SERVER-37444 Added RequiresCollectionStage and use for COLLSCAN.

This is a pure refactor with no user-facing changes. It is
the first step in making PlanExecutors check their own
validity during yield recovery, rather than requiring the
invalidating actor to issue a kill notification.

1 files changed, 57 insertions, 0 deletions

diff --git a/src/mongo/db/exec/requires_collection_stage.cpp b/src/mongo/db/exec/requires_collection_stage.cpp
new file mode 100644
index 00000000000..106767eed73
--- /dev/null
+++ b/src/mongo/db/exec/requires_collection_stage.cpp
@@ -0,0 +1,57 @@
+/**
+ *    Copyright (C) 2018-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.
+ */
+
+#include "mongo/platform/basic.h"
+
+#include "mongo/db/exec/requires_collection_stage.h"
+
+#include "mongo/db/catalog/uuid_catalog.h"
+
+namespace mongo {
+
+void RequiresCollectionStage::doSaveState() {
+    // A stage may not access storage while in a saved state.
+    _collection = nullptr;
+
+    saveState(RequiresCollTag{});
+}
+
+void RequiresCollectionStage::doRestoreState() {
+    invariant(!_collection);
+
+    const UUIDCatalog& catalog = UUIDCatalog::get(getOpCtx());
+    _collection = catalog.lookupCollectionByUUID(_collectionUUID);
+    uassert(ErrorCodes::QueryPlanKilled,
+            str::stream() << "UUID " << _collectionUUID << " no longer exists.",
+            _collection);
+
+    restoreState(RequiresCollTag{});
+}
+
+}  // namespace mongo