SERVER-13674: Refactor CachedPlanRunner and MultiPlanRunner as stages

1 files changed, 94 insertions, 0 deletions

diff --git a/src/mongo/db/exec/cached_plan.h b/src/mongo/db/exec/cached_plan.h
new file mode 100644
index 00000000000..7bdd16f4f6a
--- /dev/null
+++ b/src/mongo/db/exec/cached_plan.h
@@ -0,0 +1,94 @@
+/**
+ *    Copyright (C) 2014 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/diskloc.h"
+#include "mongo/db/jsobj.h"
+#include "mongo/db/exec/plan_stage.h"
+#include "mongo/db/exec/working_set.h"
+#include "mongo/db/query/canonical_query.h"
+
+namespace mongo {
+
+    /**
+     * This stage outputs its mainChild, and possibly its backup child
+     * and also updates the cache.
+     *
+     * Preconditions: Valid DiskLoc.
+     *
+     */
+    class CachedPlanStage : public PlanStage {
+    public:
+        CachedPlanStage(const Collection* collection,
+                        CanonicalQuery* cq,
+                        PlanStage* mainChild,
+                        PlanStage* backupChild=NULL);
+
+        virtual ~CachedPlanStage();
+
+        virtual bool isEOF();
+
+        virtual StageState work(WorkingSetID* out);
+
+        virtual void prepareToYield();
+        virtual void recoverFromYield();
+        virtual void invalidate(const DiskLoc& dl, InvalidationType type);
+
+        virtual PlanStageStats* getStats();
+
+    private:
+        PlanStage* getActiveChild() const;
+        void updateCache();
+
+        // not owned
+        const Collection* _collection;
+
+        // not owned
+	CanonicalQuery* _canonicalQuery;
+
+        // owned by us
+        boost::scoped_ptr<PlanStage> _mainChildPlan;
+        boost::scoped_ptr<PlanStage> _backupChildPlan;
+
+        // True if the main plan errors before producing results
+        // and if a backup plan is available (can happen with blocking sorts)
+        bool _usingBackupChild;
+
+        // True if the childPlan has produced results yet.
+        bool _alreadyProduced;
+
+        // Have we updated the cache with our plan stats yet?
+        bool _updatedCache;
+
+        // Stats
+        CommonStats _commonStats;
+        CachedPlanStats _specificStats;
+    };
+
+}  // namespace mongo