1 files changed, 82 insertions, 0 deletions
diff --git a/src/mongo/db/pipeline/document_source_check_invalidate.h b/src/mongo/db/pipeline/document_source_check_invalidate.h
new file mode 100644
index 00000000000..18e51524709
--- /dev/null
+++ b/src/mongo/db/pipeline/document_source_check_invalidate.h
@@ -0,0 +1,82 @@
+/**
+ * Copyright (C) 2018 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.
+ */
+
+#pragma once
+
+#include "mongo/db/pipeline/document_source.h"
+
+namespace mongo {
+
+/**
+ * This stage is used internally for change stream notifications to artifically generate an
+ * "invalidate" entry for commands that should invalidate the change stream (e.g. collection drop
+ * for a single-collection change stream). It is not intended to be created by the user.
+ */
+class DocumentSourceCheckInvalidate final : public DocumentSource {
+public:
+    GetNextResult getNext() final;
+
+    const char* getSourceName() const final {
+        // This is used in error reporting.
+        return "$_checkInvalidate";
+    }
+
+    StageConstraints constraints(Pipeline::SplitState pipeState) const final {
+        return {StreamType::kStreaming,
+                PositionRequirement::kNone,
+                HostTypeRequirement::kNone,
+                DiskUseRequirement::kNoDiskUse,
+                FacetRequirement::kNotAllowed,
+                TransactionRequirement::kNotAllowed,
+                ChangeStreamRequirement::kChangeStreamStage};
+    }
+
+    Value serialize(boost::optional<ExplainOptions::Verbosity> explain = boost::none) const final {
+        // This stage is created by the DocumentSourceChangeStream stage, so serializing it here
+        // would result in it being created twice.
+        return Value();
+    }
+
+    static boost::intrusive_ptr<DocumentSourceCheckInvalidate> create(
+        const boost::intrusive_ptr<ExpressionContext>& expCtx, bool ignoreFirstInvalidate) {
+        return new DocumentSourceCheckInvalidate(expCtx, ignoreFirstInvalidate);
+    }
+
+private:
+    /**
+     * Use the create static method to create a DocumentSourceCheckInvalidate.
+     */
+    DocumentSourceCheckInvalidate(const boost::intrusive_ptr<ExpressionContext>& expCtx,
+                                  bool ignoreFirstInvalidate)
+        : DocumentSource(expCtx), _ignoreFirstInvalidate(ignoreFirstInvalidate) {}
+
+    boost::optional<Document> _queuedInvalidate;
+    bool _ignoreFirstInvalidate;
+};
+
+}  // namespace mongo