SERVER-35024 atClusterTime incorrectly uses round_to_oldest option when opening transactions. Refactor WiredTigerBeginTxnBlock to use enum parameters with safe defaults.

1 files changed, 80 insertions, 0 deletions

diff --git a/src/mongo/db/storage/wiredtiger/wiredtiger_begin_transaction_block.h b/src/mongo/db/storage/wiredtiger/wiredtiger_begin_transaction_block.h
new file mode 100644
index 00000000000..c7010cf1e4b
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+++ b/src/mongo/db/storage/wiredtiger/wiredtiger_begin_transaction_block.h
@@ -0,0 +1,80 @@
+/**
+ *    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 <string>
+
+#include <wiredtiger.h>
+
+#include "mongo/base/status.h"
+#include "mongo/bson/timestamp.h"
+
+namespace mongo {
+
+/**
+ * When constructed, this object begins a WiredTiger transaction on the provided session. The
+ * transaction will be rolled back if dismissRollback is not called before the object is destructed.
+ */
+class WiredTigerBeginTxnBlock {
+public:
+    // Whether or not to ignore prepared transactions.
+    enum class IgnorePrepared {
+        kNoIgnore,  // Do not ignore prepared transactions and return prepare conflicts.
+        kIgnore     // Ignore prepared transactions and show prepared, but uncommitted data.
+    };
+
+    // Whether or not to round up to the oldest timestamp when the read timestamp is behind it.
+    enum class RoundToOldest {
+        kNoRound,  // Do not round to the oldest timestamp. BadValue error may be returned.
+        kRound     // Round the read timestamp up to the oldest timestamp when it is behind.
+    };
+
+    WiredTigerBeginTxnBlock(WT_SESSION* session,
+                            IgnorePrepared ignorePrepared = IgnorePrepared::kNoIgnore);
+    WiredTigerBeginTxnBlock(WT_SESSION* session, const char* config);
+    ~WiredTigerBeginTxnBlock();
+
+    /**
+     * Sets the read timestamp on the opened transaction. Cannot be called after a call to done().
+     */
+    Status setTimestamp(Timestamp, RoundToOldest roundToOldest = RoundToOldest::kNoRound);
+
+    /**
+     * End the begin transaction block. Must be called to ensure the opened transaction
+     * is not be rolled back.
+     */
+    void done();
+
+private:
+    WT_SESSION* _session;
+    bool _rollback = false;
+};
+
+}  // namespace mongo