SERVER-32843 Allow multiple times in OpObservers

The OpObserverRegistry was introduced as an abstraction to allow
decoupling making data modifications from the side effects, which
need to happen as a result of these modifications, such as op log
writes, retryable writes, etc.

Some of the OpObserver's methods currently return the OpTime which
resulted from logging the operation to the replication oplog. In
addition, in certain cases, the OpTime resulting from an earlier
OpObserver might be needed by a later one, which is the case with
retryable writes.

In order to support these requirements, the OpObserver(s) chain
should have access to some common per-operation structure, where
runtime information could be persisted.

1 files changed, 41 insertions, 0 deletions

diff --git a/src/mongo/db/op_observer.cpp b/src/mongo/db/op_observer.cpp
new file mode 100644
index 00000000000..7e0532b2225
--- /dev/null
+++ b/src/mongo/db/op_observer.cpp
@@ -0,0 +1,41 @@
+/**
+ *    Copyright 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.
+ */
+
+#include "mongo/db/op_observer.h"
+
+#include "mongo/db/operation_context.h"
+namespace mongo {
+namespace {
+const auto getOpObserverTimes = OperationContext::declareDecoration<OpObserver::Times>();
+}  // namespace
+
+auto OpObserver::Times::get(OperationContext* const opCtx) -> Times& {
+    return getOpObserverTimes(opCtx);
+}
+
+}  // namespace mongo