformation::serializeStageOptions(
boost::optional<ExplainOptions::Verbosity> explain) const {
return Document();
}
DocumentSource::GetDepsReturn DocumentSourceChangeNotification::Transformation::addDependencies(
DepsTracker* deps) const {
deps->fields.insert(kOpTypeField.toString());
deps->fields.insert(kTimestmapField.toString());
deps->fields.insert(kNamespaceField.toString());
deps->fields.insert(kOField.toString());
deps->fields.insert("o2");
return DocumentSource::GetDepsReturn::EXHAUSTIVE_ALL;
}
DocumentSource::GetModPathsReturn
DocumentSourceChangeNotification::Transformation::getModifiedPaths() const {
// All paths are modified.
return {DocumentSource::GetModPathsReturn::Type::kAllPaths, std::set<string>{}, {}};
}
} // namespace mongo
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