SERVER-63159 Implement the $_internalApplyOplogUpdate aggregation stage

1 files changed, 92 insertions, 0 deletions

diff --git a/src/mongo/db/pipeline/document_source_internal_apply_oplog_update.h b/src/mongo/db/pipeline/document_source_internal_apply_oplog_update.h
new file mode 100644
index 00000000000..b4801181bd7
--- /dev/null
+++ b/src/mongo/db/pipeline/document_source_internal_apply_oplog_update.h
@@ -0,0 +1,92 @@
+/**
+ *    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.
+ */
+
+#pragma once
+
+#include "mongo/db/pipeline/document_source.h"
+#include "mongo/db/pipeline/document_source_single_document_transformation.h"
+#include "mongo/db/update/update_driver.h"
+
+namespace mongo {
+
+/**
+ * This is an internal stage that takes an oplog update description and applies the update to the
+ * input Document.
+ */
+class DocumentSourceInternalApplyOplogUpdate final : public DocumentSource {
+public:
+    static constexpr StringData kStageName = "$_internalApplyOplogUpdate"_sd;
+    static constexpr StringData kOplogUpdateFieldName = "oplogUpdate"_sd;
+
+    static boost::intrusive_ptr<DocumentSource> createFromBson(
+        BSONElement elem, const boost::intrusive_ptr<ExpressionContext>& pExpCtx);
+
+    DocumentSourceInternalApplyOplogUpdate(const boost::intrusive_ptr<ExpressionContext>& pExpCtx,
+                                           const BSONObj& oplogUpdate);
+
+    const char* getSourceName() const override {
+        return kStageName.rawData();
+    }
+
+    StageConstraints constraints(Pipeline::SplitState pipeState) const override {
+        StageConstraints constraints(StreamType::kStreaming,
+                                     PositionRequirement::kNone,
+                                     HostTypeRequirement::kNone,
+                                     DiskUseRequirement::kNoDiskUse,
+                                     FacetRequirement::kNotAllowed,
+                                     TransactionRequirement::kAllowed,
+                                     LookupRequirement::kNotAllowed,
+                                     UnionRequirement::kNotAllowed,
+                                     ChangeStreamRequirement::kDenylist);
+        constraints.canSwapWithMatch = false;
+        constraints.canSwapWithSkippingOrLimitingStage = true;
+        constraints.isAllowedWithinUpdatePipeline = true;
+        constraints.isIndependentOfAnyCollection = false;
+        return constraints;
+    }
+
+    DocumentSource::GetModPathsReturn getModifiedPaths() const final {
+        return {GetModPathsReturn::Type::kAllPaths, {}, {}};
+    }
+
+    boost::optional<DistributedPlanLogic> distributedPlanLogic() override {
+        return boost::none;
+    }
+
+private:
+    Value serialize(
+        boost::optional<ExplainOptions::Verbosity> explain = boost::none) const override;
+
+    GetNextResult doGetNext() override;
+
+    BSONObj _oplogUpdate;
+    UpdateDriver _updateDriver;
+};
+
+}  // namespace mongo