migrate hash index to new index api SERVER-8791 SERVER-9164

1 files changed, 69 insertions, 0 deletions

diff --git a/src/mongo/db/index/hash_access_method.h b/src/mongo/db/index/hash_access_method.h
new file mode 100644
index 00000000000..9fe10dc463c
--- /dev/null
+++ b/src/mongo/db/index/hash_access_method.h
@@ -0,0 +1,69 @@
+/**
+*    Copyright (C) 2013 10gen 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/>.
+*/
+
+#pragma once
+
+#include <string>
+
+#include "mongo/base/status.h"
+#include "mongo/db/hasher.h"  // For HashSeed.
+#include "mongo/db/index/index_descriptor.h"
+#include "mongo/db/index/btree_access_method_internal.h"
+#include "mongo/db/jsobj.h"
+
+namespace mongo {
+
+    /**
+     * This is the access method for "hashed" indices.
+     */
+    class HashAccessMethod : public BtreeBasedAccessMethod {
+    public:
+        using BtreeBasedAccessMethod::_descriptor;
+        using BtreeBasedAccessMethod::_ordering;
+
+        HashAccessMethod(IndexDescriptor* descriptor);
+
+        virtual Status newCursor(IndexCursor** out);
+
+        // This is a NO-OP.
+        virtual Status setOptions(const CursorOptions& options) {
+            return Status::OK();
+        }
+
+        /**
+         * Hashing function used by both this class and the cursors we create.
+         */
+        static long long int makeSingleKey(const BSONElement& e, HashSeed seed, int v);
+
+    private:
+        virtual void getKeys(const BSONObj& obj, BSONObjSet* keys);
+
+        // Only one of our fields is hashed.  This is the field name for it.
+        string _hashedField;
+
+        // _seed defaults to zero.
+        HashSeed _seed;
+
+        // _hashVersion defaults to zero.
+        int _hashVersion;
+
+        // What key do we insert when the field is missing?
+        // TODO: fix migration code to do the right thing.
+        // TODO: see http://codereview.10gen.com/9497028/patch/3001/4007
+        BSONObj _missingKey;
+    };
+
+}  // namespace mongo