SERVER-16101 replace DeleteExecutor with ParsedDelete

1 files changed, 109 insertions, 0 deletions

diff --git a/src/mongo/db/ops/parsed_delete.h b/src/mongo/db/ops/parsed_delete.h
new file mode 100644
index 00000000000..c117db28cb7
--- /dev/null
+++ b/src/mongo/db/ops/parsed_delete.h
@@ -0,0 +1,109 @@
+/**
+ *    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/base/disallow_copying.h"
+#include "mongo/base/status.h"
+#include "mongo/db/query/plan_executor.h"
+
+namespace mongo {
+
+    class CanonicalQuery;
+    class Database;
+    class DeleteRequest;
+    class OperationContext;
+
+    /**
+     * This class takes a pointer to a DeleteRequest, and converts that request into a parsed form
+     * via the parseRequest() method. A ParsedDelete can then be used to retrieve a PlanExecutor
+     * capable of executing the delete.
+     *
+     * A delete request is parsed to a CanonicalQuery, so this class is a thin, delete-specific
+     * wrapper around canonicalization.
+     *
+     * No locks need to be held during parsing.
+     */
+    class ParsedDelete {
+        MONGO_DISALLOW_COPYING(ParsedDelete);
+    public:
+        /**
+         * Constructs a parsed delete.
+         *
+         * The object pointed to by "request" must stay in scope for the life of the constructed
+         * ParsedDelete.
+         */
+        ParsedDelete(OperationContext* txn, const DeleteRequest* request);
+
+        /**
+         * Parses the delete request to a canonical query. On success, the parsed delete can be
+         * used to create a PlanExecutor capable of executing this delete.
+         */
+        Status parseRequest();
+
+        /**
+         * As an optimization, we do not create a canonical query if the predicate is a simple
+         * _id equality. This method can be used to force full parsing to a canonical query,
+         * as a fallback if the idhack path is not available (e.g. no _id index).
+         */
+        Status parseQueryToCQ();
+
+        /**
+         * Get the raw request.
+         */
+        const DeleteRequest* getRequest() const;
+
+        /**
+         * Is this delete allowed to yield?
+         */
+        bool canYield() const;
+
+        /**
+         * As an optimization, we don't create a canonical query for updates with simple _id
+         * queries. Use this method to determine whether or not we actually parsed the query.
+         */
+        bool hasParsedQuery() const;
+
+        /**
+         * Releases ownership of the canonical query to the caller.
+         */
+        CanonicalQuery* releaseParsedQuery();
+
+    private:
+        // Transactional context.  Not owned by us.
+        OperationContext* _txn;
+
+        // Unowned pointer to the request object that this executor will process.
+        const DeleteRequest* const _request;
+
+        // Parsed query object, or NULL if the query proves to be an id hack query.
+        std::auto_ptr<CanonicalQuery> _canonicalQuery;
+
+    };
+
+}  // namespace mongo