SERVER-32645 Create a shim helper framework.

The `MONGO_DECLARE_SHIM`, `MONGO_DEFINE_SHIM`, and `MONGO_REGISTER_SHIM`
macros can be used to create specialized types which are customization
and auto-registration points for late-binding functions.  In some
sense they work like weak-symbols; however, they also are useful for
tracking dependencies upon shimmed-out implementations.

1 files changed, 36 insertions, 0 deletions

diff --git a/src/mongo/base/shim.cpp b/src/mongo/base/shim.cpp
new file mode 100644
index 00000000000..b5834086563
--- /dev/null
+++ b/src/mongo/base/shim.cpp
@@ -0,0 +1,36 @@
+/**
+ *    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.
+ */
+
+#include "mongo/base/shim.h"
+
+
+namespace mongo {
+namespace {
+MONGO_INITIALIZER_GROUP(ShimHooks, MONGO_NO_PREREQUISITES, ("default"));
+}  // namespace
+}  // namespace mongo