SERVER-63159 Implement the $_internalApplyOplogUpdate aggregation stage

1 files changed, 103 insertions, 0 deletions

diff --git a/src/mongo/db/pipeline/document_source_internal_apply_oplog_update.cpp b/src/mongo/db/pipeline/document_source_internal_apply_oplog_update.cpp
new file mode 100644
index 00000000000..51b0dee8ac1
--- /dev/null
+++ b/src/mongo/db/pipeline/document_source_internal_apply_oplog_update.cpp
@@ -0,0 +1,103 @@
+/**
+ *    Copyright (C) 2022-present MongoDB, Inc.
+ *
+ *    This program is free software: you can redistribute it and/or modify
+ *    it under the terms of the Server Side Public License, version 1,
+ *    as published by MongoDB, Inc.
+ *
+ *    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
+ *    Server Side Public License for more details.
+ *
+ *    You should have received a copy of the Server Side Public License
+ *    along with this program. If not, see
+ *    <http://www.mongodb.com/licensing/server-side-public-license>.
+ *
+ *    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 Server Side 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_LOGV2_DEFAULT_COMPONENT ::mongo::logv2::LogComponent::kQuery
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/db/pipeline/document_source_internal_apply_oplog_update.h"
+
+#include <boost/optional.hpp>
+#include <boost/smart_ptr/intrusive_ptr.hpp>
+
+#include "mongo/db/exec/add_fields_projection_executor.h"
+#include "mongo/db/exec/document_value/document.h"
+#include "mongo/db/ops/write_ops_parsers.h"
+#include "mongo/db/pipeline/document_source_internal_apply_oplog_update_gen.h"
+#include "mongo/db/pipeline/lite_parsed_document_source.h"
+#include "mongo/db/update/update_driver.h"
+
+namespace mongo {
+
+REGISTER_DOCUMENT_SOURCE(_internalApplyOplogUpdate,
+                         LiteParsedDocumentSourceDefault::parse,
+                         DocumentSourceInternalApplyOplogUpdate::createFromBson,
+                         AllowedWithApiStrict::kNeverInVersion1);
+
+boost::intrusive_ptr<DocumentSource> DocumentSourceInternalApplyOplogUpdate::createFromBson(
+    BSONElement elem, const boost::intrusive_ptr<ExpressionContext>& pExpCtx) {
+    uassert(6315901,
+            str::stream() << "Argument to " << kStageName
+                          << " stage must be an object, but found type: " << typeName(elem.type()),
+            elem.type() == BSONType::Object);
+
+    auto spec = InternalApplyOplogUpdateSpec::parse(IDLParserErrorContext(kStageName),
+                                                    elem.embeddedObject());
+
+    return new DocumentSourceInternalApplyOplogUpdate(pExpCtx, spec.getOplogUpdate());
+}
+
+DocumentSourceInternalApplyOplogUpdate::DocumentSourceInternalApplyOplogUpdate(
+    const boost::intrusive_ptr<ExpressionContext>& pExpCtx, const BSONObj& oplogUpdate)
+    : DocumentSource(kStageName, pExpCtx),
+      _oplogUpdate(std::move(oplogUpdate)),
+      _updateDriver(pExpCtx) {
+    // Parse the raw oplog update description.
+    const auto updateMod = write_ops::UpdateModification::parseFromOplogEntry(
+        _oplogUpdate, {true /* mustCheckExistenceForInsertOperations */});
+
+    // UpdateDriver only expects to apply a diff in the context of oplog application.
+    _updateDriver.setFromOplogApplication(true);
+    _updateDriver.parse(updateMod, {});
+}
+
+DocumentSource::GetNextResult DocumentSourceInternalApplyOplogUpdate::doGetNext() {
+    auto next = pSource->getNext();
+    if (!next.isAdvanced()) {
+        return next;
+    }
+
+    // Use _updateDriver to apply the update to the document.
+    mutablebson::Document doc(next.getDocument().toBson());
+    uassertStatusOK(_updateDriver.update(pExpCtx->opCtx,
+                                         StringData(),
+                                         &doc,
+                                         false /* validateForStorage */,
+                                         FieldRefSet(),
+                                         false /* isInsert */));
+
+    return Document(doc.getObject());
+}
+
+Value DocumentSourceInternalApplyOplogUpdate::serialize(
+    boost::optional<ExplainOptions::Verbosity> explain) const {
+    return Value(Document{{kStageName, Document{{kOplogUpdateFieldName, _oplogUpdate}}}});
+}
+
+}  // namespace mongo